diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0090-x86-retpoline-Optimize-inline-assembler-for-vmexit_f.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0090-x86-retpoline-Optimize-inline-assembler-for-vmexit_f.patch | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0090-x86-retpoline-Optimize-inline-assembler-for-vmexit_f.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0090-x86-retpoline-Optimize-inline-assembler-for-vmexit_f.patch new file mode 100644 index 00000000..5cfbebeb --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0090-x86-retpoline-Optimize-inline-assembler-for-vmexit_f.patch @@ -0,0 +1,61 @@ +From e06fc5b3f4c084453bad0d92f40888aad431d9bb Mon Sep 17 00:00:00 2001 +From: Andi Kleen <ak@linux.intel.com> +Date: Wed, 17 Jan 2018 14:53:28 -0800 +Subject: [PATCH 090/103] x86/retpoline: Optimize inline assembler for + vmexit_fill_RSB + +commit 3f7d875566d8e79c5e0b2c9a413e91b2c29e0854 upstream. + +The generated assembler for the C fill RSB inline asm operations has +several issues: + +- The C code sets up the loop register, which is then immediately + overwritten in __FILL_RETURN_BUFFER with the same value again. + +- The C code also passes in the iteration count in another register, which + is not used at all. + +Remove these two unnecessary operations. Just rely on the single constant +passed to the macro for the iterations. + +Signed-off-by: Andi Kleen <ak@linux.intel.com> +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Acked-by: David Woodhouse <dwmw@amazon.co.uk> +Cc: dave.hansen@intel.com +Cc: gregkh@linuxfoundation.org +Cc: torvalds@linux-foundation.org +Cc: arjan@linux.intel.com +Link: https://lkml.kernel.org/r/20180117225328.15414-1-andi@firstfloor.org +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/include/asm/nospec-branch.h | 7 ++++--- + 1 file changed, 4 insertions(+), 3 deletions(-) + +diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h +index 19ba5ad..4ad4108 100644 +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -206,16 +206,17 @@ extern char __indirect_thunk_end[]; + static inline void vmexit_fill_RSB(void) + { + #ifdef CONFIG_RETPOLINE +- unsigned long loops = RSB_CLEAR_LOOPS / 2; ++ unsigned long loops; + + asm volatile (ANNOTATE_NOSPEC_ALTERNATIVE + ALTERNATIVE("jmp 910f", + __stringify(__FILL_RETURN_BUFFER(%0, RSB_CLEAR_LOOPS, %1)), + X86_FEATURE_RETPOLINE) + "910:" +- : "=&r" (loops), ASM_CALL_CONSTRAINT +- : "r" (loops) : "memory" ); ++ : "=r" (loops), ASM_CALL_CONSTRAINT ++ : : "memory" ); + #endif + } ++ + #endif /* __ASSEMBLY__ */ + #endif /* __NOSPEC_BRANCH_H__ */ +-- +2.7.4 + |