* [PATCH v2 05/12] arm64: stacktrace: Use %pSb for backtrace printing
2021-03-24 2:04 [PATCH v2 00/12] Add build ID to stacktraces Stephen Boyd
@ 2021-03-24 2:04 ` Stephen Boyd
2021-03-24 8:55 ` [PATCH v2 00/12] Add build ID to stacktraces Christoph Hellwig
` (2 subsequent siblings)
3 siblings, 0 replies; 9+ messages in thread
From: Stephen Boyd @ 2021-03-24 2:04 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-kernel, Catalin Marinas, Will Deacon, linux-arm-kernel,
Jiri Olsa, Alexei Starovoitov, Jessica Yu, Evan Green,
Hsin-Yi Wang, Petr Mladek, Steven Rostedt, Andy Shevchenko,
Matthew Wilcox
Let's use the new printk format to print the stacktrace entry when
printing a backtrace to the kernel logs. This will include any module's
build ID[1] in it so that offline/crash debugging can easily locate the
debuginfo for a module via something like debuginfod[2].
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1]
Link: https://sourceware.org/elfutils/Debuginfod.html [2]
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
arch/arm64/kernel/stacktrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ad20981dfda4..9d38da01ff98 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -129,7 +129,7 @@ NOKPROBE_SYMBOL(walk_stackframe);
static void dump_backtrace_entry(unsigned long where, const char *loglvl)
{
- printk("%s %pS\n", loglvl, (void *)where);
+ printk("%s %pSb\n", loglvl, (void *)where);
}
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
--
https://chromeos.dev
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^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-24 2:04 [PATCH v2 00/12] Add build ID to stacktraces Stephen Boyd
2021-03-24 2:04 ` [PATCH v2 05/12] arm64: stacktrace: Use %pSb for backtrace printing Stephen Boyd
@ 2021-03-24 8:55 ` Christoph Hellwig
2021-03-25 11:06 ` peter enderborg
[not found] ` <32011616573677@mail.yandex-team.ru>
2021-03-25 11:14 ` peter enderborg
3 siblings, 1 reply; 9+ messages in thread
From: Christoph Hellwig @ 2021-03-24 8:55 UTC (permalink / raw)
To: Stephen Boyd
Cc: Andrew Morton, linux-kernel, Alexei Starovoitov, Andy Shevchenko,
Baoquan He, Borislav Petkov, Catalin Marinas, Dave Young,
Evan Green, Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa,
kexec, Konstantin Khlebnikov, linux-arm-kernel, linux-doc,
Matthew Wilcox, Petr Mladek, Rasmus Villemoes, Sasha Levin,
Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner, Vivek Goyal,
Will Deacon, x86
On Tue, Mar 23, 2021 at 07:04:31PM -0700, Stephen Boyd wrote:
> x5 : 0000000000000000 x4 : 0000000000000001
> x3 : 0000000000000008 x2 : ffffff93fef25a70
> x1 : ffffff93fef15788 x0 : ffffffe3622352e0
> Call trace:
> lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
Yikes. No, please do not make the backtraces a complete mess for
something that serves absolutely no need.
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^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-24 8:55 ` [PATCH v2 00/12] Add build ID to stacktraces Christoph Hellwig
@ 2021-03-25 11:06 ` peter enderborg
2021-03-25 23:21 ` Stephen Boyd
0 siblings, 1 reply; 9+ messages in thread
From: peter enderborg @ 2021-03-25 11:06 UTC (permalink / raw)
To: Christoph Hellwig, Stephen Boyd
Cc: Andrew Morton, linux-kernel, Alexei Starovoitov, Andy Shevchenko,
Baoquan He, Borislav Petkov, Catalin Marinas, Dave Young,
Evan Green, Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa,
kexec, Konstantin Khlebnikov, linux-arm-kernel, linux-doc,
Matthew Wilcox, Petr Mladek, Rasmus Villemoes, Sasha Levin,
Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner, Vivek Goyal,
Will Deacon, x86
On 3/24/21 9:55 AM, Christoph Hellwig wrote:
> On Tue, Mar 23, 2021 at 07:04:31PM -0700, Stephen Boyd wrote:
>> x5 : 0000000000000000 x4 : 0000000000000001
>> x3 : 0000000000000008 x2 : ffffff93fef25a70
>> x1 : ffffff93fef15788 x0 : ffffffe3622352e0
>> Call trace:
>> lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
>> direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> Yikes. No, please do not make the backtraces a complete mess for
> something that serves absolutely no need.
Would a "verbose" flag be acceptable solution? Something like write 1 to /sys/kernel/debug/verbose_stack to get the extra info.
I think I see a need for it.
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-25 11:06 ` peter enderborg
@ 2021-03-25 23:21 ` Stephen Boyd
2021-03-30 10:59 ` Petr Mladek
0 siblings, 1 reply; 9+ messages in thread
From: Stephen Boyd @ 2021-03-25 23:21 UTC (permalink / raw)
To: Christoph Hellwig, peter enderborg
Cc: Andrew Morton, linux-kernel, Alexei Starovoitov, Andy Shevchenko,
Baoquan He, Borislav Petkov, Catalin Marinas, Dave Young,
Evan Green, Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa,
kexec, Konstantin Khlebnikov, linux-arm-kernel, linux-doc,
Matthew Wilcox, Petr Mladek, Rasmus Villemoes, Sasha Levin,
Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner, Vivek Goyal,
Will Deacon, x86
Quoting peter enderborg (2021-03-25 04:06:17)
> On 3/24/21 9:55 AM, Christoph Hellwig wrote:
> > On Tue, Mar 23, 2021 at 07:04:31PM -0700, Stephen Boyd wrote:
> >> x5 : 0000000000000000 x4 : 0000000000000001
> >> x3 : 0000000000000008 x2 : ffffff93fef25a70
> >> x1 : ffffff93fef15788 x0 : ffffffe3622352e0
> >> Call trace:
> >> lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> >> direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> > Yikes. No, please do not make the backtraces a complete mess for
> > something that serves absolutely no need.
It serves a need. Please look at the patches to understand that I'm
adding the buildid to automatically find the associated debug
information on distros.
>
> Would a "verbose" flag be acceptable solution? Something like write 1 to /sys/kernel/debug/verbose_stack to get the extra info.
>
> I think I see a need for it.
>
Or a kernel config option and a commandline parameter? That would be OK
for me as I said on v1 of this series. I'll add that in for the next
patch series given all the distaste for some more hex characters next to
the module name.
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-25 23:21 ` Stephen Boyd
@ 2021-03-30 10:59 ` Petr Mladek
0 siblings, 0 replies; 9+ messages in thread
From: Petr Mladek @ 2021-03-30 10:59 UTC (permalink / raw)
To: Stephen Boyd
Cc: Christoph Hellwig, peter enderborg, Andrew Morton, linux-kernel,
Alexei Starovoitov, Andy Shevchenko, Baoquan He, Borislav Petkov,
Catalin Marinas, Dave Young, Evan Green, Hsin-Yi Wang,
Ingo Molnar, Jessica Yu, Jiri Olsa, kexec, Konstantin Khlebnikov,
linux-arm-kernel, linux-doc, Matthew Wilcox, Rasmus Villemoes,
Sasha Levin, Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner,
Vivek Goyal, Will Deacon, x86
On Thu 2021-03-25 16:21:46, Stephen Boyd wrote:
> Quoting peter enderborg (2021-03-25 04:06:17)
> > On 3/24/21 9:55 AM, Christoph Hellwig wrote:
> > > On Tue, Mar 23, 2021 at 07:04:31PM -0700, Stephen Boyd wrote:
> > >> x5 : 0000000000000000 x4 : 0000000000000001
> > >> x3 : 0000000000000008 x2 : ffffff93fef25a70
> > >> x1 : ffffff93fef15788 x0 : ffffffe3622352e0
> > >> Call trace:
> > >> lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> > >> direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> > > Yikes. No, please do not make the backtraces a complete mess for
> > > something that serves absolutely no need.
>
> It serves a need. Please look at the patches to understand that I'm
> adding the buildid to automatically find the associated debug
> information on distros.
>
> >
> > Would a "verbose" flag be acceptable solution? Something like write 1 to /sys/kernel/debug/verbose_stack to get the extra info.
> >
> > I think I see a need for it.
> >
>
> Or a kernel config option and a commandline parameter? That would be OK
> for me as I said on v1 of this series. I'll add that in for the next
> patch series given all the distaste for some more hex characters next to
> the module name.
IMHO, a build configure option would fit the best here.
It does not make sense to show the ID when the kernel vendor does
not have a service to download the related binaries. But it makes
sense to show the buildid by default when the provider/distro has
the service and want to use the ID when handling bug reports.
We could always add boot/run time options when people really need it.
Best Regards,
Petr
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^ permalink raw reply [flat|nested] 9+ messages in thread
[parent not found: <32011616573677@mail.yandex-team.ru>]
* Re: [PATCH v2 00/12] Add build ID to stacktraces
[not found] ` <32011616573677@mail.yandex-team.ru>
@ 2021-03-24 19:04 ` Stephen Boyd
0 siblings, 0 replies; 9+ messages in thread
From: Stephen Boyd @ 2021-03-24 19:04 UTC (permalink / raw)
To: Andrew Morton, Konstantin Khlebnikov
Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov, Andy Shevchenko,
Baoquan He, Borislav Petkov, Catalin Marinas, Dave Young,
Evan Green, Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa,
kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
linux-doc@vger.kernel.org, Matthew Wilcox, Petr Mladek,
Rasmus Villemoes, Sasha Levin, Sergey Senozhatsky, Steven Rostedt,
Thomas Gleixner, Vivek Goyal, Will Deacon, x86@kernel.org
HTML mail?
Quoting Konstantin Khlebnikov (2021-03-24 01:23:55)
> 24.03.2021, 05:04, "Stephen Boyd" <swboyd@chromium.org>:
>
> Looks too noisy for me. Maybe print id in the line "Modules linked in:"?
> I suppose only out-of-tree modules need this?
>
Please see this note in patch 4:
Originally, I put this on the %pS format, but that was quickly rejected
given that %pS is used in other places such as ftrace where build IDs
aren't meaningful. There was some discussions on the list to put every
module build ID into the "Modules linked in:" section of the stacktrace
message but that quickly becomes very hard to read once you have more
than three or four modules linked in. It also provides too much
information when we don't expect each module to be traversed in a
stacktrace. Having the build ID for modules that aren't important just
makes things messy. Splitting it to multiple lines for each module
quickly explodes the number of lines printed in an oops too, possibly
wrapping the warning off the console. And finally, trying to stash away
each module used in a callstack to provide the ID of each symbol printed
is cumbersome and would require changes to each architecture to stash
away modules and return their build IDs once unwinding has completed.
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-24 2:04 [PATCH v2 00/12] Add build ID to stacktraces Stephen Boyd
` (2 preceding siblings ...)
[not found] ` <32011616573677@mail.yandex-team.ru>
@ 2021-03-25 11:14 ` peter enderborg
2021-03-25 23:18 ` Stephen Boyd
3 siblings, 1 reply; 9+ messages in thread
From: peter enderborg @ 2021-03-25 11:14 UTC (permalink / raw)
To: Stephen Boyd, Andrew Morton
Cc: linux-kernel, Alexei Starovoitov, Andy Shevchenko, Baoquan He,
Borislav Petkov, Catalin Marinas, Dave Young, Evan Green,
Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa, kexec,
Konstantin Khlebnikov, linux-arm-kernel, linux-doc,
Matthew Wilcox, Petr Mladek, Rasmus Villemoes, Sasha Levin,
Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner, Vivek Goyal,
Will Deacon, x86
On 3/24/21 3:04 AM, Stephen Boyd wrote:
> This series adds the kernel's build ID[1] to the stacktrace header printed
> in oops messages, warnings, etc. and the build ID for any module that
> appears in the stacktrace after the module name. The goal is to make the
> stacktrace more self-contained and descriptive by including the relevant
> build IDs in the kernel logs when something goes wrong. This can be used
> by post processing tools like script/decode_stacktrace.sh and kernel
> developers to easily locate the debug info associated with a kernel
> crash and line up what line and file things started falling apart at.
>
> To show how this can be used I've included a patch to
> decode_stacktrace.sh that downloads the debuginfo from a debuginfod
> server.
>
> This also includes some patches to make the buildid.c file use more
> const arguments and consolidate logic into buildid.c from kdump. These
> are left to the end as they were mostly cleanup patches. I don't know
> who exactly maintains this so I guess Andrew is the best option to merge
> all this code.
>
> Here's an example lkdtm stacktrace on arm64.
>
> WARNING: CPU: 4 PID: 3255 at drivers/misc/lkdtm/bugs.c:83 lkdtm_WARNING+0x28/0x30 [lkdtm]
> Modules linked in: lkdtm rfcomm algif_hash algif_skcipher af_alg xt_cgroup uinput xt_MASQUERADE
> CPU: 4 PID: 3255 Comm: bash Not tainted 5.11 #3 aa23f7a1231c229de205662d5a9e0d4c580f19a1
> Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
> pstate: 00400009 (nzcv daif +PAN -UAO -TCO BTYPE=--)
> pc : lkdtm_WARNING+0x28/0x30 [lkdtm]
> lr : lkdtm_do_action+0x24/0x40 [lkdtm]
> sp : ffffffc0134fbca0
> x29: ffffffc0134fbca0 x28: ffffff92d53ba240
> x27: 0000000000000000 x26: 0000000000000000
> x25: 0000000000000000 x24: ffffffe3622352c0
> x23: 0000000000000020 x22: ffffffe362233366
> x21: ffffffe3622352e0 x20: ffffffc0134fbde0
> x19: 0000000000000008 x18: 0000000000000000
> x17: ffffff929b6536fc x16: 0000000000000000
> x15: 0000000000000000 x14: 0000000000000012
> x13: ffffffe380ed892c x12: ffffffe381d05068
> x11: 0000000000000000 x10: 0000000000000000
> x9 : 0000000000000001 x8 : ffffffe362237000
> x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000000
> x5 : 0000000000000000 x4 : 0000000000000001
> x3 : 0000000000000008 x2 : ffffff93fef25a70
> x1 : ffffff93fef15788 x0 : ffffffe3622352e0
> Call trace:
> lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e]
> full_proxy_write+0x74/0xa4
> vfs_write+0xec/0x2e8
> ksys_write+0x84/0xf0
> __arm64_sys_write+0x24/0x30
> el0_svc_common+0xf4/0x1c0
> do_el0_svc_compat+0x28/0x3c
> el0_svc_compat+0x10/0x1c
> el0_sync_compat_handler+0xa8/0xcc
> el0_sync_compat+0x178/0x180
> ---[ end trace 3d95032303e59e68 ]---
How will this work with the ftrace?
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^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v2 00/12] Add build ID to stacktraces
2021-03-25 11:14 ` peter enderborg
@ 2021-03-25 23:18 ` Stephen Boyd
0 siblings, 0 replies; 9+ messages in thread
From: Stephen Boyd @ 2021-03-25 23:18 UTC (permalink / raw)
To: Andrew Morton, peter enderborg
Cc: linux-kernel, Alexei Starovoitov, Andy Shevchenko, Baoquan He,
Borislav Petkov, Catalin Marinas, Dave Young, Evan Green,
Hsin-Yi Wang, Ingo Molnar, Jessica Yu, Jiri Olsa, kexec,
Konstantin Khlebnikov, linux-arm-kernel, linux-doc,
Matthew Wilcox, Petr Mladek, Rasmus Villemoes, Sasha Levin,
Sergey Senozhatsky, Steven Rostedt, Thomas Gleixner, Vivek Goyal,
Will Deacon, x86
Quoting peter enderborg (2021-03-25 04:14:31)
> > el0_sync_compat_handler+0xa8/0xcc
> > el0_sync_compat+0x178/0x180
> > ---[ end trace 3d95032303e59e68 ]---
>
> How will this work with the ftrace?
>
It won't affect ftrace, if that's the question you're asking.
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