* [PATCH] kallsyms: ignore all local labels prefixed by '.L'
@ 2022-02-01 1:32 Changbin Du
2022-02-01 16:33 ` Nathan Chancellor
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Changbin Du @ 2022-02-01 1:32 UTC (permalink / raw)
To: Nick Desaulniers, Nathan Chancellor, Masahiro Yamada
Cc: linux-kernel, linux-riscv, llvm, Changbin Du
The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
'.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
And they might overlap with handwritten symbols.
Before this change, a dumpstack shows a local symbol for epc:
[ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
[ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
[ 0.040452][ T0] ra : restore_all+0x12/0x6e
The simple solution is that we can ignore all local labels prefixed by '.L'.
For handwritten symbols which need to be preserved should drop the '.L'
prefix.
After this change, the C defined symbol is shown so we can locate the
problematical code immediately:
[ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
[ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
[ 0.036567][ T0] ra : restore_all+0x12/0x6e
Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
scripts/kallsyms.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 54ad86d13784..8caabddf817c 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
/* Symbol names that begin with the following are ignored.*/
static const char * const ignored_prefixes[] = {
"$", /* local symbols for ARM, MIPS, etc. */
- ".LASANPC", /* s390 kasan local symbols */
+ ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
"__crc_", /* modversions */
"__efistub_", /* arm64 EFI stub namespace */
"__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
--
2.32.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] kallsyms: ignore all local labels prefixed by '.L'
2022-02-01 1:32 [PATCH] kallsyms: ignore all local labels prefixed by '.L' Changbin Du
@ 2022-02-01 16:33 ` Nathan Chancellor
2022-02-01 19:42 ` Nick Desaulniers
2022-02-21 14:37 ` Changbin Du
2 siblings, 0 replies; 6+ messages in thread
From: Nathan Chancellor @ 2022-02-01 16:33 UTC (permalink / raw)
To: Changbin Du
Cc: Nick Desaulniers, Masahiro Yamada, linux-kernel, linux-riscv, llvm
On Tue, Feb 01, 2022 at 09:32:57AM +0800, Changbin Du wrote:
> The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
> '.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
> And they might overlap with handwritten symbols.
>
> Before this change, a dumpstack shows a local symbol for epc:
> [ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
> [ 0.040452][ T0] ra : restore_all+0x12/0x6e
>
> The simple solution is that we can ignore all local labels prefixed by '.L'.
> For handwritten symbols which need to be preserved should drop the '.L'
> prefix.
>
> After this change, the C defined symbol is shown so we can locate the
> problematical code immediately:
> [ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
> [ 0.036567][ T0] ra : restore_all+0x12/0x6e
>
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
Does not seem too unreasonable to me.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---
> scripts/kallsyms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 54ad86d13784..8caabddf817c 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
> /* Symbol names that begin with the following are ignored.*/
> static const char * const ignored_prefixes[] = {
> "$", /* local symbols for ARM, MIPS, etc. */
> - ".LASANPC", /* s390 kasan local symbols */
> + ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
> "__crc_", /* modversions */
> "__efistub_", /* arm64 EFI stub namespace */
> "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
> --
> 2.32.0
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kallsyms: ignore all local labels prefixed by '.L'
2022-02-01 1:32 [PATCH] kallsyms: ignore all local labels prefixed by '.L' Changbin Du
2022-02-01 16:33 ` Nathan Chancellor
@ 2022-02-01 19:42 ` Nick Desaulniers
2022-02-03 1:01 ` Changbin Du
2022-02-21 14:37 ` Changbin Du
2 siblings, 1 reply; 6+ messages in thread
From: Nick Desaulniers @ 2022-02-01 19:42 UTC (permalink / raw)
To: Changbin Du
Cc: Nathan Chancellor, Masahiro Yamada, linux-kernel, linux-riscv, llvm
On Mon, Jan 31, 2022 at 5:33 PM Changbin Du <changbin.du@gmail.com> wrote:
Make sure to mark the version of your patches (this is v2, IIUC). `git
format-patch -v2 HEAD~`
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
>
> The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
> '.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
> And they might overlap with handwritten symbols.
>
> Before this change, a dumpstack shows a local symbol for epc:
> [ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
> [ 0.040452][ T0] ra : restore_all+0x12/0x6e
>
> The simple solution is that we can ignore all local labels prefixed by '.L'.
> For handwritten symbols which need to be preserved should drop the '.L'
> prefix.
>
> After this change, the C defined symbol is shown so we can locate the
> problematical code immediately:
> [ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
> [ 0.036567][ T0] ra : restore_all+0x12/0x6e
>
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
> scripts/kallsyms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 54ad86d13784..8caabddf817c 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
> /* Symbol names that begin with the following are ignored.*/
> static const char * const ignored_prefixes[] = {
> "$", /* local symbols for ARM, MIPS, etc. */
> - ".LASANPC", /* s390 kasan local symbols */
> + ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
> "__crc_", /* modversions */
> "__efistub_", /* arm64 EFI stub namespace */
> "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
> --
> 2.32.0
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kallsyms: ignore all local labels prefixed by '.L'
2022-02-01 19:42 ` Nick Desaulniers
@ 2022-02-03 1:01 ` Changbin Du
0 siblings, 0 replies; 6+ messages in thread
From: Changbin Du @ 2022-02-03 1:01 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Changbin Du, Nathan Chancellor, Masahiro Yamada, linux-kernel,
linux-riscv, llvm
On Tue, Feb 01, 2022 at 11:42:59AM -0800, Nick Desaulniers wrote:
> On Mon, Jan 31, 2022 at 5:33 PM Changbin Du <changbin.du@gmail.com> wrote:
>
> Make sure to mark the version of your patches (this is v2, IIUC). `git
> format-patch -v2 HEAD~`
>
Sure, I fogot to add version NO. this time. Thanks for your reminding.
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
>
> >
> > The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
> > '.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
> > And they might overlap with handwritten symbols.
> >
> > Before this change, a dumpstack shows a local symbol for epc:
> > [ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
> > [ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
> > [ 0.040452][ T0] ra : restore_all+0x12/0x6e
> >
> > The simple solution is that we can ignore all local labels prefixed by '.L'.
> > For handwritten symbols which need to be preserved should drop the '.L'
> > prefix.
> >
> > After this change, the C defined symbol is shown so we can locate the
> > problematical code immediately:
> > [ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
> > [ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
> > [ 0.036567][ T0] ra : restore_all+0x12/0x6e
> >
> > Signed-off-by: Changbin Du <changbin.du@gmail.com>
> > ---
> > scripts/kallsyms.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> > index 54ad86d13784..8caabddf817c 100644
> > --- a/scripts/kallsyms.c
> > +++ b/scripts/kallsyms.c
> > @@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
> > /* Symbol names that begin with the following are ignored.*/
> > static const char * const ignored_prefixes[] = {
> > "$", /* local symbols for ARM, MIPS, etc. */
> > - ".LASANPC", /* s390 kasan local symbols */
> > + ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
> > "__crc_", /* modversions */
> > "__efistub_", /* arm64 EFI stub namespace */
> > "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
> > --
> > 2.32.0
> >
>
>
> --
> Thanks,
> ~Nick Desaulniers
--
Cheers,
Changbin Du
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kallsyms: ignore all local labels prefixed by '.L'
2022-02-01 1:32 [PATCH] kallsyms: ignore all local labels prefixed by '.L' Changbin Du
2022-02-01 16:33 ` Nathan Chancellor
2022-02-01 19:42 ` Nick Desaulniers
@ 2022-02-21 14:37 ` Changbin Du
2022-02-21 15:47 ` Masahiro Yamada
2 siblings, 1 reply; 6+ messages in thread
From: Changbin Du @ 2022-02-21 14:37 UTC (permalink / raw)
To: Changbin Du
Cc: Nick Desaulniers, Nathan Chancellor, Masahiro Yamada,
linux-kernel, linux-riscv, llvm
Hi, Masahiro,
Could you consider picking up this change if you have no objection?
On Tue, Feb 01, 2022 at 09:32:57AM +0800, Changbin Du wrote:
> The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
> '.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
> And they might overlap with handwritten symbols.
>
> Before this change, a dumpstack shows a local symbol for epc:
> [ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
> [ 0.040452][ T0] ra : restore_all+0x12/0x6e
>
> The simple solution is that we can ignore all local labels prefixed by '.L'.
> For handwritten symbols which need to be preserved should drop the '.L'
> prefix.
>
> After this change, the C defined symbol is shown so we can locate the
> problematical code immediately:
> [ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
> [ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
> [ 0.036567][ T0] ra : restore_all+0x12/0x6e
>
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
> scripts/kallsyms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 54ad86d13784..8caabddf817c 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
> /* Symbol names that begin with the following are ignored.*/
> static const char * const ignored_prefixes[] = {
> "$", /* local symbols for ARM, MIPS, etc. */
> - ".LASANPC", /* s390 kasan local symbols */
> + ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
> "__crc_", /* modversions */
> "__efistub_", /* arm64 EFI stub namespace */
> "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
> --
> 2.32.0
>
--
Cheers,
Changbin Du
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kallsyms: ignore all local labels prefixed by '.L'
2022-02-21 14:37 ` Changbin Du
@ 2022-02-21 15:47 ` Masahiro Yamada
0 siblings, 0 replies; 6+ messages in thread
From: Masahiro Yamada @ 2022-02-21 15:47 UTC (permalink / raw)
To: Changbin Du
Cc: Nick Desaulniers, Nathan Chancellor, Linux Kernel Mailing List,
open list:SIFIVE DRIVERS, llvm
On Mon, Feb 21, 2022 at 11:38 PM Changbin Du <changbin.du@gmail.com> wrote:
>
> Hi, Masahiro,
> Could you consider picking up this change if you have no objection?
>
> On Tue, Feb 01, 2022 at 09:32:57AM +0800, Changbin Du wrote:
> > The llvm compiler can generate lots of local labels ('.LBB', '.Ltmpxxx',
> > '.L__unnamed_xx', etc.). These symbols usually are useless for debugging.
> > And they might overlap with handwritten symbols.
> >
> > Before this change, a dumpstack shows a local symbol for epc:
> > [ 0.040341][ T0] Hardware name: riscv-virtio,qemu (DT)
> > [ 0.040376][ T0] epc : .LBB6_14+0x22/0x6a
> > [ 0.040452][ T0] ra : restore_all+0x12/0x6e
> >
> > The simple solution is that we can ignore all local labels prefixed by '.L'.
> > For handwritten symbols which need to be preserved should drop the '.L'
> > prefix.
> >
> > After this change, the C defined symbol is shown so we can locate the
> > problematical code immediately:
> > [ 0.035795][ T0] Hardware name: riscv-virtio,qemu (DT)
> > [ 0.036332][ T0] epc : trace_hardirqs_on+0x54/0x13c
> > [ 0.036567][ T0] ra : restore_all+0x12/0x6e
> >
> > Signed-off-by: Changbin Du <changbin.du@gmail.com>
Now applied to linux-kbuild. Thanks.
> > ---
> > scripts/kallsyms.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> > index 54ad86d13784..8caabddf817c 100644
> > --- a/scripts/kallsyms.c
> > +++ b/scripts/kallsyms.c
> > @@ -108,7 +108,7 @@ static bool is_ignored_symbol(const char *name, char type)
> > /* Symbol names that begin with the following are ignored.*/
> > static const char * const ignored_prefixes[] = {
> > "$", /* local symbols for ARM, MIPS, etc. */
> > - ".LASANPC", /* s390 kasan local symbols */
> > + ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
> > "__crc_", /* modversions */
> > "__efistub_", /* arm64 EFI stub namespace */
> > "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
> > --
> > 2.32.0
> >
>
> --
> Cheers,
> Changbin Du
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-02-21 15:48 UTC | newest]
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2022-02-01 1:32 [PATCH] kallsyms: ignore all local labels prefixed by '.L' Changbin Du
2022-02-01 16:33 ` Nathan Chancellor
2022-02-01 19:42 ` Nick Desaulniers
2022-02-03 1:01 ` Changbin Du
2022-02-21 14:37 ` Changbin Du
2022-02-21 15:47 ` Masahiro Yamada
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