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-rw-r--r--common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-spectre_v1-Disable-compiler-optimizations-over-a.patch84
1 files changed, 0 insertions, 84 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-spectre_v1-Disable-compiler-optimizations-over-a.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-spectre_v1-Disable-compiler-optimizations-over-a.patch
deleted file mode 100644
index a8632983..00000000
--- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-spectre_v1-Disable-compiler-optimizations-over-a.patch
+++ /dev/null
@@ -1,84 +0,0 @@
-From d98751217028054a791c98512d1ed81d406f55da Mon Sep 17 00:00:00 2001
-From: Dan Williams <dan.j.williams@intel.com>
-Date: Thu, 7 Jun 2018 09:13:48 -0700
-Subject: [PATCH 06/10] x86/spectre_v1: Disable compiler optimizations over
- array_index_mask_nospec()
-
-commit eab6870fee877258122a042bfd99ee7908c40280 upstream.
-
-Mark Rutland noticed that GCC optimization passes have the potential to elide
-necessary invocations of the array_index_mask_nospec() instruction sequence,
-so mark the asm() volatile.
-
-Mark explains:
-
-"The volatile will inhibit *some* cases where the compiler could lift the
- array_index_nospec() call out of a branch, e.g. where there are multiple
- invocations of array_index_nospec() with the same arguments:
-
- if (idx < foo) {
- idx1 = array_idx_nospec(idx, foo)
- do_something(idx1);
- }
-
- < some other code >
-
- if (idx < foo) {
- idx2 = array_idx_nospec(idx, foo);
- do_something_else(idx2);
- }
-
- ... since the compiler can determine that the two invocations yield the same
- result, and reuse the first result (likely the same register as idx was in
- originally) for the second branch, effectively re-writing the above as:
-
- if (idx < foo) {
- idx = array_idx_nospec(idx, foo);
- do_something(idx);
- }
-
- < some other code >
-
- if (idx < foo) {
- do_something_else(idx);
- }
-
- ... if we don't take the first branch, then speculatively take the second, we
- lose the nospec protection.
-
- There's more info on volatile asm in the GCC docs:
-
- https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Volatile
- "
-
-Reported-by: Mark Rutland <mark.rutland@arm.com>
-Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-Acked-by: Mark Rutland <mark.rutland@arm.com>
-Acked-by: Thomas Gleixner <tglx@linutronix.de>
-Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
-Cc: <stable@vger.kernel.org>
-Cc: Peter Zijlstra <peterz@infradead.org>
-Fixes: babdde2698d4 ("x86: Implement array_index_mask_nospec")
-Link: https://lkml.kernel.org/lkml/152838798950.14521.4893346294059739135.stgit@dwillia2-desk3.amr.corp.intel.com
-Signed-off-by: Ingo Molnar <mingo@kernel.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- arch/x86/include/asm/barrier.h | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
-index 78d1c6a..eb53c2c 100644
---- a/arch/x86/include/asm/barrier.h
-+++ b/arch/x86/include/asm/barrier.h
-@@ -37,7 +37,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
- {
- unsigned long mask;
-
-- asm ("cmp %1,%2; sbb %0,%0;"
-+ asm volatile ("cmp %1,%2; sbb %0,%0;"
- :"=r" (mask)
- :"g"(size),"r" (index)
- :"cc");
---
-2.7.4
-