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.d...@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
