Messages in this thread Patch in this message | | | Date | Mon, 17 Sep 2018 22:17:30 -0700 (PDT) | From | Zhenzhong Duan <> | Subject | [PATCH] x86/speculation: Use AMD specific retpoline for inline asm on AMD |
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Lfence is preferred than general retpoline on AMD, add this option in C / inline asm just as the ASM code does.
For x86_64, it still help to have minimal retpoline for kernel even if gcc doesn't support it, change the inline asm for x86 so that it could also be used by x86_64.
Add ANNOTATE_NOSPEC_ALTERNATIVE for i386 to avoid below warning: "warning: objtool: .altinstr_replacement+0x10: unsupported intra-function call" "warning: objtool: If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE."
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> --- arch/x86/include/asm/nospec-branch.h | 23 ++++++++++++++++------- 1 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index fd2a8c1..2d49eab 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -170,21 +170,26 @@ */ # define CALL_NOSPEC \ ANNOTATE_NOSPEC_ALTERNATIVE \ - ALTERNATIVE( \ + ALTERNATIVE_2( \ ANNOTATE_RETPOLINE_SAFE \ "call *%[thunk_target]\n", \ "call __x86_indirect_thunk_%V[thunk_target]\n", \ - X86_FEATURE_RETPOLINE) + X86_FEATURE_RETPOLINE, \ + "lfence;\n" \ + ANNOTATE_RETPOLINE_SAFE \ + "call *%[thunk_target]\n", \ + X86_FEATURE_RETPOLINE_AMD) # define THUNK_TARGET(addr) [thunk_target] "r" (addr) -#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE) +#elif defined(CONFIG_RETPOLINE) /* * For i386 we use the original ret-equivalent retpoline, because * otherwise we'll run out of registers. We don't care about CET * here, anyway. */ # define CALL_NOSPEC \ - ALTERNATIVE( \ + ANNOTATE_NOSPEC_ALTERNATIVE \ + ALTERNATIVE_2( \ ANNOTATE_RETPOLINE_SAFE \ "call *%[thunk_target]\n", \ " jmp 904f;\n" \ @@ -194,12 +199,16 @@ " lfence;\n" \ " jmp 902b;\n" \ " .align 16\n" \ - "903: addl $4, %%esp;\n" \ - " pushl %[thunk_target];\n" \ + "903: add $4, %%" _ASM_SP ";\n" \ + " push %[thunk_target];\n" \ " ret;\n" \ " .align 16\n" \ "904: call 901b;\n", \ - X86_FEATURE_RETPOLINE) + X86_FEATURE_RETPOLINE, \ + "lfence;\n" \ + ANNOTATE_RETPOLINE_SAFE \ + "call *%[thunk_target]\n", \ + X86_FEATURE_RETPOLINE_AMD) # define THUNK_TARGET(addr) [thunk_target] "rm" (addr) #else /* No retpoline for C / inline asm */ -- 1.7.3
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