[PATCH 4.19 052/346] arm64: Change .weak to SYM_FUNC_START_WEAK_PI for arch/arm64/lib/mem*.S

Greg Kroah-Hartman
2020-12-28T13:24:12Z

From: Fangrui Song <maskray@google.com>

commit ec9d78070de986ecf581ea204fd322af4d2477ec upstream.

Commit 39d114ddc682 ("arm64: add KASAN support") added .weak directives to
arch/arm64/lib/mem*.S instead of changing the existing SYM_FUNC_START_PI
macros. 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.

Use the appropriate SYM_FUNC_START_WEAK_PI instead.

Fixes: 39d114ddc682 ("arm64: add KASAN support")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201029181951.1866093-1-maskray@google.com
Signed-off-by: Will Deacon <will@kernel.org>
[nd: backport to adjust for missing:
commit 3ac0f4526dfb ("arm64: lib: Use modern annotations for assembly functions")
commit 35e61c77ef38 ("arm64: asm: Add new-style position independent function annotations")]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/lib/memcpy.S | 3 +--
arch/arm64/lib/memmove.S | 3 +--
arch/arm64/lib/memset.S | 3 +--
3 files changed, 3 insertions(+), 6 deletions(-)

--- a/arch/arm64/lib/memcpy.S
+++ b/arch/arm64/lib/memcpy.S
@@ -68,9 +68,8 @@
stp \ptr, \regB, [\regC], \val
.endm

- .weak memcpy
ENTRY(__memcpy)
-ENTRY(memcpy)
+WEAK(memcpy)
#include "copy_template.S"
ret
ENDPIPROC(memcpy)
--- a/arch/arm64/lib/memmove.S
+++ b/arch/arm64/lib/memmove.S
@@ -57,9 +57,8 @@ C_h .req x12
D_l .req x13
D_h .req x14

- .weak memmove
ENTRY(__memmove)
-ENTRY(memmove)
+WEAK(memmove)
cmp dstin, src
b.lo __memcpy
add tmp1, src, count
--- a/arch/arm64/lib/memset.S
+++ b/arch/arm64/lib/memset.S
@@ -54,9 +54,8 @@ dst .req x8
tmp3w .req w9
tmp3 .req x9

- .weak memset
ENTRY(__memset)
-ENTRY(memset)
+WEAK(memset)
mov dst, dstin /* Preserve return value. */
and A_lw, val, #255
orr A_lw, A_lw, A_lw, lsl #8