* 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