| Message ID | 20210511003845.2429846-1-swboyd@chromium.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add build ID to stacktraces | expand |
On Mon 2021-05-10 17:38:32, 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. The entire series looks good to me. I reviewed carefully only the 5th patch touching printk/kallsyms/module code. I just scanned over the other patches touching kernel code and did not notice any obvious problem. I did not check the changes in decode_stacktrace.sh at all. I tried to get stacktraces on x86_64 and it worked as expected. Best Regards, Petr
From: Stephen Boyd > Sent: 11 May 2021 01:39 > > 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. ... > 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) ... > x1 : ffffff93fef15788 x0 : ffffffe3622352e0 > Call trace: > lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > full_proxy_write+0x74/0xa4 Is there any way to get it to print each module ID only once? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Tue, 11 May 2021 12:36:06 +0000 David Laight <David.Laight@ACULAB.COM> wrote: > > x1 : ffffff93fef15788 x0 : ffffffe3622352e0 > > Call trace: > > lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > full_proxy_write+0x74/0xa4 > > Is there any way to get it to print each module ID only once? If there's a trivial way to do that, then perhaps it should be done, but for now, this patch series isn't as obnoxious as the previous versions. It only affects stack traces, and I'm fine with that. -- Steve
From: Steven Rostedt > Sent: 11 May 2021 13:53 > > On Tue, 11 May 2021 12:36:06 +0000 > David Laight <David.Laight@ACULAB.COM> wrote: > > > > x1 : ffffff93fef15788 x0 : ffffffe3622352e0 > > > Call trace: > > > lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > full_proxy_write+0x74/0xa4 > > > > Is there any way to get it to print each module ID only once? > > If there's a trivial way to do that, then perhaps it should be done, but for > now, this patch series isn't as obnoxious as the previous versions. It only > affects stack traces, and I'm fine with that. True. Printing the id in the module list was horrid. The real downside is all the extra text that will overflow the in-kernel buffer. At least it shouldn't be extra lines causing screen wrap. Unless the variable names are long - hi rust :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Tue 2021-05-11 12:58:47, David Laight wrote: > From: Steven Rostedt > > Sent: 11 May 2021 13:53 > > > > On Tue, 11 May 2021 12:36:06 +0000 > > David Laight <David.Laight@ACULAB.COM> wrote: > > > > > > x1 : ffffff93fef15788 x0 : ffffffe3622352e0 > > > > Call trace: > > > > lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > > direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > > full_proxy_write+0x74/0xa4 > > > > > > Is there any way to get it to print each module ID only once? > > > > If there's a trivial way to do that, then perhaps it should be done, but for > > now, this patch series isn't as obnoxious as the previous versions. It only > > affects stack traces, and I'm fine with that. > > True. Printing the id in the module list was horrid. > > The real downside is all the extra text that will overflow the > in-kernel buffer. > At least it shouldn't be extra lines causing screen wrap. > Unless the variable names are long - hi rust :-) Note that the ID is printed only when CONFIG_STACKTRACE_BUILD_ID is enabled. It will be used only by some distros/vendors that use it to download the debuginfo packages. Best Regards, Petr
From: Petr Mladek > Sent: 11 May 2021 15:22 > > On Tue 2021-05-11 12:58:47, David Laight wrote: > > From: Steven Rostedt > > > Sent: 11 May 2021 13:53 > > > > > > On Tue, 11 May 2021 12:36:06 +0000 > > > David Laight <David.Laight@ACULAB.COM> wrote: > > > > > > > > x1 : ffffff93fef15788 x0 : ffffffe3622352e0 > > > > > Call trace: > > > > > lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > > > direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] > > > > > full_proxy_write+0x74/0xa4 > > > > > > > > Is there any way to get it to print each module ID only once? > > > > > > If there's a trivial way to do that, then perhaps it should be done, but for > > > now, this patch series isn't as obnoxious as the previous versions. It only > > > affects stack traces, and I'm fine with that. > > > > True. Printing the id in the module list was horrid. > > > > The real downside is all the extra text that will overflow the > > in-kernel buffer. > > At least it shouldn't be extra lines causing screen wrap. > > Unless the variable names are long - hi rust :-) > > Note that the ID is printed only when CONFIG_STACKTRACE_BUILD_ID > is enabled. It will be used only by some distros/vendors that > use it to download the debuginfo packages. Until Ubuntu decide to turn it on :-) Actually, for the use case, the id could be trimmed significantly. It is only trying to differentiate between builds of a specific module. So even 8 digits would be plenty. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Tue, May 11, 2021 at 02:31:38PM +0000, David Laight wrote: > Actually, for the use case, the id could be trimmed significantly. > It is only trying to differentiate between builds of a specific module. > So even 8 digits would be plenty. asked and answered. please review the bidding.
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. Otherwise, Petr mentioned it could possibly go through the printk tree given that it touches mostly printk things. 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 ]--- Changes from v5 (https://lore.kernel.org/r/20210420215003.3510247-1-swboyd@chromium.org): * Rebased onto v5.12 * Moved logic for when to include build ID code to kdump patch * Simplified commit text to show before/after details Changes from v4 (https://lore.kernel.org/r/20210410015300.3764485-1-swboyd@chromium.org): * Stubbed out more code when CONFIG_STACKTRACE_BUILD_ID=n * Use static_assert instead of BUILD_BUG_ON() * Dropped bad printk change to IP on x86 Changes from v3 (https://lore.kernel.org/r/20210331030520.3816265-1-swboyd@chromium.org): * Fixed compilation warnings due to config changes * Fixed kernel-doc on init_vmlinx_build_id() * Totally removed add_build_id_vmcoreinfo() * Added another printk format %pBb to help x86 print backtraces * Some BUILD_BUG_ON() checks to make sure the buildid doesn't get bigger or smaller Changes from v2 (https://lore.kernel.org/r/20210324020443.1815557-1-swboyd@chromium.org): * Renamed symbol printing function to indicate build IDness * Put build ID information behind Kconfig knob * Build ID for vmlinux is calculated in early init instead of on demand * printk format is %pS[R]b Changes from v1 (https://lore.kernel.org/r/20210301174749.1269154-1-swboyd@chromium.org): * New printk format %pSb and %pSr * Return binary format instead of hex format string from build ID APIs * Some new patches to cleanup buildid/decode_stacktrace.sh * A new patch to decode_stacktrace.sh to parse output [1] https://fedoraproject.org/wiki/Releases/FeatureBuildId Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Young <dyoung@redhat.com> Cc: Evan Green <evgreen@chromium.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: <kexec@lists.infradead.org> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: <linux-arm-kernel@lists.infradead.org> Cc: <linux-doc@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Sasha Levin <sashal@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: <x86@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: peter enderborg <peter.enderborg@sony.com> Stephen Boyd (13): buildid: Only consider GNU notes for build ID parsing buildid: Add API to parse build ID out of buffer buildid: Stash away kernels build ID on init dump_stack: Add vmlinux build ID to stack traces module: Add printk formats to add module build ID to stacktraces arm64: stacktrace: Use %pSb for backtrace printing x86/dumpstack: Use %pSb/%pBb for backtrace printing scripts/decode_stacktrace.sh: Support debuginfod scripts/decode_stacktrace.sh: Silence stderr messages from addr2line/nm scripts/decode_stacktrace.sh: Indicate 'auto' can be used for base path buildid: Mark some arguments const buildid: Fix kernel-doc notation kdump: Use vmlinux_build_id to simplify Documentation/core-api/printk-formats.rst | 11 +++ arch/arm64/kernel/stacktrace.c | 2 +- arch/x86/kernel/dumpstack.c | 2 +- include/linux/buildid.h | 8 ++ include/linux/crash_core.h | 12 +-- include/linux/kallsyms.h | 20 ++++- include/linux/module.h | 8 +- init/main.c | 1 + kernel/crash_core.c | 50 +---------- kernel/kallsyms.c | 101 +++++++++++++++++----- kernel/module.c | 31 ++++++- lib/Kconfig.debug | 11 +++ lib/buildid.c | 74 ++++++++++++---- lib/dump_stack.c | 13 ++- lib/vsprintf.c | 8 +- scripts/decode_stacktrace.sh | 89 +++++++++++++++---- 16 files changed, 327 insertions(+), 114 deletions(-) base-commit: 9f4ad9e425a1d3b6a34617b8ea226d56a119a717