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| author | Peter Zijlstra <peterz@infradead.org> | 2020-04-14 12:36:16 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-04-30 20:14:34 +0200 |
| commit | 089dd8e53126ebaf506e2dc0bf89d652c36bfc12 (patch) | |
| tree | 7a3823e8af26ae775f76352b555eb7907ee09a0d /arch/x86/include/asm/nospec-branch.h | |
| parent | 8aa8eb2a8f5b3305a95f39957dd2b715fa668e21 (diff) | |
| download | linux-stable-089dd8e53126ebaf506e2dc0bf89d652c36bfc12.tar.gz linux-stable-089dd8e53126ebaf506e2dc0bf89d652c36bfc12.tar.bz2 linux-stable-089dd8e53126ebaf506e2dc0bf89d652c36bfc12.zip | |
x86/speculation: Change FILL_RETURN_BUFFER to work with objtool
Change FILL_RETURN_BUFFER so that objtool groks it and can generate
correct ORC unwind information.
- Since ORC is alternative invariant; that is, all alternatives
should have the same ORC entries, the __FILL_RETURN_BUFFER body
can not be part of an alternative.
Therefore, move it out of the alternative and keep the alternative
as a sort of jump_label around it.
- Use the ANNOTATE_INTRA_FUNCTION_CALL annotation to white-list
these 'funny' call instructions to nowhere.
- Use UNWIND_HINT_EMPTY to 'fill' the speculation traps, otherwise
objtool will consider them unreachable.
- Move the RSP adjustment into the loop, such that the loop has a
deterministic stack layout.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191700.032079304@infradead.org
Diffstat (limited to 'arch/x86/include/asm/nospec-branch.h')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 7e9a281e2660..b8890e18f624 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -4,11 +4,13 @@ #define _ASM_X86_NOSPEC_BRANCH_H_ #include <linux/static_key.h> +#include <linux/frame.h> #include <asm/alternative.h> #include <asm/alternative-asm.h> #include <asm/cpufeatures.h> #include <asm/msr-index.h> +#include <asm/unwind_hints.h> /* * This should be used immediately before a retpoline alternative. It tells @@ -46,21 +48,25 @@ #define __FILL_RETURN_BUFFER(reg, nr, sp) \ mov $(nr/2), reg; \ 771: \ + ANNOTATE_INTRA_FUNCTION_CALL; \ call 772f; \ 773: /* speculation trap */ \ + UNWIND_HINT_EMPTY; \ pause; \ lfence; \ jmp 773b; \ 772: \ + ANNOTATE_INTRA_FUNCTION_CALL; \ call 774f; \ 775: /* speculation trap */ \ + UNWIND_HINT_EMPTY; \ pause; \ lfence; \ jmp 775b; \ 774: \ + add $(BITS_PER_LONG/8) * 2, sp; \ dec reg; \ - jnz 771b; \ - add $(BITS_PER_LONG/8) * nr, sp; + jnz 771b; #ifdef __ASSEMBLY__ @@ -137,10 +143,8 @@ */ .macro FILL_RETURN_BUFFER reg:req nr:req ftr:req #ifdef CONFIG_RETPOLINE - ANNOTATE_NOSPEC_ALTERNATIVE - ALTERNATIVE "jmp .Lskip_rsb_\@", \ - __stringify(__FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP)) \ - \ftr + ALTERNATIVE "jmp .Lskip_rsb_\@", "", \ftr + __FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP) .Lskip_rsb_\@: #endif .endm |