[PATCH v6 00/13] Add build ID to stacktraces

Stephen Boyd
2021-05-11T00:38:52Z

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
--