January 2021 - Linux-stable-mirror

[PATCH] MIPS: VDSO: Use CLANG_FLAGS instead of filtering out '--target='

by Nathan Chancellor

Commit ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO cflags") allowed the '--target=' flag from the main Makefile to filter through to the vDSO. However, it did not bring any of the other clang specific flags for controlling the integrated assembler and the GNU tools locations (--prefix=, --gcc-toolchain=, and -no-integrated-as). Without these, we will get a warning (visible with tinyconfig): arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit .pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3: ^ arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit .section .mips_abiflags, "a" ^ All of these flags are bundled up under CLANG_FLAGS in the main Makefile and exported so that they can be added to Makefiles that set their own CFLAGS. Use this value instead of filtering out '--target=' so there is no warning and all of the tools are properly used. Cc: stable(a)vger.kernel.org Fixes: ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO cflags") Link: https://github.com/ClangBuiltLinux/linux/issues/1256 Reported-by: Anders Roxell <anders.roxell(a)linaro.org> Signed-off-by: Nathan Chancellor <natechancellor(a)gmail.com> --- arch/mips/vdso/Makefile | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index 5810cc12bc1d..2131d3fd7333 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -16,16 +16,13 @@ ccflags-vdso := \ $(filter -march=%,$(KBUILD_CFLAGS)) \ $(filter -m%-float,$(KBUILD_CFLAGS)) \ $(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \ + $(CLANG_FLAGS) \ -D__VDSO__ ifndef CONFIG_64BIT ccflags-vdso += -DBUILD_VDSO32 endif -ifdef CONFIG_CC_IS_CLANG -ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS)) -endif - # # The -fno-jump-tables flag only prevents the compiler from generating # jump tables but does not prevent the compiler from emitting absolute base-commit: 7b490a8ab0f2d3ab8d838a4ff22ae86edafd34a1 -- 2.30.0

4 years, 4 months

3
2
0 0

[PATCH 2/3] drm/ingenic: Register devm action to cleanup encoders

by Paul Cercueil

Since the encoders have been devm-allocated, they will be freed way before drm_mode_config_cleanup() is called. To avoid use-after-free conditions, we then must ensure that drm_encoder_cleanup() is called before the encoders are freed. Fixes: c369cb27c267 ("drm/ingenic: Support multiple panels/bridges") Cc: <stable(a)vger.kernel.org> # 5.8+ Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> --- drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c index 368bfef8b340..d23a3292a0e0 100644 --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c @@ -803,6 +803,11 @@ static void __maybe_unused ingenic_drm_release_rmem(void *d) of_reserved_mem_device_release(d); } +static void ingenic_drm_encoder_cleanup(void *encoder) +{ + drm_encoder_cleanup(encoder); +} + static int ingenic_drm_bind(struct device *dev, bool has_components) { struct platform_device *pdev = to_platform_device(dev); @@ -1011,6 +1016,11 @@ static int ingenic_drm_bind(struct device *dev, bool has_components) return ret; } + ret = devm_add_action_or_reset(dev, ingenic_drm_encoder_cleanup, + encoder); + if (ret) + return ret; + ret = drm_bridge_attach(encoder, bridge, NULL, 0); if (ret) { dev_err(dev, "Unable to attach bridge\n"); -- 2.29.2

4 years, 4 months

3
3
0 0

[PATCH] drm/i915: Check for rq->hwsp validity after acquiring RCU lock

by Chris Wilson

Since we allow removing the timeline map at runtime, there is a risk that rq->hwsp points into a stale page. To control that risk, we hold the RCU read lock while reading *rq->hwsp, but we missed a couple of important barriers. First, the unpinning / removal of the timeline map must be after all RCU readers into that map are complete, i.e. after an rcu barrier (in this case courtesy of call_rcu()). Secondly, we must make sure that the rq->hwsp we are about to dereference under the RCU lock is valid. In this case, we make the rq->hwsp pointer safe during i915_request_retire() and so we know that rq->hwsp may become invalid only after the request has been signaled. Therefore is the request is not yet signaled when we acquire rq->hwsp under the RCU, we know that rq->hwsp will remain valid for the duration of the RCU read lock. This is a very small window that may lead to either considering the request not completed (causing a delay until the request is checked again, any wait for the request is not affected) or dereferencing an invalid pointer. Fixes: 3adac4689f58 ("drm/i915: Introduce concept of per-timeline (context) HWSP") Signed-off-by: Chris Wilson <chris(a)chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin(a)intel.com> Cc: <stable(a)vger.kernel.org> # v5.1+ Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin(a)intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20201218122421.18344-1-chris@… (cherry picked from commit 9bb36cf66091ddf2d8840e5aa705ad3c93a6279b) --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 9 ++--- drivers/gpu/drm/i915/gt/intel_timeline.c | 10 +++--- drivers/gpu/drm/i915/i915_request.h | 37 ++++++++++++++++++--- 3 files changed, 38 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index a24cc1ff08a0..0625cbb3b431 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -134,11 +134,6 @@ static bool remove_signaling_context(struct intel_breadcrumbs *b, return true; } -static inline bool __request_completed(const struct i915_request *rq) -{ - return i915_seqno_passed(__hwsp_seqno(rq), rq->fence.seqno); -} - __maybe_unused static bool check_signal_order(struct intel_context *ce, struct i915_request *rq) { @@ -257,7 +252,7 @@ static void signal_irq_work(struct irq_work *work) list_for_each_entry_rcu(rq, &ce->signals, signal_link) { bool release; - if (!__request_completed(rq)) + if (!__i915_request_is_complete(rq)) break; if (!test_and_clear_bit(I915_FENCE_FLAG_SIGNAL, @@ -379,7 +374,7 @@ static void insert_breadcrumb(struct i915_request *rq) * straight onto a signaled list, and queue the irq worker for * its signal completion. */ - if (__request_completed(rq)) { + if (__i915_request_is_complete(rq)) { if (__signal_request(rq) && llist_add(&rq->signal_node, &b->signaled_requests)) irq_work_queue(&b->irq_work); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 7ea94d201fe6..8015964043eb 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -126,6 +126,10 @@ static void __rcu_cacheline_free(struct rcu_head *rcu) struct intel_timeline_cacheline *cl = container_of(rcu, typeof(*cl), rcu); + /* Must wait until after all *rq->hwsp are complete before removing */ + i915_gem_object_unpin_map(cl->hwsp->vma->obj); + __idle_hwsp_free(cl->hwsp, ptr_unmask_bits(cl->vaddr, CACHELINE_BITS)); + i915_active_fini(&cl->active); kfree(cl); } @@ -133,11 +137,6 @@ static void __rcu_cacheline_free(struct rcu_head *rcu) static void __idle_cacheline_free(struct intel_timeline_cacheline *cl) { GEM_BUG_ON(!i915_active_is_idle(&cl->active)); - - i915_gem_object_unpin_map(cl->hwsp->vma->obj); - i915_vma_put(cl->hwsp->vma); - __idle_hwsp_free(cl->hwsp, ptr_unmask_bits(cl->vaddr, CACHELINE_BITS)); - call_rcu(&cl->rcu, __rcu_cacheline_free); } @@ -179,7 +178,6 @@ cacheline_alloc(struct intel_timeline_hwsp *hwsp, unsigned int cacheline) return ERR_CAST(vaddr); } - i915_vma_get(hwsp->vma); cl->hwsp = hwsp; cl->vaddr = page_pack_bits(vaddr, cacheline); diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 620b6fab2c5c..92adfee30c7c 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -434,7 +434,7 @@ static inline u32 hwsp_seqno(const struct i915_request *rq) static inline bool __i915_request_has_started(const struct i915_request *rq) { - return i915_seqno_passed(hwsp_seqno(rq), rq->fence.seqno - 1); + return i915_seqno_passed(__hwsp_seqno(rq), rq->fence.seqno - 1); } /** @@ -465,11 +465,19 @@ static inline bool __i915_request_has_started(const struct i915_request *rq) */ static inline bool i915_request_started(const struct i915_request *rq) { + bool result; + if (i915_request_signaled(rq)) return true; - /* Remember: started but may have since been preempted! */ - return __i915_request_has_started(rq); + result = true; + rcu_read_lock(); /* the HWSP may be freed at runtime */ + if (likely(!i915_request_signaled(rq))) + /* Remember: started but may have since been preempted! */ + result = __i915_request_has_started(rq); + rcu_read_unlock(); + + return result; } /** @@ -482,10 +490,16 @@ static inline bool i915_request_started(const struct i915_request *rq) */ static inline bool i915_request_is_running(const struct i915_request *rq) { + bool result; + if (!i915_request_is_active(rq)) return false; - return __i915_request_has_started(rq); + rcu_read_lock(); + result = __i915_request_has_started(rq) && i915_request_is_active(rq); + rcu_read_unlock(); + + return result; } /** @@ -509,12 +523,25 @@ static inline bool i915_request_is_ready(const struct i915_request *rq) return !list_empty(&rq->sched.link); } +static inline bool __i915_request_is_complete(const struct i915_request *rq) +{ + return i915_seqno_passed(__hwsp_seqno(rq), rq->fence.seqno); +} + static inline bool i915_request_completed(const struct i915_request *rq) { + bool result; + if (i915_request_signaled(rq)) return true; - return i915_seqno_passed(hwsp_seqno(rq), rq->fence.seqno); + result = true; + rcu_read_lock(); /* the HWSP may be freed at runtime */ + if (likely(!i915_request_signaled(rq))) + result = __i915_request_is_complete(rq); + rcu_read_unlock(); + + return result; } static inline void i915_request_mark_complete(struct i915_request *rq) -- 2.30.0

4 years, 4 months

2
1
0 0

[PATCH v3] i2c: bpmp-tegra: Ignore unknown I2C_M flags

by Mikko Perttunen

In order to not to start returning errors when new I2C_M flags are added, change behavior to just ignore all flags that we don't know about. This includes the I2C_M_DMA_SAFE flag that already exists. Cc: stable(a)vger.kernel.org # v4.19+ Signed-off-by: Mikko Perttunen <mperttunen(a)nvidia.com> --- v3: - Ignore all unknown flags instead of just I2C_M_DMA_SAFE --- drivers/i2c/busses/i2c-tegra-bpmp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-tegra-bpmp.c b/drivers/i2c/busses/i2c-tegra-bpmp.c index ec7a7e917edd..c0c7d01473f2 100644 --- a/drivers/i2c/busses/i2c-tegra-bpmp.c +++ b/drivers/i2c/busses/i2c-tegra-bpmp.c @@ -80,7 +80,7 @@ static int tegra_bpmp_xlate_flags(u16 flags, u16 *out) flags &= ~I2C_M_RECV_LEN; } - return (flags != 0) ? -EINVAL : 0; + return 0; } /** -- 2.30.0

4 years, 4 months

3
3
0 0

[PATCH] mtd: rawnand: gpmi: fix dst bit offset when extracting raw payload

by Sean Nyekjaer

Re-add the multiply by 8 to "step * eccsize" to correct the destination bit offset when extracting the data payload in gpmi_ecc_read_page_raw(). Fixes: e5e5631cc889 ("mtd: rawnand: gpmi: Use nand_extract_bits()") Cc: stable(a)vger.kernel.org Reported-by: Martin Hundebøll <martin(a)geanix.com> Signed-off-by: Sean Nyekjaer <sean(a)geanix.com> --- drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c index dc8104e67506..f0726e69a312 100644 --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c @@ -1611,7 +1611,7 @@ static int gpmi_ecc_read_page_raw(struct nand_chip *chip, uint8_t *buf, /* Extract interleaved payload data and ECC bits */ for (step = 0; step < nfc_geo->ecc_chunk_count; step++) { if (buf) - nand_extract_bits(buf, step * eccsize, tmp_buf, + nand_extract_bits(buf, step * eccsize * 8, tmp_buf, src_bit_off, eccsize * 8); src_bit_off += eccsize * 8; -- 2.29.2

4 years, 4 months

2
5
0 0

[PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols

by Fangrui Song

clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de00833332…) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Reported-by: Marco Elver <elver(a)google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Signed-off-by: Fangrui Song <maskray(a)google.com> Reviewed-by: Nick Desaulniers <ndesaulniers(a)google.com> Tested-by: Marco Elver <elver(a)google.com> Cc: <stable(a)vger.kernel.org> --- Changes in v2: * Fix Marco's email address * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol --- Changes in v3: * Fix the style of a multi-line comment. * Use static bool ignore_undef_symbol. --- kernel/module.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 4bf30e4b3eaa..805c49d1b86d 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2348,6 +2348,21 @@ static int verify_exported_symbols(struct module *mod) return 0; } +static bool ignore_undef_symbol(Elf_Half emachine, const char *name) +{ + /* + * On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. + * i386 has a similar problem but may not deserve a fix. + * + * If we ever have to ignore many symbols, consider refactoring the code to + * only warn if referenced by a relocation. + */ + if (emachine == EM_386 || emachine == EM_X86_64) + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); + return false; +} + /* Change all symbols so that st_value encodes the pointer directly. */ static int simplify_symbols(struct module *mod, const struct load_info *info) { @@ -2395,8 +2410,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) break; } - /* Ok if weak. */ - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) + /* Ok if weak or ignored. */ + if (!ksym && + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || + ignore_undef_symbol(info->hdr->e_machine, name))) break; ret = PTR_ERR(ksym) ?: -ENOENT; -- 2.30.0.296.g2bfb1c46d8-goog

4 years, 4 months

3
2
0 0

FAILED: patch "[PATCH] powerpc: Fix alignment bug within the init sections" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2225a8dda263edc35a0e8b858fe2945cf6240fde Mon Sep 17 00:00:00 2001 From: Ariel Marcovitch <arielmarcovitch(a)gmail.com> Date: Sat, 2 Jan 2021 22:11:56 +0200 Subject: [PATCH] powerpc: Fix alignment bug within the init sections This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch(a)gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy(a)csgroup.eu> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 8e0b1298bf19..4ab426b8b0e0 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -187,6 +187,12 @@ SECTIONS .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { _sinittext = .; INIT_TEXT + + /* + *.init.text might be RO so we must ensure this section ends on + * a page boundary. + */ + . = ALIGN(PAGE_SIZE); _einittext = .; #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); @@ -200,6 +206,8 @@ SECTIONS EXIT_TEXT } + . = ALIGN(PAGE_SIZE); + INIT_DATA_SECTION(16) . = ALIGN(8);

4 years, 4 months

1
0
0 0

FAILED: patch "[PATCH] powerpc: Fix alignment bug within the init sections" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2225a8dda263edc35a0e8b858fe2945cf6240fde Mon Sep 17 00:00:00 2001 From: Ariel Marcovitch <arielmarcovitch(a)gmail.com> Date: Sat, 2 Jan 2021 22:11:56 +0200 Subject: [PATCH] powerpc: Fix alignment bug within the init sections This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch(a)gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy(a)csgroup.eu> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 8e0b1298bf19..4ab426b8b0e0 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -187,6 +187,12 @@ SECTIONS .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { _sinittext = .; INIT_TEXT + + /* + *.init.text might be RO so we must ensure this section ends on + * a page boundary. + */ + . = ALIGN(PAGE_SIZE); _einittext = .; #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); @@ -200,6 +206,8 @@ SECTIONS EXIT_TEXT } + . = ALIGN(PAGE_SIZE); + INIT_DATA_SECTION(16) . = ALIGN(8);

4 years, 4 months

1
0
0 0

FAILED: patch "[PATCH] powerpc: Fix alignment bug within the init sections" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2225a8dda263edc35a0e8b858fe2945cf6240fde Mon Sep 17 00:00:00 2001 From: Ariel Marcovitch <arielmarcovitch(a)gmail.com> Date: Sat, 2 Jan 2021 22:11:56 +0200 Subject: [PATCH] powerpc: Fix alignment bug within the init sections This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch(a)gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy(a)csgroup.eu> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 8e0b1298bf19..4ab426b8b0e0 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -187,6 +187,12 @@ SECTIONS .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { _sinittext = .; INIT_TEXT + + /* + *.init.text might be RO so we must ensure this section ends on + * a page boundary. + */ + . = ALIGN(PAGE_SIZE); _einittext = .; #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); @@ -200,6 +206,8 @@ SECTIONS EXIT_TEXT } + . = ALIGN(PAGE_SIZE); + INIT_DATA_SECTION(16) . = ALIGN(8);

4 years, 4 months

1
0
0 0

FAILED: patch "[PATCH] powerpc: Fix alignment bug within the init sections" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2225a8dda263edc35a0e8b858fe2945cf6240fde Mon Sep 17 00:00:00 2001 From: Ariel Marcovitch <arielmarcovitch(a)gmail.com> Date: Sat, 2 Jan 2021 22:11:56 +0200 Subject: [PATCH] powerpc: Fix alignment bug within the init sections This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch(a)gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy(a)csgroup.eu> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 8e0b1298bf19..4ab426b8b0e0 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -187,6 +187,12 @@ SECTIONS .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { _sinittext = .; INIT_TEXT + + /* + *.init.text might be RO so we must ensure this section ends on + * a page boundary. + */ + . = ALIGN(PAGE_SIZE); _einittext = .; #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); @@ -200,6 +206,8 @@ SECTIONS EXIT_TEXT } + . = ALIGN(PAGE_SIZE); + INIT_DATA_SECTION(16) . = ALIGN(8);

4 years, 4 months

1
0
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-stable-mirror January 2021