From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> commit 089dd8e53126ebaf506e2dc0bf89d652c36bfc12 upstream. 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@xxxxxxxxxxxxx> Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx> Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20200428191700.032079304@xxxxxxxxxxxxx [ bp: no intra-function call validation support ] Signed-off-by: Suraj Jitindar Singh <surajjs@xxxxxxxxxx> --- arch/x86/include/asm/nospec-branch.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 3a1e3062f244..652c1159a6f6 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> /* * Fill the CPU return stack buffer. @@ -50,9 +52,9 @@ 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__ @@ -142,10 +144,8 @@ */ .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 -- 2.17.1
