* [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S
@ 2020-11-03 1:23 Fangrui Song
2020-11-03 1:46 ` Nathan Chancellor
2020-11-04 11:57 ` [tip: x86/urgent] x86/lib: " tip-bot2 for Fangrui Song
0 siblings, 2 replies; 4+ messages in thread
From: Fangrui Song @ 2020-11-03 1:23 UTC (permalink / raw)
To: x86, Thomas Gleixner, Ingo Molnar, Borislav Petkov
Cc: clang-built-linux, Jian Cai, Fangrui Song, Sami Tolvanen, stable
Commit 393f203f5fd5 ("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 ef1e03152cb0 ("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: 393f203f5fd5 ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
Fixes: ef1e03152cb0 ("x86/asm: Make some functions local")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Cc: <stable@vger.kernel.org>
---
Changes in v2
* Correct the message: SYM_FUNC_START_WEAK was not available at commit 393f203f5fd5.
* Mention Fixes: ef1e03152cb0
---
arch/x86/lib/memcpy_64.S | 4 +---
arch/x86/lib/memmove_64.S | 4 +---
arch/x86/lib/memset_64.S | 4 +---
3 files changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 037faac46b0c..1e299ac73c86 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -16,8 +16,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -30,7 +28,7 @@
* rax original destination
*/
SYM_FUNC_START_ALIAS(__memcpy)
-SYM_FUNC_START_LOCAL(memcpy)
+SYM_FUNC_START_WEAK(memcpy)
ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
"jmp memcpy_erms", X86_FEATURE_ERMS
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 7ff00ea64e4f..41902fe8b859 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -24,9 +24,7 @@
* Output:
* rax: dest
*/
-.weak memmove
-
-SYM_FUNC_START_ALIAS(memmove)
+SYM_FUNC_START_WEAK(memmove)
SYM_FUNC_START(__memmove)
mov %rdi, %rax
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9ff15ee404a4..0bfd26e4ca9e 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -6,8 +6,6 @@
#include <asm/alternative-asm.h>
#include <asm/export.h>
-.weak memset
-
/*
* 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
@@ -19,7 +17,7 @@
*
* rax original destination
*/
-SYM_FUNC_START_ALIAS(memset)
+SYM_FUNC_START_WEAK(memset)
SYM_FUNC_START(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
--
2.29.1.341.ge80a0c044ae-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S
2020-11-03 1:23 [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S Fangrui Song
@ 2020-11-03 1:46 ` Nathan Chancellor
2020-11-03 22:43 ` Nick Desaulniers
2020-11-04 11:57 ` [tip: x86/urgent] x86/lib: " tip-bot2 for Fangrui Song
1 sibling, 1 reply; 4+ messages in thread
From: Nathan Chancellor @ 2020-11-03 1:46 UTC (permalink / raw)
To: Fangrui Song
Cc: x86, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
clang-built-linux, Jian Cai, Sami Tolvanen, stable
On Mon, Nov 02, 2020 at 05:23:58PM -0800, 'Fangrui Song' via Clang Built Linux wrote:
> Commit 393f203f5fd5 ("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 ef1e03152cb0 ("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: 393f203f5fd5 ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
> Fixes: ef1e03152cb0 ("x86/asm: Make some functions local")
> Reported-by: Sami Tolvanen <samitolvanen@google.com>
> Signed-off-by: Fangrui Song <maskray@google.com>
> Cc: <stable@vger.kernel.org>
This resolves the build error I see with LLVM_IAS=1 and ToT LLVM.
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> Changes in v2
> * Correct the message: SYM_FUNC_START_WEAK was not available at commit 393f203f5fd5.
> * Mention Fixes: ef1e03152cb0
> ---
> arch/x86/lib/memcpy_64.S | 4 +---
> arch/x86/lib/memmove_64.S | 4 +---
> arch/x86/lib/memset_64.S | 4 +---
> 3 files changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
> index 037faac46b0c..1e299ac73c86 100644
> --- a/arch/x86/lib/memcpy_64.S
> +++ b/arch/x86/lib/memcpy_64.S
> @@ -16,8 +16,6 @@
> * to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
> */
>
> -.weak memcpy
> -
> /*
> * memcpy - Copy a memory block.
> *
> @@ -30,7 +28,7 @@
> * rax original destination
> */
> SYM_FUNC_START_ALIAS(__memcpy)
> -SYM_FUNC_START_LOCAL(memcpy)
> +SYM_FUNC_START_WEAK(memcpy)
> ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
> "jmp memcpy_erms", X86_FEATURE_ERMS
>
> diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
> index 7ff00ea64e4f..41902fe8b859 100644
> --- a/arch/x86/lib/memmove_64.S
> +++ b/arch/x86/lib/memmove_64.S
> @@ -24,9 +24,7 @@
> * Output:
> * rax: dest
> */
> -.weak memmove
> -
> -SYM_FUNC_START_ALIAS(memmove)
> +SYM_FUNC_START_WEAK(memmove)
> SYM_FUNC_START(__memmove)
>
> mov %rdi, %rax
> diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
> index 9ff15ee404a4..0bfd26e4ca9e 100644
> --- a/arch/x86/lib/memset_64.S
> +++ b/arch/x86/lib/memset_64.S
> @@ -6,8 +6,6 @@
> #include <asm/alternative-asm.h>
> #include <asm/export.h>
>
> -.weak memset
> -
> /*
> * 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
> @@ -19,7 +17,7 @@
> *
> * rax original destination
> */
> -SYM_FUNC_START_ALIAS(memset)
> +SYM_FUNC_START_WEAK(memset)
> SYM_FUNC_START(__memset)
> /*
> * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
> --
> 2.29.1.341.ge80a0c044ae-goog
>
> --
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S
2020-11-03 1:46 ` Nathan Chancellor
@ 2020-11-03 22:43 ` Nick Desaulniers
0 siblings, 0 replies; 4+ messages in thread
From: Nick Desaulniers @ 2020-11-03 22:43 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Fangrui Song, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Thomas Gleixner, Ingo Molnar, Borislav Petkov, clang-built-linux,
Jian Cai, Sami Tolvanen, # 3.4.x, LKML
+ LKML so I can find this easier to fetch via b4
On Mon, Nov 2, 2020 at 5:46 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Mon, Nov 02, 2020 at 05:23:58PM -0800, 'Fangrui Song' via Clang Built Linux wrote:
> > Commit 393f203f5fd5 ("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 ef1e03152cb0 ("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: 393f203f5fd5 ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
> > Fixes: ef1e03152cb0 ("x86/asm: Make some functions local")
> > Reported-by: Sami Tolvanen <samitolvanen@google.com>
> > Signed-off-by: Fangrui Song <maskray@google.com>
> > Cc: <stable@vger.kernel.org>
>
> This resolves the build error I see with LLVM_IAS=1 and ToT LLVM.
>
> Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
>
> > ---
> > Changes in v2
> > * Correct the message: SYM_FUNC_START_WEAK was not available at commit 393f203f5fd5.
> > * Mention Fixes: ef1e03152cb0
> > ---
> > arch/x86/lib/memcpy_64.S | 4 +---
> > arch/x86/lib/memmove_64.S | 4 +---
> > arch/x86/lib/memset_64.S | 4 +---
> > 3 files changed, 3 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
> > index 037faac46b0c..1e299ac73c86 100644
> > --- a/arch/x86/lib/memcpy_64.S
> > +++ b/arch/x86/lib/memcpy_64.S
> > @@ -16,8 +16,6 @@
> > * to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
> > */
> >
> > -.weak memcpy
> > -
> > /*
> > * memcpy - Copy a memory block.
> > *
> > @@ -30,7 +28,7 @@
> > * rax original destination
> > */
> > SYM_FUNC_START_ALIAS(__memcpy)
> > -SYM_FUNC_START_LOCAL(memcpy)
> > +SYM_FUNC_START_WEAK(memcpy)
> > ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
> > "jmp memcpy_erms", X86_FEATURE_ERMS
> >
> > diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
> > index 7ff00ea64e4f..41902fe8b859 100644
> > --- a/arch/x86/lib/memmove_64.S
> > +++ b/arch/x86/lib/memmove_64.S
> > @@ -24,9 +24,7 @@
> > * Output:
> > * rax: dest
> > */
> > -.weak memmove
> > -
> > -SYM_FUNC_START_ALIAS(memmove)
> > +SYM_FUNC_START_WEAK(memmove)
> > SYM_FUNC_START(__memmove)
> >
> > mov %rdi, %rax
> > diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
> > index 9ff15ee404a4..0bfd26e4ca9e 100644
> > --- a/arch/x86/lib/memset_64.S
> > +++ b/arch/x86/lib/memset_64.S
> > @@ -6,8 +6,6 @@
> > #include <asm/alternative-asm.h>
> > #include <asm/export.h>
> >
> > -.weak memset
> > -
> > /*
> > * 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
> > @@ -19,7 +17,7 @@
> > *
> > * rax original destination
> > */
> > -SYM_FUNC_START_ALIAS(memset)
> > +SYM_FUNC_START_WEAK(memset)
> > SYM_FUNC_START(__memset)
> > /*
> > * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
> > --
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip: x86/urgent] x86/lib: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S
2020-11-03 1:23 [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S Fangrui Song
2020-11-03 1:46 ` Nathan Chancellor
@ 2020-11-04 11:57 ` tip-bot2 for Fangrui Song
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot2 for Fangrui Song @ 2020-11-04 11:57 UTC (permalink / raw)
To: linux-tip-commits
Cc: Sami Tolvanen, Fangrui Song, Borislav Petkov, Nick Desaulniers,
Nathan Chancellor, stable, x86, LKML
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 4d6ffa27b8e5116c0abb318790fd01d4e12d75e6
Gitweb: https://git.kernel.org/tip/4d6ffa27b8e5116c0abb318790fd01d4e12d75e6
Author: Fangrui Song <maskray@google.com>
AuthorDate: Mon, 02 Nov 2020 17:23:58 -08:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 04 Nov 2020 12:30:20 +01:00
x86/lib: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S
Commit
393f203f5fd5 ("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
ef1e03152cb0 ("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: 393f203f5fd5 ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
Fixes: ef1e03152cb0 ("x86/asm: Make some functions local")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201103012358.168682-1-maskray@google.com
---
arch/x86/lib/memcpy_64.S | 4 +---
arch/x86/lib/memmove_64.S | 4 +---
arch/x86/lib/memset_64.S | 4 +---
3 files changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 037faac..1e299ac 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -16,8 +16,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -30,7 +28,7 @@
* rax original destination
*/
SYM_FUNC_START_ALIAS(__memcpy)
-SYM_FUNC_START_LOCAL(memcpy)
+SYM_FUNC_START_WEAK(memcpy)
ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
"jmp memcpy_erms", X86_FEATURE_ERMS
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 7ff00ea..41902fe 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -24,9 +24,7 @@
* Output:
* rax: dest
*/
-.weak memmove
-
-SYM_FUNC_START_ALIAS(memmove)
+SYM_FUNC_START_WEAK(memmove)
SYM_FUNC_START(__memmove)
mov %rdi, %rax
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9ff15ee..0bfd26e 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -6,8 +6,6 @@
#include <asm/alternative-asm.h>
#include <asm/export.h>
-.weak memset
-
/*
* 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
@@ -19,7 +17,7 @@
*
* rax original destination
*/
-SYM_FUNC_START_ALIAS(memset)
+SYM_FUNC_START_WEAK(memset)
SYM_FUNC_START(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-11-04 11:59 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-11-03 1:23 [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S Fangrui Song
2020-11-03 1:46 ` Nathan Chancellor
2020-11-03 22:43 ` Nick Desaulniers
2020-11-04 11:57 ` [tip: x86/urgent] x86/lib: " tip-bot2 for Fangrui Song
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