commit 9a868f634349e62922c226834aa23e3d1329ae7f upstream.

This commit adds security feature flags to reflect the settings we receive from firmware regarding Spectre/Meltdown mitigations.

The feature names reflect the names we are given by firmware on bare metal machines. See the hostboot source for details.

Arguably these could be firmware features, but that then requires them to be read early in boot so they're available prior to asm feature patching, but we don't actually want to use them for patching. We may also want to dynamically update them in future, which would be incompatible with the way firmware features work (at the moment at least). So for now just make them separate flags.

Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/include/asm/security_features.h | 65 ++++++++++++++++++++++++++++ arch/powerpc/kernel/Makefile | 2 +- arch/powerpc/kernel/security.c | 15 +++++++ 3 files changed, 81 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/include/asm/security_features.h create mode 100644 arch/powerpc/kernel/security.c

diff --git a/arch/powerpc/include/asm/security_features.h b/arch/powerpc/include/asm/security_features.h new file mode 100644 index 000000000000..db00ad2c72c2 --- /dev/null +++ b/arch/powerpc/include/asm/security_features.h @@ -0,0 +1,65 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Security related feature bit definitions. + * + * Copyright 2018, Michael Ellerman, IBM Corporation. + */ + +#ifndef _ASM_POWERPC_SECURITY_FEATURES_H +#define _ASM_POWERPC_SECURITY_FEATURES_H + + +extern unsigned long powerpc_security_features; + +static inline void security_ftr_set(unsigned long feature) +{ + powerpc_security_features |= feature; +} + +static inline void security_ftr_clear(unsigned long feature) +{ + powerpc_security_features &= ~feature; +} + +static inline bool security_ftr_enabled(unsigned long feature) +{ + return !!(powerpc_security_features & feature); +} + + +// Features indicating support for Spectre/Meltdown mitigations + +// The L1-D cache can be flushed with ori r30,r30,0 +#define SEC_FTR_L1D_FLUSH_ORI30 0x0000000000000001ull + +// The L1-D cache can be flushed with mtspr 882,r0 (aka SPRN_TRIG2) +#define SEC_FTR_L1D_FLUSH_TRIG2 0x0000000000000002ull + +// ori r31,r31,0 acts as a speculation barrier +#define SEC_FTR_SPEC_BAR_ORI31 0x0000000000000004ull + +// Speculation past bctr is disabled +#define SEC_FTR_BCCTRL_SERIALISED 0x0000000000000008ull + +// Entries in L1-D are private to a SMT thread +#define SEC_FTR_L1D_THREAD_PRIV 0x0000000000000010ull + +// Indirect branch prediction cache disabled +#define SEC_FTR_COUNT_CACHE_DISABLED 0x0000000000000020ull + + +// Features indicating need for Spectre/Meltdown mitigations + +// The L1-D cache should be flushed on MSR[HV] 1->0 transition (hypervisor to guest) +#define SEC_FTR_L1D_FLUSH_HV 0x0000000000000040ull + +// The L1-D cache should be flushed on MSR[PR] 0->1 transition (kernel to userspace) +#define SEC_FTR_L1D_FLUSH_PR 0x0000000000000080ull + +// A speculation barrier should be used for bounds checks (Spectre variant 1) +#define SEC_FTR_BNDS_CHK_SPEC_BAR 0x0000000000000100ull + +// Firmware configuration indicates user favours security over performance +#define SEC_FTR_FAVOUR_SECURITY 0x0000000000000200ull + +#endif /* _ASM_POWERPC_SECURITY_FEATURES_H */ diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 1b6bc7fba996..d458c45e5004 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -42,7 +42,7 @@ obj-$(CONFIG_VDSO32) += vdso32/ obj-$(CONFIG_PPC_WATCHDOG) += watchdog.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_ppc970.o cpu_setup_pa6t.o -obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_power.o +obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_power.o security.o obj-$(CONFIG_PPC_BOOK3S_64) += mce.o mce_power.o obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o idle_book3e.o obj-$(CONFIG_PPC64) += vdso64/ diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c new file mode 100644 index 000000000000..4ccba00d224c --- /dev/null +++ b/arch/powerpc/kernel/security.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0+ +// +// Security related flags and so on. +// +// Copyright 2018, Michael Ellerman, IBM Corporation. + +#include <linux/kernel.h> +#include <asm/security_features.h> + + +unsigned long powerpc_security_features __read_mostly = \ + SEC_FTR_L1D_FLUSH_HV | \ + SEC_FTR_L1D_FLUSH_PR | \ + SEC_FTR_BNDS_CHK_SPEC_BAR | \ + SEC_FTR_FAVOUR_SECURITY;

commit f636c14790ead6cc22cf62279b1f8d7e11a67116 upstream.

Now that we have feature flags for security related things, set or clear them based on what we receive from the hypercall.

Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/platforms/pseries/setup.c | 43 ++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 9116824bd7c5..78ece838a1ce 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -68,6 +68,7 @@ #include <asm/plpar_wrappers.h> #include <asm/kexec.h> #include <asm/isa-bridge.h> +#include <asm/security_features.h>

#include "pseries.h"

@@ -459,6 +460,40 @@ static void __init find_and_init_phbs(void) of_pci_check_probe_only(); }

+static void init_cpu_char_feature_flags(struct h_cpu_char_result *result) +{ + if (result->character & H_CPU_CHAR_SPEC_BAR_ORI31) + security_ftr_set(SEC_FTR_SPEC_BAR_ORI31); + + if (result->character & H_CPU_CHAR_BCCTRL_SERIALISED) + security_ftr_set(SEC_FTR_BCCTRL_SERIALISED); + + if (result->character & H_CPU_CHAR_L1D_FLUSH_ORI30) + security_ftr_set(SEC_FTR_L1D_FLUSH_ORI30); + + if (result->character & H_CPU_CHAR_L1D_FLUSH_TRIG2) + security_ftr_set(SEC_FTR_L1D_FLUSH_TRIG2); + + if (result->character & H_CPU_CHAR_L1D_THREAD_PRIV) + security_ftr_set(SEC_FTR_L1D_THREAD_PRIV); + + if (result->character & H_CPU_CHAR_COUNT_CACHE_DISABLED) + security_ftr_set(SEC_FTR_COUNT_CACHE_DISABLED); + + /* + * The features below are enabled by default, so we instead look to see + * if firmware has *disabled* them, and clear them if so. + */ + if (!(result->character & H_CPU_BEHAV_FAVOUR_SECURITY)) + security_ftr_clear(SEC_FTR_FAVOUR_SECURITY); + + if (!(result->character & H_CPU_BEHAV_L1D_FLUSH_PR)) + security_ftr_clear(SEC_FTR_L1D_FLUSH_PR); + + if (!(result->character & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR)) + security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR); +} + static void pseries_setup_rfi_flush(void) { struct h_cpu_char_result result; @@ -472,6 +507,8 @@ static void pseries_setup_rfi_flush(void)

rc = plpar_get_cpu_characteristics(&result); if (rc == H_SUCCESS) { + init_cpu_char_feature_flags(&result); + if (result.character & H_CPU_CHAR_L1D_FLUSH_TRIG2) types |= L1D_FLUSH_MTTRIG; if (result.character & H_CPU_CHAR_L1D_FLUSH_ORI30) @@ -482,6 +519,12 @@ static void pseries_setup_rfi_flush(void) enable = false; }

+ /* + * We're the guest so this doesn't apply to us, clear it to simplify + * handling of it elsewhere. + */ + security_ftr_clear(SEC_FTR_L1D_FLUSH_HV); + setup_rfi_flush(types, enable); }

commit 8ad33041563a10b34988800c682ada14b2612533 upstream.

This landed in setup_64.c for no good reason other than we had nowhere else to put it. Now that we have a security-related file, that is a better place for it so move it.

Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/kernel/security.c | 11 +++++++++++ arch/powerpc/kernel/setup_64.c | 8 -------- 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c index 4ccba00d224c..564e7f182a16 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -5,6 +5,8 @@ // Copyright 2018, Michael Ellerman, IBM Corporation.

#include <linux/kernel.h> +#include <linux/device.h> + #include <asm/security_features.h>

@@ -13,3 +15,12 @@ unsigned long powerpc_security_features __read_mostly = \ SEC_FTR_L1D_FLUSH_PR | \ SEC_FTR_BNDS_CHK_SPEC_BAR | \ SEC_FTR_FAVOUR_SECURITY; + + +ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) +{ + if (rfi_flush) + return sprintf(buf, "Mitigation: RFI Flush\n"); + + return sprintf(buf, "Vulnerable\n"); +} diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index c388cc3357fa..c27557aff394 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -927,12 +927,4 @@ static __init int rfi_flush_debugfs_init(void) } device_initcall(rfi_flush_debugfs_init); #endif - -ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) -{ - if (rfi_flush) - return sprintf(buf, "Mitigation: RFI Flush\n"); - - return sprintf(buf, "Vulnerable\n"); -} #endif /* CONFIG_PPC_BOOK3S_64 */

commit 37c0bdd00d3ae83369ab60a6712c28e11e6458d5 upstream.

Now that we have the security flags we can significantly simplify the code in pnv_setup_rfi_flush(), because we can use the flags instead of checking device tree properties and because the security flags have pessimistic defaults.

Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/platforms/powernv/setup.c | 41 +++++++++------------------------- 1 file changed, 10 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c index f5c0c7d91db1..7de050a3736b 100644 --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -66,7 +66,7 @@ static void init_fw_feat_flags(struct device_node *np) if (fw_feature_is("enabled", "fw-bcctrl-serialized", np)) security_ftr_set(SEC_FTR_BCCTRL_SERIALISED);

- if (fw_feature_is("enabled", "inst-spec-barrier-ori31,31,0", np)) + if (fw_feature_is("enabled", "inst-l1d-flush-ori30,30,0", np)) security_ftr_set(SEC_FTR_L1D_FLUSH_ORI30);

if (fw_feature_is("enabled", "inst-l1d-flush-trig2", np)) @@ -99,11 +99,10 @@ static void pnv_setup_rfi_flush(void) { struct device_node *np, *fw_features; enum l1d_flush_type type; - int enable; + bool enable;

/* Default to fallback in case fw-features are not available */ type = L1D_FLUSH_FALLBACK; - enable = 1;

np = of_find_node_by_name(NULL, "ibm,opal"); fw_features = of_get_child_by_name(np, "fw-features"); @@ -111,40 +110,20 @@ static void pnv_setup_rfi_flush(void)

if (fw_features) { init_fw_feat_flags(fw_features); + of_node_put(fw_features);

- np = of_get_child_by_name(fw_features, "inst-l1d-flush-trig2"); - if (np && of_property_read_bool(np, "enabled")) + if (security_ftr_enabled(SEC_FTR_L1D_FLUSH_TRIG2)) type = L1D_FLUSH_MTTRIG;

- of_node_put(np); - - np = of_get_child_by_name(fw_features, "inst-l1d-flush-ori30,30,0"); - if (np && of_property_read_bool(np, "enabled")) + if (security_ftr_enabled(SEC_FTR_L1D_FLUSH_ORI30)) type = L1D_FLUSH_ORI; - - of_node_put(np); - - /* Enable unless firmware says NOT to */ - enable = 2; - np = of_get_child_by_name(fw_features, "needs-l1d-flush-msr-hv-1-to-0"); - if (np && of_property_read_bool(np, "disabled")) - enable--; - - of_node_put(np); - - np = of_get_child_by_name(fw_features, "needs-l1d-flush-msr-pr-0-to-1"); - if (np && of_property_read_bool(np, "disabled")) - enable--; - - np = of_get_child_by_name(fw_features, "speculation-policy-favor-security"); - if (np && of_property_read_bool(np, "disabled")) - enable = 0; - - of_node_put(np); - of_node_put(fw_features); }

- setup_rfi_flush(type, enable > 0); + enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) && \ + (security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) || \ + security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV)); + + setup_rfi_flush(type, enable); }

static void __init pnv_setup_arch(void)

commit 56986016cb8cd9050e601831fe89f332b4e3c46e upstream.

Add a definition for cpu_show_spectre_v1() to override the generic version. Currently this just prints "Not affected" or "Vulnerable" based on the firmware flag.

Although the kernel does have array_index_nospec() in a few places, we haven't yet audited all the powerpc code to see where it's necessary, so for now we don't list that as a mitigation.

Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/kernel/security.c | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c index 865db6f8bcca..0eace3cac818 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -50,3 +50,11 @@ ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, cha

return sprintf(buf, "Vulnerable\n"); } + +ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf) +{ + if (!security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) + return sprintf(buf, "Not affected\n"); + + return sprintf(buf, "Vulnerable\n"); +}

From: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com

commit 0f9bdfe3c77091e8704d2e510eb7c2c2c6cde524 upstream.

The H_CPU_BEHAV_* flags should be checked for in the 'behaviour' field of 'struct h_cpu_char_result' -- 'character' is for H_CPU_CHAR_* flags.

Found by playing around with QEMU's implementation of the hypercall:

H_CPU_CHAR=0xf000000000000000 H_CPU_BEHAV=0x0000000000000000

This clears H_CPU_BEHAV_FAVOUR_SECURITY and H_CPU_BEHAV_L1D_FLUSH_PR so pseries_setup_rfi_flush() disables 'rfi_flush'; and it also clears H_CPU_CHAR_L1D_THREAD_PRIV flag. So there is no RFI flush mitigation at all for cpu_show_meltdown() to report; but currently it does:

Original kernel:

# cat /sys/devices/system/cpu/vulnerabilities/meltdown Mitigation: RFI Flush

Patched kernel:

# cat /sys/devices/system/cpu/vulnerabilities/meltdown Not affected

H_CPU_CHAR=0x0000000000000000 H_CPU_BEHAV=0xf000000000000000

This sets H_CPU_BEHAV_BNDS_CHK_SPEC_BAR so cpu_show_spectre_v1() should report vulnerable; but currently it doesn't:

Original kernel:

# cat /sys/devices/system/cpu/vulnerabilities/spectre_v1 Not affected

Patched kernel:

# cat /sys/devices/system/cpu/vulnerabilities/spectre_v1 Vulnerable

Brown-paper-bag-by: Michael Ellerman mpe@ellerman.id.au Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags") Signed-off-by: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- arch/powerpc/platforms/pseries/setup.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 905e54878fed..6b2152839c48 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -484,13 +484,13 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result) * The features below are enabled by default, so we instead look to see * if firmware has *disabled* them, and clear them if so. */ - if (!(result->character & H_CPU_BEHAV_FAVOUR_SECURITY)) + if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY)) security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);

- if (!(result->character & H_CPU_BEHAV_L1D_FLUSH_PR)) + if (!(result->behaviour & H_CPU_BEHAV_L1D_FLUSH_PR)) security_ftr_clear(SEC_FTR_L1D_FLUSH_PR);

- if (!(result->character & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR)) + if (!(result->behaviour & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR)) security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR); }

From: Nicholas Piggin npiggin@gmail.com

commit a048a07d7f4535baa4cbad6bc024f175317ab938 upstream.

On some CPUs we can prevent a vulnerability related to store-to-load forwarding by preventing store forwarding between privilege domains, by inserting a barrier in kernel entry and exit paths.

This is known to be the case on at least Power7, Power8 and Power9 powerpc CPUs.

Barriers must be inserted generally before the first load after moving to a higher privilege, and after the last store before moving to a lower privilege, HV and PR privilege transitions must be protected.

Barriers are added as patch sections, with all kernel/hypervisor entry points patched, and the exit points to lower privilge levels patched similarly to the RFI flush patching.

Firmware advertisement is not implemented yet, so CPU flush types are hard coded.

Thanks to Michal Suchánek for bug fixes and review.

Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com Signed-off-by: Michael Neuling mikey@neuling.org Signed-off-by: Michal Suchánek msuchanek@suse.de Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Linus Torvalds torvalds@linux-foundation.org --- arch/powerpc/include/asm/exception-64s.h | 29 ++++++ arch/powerpc/include/asm/feature-fixups.h | 19 ++++ arch/powerpc/include/asm/security_features.h | 11 ++ arch/powerpc/kernel/exceptions-64s.S | 19 +++- arch/powerpc/kernel/security.c | 149 +++++++++++++++++++++++++++ arch/powerpc/kernel/vmlinux.lds.S | 14 +++ arch/powerpc/lib/feature-fixups.c | 115 +++++++++++++++++++++ arch/powerpc/platforms/powernv/setup.c | 1 + arch/powerpc/platforms/pseries/setup.c | 1 + 9 files changed, 356 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index 471b2274fbeb..c40b4380951c 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -74,6 +74,27 @@ */ #define EX_R3 EX_DAR

+#define STF_ENTRY_BARRIER_SLOT \ + STF_ENTRY_BARRIER_FIXUP_SECTION; \ + nop; \ + nop; \ + nop + +#define STF_EXIT_BARRIER_SLOT \ + STF_EXIT_BARRIER_FIXUP_SECTION; \ + nop; \ + nop; \ + nop; \ + nop; \ + nop; \ + nop + +/* + * r10 must be free to use, r13 must be paca + */ +#define INTERRUPT_TO_KERNEL \ + STF_ENTRY_BARRIER_SLOT + /* * Macros for annotating the expected destination of (h)rfid * @@ -90,16 +111,19 @@ rfid

#define RFI_TO_USER \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ rfid; \ b rfi_flush_fallback

#define RFI_TO_USER_OR_KERNEL \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ rfid; \ b rfi_flush_fallback

#define RFI_TO_GUEST \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ rfid; \ b rfi_flush_fallback @@ -108,21 +132,25 @@ hrfid

#define HRFI_TO_USER \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ hrfid; \ b hrfi_flush_fallback

#define HRFI_TO_USER_OR_KERNEL \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ hrfid; \ b hrfi_flush_fallback

#define HRFI_TO_GUEST \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ hrfid; \ b hrfi_flush_fallback

#define HRFI_TO_UNKNOWN \ + STF_EXIT_BARRIER_SLOT; \ RFI_FLUSH_SLOT; \ hrfid; \ b hrfi_flush_fallback @@ -254,6 +282,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) #define __EXCEPTION_PROLOG_1_PRE(area) \ OPT_SAVE_REG_TO_PACA(area+EX_PPR, r9, CPU_FTR_HAS_PPR); \ OPT_SAVE_REG_TO_PACA(area+EX_CFAR, r10, CPU_FTR_CFAR); \ + INTERRUPT_TO_KERNEL; \ SAVE_CTR(r10, area); \ mfcr r9;

diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h index 1e82eb3caabd..a9b64df34e2a 100644 --- a/arch/powerpc/include/asm/feature-fixups.h +++ b/arch/powerpc/include/asm/feature-fixups.h @@ -187,6 +187,22 @@ label##3: \ FTR_ENTRY_OFFSET label##1b-label##3b; \ .popsection;

+#define STF_ENTRY_BARRIER_FIXUP_SECTION \ +953: \ + .pushsection __stf_entry_barrier_fixup,"a"; \ + .align 2; \ +954: \ + FTR_ENTRY_OFFSET 953b-954b; \ + .popsection; + +#define STF_EXIT_BARRIER_FIXUP_SECTION \ +955: \ + .pushsection __stf_exit_barrier_fixup,"a"; \ + .align 2; \ +956: \ + FTR_ENTRY_OFFSET 955b-956b; \ + .popsection; + #define RFI_FLUSH_FIXUP_SECTION \ 951: \ .pushsection __rfi_flush_fixup,"a"; \ @@ -199,6 +215,9 @@ label##3: \ #ifndef __ASSEMBLY__ #include <linux/types.h>

+extern long stf_barrier_fallback; +extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup; +extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup; extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;

void apply_feature_fixups(void); diff --git a/arch/powerpc/include/asm/security_features.h b/arch/powerpc/include/asm/security_features.h index fa4d2e1cf772..44989b22383c 100644 --- a/arch/powerpc/include/asm/security_features.h +++ b/arch/powerpc/include/asm/security_features.h @@ -12,6 +12,17 @@ extern unsigned long powerpc_security_features; extern bool rfi_flush;

+/* These are bit flags */ +enum stf_barrier_type { + STF_BARRIER_NONE = 0x1, + STF_BARRIER_FALLBACK = 0x2, + STF_BARRIER_EIEIO = 0x4, + STF_BARRIER_SYNC_ORI = 0x8, +}; + +void setup_stf_barrier(void); +void do_stf_barrier_fixups(enum stf_barrier_type types); + static inline void security_ftr_set(unsigned long feature) { powerpc_security_features |= feature; diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 1ecfd8ffb098..bf9b94e376fd 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -833,7 +833,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM) #endif

-EXC_REAL_MASKABLE(decrementer, 0x900, 0x80, IRQS_DISABLED) +EXC_REAL_OOL_MASKABLE(decrementer, 0x900, 0x80, IRQS_DISABLED) EXC_VIRT_MASKABLE(decrementer, 0x4900, 0x80, 0x900, IRQS_DISABLED) TRAMP_KVM(PACA_EXGEN, 0x900) EXC_COMMON_ASYNC(decrementer_common, 0x900, timer_interrupt) @@ -909,6 +909,7 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) mtctr r13; \ GET_PACA(r13); \ std r10,PACA_EXGEN+EX_R10(r13); \ + INTERRUPT_TO_KERNEL; \ KVMTEST_PR(0xc00); /* uses r10, branch to do_kvm_0xc00_system_call */ \ HMT_MEDIUM; \ mfctr r9; @@ -917,7 +918,8 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) #define SYSCALL_KVMTEST \ HMT_MEDIUM; \ mr r9,r13; \ - GET_PACA(r13); + GET_PACA(r13); \ + INTERRUPT_TO_KERNEL; #endif #define LOAD_SYSCALL_HANDLER(reg) \ @@ -1455,6 +1457,19 @@ masked_##_H##interrupt: \ b .; \ MASKED_DEC_HANDLER(_H)

+TRAMP_REAL_BEGIN(stf_barrier_fallback) + std r9,PACA_EXRFI+EX_R9(r13) + std r10,PACA_EXRFI+EX_R10(r13) + sync + ld r9,PACA_EXRFI+EX_R9(r13) + ld r10,PACA_EXRFI+EX_R10(r13) + ori 31,31,0 + .rept 14 + b 1f +1: + .endr + blr + TRAMP_REAL_BEGIN(rfi_flush_fallback) SET_SCRATCH0(r13); GET_PACA(r13); diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c index bab5a27ea805..b98a722da915 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -8,6 +8,7 @@ #include <linux/device.h> #include <linux/seq_buf.h>

+#include <asm/debugfs.h> #include <asm/security_features.h>

@@ -86,3 +87,151 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c

return s.len; } + +/* + * Store-forwarding barrier support. + */ + +static enum stf_barrier_type stf_enabled_flush_types; +static bool no_stf_barrier; +bool stf_barrier; + +static int __init handle_no_stf_barrier(char *p) +{ + pr_info("stf-barrier: disabled on command line."); + no_stf_barrier = true; + return 0; +} + +early_param("no_stf_barrier", handle_no_stf_barrier); + +/* This is the generic flag used by other architectures */ +static int __init handle_ssbd(char *p) +{ + if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) { + /* Until firmware tells us, we have the barrier with auto */ + return 0; + } else if (strncmp(p, "off", 3) == 0) { + handle_no_stf_barrier(NULL); + return 0; + } else + return 1; + + return 0; +} +early_param("spec_store_bypass_disable", handle_ssbd); + +/* This is the generic flag used by other architectures */ +static int __init handle_no_ssbd(char *p) +{ + handle_no_stf_barrier(NULL); + return 0; +} +early_param("nospec_store_bypass_disable", handle_no_ssbd); + +static void stf_barrier_enable(bool enable) +{ + if (enable) + do_stf_barrier_fixups(stf_enabled_flush_types); + else + do_stf_barrier_fixups(STF_BARRIER_NONE); + + stf_barrier = enable; +} + +void setup_stf_barrier(void) +{ + enum stf_barrier_type type; + bool enable, hv; + + hv = cpu_has_feature(CPU_FTR_HVMODE); + + /* Default to fallback in case fw-features are not available */ + if (cpu_has_feature(CPU_FTR_ARCH_300)) + type = STF_BARRIER_EIEIO; + else if (cpu_has_feature(CPU_FTR_ARCH_207S)) + type = STF_BARRIER_SYNC_ORI; + else if (cpu_has_feature(CPU_FTR_ARCH_206)) + type = STF_BARRIER_FALLBACK; + else + type = STF_BARRIER_NONE; + + enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) && + (security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) || + (security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && hv)); + + if (type == STF_BARRIER_FALLBACK) { + pr_info("stf-barrier: fallback barrier available\n"); + } else if (type == STF_BARRIER_SYNC_ORI) { + pr_info("stf-barrier: hwsync barrier available\n"); + } else if (type == STF_BARRIER_EIEIO) { + pr_info("stf-barrier: eieio barrier available\n"); + } + + stf_enabled_flush_types = type; + + if (!no_stf_barrier) + stf_barrier_enable(enable); +} + +ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf) +{ + if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) { + const char *type; + switch (stf_enabled_flush_types) { + case STF_BARRIER_EIEIO: + type = "eieio"; + break; + case STF_BARRIER_SYNC_ORI: + type = "hwsync"; + break; + case STF_BARRIER_FALLBACK: + type = "fallback"; + break; + default: + type = "unknown"; + } + return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type); + } + + if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && + !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR)) + return sprintf(buf, "Not affected\n"); + + return sprintf(buf, "Vulnerable\n"); +} + +#ifdef CONFIG_DEBUG_FS +static int stf_barrier_set(void *data, u64 val) +{ + bool enable; + + if (val == 1) + enable = true; + else if (val == 0) + enable = false; + else + return -EINVAL; + + /* Only do anything if we're changing state */ + if (enable != stf_barrier) + stf_barrier_enable(enable); + + return 0; +} + +static int stf_barrier_get(void *data, u64 *val) +{ + *val = stf_barrier ? 1 : 0; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set, "%llu\n"); + +static __init int stf_barrier_debugfs_init(void) +{ + debugfs_create_file("stf_barrier", 0600, powerpc_debugfs_root, NULL, &fops_stf_barrier); + return 0; +} +device_initcall(stf_barrier_debugfs_init); +#endif /* CONFIG_DEBUG_FS */ diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index c8af90ff49f0..b8d82678f8b4 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -133,6 +133,20 @@ SECTIONS RO_DATA(PAGE_SIZE)

#ifdef CONFIG_PPC64 + . = ALIGN(8); + __stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) { + __start___stf_entry_barrier_fixup = .; + *(__stf_entry_barrier_fixup) + __stop___stf_entry_barrier_fixup = .; + } + + . = ALIGN(8); + __stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) { + __start___stf_exit_barrier_fixup = .; + *(__stf_exit_barrier_fixup) + __stop___stf_exit_barrier_fixup = .; + } + . = ALIGN(8); __rfi_flush_fixup : AT(ADDR(__rfi_flush_fixup) - LOAD_OFFSET) { __start___rfi_flush_fixup = .; diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c index f61ff5a6bddb..6b3c2d405a6d 100644 --- a/arch/powerpc/lib/feature-fixups.c +++ b/arch/powerpc/lib/feature-fixups.c @@ -23,6 +23,7 @@ #include <asm/page.h> #include <asm/sections.h> #include <asm/setup.h> +#include <asm/security_features.h> #include <asm/firmware.h>

struct fixup_entry { @@ -117,6 +118,120 @@ void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end) }

#ifdef CONFIG_PPC_BOOK3S_64 +void do_stf_entry_barrier_fixups(enum stf_barrier_type types) +{ + unsigned int instrs[3], *dest; + long *start, *end; + int i; + + start = PTRRELOC(&__start___stf_entry_barrier_fixup), + end = PTRRELOC(&__stop___stf_entry_barrier_fixup); + + instrs[0] = 0x60000000; /* nop */ + instrs[1] = 0x60000000; /* nop */ + instrs[2] = 0x60000000; /* nop */ + + i = 0; + if (types & STF_BARRIER_FALLBACK) { + instrs[i++] = 0x7d4802a6; /* mflr r10 */ + instrs[i++] = 0x60000000; /* branch patched below */ + instrs[i++] = 0x7d4803a6; /* mtlr r10 */ + } else if (types & STF_BARRIER_EIEIO) { + instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */ + } else if (types & STF_BARRIER_SYNC_ORI) { + instrs[i++] = 0x7c0004ac; /* hwsync */ + instrs[i++] = 0xe94d0000; /* ld r10,0(r13) */ + instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */ + } + + for (i = 0; start < end; start++, i++) { + dest = (void *)start + *start; + + pr_devel("patching dest %lx\n", (unsigned long)dest); + + patch_instruction(dest, instrs[0]); + + if (types & STF_BARRIER_FALLBACK) + patch_branch(dest + 1, (unsigned long)&stf_barrier_fallback, + BRANCH_SET_LINK); + else + patch_instruction(dest + 1, instrs[1]); + + patch_instruction(dest + 2, instrs[2]); + } + + printk(KERN_DEBUG "stf-barrier: patched %d entry locations (%s barrier)\n", i, + (types == STF_BARRIER_NONE) ? "no" : + (types == STF_BARRIER_FALLBACK) ? "fallback" : + (types == STF_BARRIER_EIEIO) ? "eieio" : + (types == (STF_BARRIER_SYNC_ORI)) ? "hwsync" + : "unknown"); +} + +void do_stf_exit_barrier_fixups(enum stf_barrier_type types) +{ + unsigned int instrs[6], *dest; + long *start, *end; + int i; + + start = PTRRELOC(&__start___stf_exit_barrier_fixup), + end = PTRRELOC(&__stop___stf_exit_barrier_fixup); + + instrs[0] = 0x60000000; /* nop */ + instrs[1] = 0x60000000; /* nop */ + instrs[2] = 0x60000000; /* nop */ + instrs[3] = 0x60000000; /* nop */ + instrs[4] = 0x60000000; /* nop */ + instrs[5] = 0x60000000; /* nop */ + + i = 0; + if (types & STF_BARRIER_FALLBACK || types & STF_BARRIER_SYNC_ORI) { + if (cpu_has_feature(CPU_FTR_HVMODE)) { + instrs[i++] = 0x7db14ba6; /* mtspr 0x131, r13 (HSPRG1) */ + instrs[i++] = 0x7db04aa6; /* mfspr r13, 0x130 (HSPRG0) */ + } else { + instrs[i++] = 0x7db243a6; /* mtsprg 2,r13 */ + instrs[i++] = 0x7db142a6; /* mfsprg r13,1 */ + } + instrs[i++] = 0x7c0004ac; /* hwsync */ + instrs[i++] = 0xe9ad0000; /* ld r13,0(r13) */ + instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */ + if (cpu_has_feature(CPU_FTR_HVMODE)) { + instrs[i++] = 0x7db14aa6; /* mfspr r13, 0x131 (HSPRG1) */ + } else { + instrs[i++] = 0x7db242a6; /* mfsprg r13,2 */ + } + } else if (types & STF_BARRIER_EIEIO) { + instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */ + } + + for (i = 0; start < end; start++, i++) { + dest = (void *)start + *start; + + pr_devel("patching dest %lx\n", (unsigned long)dest); + + patch_instruction(dest, instrs[0]); + patch_instruction(dest + 1, instrs[1]); + patch_instruction(dest + 2, instrs[2]); + patch_instruction(dest + 3, instrs[3]); + patch_instruction(dest + 4, instrs[4]); + patch_instruction(dest + 5, instrs[5]); + } + printk(KERN_DEBUG "stf-barrier: patched %d exit locations (%s barrier)\n", i, + (types == STF_BARRIER_NONE) ? "no" : + (types == STF_BARRIER_FALLBACK) ? "fallback" : + (types == STF_BARRIER_EIEIO) ? "eieio" : + (types == (STF_BARRIER_SYNC_ORI)) ? "hwsync" + : "unknown"); +} + + +void do_stf_barrier_fixups(enum stf_barrier_type types) +{ + do_stf_entry_barrier_fixups(types); + do_stf_exit_barrier_fixups(types); +} + void do_rfi_flush_fixups(enum l1d_flush_type types) { unsigned int instrs[3], *dest; diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c index 7de050a3736b..fc0412d59149 100644 --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -131,6 +131,7 @@ static void __init pnv_setup_arch(void) set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT);

pnv_setup_rfi_flush(); + setup_stf_barrier();

/* Initialize SMP */ pnv_smp_init(); diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 6b2152839c48..21fed38bbbd5 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -699,6 +699,7 @@ static void __init pSeries_setup_arch(void) fwnmi_init();

pseries_setup_rfi_flush(); + setup_stf_barrier();

/* By default, only probe PCI (can be overridden by rtas_pci) */ pci_add_flags(PCI_PROBE_ONLY);