* [PATCH] arm64: fix clang integrated assembler build
@ 2020-05-27 14:14 Arnd Bergmann
2020-05-27 18:03 ` Nick Desaulniers
0 siblings, 1 reply; 3+ messages in thread
From: Arnd Bergmann @ 2020-05-27 14:14 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon
Cc: Arnd Bergmann, clang-built-linux, linux-kernel, stable,
Alexios Zavras, Enrico Weigelt, linux-arm-kernel
clang and gas seem to interpret the symbols in memmove.S and
memset.S differently, such that clang does not make them
'weak' as expected, which leads to a linker error, with both
ld.bfd and ld.lld:
ld.lld: error: duplicate symbol: memmove
>>> defined at common.c
>>> kasan/common.o:(memmove) in archive mm/built-in.a
>>> defined at memmove.o:(__memmove) in archive arch/arm64/lib/lib.a
ld.lld: error: duplicate symbol: memset
>>> defined at common.c
>>> kasan/common.o:(memset) in archive mm/built-in.a
>>> defined at memset.o:(__memset) in archive arch/arm64/lib/lib.a
Copy the exact way these are written in memcpy_64.S, which does
not have the same problem.
I don't know why this makes a difference, and it would be good
to have someone with a better understanding of assembler internals
review it.
It might be either a bug in the kernel or a bug in the assembler,
no idea which one. My patch makes it work with all versions of
clang and gcc, which is probably helpful even if it's a workaround
for a clang bug.
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
---
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(-)
diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S
index e0bf83d556f2..dc8d2a216a6e 100644
--- a/arch/arm64/lib/memcpy.S
+++ b/arch/arm64/lib/memcpy.S
@@ -56,9 +56,8 @@
stp \reg1, \reg2, [\ptr], \val
.endm
- .weak memcpy
SYM_FUNC_START_ALIAS(__memcpy)
-SYM_FUNC_START_PI(memcpy)
+SYM_FUNC_START_WEAK_PI(memcpy)
#include "copy_template.S"
ret
SYM_FUNC_END_PI(memcpy)
diff --git a/arch/arm64/lib/memmove.S b/arch/arm64/lib/memmove.S
index 02cda2e33bde..1035dce4bdaf 100644
--- a/arch/arm64/lib/memmove.S
+++ b/arch/arm64/lib/memmove.S
@@ -45,9 +45,8 @@ C_h .req x12
D_l .req x13
D_h .req x14
- .weak memmove
SYM_FUNC_START_ALIAS(__memmove)
-SYM_FUNC_START_PI(memmove)
+SYM_FUNC_START_WEAK_PI(memmove)
cmp dstin, src
b.lo __memcpy
add tmp1, src, count
diff --git a/arch/arm64/lib/memset.S b/arch/arm64/lib/memset.S
index 77c3c7ba0084..a9c1c9a01ea9 100644
--- a/arch/arm64/lib/memset.S
+++ b/arch/arm64/lib/memset.S
@@ -42,9 +42,8 @@ dst .req x8
tmp3w .req w9
tmp3 .req x9
- .weak memset
SYM_FUNC_START_ALIAS(__memset)
-SYM_FUNC_START_PI(memset)
+SYM_FUNC_START_WEAK_PI(memset)
mov dst, dstin /* Preserve return value. */
and A_lw, val, #255
orr A_lw, A_lw, A_lw, lsl #8
--
2.26.2
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] arm64: fix clang integrated assembler build
2020-05-27 14:14 [PATCH] arm64: fix clang integrated assembler build Arnd Bergmann
@ 2020-05-27 18:03 ` Nick Desaulniers
2020-05-27 18:28 ` Fangrui Song
0 siblings, 1 reply; 3+ messages in thread
From: Nick Desaulniers @ 2020-05-27 18:03 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Fangrui Song, Will Deacon, clang-built-linux, Catalin Marinas,
LKML, # 3.4.x, Jian Cai, Alexios Zavras, Bill Wendling,
Enrico Weigelt, Linux ARM
On Wed, May 27, 2020 at 7:14 AM Arnd Bergmann <arnd@arndb.de> wrote:
>
> clang and gas seem to interpret the symbols in memmove.S and
> memset.S differently, such that clang does not make them
> 'weak' as expected, which leads to a linker error, with both
> ld.bfd and ld.lld:
>
> ld.lld: error: duplicate symbol: memmove
> >>> defined at common.c
> >>> kasan/common.o:(memmove) in archive mm/built-in.a
> >>> defined at memmove.o:(__memmove) in archive arch/arm64/lib/lib.a
>
> ld.lld: error: duplicate symbol: memset
> >>> defined at common.c
> >>> kasan/common.o:(memset) in archive mm/built-in.a
> >>> defined at memset.o:(__memset) in archive arch/arm64/lib/lib.a
>
> Copy the exact way these are written in memcpy_64.S, which does
> not have the same problem.
>
> I don't know why this makes a difference, and it would be good
> to have someone with a better understanding of assembler internals
> review it.
>
> It might be either a bug in the kernel or a bug in the assembler,
> no idea which one. My patch makes it work with all versions of
> clang and gcc, which is probably helpful even if it's a workaround
> for a clang bug.
+ Bill, Fangrui, Jian
I think we saw this bug or a very similar bug internally around the
ordering of .weak to .global.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> ---
> 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(-)
>
> diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S
> index e0bf83d556f2..dc8d2a216a6e 100644
> --- a/arch/arm64/lib/memcpy.S
> +++ b/arch/arm64/lib/memcpy.S
> @@ -56,9 +56,8 @@
> stp \reg1, \reg2, [\ptr], \val
> .endm
>
> - .weak memcpy
> SYM_FUNC_START_ALIAS(__memcpy)
> -SYM_FUNC_START_PI(memcpy)
> +SYM_FUNC_START_WEAK_PI(memcpy)
> #include "copy_template.S"
> ret
> SYM_FUNC_END_PI(memcpy)
> diff --git a/arch/arm64/lib/memmove.S b/arch/arm64/lib/memmove.S
> index 02cda2e33bde..1035dce4bdaf 100644
> --- a/arch/arm64/lib/memmove.S
> +++ b/arch/arm64/lib/memmove.S
> @@ -45,9 +45,8 @@ C_h .req x12
> D_l .req x13
> D_h .req x14
>
> - .weak memmove
> SYM_FUNC_START_ALIAS(__memmove)
> -SYM_FUNC_START_PI(memmove)
> +SYM_FUNC_START_WEAK_PI(memmove)
> cmp dstin, src
> b.lo __memcpy
> add tmp1, src, count
> diff --git a/arch/arm64/lib/memset.S b/arch/arm64/lib/memset.S
> index 77c3c7ba0084..a9c1c9a01ea9 100644
> --- a/arch/arm64/lib/memset.S
> +++ b/arch/arm64/lib/memset.S
> @@ -42,9 +42,8 @@ dst .req x8
> tmp3w .req w9
> tmp3 .req x9
>
> - .weak memset
> SYM_FUNC_START_ALIAS(__memset)
> -SYM_FUNC_START_PI(memset)
> +SYM_FUNC_START_WEAK_PI(memset)
> mov dst, dstin /* Preserve return value. */
> and A_lw, val, #255
> orr A_lw, A_lw, A_lw, lsl #8
> --
> 2.26.2
--
Thanks,
~Nick Desaulniers
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] arm64: fix clang integrated assembler build
2020-05-27 18:03 ` Nick Desaulniers
@ 2020-05-27 18:28 ` Fangrui Song
0 siblings, 0 replies; 3+ messages in thread
From: Fangrui Song @ 2020-05-27 18:28 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Arnd Bergmann, Will Deacon, clang-built-linux, Catalin Marinas,
LKML, # 3.4.x, Jian Cai, Alexios Zavras, Bill Wendling,
Enrico Weigelt, Linux ARM
On 2020-05-27, 'Nick Desaulniers' via Clang Built Linux wrote:
>On Wed, May 27, 2020 at 7:14 AM Arnd Bergmann <arnd@arndb.de> wrote:
>>
>> clang and gas seem to interpret the symbols in memmove.S and
>> memset.S differently, such that clang does not make them
>> 'weak' as expected, which leads to a linker error, with both
>> ld.bfd and ld.lld:
>>
>> ld.lld: error: duplicate symbol: memmove
>> >>> defined at common.c
>> >>> kasan/common.o:(memmove) in archive mm/built-in.a
>> >>> defined at memmove.o:(__memmove) in archive arch/arm64/lib/lib.a
>>
>> ld.lld: error: duplicate symbol: memset
>> >>> defined at common.c
>> >>> kasan/common.o:(memset) in archive mm/built-in.a
>> >>> defined at memset.o:(__memset) in archive arch/arm64/lib/lib.a
>>
>> Copy the exact way these are written in memcpy_64.S, which does
>> not have the same problem.
>>
>> I don't know why this makes a difference, and it would be good
>> to have someone with a better understanding of assembler internals
>> review it.
>>
>> It might be either a bug in the kernel or a bug in the assembler,
>> no idea which one. My patch makes it work with all versions of
>> clang and gcc, which is probably helpful even if it's a workaround
>> for a clang bug.
>
>+ Bill, Fangrui, Jian
>I think we saw this bug or a very similar bug internally around the
>ordering of .weak to .global.
This may be another instance of
https://sourceware.org/pipermail/binutils/2020-March/000299.html
https://lore.kernel.org/linuxppc-dev/20200325164257.170229-1-maskray@google.com/
I haven't checked but there may be both a .globl directive and a .weak
directive
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>> ---
>> 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(-)
>>
>> diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S
>> index e0bf83d556f2..dc8d2a216a6e 100644
>> --- a/arch/arm64/lib/memcpy.S
>> +++ b/arch/arm64/lib/memcpy.S
>> @@ -56,9 +56,8 @@
>> stp \reg1, \reg2, [\ptr], \val
>> .endm
>>
>> - .weak memcpy
>> SYM_FUNC_START_ALIAS(__memcpy)
>> -SYM_FUNC_START_PI(memcpy)
>> +SYM_FUNC_START_WEAK_PI(memcpy)
>> #include "copy_template.S"
>> ret
>> SYM_FUNC_END_PI(memcpy)
>> diff --git a/arch/arm64/lib/memmove.S b/arch/arm64/lib/memmove.S
>> index 02cda2e33bde..1035dce4bdaf 100644
>> --- a/arch/arm64/lib/memmove.S
>> +++ b/arch/arm64/lib/memmove.S
>> @@ -45,9 +45,8 @@ C_h .req x12
>> D_l .req x13
>> D_h .req x14
>>
>> - .weak memmove
>> SYM_FUNC_START_ALIAS(__memmove)
>> -SYM_FUNC_START_PI(memmove)
>> +SYM_FUNC_START_WEAK_PI(memmove)
>> cmp dstin, src
>> b.lo __memcpy
>> add tmp1, src, count
>> diff --git a/arch/arm64/lib/memset.S b/arch/arm64/lib/memset.S
>> index 77c3c7ba0084..a9c1c9a01ea9 100644
>> --- a/arch/arm64/lib/memset.S
>> +++ b/arch/arm64/lib/memset.S
>> @@ -42,9 +42,8 @@ dst .req x8
>> tmp3w .req w9
>> tmp3 .req x9
>>
>> - .weak memset
>> SYM_FUNC_START_ALIAS(__memset)
>> -SYM_FUNC_START_PI(memset)
>> +SYM_FUNC_START_WEAK_PI(memset)
>> mov dst, dstin /* Preserve return value. */
>> and A_lw, val, #255
>> orr A_lw, A_lw, A_lw, lsl #8
>> --
>> 2.26.2
>
>--
>Thanks,
>~Nick Desaulniers
>
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2020-05-27 18:03 ` Nick Desaulniers
2020-05-27 18:28 ` Fangrui Song
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