| From 9dc5c280e4a5a14bf2df1679d78dc30b85fe750f Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 31 Oct 2019 12:46:52 -0700 |
| Subject: arm64: fix alternatives with LLVM's integrated assembler |
| |
| From: Sami Tolvanen <samitolvanen@google.com> |
| |
| [ Upstream commit c54f90c2627cc316d365e3073614731e17dbc631 ] |
| |
| LLVM's integrated assembler fails with the following error when |
| building KVM: |
| |
| <inline asm>:12:6: error: expected absolute expression |
| .if kvm_update_va_mask == 0 |
| ^ |
| <inline asm>:21:6: error: expected absolute expression |
| .if kvm_update_va_mask == 0 |
| ^ |
| <inline asm>:24:2: error: unrecognized instruction mnemonic |
| NOT_AN_INSTRUCTION |
| ^ |
| LLVM ERROR: Error parsing inline asm |
| |
| These errors come from ALTERNATIVE_CB and __ALTERNATIVE_CFG, |
| which test for the existence of the callback parameter in inline |
| assembly using the following expression: |
| |
| " .if " __stringify(cb) " == 0\n" |
| |
| This works with GNU as, but isn't supported by LLVM. This change |
| splits __ALTERNATIVE_CFG and ALTINSTR_ENTRY into separate macros |
| to fix the LLVM build. |
| |
| Link: https://github.com/ClangBuiltLinux/linux/issues/472 |
| Signed-off-by: Sami Tolvanen <samitolvanen@google.com> |
| Tested-by: Nick Desaulniers <ndesaulniers@google.com> |
| Reviewed-by: Kees Cook <keescook@chromium.org> |
| Signed-off-by: Will Deacon <will@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/arm64/include/asm/alternative.h | 32 ++++++++++++++++++---------- |
| 1 file changed, 21 insertions(+), 11 deletions(-) |
| |
| diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h |
| index b9f8d787eea9f..324e7d5ab37ed 100644 |
| --- a/arch/arm64/include/asm/alternative.h |
| +++ b/arch/arm64/include/asm/alternative.h |
| @@ -35,13 +35,16 @@ void apply_alternatives_module(void *start, size_t length); |
| static inline void apply_alternatives_module(void *start, size_t length) { } |
| #endif |
| |
| -#define ALTINSTR_ENTRY(feature,cb) \ |
| +#define ALTINSTR_ENTRY(feature) \ |
| " .word 661b - .\n" /* label */ \ |
| - " .if " __stringify(cb) " == 0\n" \ |
| " .word 663f - .\n" /* new instruction */ \ |
| - " .else\n" \ |
| + " .hword " __stringify(feature) "\n" /* feature bit */ \ |
| + " .byte 662b-661b\n" /* source len */ \ |
| + " .byte 664f-663f\n" /* replacement len */ |
| + |
| +#define ALTINSTR_ENTRY_CB(feature, cb) \ |
| + " .word 661b - .\n" /* label */ \ |
| " .word " __stringify(cb) "- .\n" /* callback */ \ |
| - " .endif\n" \ |
| " .hword " __stringify(feature) "\n" /* feature bit */ \ |
| " .byte 662b-661b\n" /* source len */ \ |
| " .byte 664f-663f\n" /* replacement len */ |
| @@ -62,15 +65,14 @@ static inline void apply_alternatives_module(void *start, size_t length) { } |
| * |
| * Alternatives with callbacks do not generate replacement instructions. |
| */ |
| -#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled, cb) \ |
| +#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled) \ |
| ".if "__stringify(cfg_enabled)" == 1\n" \ |
| "661:\n\t" \ |
| oldinstr "\n" \ |
| "662:\n" \ |
| ".pushsection .altinstructions,\"a\"\n" \ |
| - ALTINSTR_ENTRY(feature,cb) \ |
| + ALTINSTR_ENTRY(feature) \ |
| ".popsection\n" \ |
| - " .if " __stringify(cb) " == 0\n" \ |
| ".pushsection .altinstr_replacement, \"a\"\n" \ |
| "663:\n\t" \ |
| newinstr "\n" \ |
| @@ -78,17 +80,25 @@ static inline void apply_alternatives_module(void *start, size_t length) { } |
| ".popsection\n\t" \ |
| ".org . - (664b-663b) + (662b-661b)\n\t" \ |
| ".org . - (662b-661b) + (664b-663b)\n" \ |
| - ".else\n\t" \ |
| + ".endif\n" |
| + |
| +#define __ALTERNATIVE_CFG_CB(oldinstr, feature, cfg_enabled, cb) \ |
| + ".if "__stringify(cfg_enabled)" == 1\n" \ |
| + "661:\n\t" \ |
| + oldinstr "\n" \ |
| + "662:\n" \ |
| + ".pushsection .altinstructions,\"a\"\n" \ |
| + ALTINSTR_ENTRY_CB(feature, cb) \ |
| + ".popsection\n" \ |
| "663:\n\t" \ |
| "664:\n\t" \ |
| - ".endif\n" \ |
| ".endif\n" |
| |
| #define _ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg, ...) \ |
| - __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg), 0) |
| + __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg)) |
| |
| #define ALTERNATIVE_CB(oldinstr, cb) \ |
| - __ALTERNATIVE_CFG(oldinstr, "NOT_AN_INSTRUCTION", ARM64_CB_PATCH, 1, cb) |
| + __ALTERNATIVE_CFG_CB(oldinstr, ARM64_CB_PATCH, 1, cb) |
| #else |
| |
| #include <asm/assembler.h> |
| -- |
| 2.20.1 |
| |