* 5.4 and 4.19 fix for LLVM_IAS/clang-12
@ 2020-12-09 0:12 Nick Desaulniers
2020-12-09 7:20 ` Jiri Slaby
0 siblings, 1 reply; 5+ messages in thread
From: Nick Desaulniers @ 2020-12-09 0:12 UTC (permalink / raw)
To: Greg KH, Sasha Levin, Jiri Slaby
Cc: stable, Jian Cai, Fangrui Song, Sami Tolvanen, Borislav Petkov,
Nathan Chancellor, clang-built-linux
[-- Attachment #1: Type: text/plain, Size: 1259 bytes --]
Dear stable kernel maintainers,
Please consider accepting the following backport to 5.4 and 4.19 of
commit 4d6ffa27b8e5 ("x86/lib: Change .weak to SYM_FUNC_START_WEAK for
arch/x86/lib/mem*_64.S"), attached.
The patch to 5.4 had a conflict due to 5.4 missing upstream commit
e9b9d020c487 ("x86/asm: Annotate aliases") which first landed in
v5.5-rc1.
The patch to 4.19 had a conflict due to 4.19 missing the above commit
and ffedeeb780dc ("linkage: Introduce new macros for assembler
symbols") which also first landed in v5.5-rc1 but was backported to
linux-5.4.y as commit 840d8c9b3e5f ("linkage: Introduce new macros for
assembler symbols") which shipped in v5.4.76.
This patch fixes a build error from clang's assembler when building
with Clang-12, which now errors when symbols are redeclared with
different bindings. We're using clang's assembler in Android and
ChromeOS for 4.19+.
Jiri, would you mind reviewing the 4.19 patch (or both)? It simply
open codes what the upstream macros would expand to; this can be and
was observed from running:
$ make ... arch/x86/lib/memmove_64.s
(ie. lowercase s, to invoke the C preprocessor on the uppercase .S file)
See also: https://github.com/ClangBuiltLinux/linux/issues/1190.
--
Thanks,
~Nick Desaulniers
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From fecddb0ab4ab58b69e29cb936b05336574cb029f Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Mon, 2 Nov 2020 17:23:58 -0800
Subject: [PATCH] x86/lib: Change .weak to SYM_FUNC_START_WEAK for
arch/x86/lib/mem*_64.S
commit 4d6ffa27b8e5116c0abb318790fd01d4e12d75e6 upstream.
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
[nd: backport due to missing commit e9b9d020c487 ("x86/asm: Annotate aliases")]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/x86/lib/memcpy_64.S | 6 ++----
arch/x86/lib/memmove_64.S | 6 ++----
arch/x86/lib/memset_64.S | 6 ++----
3 files changed, 6 insertions(+), 12 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 92748660ba51..29f1eecffdfd 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -15,8 +15,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -28,8 +26,8 @@
* Output:
* rax original destination
*/
-ENTRY(__memcpy)
-ENTRY(memcpy)
+SYM_FUNC_START_ALIAS(__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 bbec69d8223b..f8deefb5a994 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -24,10 +24,8 @@
* Output:
* rax: dest
*/
-.weak memmove
-
-ENTRY(memmove)
-ENTRY(__memmove)
+SYM_FUNC_START_WEAK(memmove)
+SYM_FUNC_START(__memmove)
/* Handle more 32 bytes in loop */
mov %rdi, %rax
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9bc861c71e75..65837f7eeb32 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
@@ -19,8 +17,8 @@
*
* rax original destination
*/
-ENTRY(memset)
-ENTRY(__memset)
+SYM_FUNC_START_WEAK(memset)
+SYM_FUNC_START(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
* to use it when possible. If not available, use fast string instructions.
--
2.29.2.576.ga3fc446d84-goog
[-- Attachment #3: 4d6ffa27b8e5.4.19.patch.txt --]
[-- Type: text/plain, Size: 3792 bytes --]
From f30647cb41dee6a219609b3f7f5552ba576e4807 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Mon, 2 Nov 2020 17:23:58 -0800
Subject: [PATCH] x86/lib: Change .weak to SYM_FUNC_START_WEAK for
arch/x86/lib/mem*_64.S
commit 4d6ffa27b8e5116c0abb318790fd01d4e12d75e6 upstream.
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
[nd: backport due to missing
commit e9b9d020c487 ("x86/asm: Annotate aliases")
commit ffedeeb780dc ("linkage: Introduce new macros for assembler symbols")]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/x86/lib/memcpy_64.S | 10 ++++++----
arch/x86/lib/memmove_64.S | 8 +++++---
arch/x86/lib/memset_64.S | 10 ++++++----
3 files changed, 17 insertions(+), 11 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 9d05572370ed..5e9fec9052ae 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -14,8 +14,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -27,8 +25,12 @@
* Output:
* rax original destination
*/
-ENTRY(__memcpy)
-ENTRY(memcpy)
+.globl __memcpy
+.p2align 4, 0x90
+__memcpy:
+.weak memcpy
+.p2align 4, 0x90
+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 bbec69d8223b..00c1f4fe3c02 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -25,9 +25,11 @@
* rax: dest
*/
.weak memmove
-
-ENTRY(memmove)
-ENTRY(__memmove)
+.p2align 4, 0x90
+memmove:
+.globl __memmove
+.p2align 4, 0x90
+__memmove:
/* Handle more 32 bytes in loop */
mov %rdi, %rax
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9bc861c71e75..116750bb555d 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
@@ -19,8 +17,12 @@
*
* rax original destination
*/
-ENTRY(memset)
-ENTRY(__memset)
+.weak memset
+.p2align 4, 0x90
+memset:
+.globl __memset
+.p2align 4, 0x90
+__memset:
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
* to use it when possible. If not available, use fast string instructions.
--
2.29.2.576.ga3fc446d84-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: 5.4 and 4.19 fix for LLVM_IAS/clang-12
2020-12-09 0:12 5.4 and 4.19 fix for LLVM_IAS/clang-12 Nick Desaulniers
@ 2020-12-09 7:20 ` Jiri Slaby
2020-12-09 7:21 ` Jiri Slaby
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Slaby @ 2020-12-09 7:20 UTC (permalink / raw)
To: Nick Desaulniers, Greg KH, Sasha Levin
Cc: stable, Jian Cai, Fangrui Song, Sami Tolvanen, Borislav Petkov,
Nathan Chancellor, clang-built-linux
On 09. 12. 20, 1:12, Nick Desaulniers wrote:
> Dear stable kernel maintainers,
> Please consider accepting the following backport to 5.4 and 4.19 of
> commit 4d6ffa27b8e5 ("x86/lib: Change .weak to SYM_FUNC_START_WEAK for
> arch/x86/lib/mem*_64.S"), attached.
>
> The patch to 5.4 had a conflict due to 5.4 missing upstream commit
> e9b9d020c487 ("x86/asm: Annotate aliases") which first landed in
> v5.5-rc1.
>
> The patch to 4.19 had a conflict due to 4.19 missing the above commit
> and ffedeeb780dc ("linkage: Introduce new macros for assembler
> symbols") which also first landed in v5.5-rc1 but was backported to
> linux-5.4.y as commit 840d8c9b3e5f ("linkage: Introduce new macros for
> assembler symbols") which shipped in v5.4.76.
>
> This patch fixes a build error from clang's assembler when building
> with Clang-12, which now errors when symbols are redeclared with
> different bindings. We're using clang's assembler in Android and
> ChromeOS for 4.19+.
>
> Jiri, would you mind reviewing the 4.19 patch (or both)? It simply
> open codes what the upstream macros would expand to; this can be and
> was observed from running:
You don't have to touch (expand) __memcpy, __memmove, and __memset, right?
thanks,
--
js
suse labs
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: 5.4 and 4.19 fix for LLVM_IAS/clang-12
2020-12-09 7:20 ` Jiri Slaby
@ 2020-12-09 7:21 ` Jiri Slaby
2020-12-10 21:15 ` Nick Desaulniers
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Slaby @ 2020-12-09 7:21 UTC (permalink / raw)
To: Nick Desaulniers, Greg KH, Sasha Levin
Cc: stable, Jian Cai, Fangrui Song, Sami Tolvanen, Borislav Petkov,
Nathan Chancellor, clang-built-linux
On 09. 12. 20, 8:20, Jiri Slaby wrote:
> On 09. 12. 20, 1:12, Nick Desaulniers wrote:
>> Dear stable kernel maintainers,
>> Please consider accepting the following backport to 5.4 and 4.19 of
>> commit 4d6ffa27b8e5 ("x86/lib: Change .weak to SYM_FUNC_START_WEAK for
>> arch/x86/lib/mem*_64.S"), attached.
>>
>> The patch to 5.4 had a conflict due to 5.4 missing upstream commit
>> e9b9d020c487 ("x86/asm: Annotate aliases") which first landed in
>> v5.5-rc1.
>>
>> The patch to 4.19 had a conflict due to 4.19 missing the above commit
>> and ffedeeb780dc ("linkage: Introduce new macros for assembler
>> symbols") which also first landed in v5.5-rc1 but was backported to
>> linux-5.4.y as commit 840d8c9b3e5f ("linkage: Introduce new macros for
>> assembler symbols") which shipped in v5.4.76.
>>
>> This patch fixes a build error from clang's assembler when building
>> with Clang-12, which now errors when symbols are redeclared with
>> different bindings. We're using clang's assembler in Android and
>> ChromeOS for 4.19+.
>>
>> Jiri, would you mind reviewing the 4.19 patch (or both)? It simply
>> open codes what the upstream macros would expand to; this can be and
>> was observed from running:
>
> You don't have to touch (expand) __memcpy, __memmove, and __memset, right?
Also, no need for doubled p2align.
> thanks,
--
js
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: 5.4 and 4.19 fix for LLVM_IAS/clang-12
2020-12-09 7:21 ` Jiri Slaby
@ 2020-12-10 21:15 ` Nick Desaulniers
2020-12-11 14:41 ` Greg KH
0 siblings, 1 reply; 5+ messages in thread
From: Nick Desaulniers @ 2020-12-10 21:15 UTC (permalink / raw)
To: Jiri Slaby, Greg KH
Cc: Sasha Levin, stable, Jian Cai, Fangrui Song, Sami Tolvanen,
Borislav Petkov, Nathan Chancellor, clang-built-linux
[-- Attachment #1: Type: text/plain, Size: 2290 bytes --]
On Tue, Dec 8, 2020 at 11:21 PM Jiri Slaby <jirislaby@kernel.org> wrote:
>
> On 09. 12. 20, 8:20, Jiri Slaby wrote:
> > On 09. 12. 20, 1:12, Nick Desaulniers wrote:
> >> Dear stable kernel maintainers,
> >> Please consider accepting the following backport to 5.4 and 4.19 of
> >> commit 4d6ffa27b8e5 ("x86/lib: Change .weak to SYM_FUNC_START_WEAK for
> >> arch/x86/lib/mem*_64.S"), attached.
Also, first landed in v5.10-rc3. Exists in v5.9.7 as
305da744c138487864a46b2fb0bd7cf54e1e03b4.
> >>
> >> The patch to 5.4 had a conflict due to 5.4 missing upstream commit
> >> e9b9d020c487 ("x86/asm: Annotate aliases") which first landed in
> >> v5.5-rc1.
> >>
> >> The patch to 4.19 had a conflict due to 4.19 missing the above commit
> >> and ffedeeb780dc ("linkage: Introduce new macros for assembler
> >> symbols") which also first landed in v5.5-rc1 but was backported to
> >> linux-5.4.y as commit 840d8c9b3e5f ("linkage: Introduce new macros for
> >> assembler symbols") which shipped in v5.4.76.
> >>
> >> This patch fixes a build error from clang's assembler when building
> >> with Clang-12, which now errors when symbols are redeclared with
> >> different bindings. We're using clang's assembler in Android and
> >> ChromeOS for 4.19+.
> >>
> >> Jiri, would you mind reviewing the 4.19 patch (or both)? It simply
> >> open codes what the upstream macros would expand to; this can be and
> >> was observed from running:
> >
> > You don't have to touch (expand) __memcpy, __memmove, and __memset, right?
Sure, attached a v2. It's actually a little cleaner (smaller
diffstat) that way.
>
> Also, no need for doubled p2align.
eh, maybe, but
1. it's what SYM_FUNC_START expands to precisely; removing it would be
(too) different from what upstream is doing IMO.
2. it's obviously doubled when in v1 I was expanding the __ prefixed
symbols as well; not so obvious in v2.
3. the order of __ prefixed symbols differs between these three; I'd
rather not rely on the order or have to reorder them to get the
initial symbol realigned; specifying the alignment for both seems
safer to me.
So I haven't included that suggestion in v2, but please feel free to
convince me otherwise if you feel strongly.
Thanks for taking the time to review. I appreciate it.
--
Thanks,
~Nick Desaulniers
[-- Attachment #2: 4d6ffa27b8e5.4.19.v2.patch.txt --]
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From 5707bea0fcef6263d3b23c5f0b61e6a289d54c22 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Mon, 2 Nov 2020 17:23:58 -0800
Subject: [PATCH] x86/lib: Change .weak to SYM_FUNC_START_WEAK for
arch/x86/lib/mem*_64.S
commit 4d6ffa27b8e5116c0abb318790fd01d4e12d75e6 upstream.
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
[nd: backport due to missing
commit e9b9d020c487 ("x86/asm: Annotate aliases")
commit ffedeeb780dc ("linkage: Introduce new macros for assembler symbols")]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/x86/lib/memcpy_64.S | 6 +++---
arch/x86/lib/memmove_64.S | 4 ++--
arch/x86/lib/memset_64.S | 6 +++---
3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 9d05572370ed..84b0078272d1 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -14,8 +14,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -28,7 +26,9 @@
* rax original destination
*/
ENTRY(__memcpy)
-ENTRY(memcpy)
+.weak memcpy
+.p2align 4, 0x90
+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 bbec69d8223b..e1cfc880f42d 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -25,8 +25,8 @@
* rax: dest
*/
.weak memmove
-
-ENTRY(memmove)
+.p2align 4, 0x90
+memmove:
ENTRY(__memmove)
/* Handle more 32 bytes in loop */
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9bc861c71e75..084189acdcd0 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 +17,9 @@
*
* rax original destination
*/
-ENTRY(memset)
+.weak memset
+.p2align 4, 0x90
+memset:
ENTRY(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
--
2.29.2.576.ga3fc446d84-goog
[-- Attachment #3: 4d6ffa27b8e5.5.4.v2.patch.txt --]
[-- Type: text/plain, Size: 3431 bytes --]
From 4985e5d070135c56ce091bd1601996ec47419d07 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Mon, 2 Nov 2020 17:23:58 -0800
Subject: [PATCH] x86/lib: Change .weak to SYM_FUNC_START_WEAK for
arch/x86/lib/mem*_64.S
commit 4d6ffa27b8e5116c0abb318790fd01d4e12d75e6 upstream.
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
[nd: backport due to missing commit e9b9d020c487 ("x86/asm: Annotate aliases")]
Signed-off-by: Nick Desaulniers <ndesaulniers@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 92748660ba51..dc2fb886db2b 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -15,8 +15,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
-.weak memcpy
-
/*
* memcpy - Copy a memory block.
*
@@ -29,7 +27,7 @@
* rax original destination
*/
ENTRY(__memcpy)
-ENTRY(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 bbec69d8223b..b292445467b6 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -24,9 +24,7 @@
* Output:
* rax: dest
*/
-.weak memmove
-
-ENTRY(memmove)
+SYM_FUNC_START_WEAK(memmove)
ENTRY(__memmove)
/* Handle more 32 bytes in loop */
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 9bc861c71e75..e3376c7d4c97 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
*/
-ENTRY(memset)
+SYM_FUNC_START_WEAK(memset)
ENTRY(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
--
2.29.2.576.ga3fc446d84-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: 5.4 and 4.19 fix for LLVM_IAS/clang-12
2020-12-10 21:15 ` Nick Desaulniers
@ 2020-12-11 14:41 ` Greg KH
0 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2020-12-11 14:41 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Jiri Slaby, Sasha Levin, stable, Jian Cai, Fangrui Song,
Sami Tolvanen, Borislav Petkov, Nathan Chancellor,
clang-built-linux
On Thu, Dec 10, 2020 at 01:15:29PM -0800, Nick Desaulniers wrote:
> On Tue, Dec 8, 2020 at 11:21 PM Jiri Slaby <jirislaby@kernel.org> wrote:
> >
> > On 09. 12. 20, 8:20, Jiri Slaby wrote:
> > > On 09. 12. 20, 1:12, Nick Desaulniers wrote:
> > >> Dear stable kernel maintainers,
> > >> Please consider accepting the following backport to 5.4 and 4.19 of
> > >> commit 4d6ffa27b8e5 ("x86/lib: Change .weak to SYM_FUNC_START_WEAK for
> > >> arch/x86/lib/mem*_64.S"), attached.
>
> Also, first landed in v5.10-rc3. Exists in v5.9.7 as
> 305da744c138487864a46b2fb0bd7cf54e1e03b4.
>
> > >>
> > >> The patch to 5.4 had a conflict due to 5.4 missing upstream commit
> > >> e9b9d020c487 ("x86/asm: Annotate aliases") which first landed in
> > >> v5.5-rc1.
> > >>
> > >> The patch to 4.19 had a conflict due to 4.19 missing the above commit
> > >> and ffedeeb780dc ("linkage: Introduce new macros for assembler
> > >> symbols") which also first landed in v5.5-rc1 but was backported to
> > >> linux-5.4.y as commit 840d8c9b3e5f ("linkage: Introduce new macros for
> > >> assembler symbols") which shipped in v5.4.76.
> > >>
> > >> This patch fixes a build error from clang's assembler when building
> > >> with Clang-12, which now errors when symbols are redeclared with
> > >> different bindings. We're using clang's assembler in Android and
> > >> ChromeOS for 4.19+.
> > >>
> > >> Jiri, would you mind reviewing the 4.19 patch (or both)? It simply
> > >> open codes what the upstream macros would expand to; this can be and
> > >> was observed from running:
> > >
> > > You don't have to touch (expand) __memcpy, __memmove, and __memset, right?
>
> Sure, attached a v2. It's actually a little cleaner (smaller
> diffstat) that way.
Applied, thanks.
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-12-11 15:41 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-09 0:12 5.4 and 4.19 fix for LLVM_IAS/clang-12 Nick Desaulniers
2020-12-09 7:20 ` Jiri Slaby
2020-12-09 7:21 ` Jiri Slaby
2020-12-10 21:15 ` Nick Desaulniers
2020-12-11 14:41 ` Greg KH
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