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x86/lib: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S

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Commit

  393f203f5f ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")

added .weak directives to arch/x86/lib/mem*_64.S instead of changing the
existing ENTRY macros to WEAK. This can lead to the assembly snippet

  .weak memcpy
  ...
  .globl memcpy

which will produce a STB_WEAK memcpy with GNU as but STB_GLOBAL memcpy
with LLVM's integrated assembler before LLVM 12. LLVM 12 (since
https://reviews.llvm.org/D90108) will error on such an overridden symbol
binding.

Commit

  ef1e03152c ("x86/asm: Make some functions local")

changed ENTRY in arch/x86/lib/memcpy_64.S to SYM_FUNC_START_LOCAL, which
was ineffective due to the preceding .weak directive.

Use the appropriate SYM_FUNC_START_WEAK instead.

Fixes: 393f203f5f ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
Fixes: ef1e03152c ("x86/asm: Make some functions local")
Reported-by: Sami Tolvanen <[email protected]>
Signed-off-by: Fangrui Song <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Tested-by: Nick Desaulniers <[email protected]>
Cc: <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
This commit is contained in:
Fangrui Song authored and Borislav Petkov committed 2020-11-04 12:30:20 +01:00
1 parent 3cea11cd5e
commit 4d6ffa27b8
3 files changed
+3 -9
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arch/x86/lib/memcpy_64.S
+1 -3
View File
@@ -16,8 +16,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy. * to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/ */
.weak memcpy
/* /*
* memcpy - Copy a memory block. * memcpy - Copy a memory block.
* *
@@ -30,7 +28,7 @@
* rax original destination * rax original destination
*/ */
SYM_FUNC_START_ALIAS(__memcpy) SYM_FUNC_START_ALIAS(__memcpy)
SYM_FUNC_START_LOCAL(memcpy) SYM_FUNC_START_WEAK(memcpy)
ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
"jmp memcpy_erms", X86_FEATURE_ERMS "jmp memcpy_erms", X86_FEATURE_ERMS
arch/x86/lib/memmove_64.S
+1 -3
View File
@@ -24,9 +24,7 @@
* Output: * Output:
* rax: dest * rax: dest
*/ */
.weak memmove SYM_FUNC_START_WEAK(memmove)
SYM_FUNC_START_ALIAS(memmove)
SYM_FUNC_START(__memmove) SYM_FUNC_START(__memmove)
mov %rdi, %rax mov %rdi, %rax
arch/x86/lib/memset_64.S
+1 -3
View File
@@ -6,8 +6,6 @@
#include <asm/alternative-asm.h> #include <asm/alternative-asm.h>
#include <asm/export.h> #include <asm/export.h>
.weak memset
/* /*
* ISO C memset - set a memory block to a byte value. This function uses fast * ISO C memset - set a memory block to a byte value. This function uses fast
* string to get better performance than the original function. The code is * string to get better performance than the original function. The code is
@@ -19,7 +17,7 @@
* *
* rax original destination * rax original destination
*/ */
SYM_FUNC_START_ALIAS(memset) SYM_FUNC_START_WEAK(memset)
SYM_FUNC_START(__memset) SYM_FUNC_START(__memset)
/* /*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended