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FAILED: patch "[PATCH] staging: rtl8723bs: Avoid memset() in aes_cipher() and" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x a55bc4ffc06d8c965a7d6f0a01ed0ed41380df28 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063055-overfed-dispute-71ba@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From a55bc4ffc06d8c965a7d6f0a01ed0ed41380df28 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor <nathan(a)kernel.org> Date: Mon, 9 Jun 2025 14:13:14 -0700 Subject: [PATCH] staging: rtl8723bs: Avoid memset() in aes_cipher() and aes_decipher() After commit 6f110a5e4f99 ("Disable SLUB_TINY for build testing"), which causes CONFIG_KASAN to be enabled in allmodconfig again, arm64 allmodconfig builds with older versions of clang (15 through 17) show an instance of -Wframe-larger-than (which breaks the build with CONFIG_WERROR=y): drivers/staging/rtl8723bs/core/rtw_security.c:1287:5: error: stack frame size (2208) exceeds limit (2048) in 'rtw_aes_decrypt' [-Werror,-Wframe-larger-than] 1287 | u32 rtw_aes_decrypt(struct adapter *padapter, u8 *precvframe) | ^ This comes from aes_decipher() being inlined in rtw_aes_decrypt(). Running the same build with CONFIG_FRAME_WARN=128 shows aes_cipher() also uses a decent amount of stack, just under the limit of 2048: drivers/staging/rtl8723bs/core/rtw_security.c:864:19: warning: stack frame size (1952) exceeds limit (128) in 'aes_cipher' [-Wframe-larger-than] 864 | static signed int aes_cipher(u8 *key, uint hdrlen, | ^ -Rpass-analysis=stack-frame-layout only shows one large structure on the stack, which is the ctx variable inlined from aes128k128d(). A good number of the other variables come from the additional checks of fortified string routines, which are present in memset(), which both aes_cipher() and aes_decipher() use to initialize some temporary buffers. In this case, since the size is known at compile time, these additional checks should not result in any code generation changes but allmodconfig has several sanitizers enabled, which may make it harder for the compiler to eliminate the compile time checks and the variables that come about from them. The memset() calls are just initializing these buffers to zero, so use '= {}' instead, which is used all over the kernel and does the exact same thing as memset() without the fortify checks, which drops the stack usage of these functions by a few hundred kilobytes. drivers/staging/rtl8723bs/core/rtw_security.c:864:19: warning: stack frame size (1584) exceeds limit (128) in 'aes_cipher' [-Wframe-larger-than] 864 | static signed int aes_cipher(u8 *key, uint hdrlen, | ^ drivers/staging/rtl8723bs/core/rtw_security.c:1271:5: warning: stack frame size (1456) exceeds limit (128) in 'rtw_aes_decrypt' [-Wframe-larger-than] 1271 | u32 rtw_aes_decrypt(struct adapter *padapter, u8 *precvframe) | ^ Cc: stable(a)vger.kernel.org Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver") Signed-off-by: Nathan Chancellor <nathan(a)kernel.org> Reviewed-by: Dan Carpenter <dan.carpenter(a)linaro.org> Link: https://lore.kernel.org/r/20250609-rtl8723bs-fix-clang-arm64-wflt-v1-1-e2ac… Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/staging/rtl8723bs/core/rtw_security.c b/drivers/staging/rtl8723bs/core/rtw_security.c index 1e9eff01b1aa..e9f382c280d9 100644 --- a/drivers/staging/rtl8723bs/core/rtw_security.c +++ b/drivers/staging/rtl8723bs/core/rtw_security.c @@ -868,29 +868,21 @@ static signed int aes_cipher(u8 *key, uint hdrlen, num_blocks, payload_index; u8 pn_vector[6]; - u8 mic_iv[16]; - u8 mic_header1[16]; - u8 mic_header2[16]; - u8 ctr_preload[16]; + u8 mic_iv[16] = {}; + u8 mic_header1[16] = {}; + u8 mic_header2[16] = {}; + u8 ctr_preload[16] = {}; /* Intermediate Buffers */ - u8 chain_buffer[16]; - u8 aes_out[16]; - u8 padded_buffer[16]; + u8 chain_buffer[16] = {}; + u8 aes_out[16] = {}; + u8 padded_buffer[16] = {}; u8 mic[8]; uint frtype = GetFrameType(pframe); uint frsubtype = GetFrameSubType(pframe); frsubtype = frsubtype>>4; - memset((void *)mic_iv, 0, 16); - memset((void *)mic_header1, 0, 16); - memset((void *)mic_header2, 0, 16); - memset((void *)ctr_preload, 0, 16); - memset((void *)chain_buffer, 0, 16); - memset((void *)aes_out, 0, 16); - memset((void *)padded_buffer, 0, 16); - if ((hdrlen == WLAN_HDR_A3_LEN) || (hdrlen == WLAN_HDR_A3_QOS_LEN)) a4_exists = 0; else @@ -1080,15 +1072,15 @@ static signed int aes_decipher(u8 *key, uint hdrlen, num_blocks, payload_index; signed int res = _SUCCESS; u8 pn_vector[6]; - u8 mic_iv[16]; - u8 mic_header1[16]; - u8 mic_header2[16]; - u8 ctr_preload[16]; + u8 mic_iv[16] = {}; + u8 mic_header1[16] = {}; + u8 mic_header2[16] = {}; + u8 ctr_preload[16] = {}; /* Intermediate Buffers */ - u8 chain_buffer[16]; - u8 aes_out[16]; - u8 padded_buffer[16]; + u8 chain_buffer[16] = {}; + u8 aes_out[16] = {}; + u8 padded_buffer[16] = {}; u8 mic[8]; uint frtype = GetFrameType(pframe); @@ -1096,14 +1088,6 @@ static signed int aes_decipher(u8 *key, uint hdrlen, frsubtype = frsubtype>>4; - memset((void *)mic_iv, 0, 16); - memset((void *)mic_header1, 0, 16); - memset((void *)mic_header2, 0, 16); - memset((void *)ctr_preload, 0, 16); - memset((void *)chain_buffer, 0, 16); - memset((void *)aes_out, 0, 16); - memset((void *)padded_buffer, 0, 16); - /* start to decrypt the payload */ num_blocks = (plen-8) / 16; /* plen including LLC, payload_length and mic) */

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FAILED: patch "[PATCH] x86/traps: Initialize DR7 by writing its architectural reset" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x fa7d0f83c5c4223a01598876352473cb3d3bd4d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063028-reproduce-turtle-6e00@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fa7d0f83c5c4223a01598876352473cb3d3bd4d7 Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:04 -0700 Subject: [PATCH] x86/traps: Initialize DR7 by writing its architectural reset value Initialize DR7 by writing its architectural reset value to always set bit 10, which is reserved to '1', when "clearing" DR7 so as not to trigger unanticipated behavior if said bit is ever unreserved, e.g. as a feature enabling flag with inverted polarity. Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Sean Christopherson <seanjc(a)google.com> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-3-xin%40zytor.com diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f6c280a94f0..27125e009847 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2246,7 +2246,7 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); static void initialize_debug_regs(void) { /* Control register first -- to make sure everything is disabled. */ - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(DR6_RESERVED, 6); /* dr5 and dr4 don't exist */ set_debugreg(0, 3); diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 102641fd2172..8b1a9733d13e 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -385,7 +385,7 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) struct perf_event *bp; /* Disable hardware debugging while we are in kgdb: */ - set_debugreg(0UL, 7); + set_debugreg(DR7_FIXED_1, 7); for (i = 0; i < HBP_NUM; i++) { if (!breakinfo[i].enabled) continue; diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a10e180cbf23..3ef15c2f152f 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400)) + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1)) return; printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8d6cf25127aa..b972bf72fb8b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -133,7 +133,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400))) { + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1))) { printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", log_lvl, d0, d1, d2); printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..a9d992d5652f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11035,7 +11035,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs && !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); @@ -11044,7 +11044,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); } else if (unlikely(hw_breakpoint_active())) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); } vcpu->arch.host_debugctl = get_debugctlmsr();

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FAILED: patch "[PATCH] x86/traps: Initialize DR7 by writing its architectural reset" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x fa7d0f83c5c4223a01598876352473cb3d3bd4d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063027-herring-canned-83b0@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fa7d0f83c5c4223a01598876352473cb3d3bd4d7 Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:04 -0700 Subject: [PATCH] x86/traps: Initialize DR7 by writing its architectural reset value Initialize DR7 by writing its architectural reset value to always set bit 10, which is reserved to '1', when "clearing" DR7 so as not to trigger unanticipated behavior if said bit is ever unreserved, e.g. as a feature enabling flag with inverted polarity. Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Sean Christopherson <seanjc(a)google.com> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-3-xin%40zytor.com diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f6c280a94f0..27125e009847 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2246,7 +2246,7 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); static void initialize_debug_regs(void) { /* Control register first -- to make sure everything is disabled. */ - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(DR6_RESERVED, 6); /* dr5 and dr4 don't exist */ set_debugreg(0, 3); diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 102641fd2172..8b1a9733d13e 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -385,7 +385,7 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) struct perf_event *bp; /* Disable hardware debugging while we are in kgdb: */ - set_debugreg(0UL, 7); + set_debugreg(DR7_FIXED_1, 7); for (i = 0; i < HBP_NUM; i++) { if (!breakinfo[i].enabled) continue; diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a10e180cbf23..3ef15c2f152f 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400)) + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1)) return; printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8d6cf25127aa..b972bf72fb8b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -133,7 +133,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400))) { + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1))) { printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", log_lvl, d0, d1, d2); printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..a9d992d5652f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11035,7 +11035,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs && !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); @@ -11044,7 +11044,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); } else if (unlikely(hw_breakpoint_active())) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); } vcpu->arch.host_debugctl = get_debugctlmsr();

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FAILED: patch "[PATCH] x86/traps: Initialize DR7 by writing its architectural reset" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x fa7d0f83c5c4223a01598876352473cb3d3bd4d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063027-myspace-germproof-6a5c@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fa7d0f83c5c4223a01598876352473cb3d3bd4d7 Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:04 -0700 Subject: [PATCH] x86/traps: Initialize DR7 by writing its architectural reset value Initialize DR7 by writing its architectural reset value to always set bit 10, which is reserved to '1', when "clearing" DR7 so as not to trigger unanticipated behavior if said bit is ever unreserved, e.g. as a feature enabling flag with inverted polarity. Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Sean Christopherson <seanjc(a)google.com> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-3-xin%40zytor.com diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f6c280a94f0..27125e009847 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2246,7 +2246,7 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); static void initialize_debug_regs(void) { /* Control register first -- to make sure everything is disabled. */ - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(DR6_RESERVED, 6); /* dr5 and dr4 don't exist */ set_debugreg(0, 3); diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 102641fd2172..8b1a9733d13e 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -385,7 +385,7 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) struct perf_event *bp; /* Disable hardware debugging while we are in kgdb: */ - set_debugreg(0UL, 7); + set_debugreg(DR7_FIXED_1, 7); for (i = 0; i < HBP_NUM; i++) { if (!breakinfo[i].enabled) continue; diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a10e180cbf23..3ef15c2f152f 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400)) + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1)) return; printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8d6cf25127aa..b972bf72fb8b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -133,7 +133,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400))) { + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1))) { printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", log_lvl, d0, d1, d2); printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..a9d992d5652f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11035,7 +11035,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs && !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); @@ -11044,7 +11044,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); } else if (unlikely(hw_breakpoint_active())) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); } vcpu->arch.host_debugctl = get_debugctlmsr();

19 hours, 5 minutes

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FAILED: patch "[PATCH] x86/traps: Initialize DR7 by writing its architectural reset" failed to apply to 6.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y git checkout FETCH_HEAD git cherry-pick -x fa7d0f83c5c4223a01598876352473cb3d3bd4d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063026-replace-hardly-8dd1@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fa7d0f83c5c4223a01598876352473cb3d3bd4d7 Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:04 -0700 Subject: [PATCH] x86/traps: Initialize DR7 by writing its architectural reset value Initialize DR7 by writing its architectural reset value to always set bit 10, which is reserved to '1', when "clearing" DR7 so as not to trigger unanticipated behavior if said bit is ever unreserved, e.g. as a feature enabling flag with inverted polarity. Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Sean Christopherson <seanjc(a)google.com> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-3-xin%40zytor.com diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f6c280a94f0..27125e009847 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2246,7 +2246,7 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); static void initialize_debug_regs(void) { /* Control register first -- to make sure everything is disabled. */ - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(DR6_RESERVED, 6); /* dr5 and dr4 don't exist */ set_debugreg(0, 3); diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 102641fd2172..8b1a9733d13e 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -385,7 +385,7 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) struct perf_event *bp; /* Disable hardware debugging while we are in kgdb: */ - set_debugreg(0UL, 7); + set_debugreg(DR7_FIXED_1, 7); for (i = 0; i < HBP_NUM; i++) { if (!breakinfo[i].enabled) continue; diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a10e180cbf23..3ef15c2f152f 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400)) + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1)) return; printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8d6cf25127aa..b972bf72fb8b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -133,7 +133,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400))) { + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1))) { printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", log_lvl, d0, d1, d2); printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..a9d992d5652f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11035,7 +11035,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs && !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); @@ -11044,7 +11044,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); } else if (unlikely(hw_breakpoint_active())) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); } vcpu->arch.host_debugctl = get_debugctlmsr();

19 hours, 5 minutes

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FAILED: patch "[PATCH] x86/traps: Initialize DR7 by writing its architectural reset" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x fa7d0f83c5c4223a01598876352473cb3d3bd4d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063026-grandma-tributary-5bd8@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fa7d0f83c5c4223a01598876352473cb3d3bd4d7 Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:04 -0700 Subject: [PATCH] x86/traps: Initialize DR7 by writing its architectural reset value Initialize DR7 by writing its architectural reset value to always set bit 10, which is reserved to '1', when "clearing" DR7 so as not to trigger unanticipated behavior if said bit is ever unreserved, e.g. as a feature enabling flag with inverted polarity. Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Sean Christopherson <seanjc(a)google.com> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-3-xin%40zytor.com diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f6c280a94f0..27125e009847 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2246,7 +2246,7 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); static void initialize_debug_regs(void) { /* Control register first -- to make sure everything is disabled. */ - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(DR6_RESERVED, 6); /* dr5 and dr4 don't exist */ set_debugreg(0, 3); diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 102641fd2172..8b1a9733d13e 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -385,7 +385,7 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) struct perf_event *bp; /* Disable hardware debugging while we are in kgdb: */ - set_debugreg(0UL, 7); + set_debugreg(DR7_FIXED_1, 7); for (i = 0; i < HBP_NUM; i++) { if (!breakinfo[i].enabled) continue; diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a10e180cbf23..3ef15c2f152f 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400)) + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1)) return; printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8d6cf25127aa..b972bf72fb8b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -133,7 +133,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && - (d6 == DR6_RESERVED) && (d7 == 0x400))) { + (d6 == DR6_RESERVED) && (d7 == DR7_FIXED_1))) { printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", log_lvl, d0, d1, d2); printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..a9d992d5652f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11035,7 +11035,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs && !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); set_debugreg(vcpu->arch.eff_db[2], 2); @@ -11044,7 +11044,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); } else if (unlikely(hw_breakpoint_active())) { - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); } vcpu->arch.host_debugctl = get_debugctlmsr();

19 hours, 5 minutes

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FAILED: patch "[PATCH] x86/traps: Initialize DR6 by writing its architectural reset" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 5f465c148c61e876b6d6eacd8e8e365f2d47758f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063013-city-unloaded-a949@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5f465c148c61e876b6d6eacd8e8e365f2d47758f Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:03 -0700 Subject: [PATCH] x86/traps: Initialize DR6 by writing its architectural reset value Initialize DR6 by writing its architectural reset value to avoid incorrectly zeroing DR6 to clear DR6.BLD at boot time, which leads to a false bus lock detected warning. The Intel SDM says: 1) Certain debug exceptions may clear bits 0-3 of DR6. 2) BLD induced #DB clears DR6.BLD and any other debug exception doesn't modify DR6.BLD. 3) RTM induced #DB clears DR6.RTM and any other debug exception sets DR6.RTM. To avoid confusion in identifying debug exceptions, debug handlers should set DR6.BLD and DR6.RTM, and clear other DR6 bits before returning. The DR6 architectural reset value 0xFFFF0FF0, already defined as macro DR6_RESERVED, satisfies these requirements, so just use it to reinitialize DR6 whenever needed. Since clear_all_debug_regs() no longer zeros all debug registers, rename it to initialize_debug_regs() to better reflect its current behavior. Since debug_read_clear_dr6() no longer clears DR6, rename it to debug_read_reset_dr6() to better reflect its current behavior. Fixes: ebb1064e7c2e9 ("x86/traps: Handle #DB for bus lock") Reported-by: Sohil Mehta <sohil.mehta(a)intel.com> Suggested-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Link: https://lore.kernel.org/lkml/06e68373-a92b-472e-8fd9-ba548119770c@intel.com/ Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-2-xin%40zytor.com diff --git a/arch/x86/include/uapi/asm/debugreg.h b/arch/x86/include/uapi/asm/debugreg.h index 0007ba077c0c..41da492dfb01 100644 --- a/arch/x86/include/uapi/asm/debugreg.h +++ b/arch/x86/include/uapi/asm/debugreg.h @@ -15,7 +15,26 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ -/* Define reserved bits in DR6 which are always set to 1 */ +/* + * Define bits in DR6 which are set to 1 by default. + * + * This is also the DR6 architectural value following Power-up, Reset or INIT. + * + * Note, with the introduction of Bus Lock Detection (BLD) and Restricted + * Transactional Memory (RTM), the DR6 register has been modified: + * + * 1) BLD flag (bit 11) is no longer reserved to 1 if the CPU supports + * Bus Lock Detection. The assertion of a bus lock could clear it. + * + * 2) RTM flag (bit 16) is no longer reserved to 1 if the CPU supports + * restricted transactional memory. #DB occurred inside an RTM region + * could clear it. + * + * Apparently, DR6.BLD and DR6.RTM are active low bits. + * + * As a result, DR6_RESERVED is an incorrect name now, but it is kept for + * compatibility. + */ #define DR6_RESERVED (0xFFFF0FF0) #define DR_TRAP0 (0x1) /* db0 */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8feb8fd2957a..0f6c280a94f0 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2243,20 +2243,16 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); #endif #endif -/* - * Clear all 6 debug registers: - */ -static void clear_all_debug_regs(void) +static void initialize_debug_regs(void) { - int i; - - for (i = 0; i < 8; i++) { - /* Ignore db4, db5 */ - if ((i == 4) || (i == 5)) - continue; - - set_debugreg(0, i); - } + /* Control register first -- to make sure everything is disabled. */ + set_debugreg(0, 7); + set_debugreg(DR6_RESERVED, 6); + /* dr5 and dr4 don't exist */ + set_debugreg(0, 3); + set_debugreg(0, 2); + set_debugreg(0, 1); + set_debugreg(0, 0); } #ifdef CONFIG_KGDB @@ -2417,7 +2413,7 @@ void cpu_init(void) load_mm_ldt(&init_mm); - clear_all_debug_regs(); + initialize_debug_regs(); dbg_restore_debug_regs(); doublefault_init_cpu_tss(); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c5c897a86418..36354b470590 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1022,24 +1022,32 @@ static bool is_sysenter_singlestep(struct pt_regs *regs) #endif } -static __always_inline unsigned long debug_read_clear_dr6(void) +static __always_inline unsigned long debug_read_reset_dr6(void) { unsigned long dr6; + get_debugreg(dr6, 6); + dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ + /* * The Intel SDM says: * - * Certain debug exceptions may clear bits 0-3. The remaining - * contents of the DR6 register are never cleared by the - * processor. To avoid confusion in identifying debug - * exceptions, debug handlers should clear the register before - * returning to the interrupted task. + * Certain debug exceptions may clear bits 0-3 of DR6. * - * Keep it simple: clear DR6 immediately. + * BLD induced #DB clears DR6.BLD and any other debug + * exception doesn't modify DR6.BLD. + * + * RTM induced #DB clears DR6.RTM and any other debug + * exception sets DR6.RTM. + * + * To avoid confusion in identifying debug exceptions, + * debug handlers should set DR6.BLD and DR6.RTM, and + * clear other DR6 bits before returning. + * + * Keep it simple: write DR6 with its architectural reset + * value 0xFFFF0FF0, defined as DR6_RESERVED, immediately. */ - get_debugreg(dr6, 6); set_debugreg(DR6_RESERVED, 6); - dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ return dr6; } @@ -1239,13 +1247,13 @@ static noinstr void exc_debug_user(struct pt_regs *regs, unsigned long dr6) /* IST stack entry */ DEFINE_IDTENTRY_DEBUG(exc_debug) { - exc_debug_kernel(regs, debug_read_clear_dr6()); + exc_debug_kernel(regs, debug_read_reset_dr6()); } /* User entry, runs on regular task stack */ DEFINE_IDTENTRY_DEBUG_USER(exc_debug) { - exc_debug_user(regs, debug_read_clear_dr6()); + exc_debug_user(regs, debug_read_reset_dr6()); } #ifdef CONFIG_X86_FRED @@ -1264,7 +1272,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) { /* * FRED #DB stores DR6 on the stack in the format which - * debug_read_clear_dr6() returns for the IDT entry points. + * debug_read_reset_dr6() returns for the IDT entry points. */ unsigned long dr6 = fred_event_data(regs); @@ -1279,7 +1287,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) /* 32 bit does not have separate entry points. */ DEFINE_IDTENTRY_RAW(exc_debug) { - unsigned long dr6 = debug_read_clear_dr6(); + unsigned long dr6 = debug_read_reset_dr6(); if (user_mode(regs)) exc_debug_user(regs, dr6);

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FAILED: patch "[PATCH] x86/traps: Initialize DR6 by writing its architectural reset" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 5f465c148c61e876b6d6eacd8e8e365f2d47758f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063012-clammy-bluish-930d@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5f465c148c61e876b6d6eacd8e8e365f2d47758f Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:03 -0700 Subject: [PATCH] x86/traps: Initialize DR6 by writing its architectural reset value Initialize DR6 by writing its architectural reset value to avoid incorrectly zeroing DR6 to clear DR6.BLD at boot time, which leads to a false bus lock detected warning. The Intel SDM says: 1) Certain debug exceptions may clear bits 0-3 of DR6. 2) BLD induced #DB clears DR6.BLD and any other debug exception doesn't modify DR6.BLD. 3) RTM induced #DB clears DR6.RTM and any other debug exception sets DR6.RTM. To avoid confusion in identifying debug exceptions, debug handlers should set DR6.BLD and DR6.RTM, and clear other DR6 bits before returning. The DR6 architectural reset value 0xFFFF0FF0, already defined as macro DR6_RESERVED, satisfies these requirements, so just use it to reinitialize DR6 whenever needed. Since clear_all_debug_regs() no longer zeros all debug registers, rename it to initialize_debug_regs() to better reflect its current behavior. Since debug_read_clear_dr6() no longer clears DR6, rename it to debug_read_reset_dr6() to better reflect its current behavior. Fixes: ebb1064e7c2e9 ("x86/traps: Handle #DB for bus lock") Reported-by: Sohil Mehta <sohil.mehta(a)intel.com> Suggested-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Link: https://lore.kernel.org/lkml/06e68373-a92b-472e-8fd9-ba548119770c@intel.com/ Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-2-xin%40zytor.com diff --git a/arch/x86/include/uapi/asm/debugreg.h b/arch/x86/include/uapi/asm/debugreg.h index 0007ba077c0c..41da492dfb01 100644 --- a/arch/x86/include/uapi/asm/debugreg.h +++ b/arch/x86/include/uapi/asm/debugreg.h @@ -15,7 +15,26 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ -/* Define reserved bits in DR6 which are always set to 1 */ +/* + * Define bits in DR6 which are set to 1 by default. + * + * This is also the DR6 architectural value following Power-up, Reset or INIT. + * + * Note, with the introduction of Bus Lock Detection (BLD) and Restricted + * Transactional Memory (RTM), the DR6 register has been modified: + * + * 1) BLD flag (bit 11) is no longer reserved to 1 if the CPU supports + * Bus Lock Detection. The assertion of a bus lock could clear it. + * + * 2) RTM flag (bit 16) is no longer reserved to 1 if the CPU supports + * restricted transactional memory. #DB occurred inside an RTM region + * could clear it. + * + * Apparently, DR6.BLD and DR6.RTM are active low bits. + * + * As a result, DR6_RESERVED is an incorrect name now, but it is kept for + * compatibility. + */ #define DR6_RESERVED (0xFFFF0FF0) #define DR_TRAP0 (0x1) /* db0 */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8feb8fd2957a..0f6c280a94f0 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2243,20 +2243,16 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); #endif #endif -/* - * Clear all 6 debug registers: - */ -static void clear_all_debug_regs(void) +static void initialize_debug_regs(void) { - int i; - - for (i = 0; i < 8; i++) { - /* Ignore db4, db5 */ - if ((i == 4) || (i == 5)) - continue; - - set_debugreg(0, i); - } + /* Control register first -- to make sure everything is disabled. */ + set_debugreg(0, 7); + set_debugreg(DR6_RESERVED, 6); + /* dr5 and dr4 don't exist */ + set_debugreg(0, 3); + set_debugreg(0, 2); + set_debugreg(0, 1); + set_debugreg(0, 0); } #ifdef CONFIG_KGDB @@ -2417,7 +2413,7 @@ void cpu_init(void) load_mm_ldt(&init_mm); - clear_all_debug_regs(); + initialize_debug_regs(); dbg_restore_debug_regs(); doublefault_init_cpu_tss(); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c5c897a86418..36354b470590 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1022,24 +1022,32 @@ static bool is_sysenter_singlestep(struct pt_regs *regs) #endif } -static __always_inline unsigned long debug_read_clear_dr6(void) +static __always_inline unsigned long debug_read_reset_dr6(void) { unsigned long dr6; + get_debugreg(dr6, 6); + dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ + /* * The Intel SDM says: * - * Certain debug exceptions may clear bits 0-3. The remaining - * contents of the DR6 register are never cleared by the - * processor. To avoid confusion in identifying debug - * exceptions, debug handlers should clear the register before - * returning to the interrupted task. + * Certain debug exceptions may clear bits 0-3 of DR6. * - * Keep it simple: clear DR6 immediately. + * BLD induced #DB clears DR6.BLD and any other debug + * exception doesn't modify DR6.BLD. + * + * RTM induced #DB clears DR6.RTM and any other debug + * exception sets DR6.RTM. + * + * To avoid confusion in identifying debug exceptions, + * debug handlers should set DR6.BLD and DR6.RTM, and + * clear other DR6 bits before returning. + * + * Keep it simple: write DR6 with its architectural reset + * value 0xFFFF0FF0, defined as DR6_RESERVED, immediately. */ - get_debugreg(dr6, 6); set_debugreg(DR6_RESERVED, 6); - dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ return dr6; } @@ -1239,13 +1247,13 @@ static noinstr void exc_debug_user(struct pt_regs *regs, unsigned long dr6) /* IST stack entry */ DEFINE_IDTENTRY_DEBUG(exc_debug) { - exc_debug_kernel(regs, debug_read_clear_dr6()); + exc_debug_kernel(regs, debug_read_reset_dr6()); } /* User entry, runs on regular task stack */ DEFINE_IDTENTRY_DEBUG_USER(exc_debug) { - exc_debug_user(regs, debug_read_clear_dr6()); + exc_debug_user(regs, debug_read_reset_dr6()); } #ifdef CONFIG_X86_FRED @@ -1264,7 +1272,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) { /* * FRED #DB stores DR6 on the stack in the format which - * debug_read_clear_dr6() returns for the IDT entry points. + * debug_read_reset_dr6() returns for the IDT entry points. */ unsigned long dr6 = fred_event_data(regs); @@ -1279,7 +1287,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) /* 32 bit does not have separate entry points. */ DEFINE_IDTENTRY_RAW(exc_debug) { - unsigned long dr6 = debug_read_clear_dr6(); + unsigned long dr6 = debug_read_reset_dr6(); if (user_mode(regs)) exc_debug_user(regs, dr6);

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FAILED: patch "[PATCH] x86/traps: Initialize DR6 by writing its architectural reset" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 5f465c148c61e876b6d6eacd8e8e365f2d47758f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063008-shimmy-doorstep-3c89@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5f465c148c61e876b6d6eacd8e8e365f2d47758f Mon Sep 17 00:00:00 2001 From: "Xin Li (Intel)" <xin(a)zytor.com> Date: Fri, 20 Jun 2025 16:15:03 -0700 Subject: [PATCH] x86/traps: Initialize DR6 by writing its architectural reset value Initialize DR6 by writing its architectural reset value to avoid incorrectly zeroing DR6 to clear DR6.BLD at boot time, which leads to a false bus lock detected warning. The Intel SDM says: 1) Certain debug exceptions may clear bits 0-3 of DR6. 2) BLD induced #DB clears DR6.BLD and any other debug exception doesn't modify DR6.BLD. 3) RTM induced #DB clears DR6.RTM and any other debug exception sets DR6.RTM. To avoid confusion in identifying debug exceptions, debug handlers should set DR6.BLD and DR6.RTM, and clear other DR6 bits before returning. The DR6 architectural reset value 0xFFFF0FF0, already defined as macro DR6_RESERVED, satisfies these requirements, so just use it to reinitialize DR6 whenever needed. Since clear_all_debug_regs() no longer zeros all debug registers, rename it to initialize_debug_regs() to better reflect its current behavior. Since debug_read_clear_dr6() no longer clears DR6, rename it to debug_read_reset_dr6() to better reflect its current behavior. Fixes: ebb1064e7c2e9 ("x86/traps: Handle #DB for bus lock") Reported-by: Sohil Mehta <sohil.mehta(a)intel.com> Suggested-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Signed-off-by: Xin Li (Intel) <xin(a)zytor.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa(a)zytor.com> Reviewed-by: Sohil Mehta <sohil.mehta(a)intel.com> Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Tested-by: Sohil Mehta <sohil.mehta(a)intel.com> Link: https://lore.kernel.org/lkml/06e68373-a92b-472e-8fd9-ba548119770c@intel.com/ Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250620231504.2676902-2-xin%40zytor.com diff --git a/arch/x86/include/uapi/asm/debugreg.h b/arch/x86/include/uapi/asm/debugreg.h index 0007ba077c0c..41da492dfb01 100644 --- a/arch/x86/include/uapi/asm/debugreg.h +++ b/arch/x86/include/uapi/asm/debugreg.h @@ -15,7 +15,26 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ -/* Define reserved bits in DR6 which are always set to 1 */ +/* + * Define bits in DR6 which are set to 1 by default. + * + * This is also the DR6 architectural value following Power-up, Reset or INIT. + * + * Note, with the introduction of Bus Lock Detection (BLD) and Restricted + * Transactional Memory (RTM), the DR6 register has been modified: + * + * 1) BLD flag (bit 11) is no longer reserved to 1 if the CPU supports + * Bus Lock Detection. The assertion of a bus lock could clear it. + * + * 2) RTM flag (bit 16) is no longer reserved to 1 if the CPU supports + * restricted transactional memory. #DB occurred inside an RTM region + * could clear it. + * + * Apparently, DR6.BLD and DR6.RTM are active low bits. + * + * As a result, DR6_RESERVED is an incorrect name now, but it is kept for + * compatibility. + */ #define DR6_RESERVED (0xFFFF0FF0) #define DR_TRAP0 (0x1) /* db0 */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8feb8fd2957a..0f6c280a94f0 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2243,20 +2243,16 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); #endif #endif -/* - * Clear all 6 debug registers: - */ -static void clear_all_debug_regs(void) +static void initialize_debug_regs(void) { - int i; - - for (i = 0; i < 8; i++) { - /* Ignore db4, db5 */ - if ((i == 4) || (i == 5)) - continue; - - set_debugreg(0, i); - } + /* Control register first -- to make sure everything is disabled. */ + set_debugreg(0, 7); + set_debugreg(DR6_RESERVED, 6); + /* dr5 and dr4 don't exist */ + set_debugreg(0, 3); + set_debugreg(0, 2); + set_debugreg(0, 1); + set_debugreg(0, 0); } #ifdef CONFIG_KGDB @@ -2417,7 +2413,7 @@ void cpu_init(void) load_mm_ldt(&init_mm); - clear_all_debug_regs(); + initialize_debug_regs(); dbg_restore_debug_regs(); doublefault_init_cpu_tss(); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c5c897a86418..36354b470590 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1022,24 +1022,32 @@ static bool is_sysenter_singlestep(struct pt_regs *regs) #endif } -static __always_inline unsigned long debug_read_clear_dr6(void) +static __always_inline unsigned long debug_read_reset_dr6(void) { unsigned long dr6; + get_debugreg(dr6, 6); + dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ + /* * The Intel SDM says: * - * Certain debug exceptions may clear bits 0-3. The remaining - * contents of the DR6 register are never cleared by the - * processor. To avoid confusion in identifying debug - * exceptions, debug handlers should clear the register before - * returning to the interrupted task. + * Certain debug exceptions may clear bits 0-3 of DR6. * - * Keep it simple: clear DR6 immediately. + * BLD induced #DB clears DR6.BLD and any other debug + * exception doesn't modify DR6.BLD. + * + * RTM induced #DB clears DR6.RTM and any other debug + * exception sets DR6.RTM. + * + * To avoid confusion in identifying debug exceptions, + * debug handlers should set DR6.BLD and DR6.RTM, and + * clear other DR6 bits before returning. + * + * Keep it simple: write DR6 with its architectural reset + * value 0xFFFF0FF0, defined as DR6_RESERVED, immediately. */ - get_debugreg(dr6, 6); set_debugreg(DR6_RESERVED, 6); - dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ return dr6; } @@ -1239,13 +1247,13 @@ static noinstr void exc_debug_user(struct pt_regs *regs, unsigned long dr6) /* IST stack entry */ DEFINE_IDTENTRY_DEBUG(exc_debug) { - exc_debug_kernel(regs, debug_read_clear_dr6()); + exc_debug_kernel(regs, debug_read_reset_dr6()); } /* User entry, runs on regular task stack */ DEFINE_IDTENTRY_DEBUG_USER(exc_debug) { - exc_debug_user(regs, debug_read_clear_dr6()); + exc_debug_user(regs, debug_read_reset_dr6()); } #ifdef CONFIG_X86_FRED @@ -1264,7 +1272,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) { /* * FRED #DB stores DR6 on the stack in the format which - * debug_read_clear_dr6() returns for the IDT entry points. + * debug_read_reset_dr6() returns for the IDT entry points. */ unsigned long dr6 = fred_event_data(regs); @@ -1279,7 +1287,7 @@ DEFINE_FREDENTRY_DEBUG(exc_debug) /* 32 bit does not have separate entry points. */ DEFINE_IDTENTRY_RAW(exc_debug) { - unsigned long dr6 = debug_read_clear_dr6(); + unsigned long dr6 = debug_read_reset_dr6(); if (user_mode(regs)) exc_debug_user(regs, dr6);

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FAILED: patch "[PATCH] EDAC/amd64: Fix size calculation for Non-Power-of-Two DIMMs" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x a3f3040657417aeadb9622c629d4a0c2693a0f93 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025063041-arrival-closable-5d15@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From a3f3040657417aeadb9622c629d4a0c2693a0f93 Mon Sep 17 00:00:00 2001 From: Avadhut Naik <avadhut.naik(a)amd.com> Date: Thu, 29 May 2025 20:50:04 +0000 Subject: [PATCH] EDAC/amd64: Fix size calculation for Non-Power-of-Two DIMMs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Each Chip-Select (CS) of a Unified Memory Controller (UMC) on AMD Zen-based SOCs has an Address Mask and a Secondary Address Mask register associated with it. The amd64_edac module logs DIMM sizes on a per-UMC per-CS granularity during init using these two registers. Currently, the module primarily considers only the Address Mask register for computing DIMM sizes. The Secondary Address Mask register is only considered for odd CS. Additionally, if it has been considered, the Address Mask register is ignored altogether for that CS. For power-of-two DIMMs i.e. DIMMs whose total capacity is a power of two (32GB, 64GB, etc), this is not an issue since only the Address Mask register is used. For non-power-of-two DIMMs i.e., DIMMs whose total capacity is not a power of two (48GB, 96GB, etc), however, the Secondary Address Mask register is used in conjunction with the Address Mask register. However, since the module only considers either of the two registers for a CS, the size computed by the module is incorrect. The Secondary Address Mask register is not considered for even CS, and the Address Mask register is not considered for odd CS. Introduce a new helper function so that both Address Mask and Secondary Address Mask registers are considered, when valid, for computing DIMM sizes. Furthermore, also rename some variables for greater clarity. Fixes: 81f5090db843 ("EDAC/amd64: Support asymmetric dual-rank DIMMs") Closes: https://lore.kernel.org/dbec22b6-00f2-498b-b70d-ab6f8a5ec87e@natrix.lt Reported-by: Žilvinas Žaltiena <zilvinas(a)natrix.lt> Signed-off-by: Avadhut Naik <avadhut.naik(a)amd.com> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de> Reviewed-by: Yazen Ghannam <yazen.ghannam(a)amd.com> Tested-by: Žilvinas Žaltiena <zilvinas(a)natrix.lt> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/20250529205013.403450-1-avadhut.naik@amd.com diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c index b681c0663203..07f1e9dc1ca7 100644 --- a/drivers/edac/amd64_edac.c +++ b/drivers/edac/amd64_edac.c @@ -1209,7 +1209,9 @@ static int umc_get_cs_mode(int dimm, u8 ctrl, struct amd64_pvt *pvt) if (csrow_enabled(2 * dimm + 1, ctrl, pvt)) cs_mode |= CS_ODD_PRIMARY; - /* Asymmetric dual-rank DIMM support. */ + if (csrow_sec_enabled(2 * dimm, ctrl, pvt)) + cs_mode |= CS_EVEN_SECONDARY; + if (csrow_sec_enabled(2 * dimm + 1, ctrl, pvt)) cs_mode |= CS_ODD_SECONDARY; @@ -1230,12 +1232,13 @@ static int umc_get_cs_mode(int dimm, u8 ctrl, struct amd64_pvt *pvt) return cs_mode; } -static int __addr_mask_to_cs_size(u32 addr_mask_orig, unsigned int cs_mode, - int csrow_nr, int dimm) +static int calculate_cs_size(u32 mask, unsigned int cs_mode) { - u32 msb, weight, num_zero_bits; - u32 addr_mask_deinterleaved; - int size = 0; + int msb, weight, num_zero_bits; + u32 deinterleaved_mask; + + if (!mask) + return 0; /* * The number of zero bits in the mask is equal to the number of bits @@ -1248,19 +1251,30 @@ static int __addr_mask_to_cs_size(u32 addr_mask_orig, unsigned int cs_mode, * without swapping with the most significant bit. This can be handled * by keeping the MSB where it is and ignoring the single zero bit. */ - msb = fls(addr_mask_orig) - 1; - weight = hweight_long(addr_mask_orig); + msb = fls(mask) - 1; + weight = hweight_long(mask); num_zero_bits = msb - weight - !!(cs_mode & CS_3R_INTERLEAVE); /* Take the number of zero bits off from the top of the mask. */ - addr_mask_deinterleaved = GENMASK_ULL(msb - num_zero_bits, 1); + deinterleaved_mask = GENMASK(msb - num_zero_bits, 1); + edac_dbg(1, " Deinterleaved AddrMask: 0x%x\n", deinterleaved_mask); + + return (deinterleaved_mask >> 2) + 1; +} + +static int __addr_mask_to_cs_size(u32 addr_mask, u32 addr_mask_sec, + unsigned int cs_mode, int csrow_nr, int dimm) +{ + int size; edac_dbg(1, "CS%d DIMM%d AddrMasks:\n", csrow_nr, dimm); - edac_dbg(1, " Original AddrMask: 0x%x\n", addr_mask_orig); - edac_dbg(1, " Deinterleaved AddrMask: 0x%x\n", addr_mask_deinterleaved); + edac_dbg(1, " Primary AddrMask: 0x%x\n", addr_mask); /* Register [31:1] = Address [39:9]. Size is in kBs here. */ - size = (addr_mask_deinterleaved >> 2) + 1; + size = calculate_cs_size(addr_mask, cs_mode); + + edac_dbg(1, " Secondary AddrMask: 0x%x\n", addr_mask_sec); + size += calculate_cs_size(addr_mask_sec, cs_mode); /* Return size in MBs. */ return size >> 10; @@ -1269,8 +1283,8 @@ static int __addr_mask_to_cs_size(u32 addr_mask_orig, unsigned int cs_mode, static int umc_addr_mask_to_cs_size(struct amd64_pvt *pvt, u8 umc, unsigned int cs_mode, int csrow_nr) { + u32 addr_mask = 0, addr_mask_sec = 0; int cs_mask_nr = csrow_nr; - u32 addr_mask_orig; int dimm, size = 0; /* No Chip Selects are enabled. */ @@ -1308,13 +1322,13 @@ static int umc_addr_mask_to_cs_size(struct amd64_pvt *pvt, u8 umc, if (!pvt->flags.zn_regs_v2) cs_mask_nr >>= 1; - /* Asymmetric dual-rank DIMM support. */ - if ((csrow_nr & 1) && (cs_mode & CS_ODD_SECONDARY)) - addr_mask_orig = pvt->csels[umc].csmasks_sec[cs_mask_nr]; - else - addr_mask_orig = pvt->csels[umc].csmasks[cs_mask_nr]; + if (cs_mode & (CS_EVEN_PRIMARY | CS_ODD_PRIMARY)) + addr_mask = pvt->csels[umc].csmasks[cs_mask_nr]; - return __addr_mask_to_cs_size(addr_mask_orig, cs_mode, csrow_nr, dimm); + if (cs_mode & (CS_EVEN_SECONDARY | CS_ODD_SECONDARY)) + addr_mask_sec = pvt->csels[umc].csmasks_sec[cs_mask_nr]; + + return __addr_mask_to_cs_size(addr_mask, addr_mask_sec, cs_mode, csrow_nr, dimm); } static void umc_debug_display_dimm_sizes(struct amd64_pvt *pvt, u8 ctrl) @@ -3512,9 +3526,10 @@ static void gpu_get_err_info(struct mce *m, struct err_info *err) static int gpu_addr_mask_to_cs_size(struct amd64_pvt *pvt, u8 umc, unsigned int cs_mode, int csrow_nr) { - u32 addr_mask_orig = pvt->csels[umc].csmasks[csrow_nr]; + u32 addr_mask = pvt->csels[umc].csmasks[csrow_nr]; + u32 addr_mask_sec = pvt->csels[umc].csmasks_sec[csrow_nr]; - return __addr_mask_to_cs_size(addr_mask_orig, cs_mode, csrow_nr, csrow_nr >> 1); + return __addr_mask_to_cs_size(addr_mask, addr_mask_sec, cs_mode, csrow_nr, csrow_nr >> 1); } static void gpu_debug_display_dimm_sizes(struct amd64_pvt *pvt, u8 ctrl)

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