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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-08 03:21:31 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-08 03:21:31 +0000 |
| commit | 5dca02f2ee931aef66bb21dd8067c8b1af1e0d3e (patch) | |
| tree | 6581b770eb1bd6cac1252a5451b89c092ea4c797 /arch/x86/include/asm/nospec-branch.h | |
| parent | Adding debian version 4.19.249-2. (diff) | |
| download | linux-5dca02f2ee931aef66bb21dd8067c8b1af1e0d3e.tar.xz linux-5dca02f2ee931aef66bb21dd8067c8b1af1e0d3e.zip | |
Merging upstream version 4.19.260.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/include/asm/nospec-branch.h')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index d3d68b676..17a236a8b 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -35,6 +35,7 @@ * the optimal version — two calls, each with their own speculation * trap should their return address end up getting used, in a loop. */ +#ifdef CONFIG_X86_64 #define __FILL_RETURN_BUFFER(reg, nr, sp) \ mov $(nr/2), reg; \ 771: \ @@ -52,7 +53,30 @@ 774: \ dec reg; \ jnz 771b; \ + add $(BITS_PER_LONG/8) * nr, sp; \ + /* barrier for jnz misprediction */ \ + lfence; +#else +/* + * i386 doesn't unconditionally have LFENCE, as such it can't + * do a loop. + */ +#define __FILL_RETURN_BUFFER(reg, nr, sp) \ + .rept nr; \ + call 772f; \ + int3; \ +772:; \ + .endr; \ add $(BITS_PER_LONG/8) * nr, sp; +#endif + +/* Sequence to mitigate PBRSB on eIBRS CPUs */ +#define __ISSUE_UNBALANCED_RET_GUARD(sp) \ + call 881f; \ + int3; \ +881: \ + add $(BITS_PER_LONG/8), sp; \ + lfence; #ifdef __ASSEMBLY__ @@ -269,6 +293,13 @@ static inline void vmexit_fill_RSB(void) : "=r" (loops), ASM_CALL_CONSTRAINT : : "memory" ); #endif + asm volatile (ANNOTATE_NOSPEC_ALTERNATIVE + ALTERNATIVE("jmp 920f", + __stringify(__ISSUE_UNBALANCED_RET_GUARD(%0)), + X86_FEATURE_RSB_VMEXIT_LITE) + "920:" + : ASM_CALL_CONSTRAINT + : : "memory" ); } static __always_inline |