The patch titled
Subject: x86: use static_cpu_has in uaccess region to avoid instrumentation
has been added to the -mm tree. Its filename is
x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation.patch
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------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
Subject: x86: use static_cpu_has in uaccess region to avoid instrumentation
This patch is a pre-requisite for enabling KASAN bitops instrumentation;
using static_cpu_has instead of boot_cpu_has avoids instrumentation of
test_bit inside the uaccess region. With instrumentation, the KASAN check
would otherwise be flagged by objtool.
For consistency, kernel/signal.c was changed to mirror this change,
however, is never instrumented with KASAN (currently unsupported under x86
32bit).
Link: http://lkml.kernel.org/r/20190613125950.197667-3-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Suggested-by: H. Peter Anvin <hpa@xxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/ia32/ia32_signal.c | 2 +-
arch/x86/kernel/signal.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/ia32/ia32_signal.c~x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation
+++ a/arch/x86/ia32/ia32_signal.c
@@ -358,7 +358,7 @@ int ia32_setup_rt_frame(int sig, struct
put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
/* Create the ucontext. */
- if (boot_cpu_has(X86_FEATURE_XSAVE))
+ if (static_cpu_has(X86_FEATURE_XSAVE))
put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
else
put_user_ex(0, &frame->uc.uc_flags);
--- a/arch/x86/kernel/signal.c~x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation
+++ a/arch/x86/kernel/signal.c
@@ -391,7 +391,7 @@ static int __setup_rt_frame(int sig, str
put_user_ex(&frame->uc, &frame->puc);
/* Create the ucontext. */
- if (boot_cpu_has(X86_FEATURE_XSAVE))
+ if (static_cpu_has(X86_FEATURE_XSAVE))
put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
else
put_user_ex(0, &frame->uc.uc_flags);
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
lib-test_kasan-add-bitops-tests.patch
x86-use-static_cpu_has-in-uaccess-region-to-avoid-instrumentation.patch
asm-generic-x86-add-bitops-instrumentation-for-kasan.patch
mm-kasan-print-frame-description-for-stack-bugs.patch
