linux.git/include/linux/buildid.h, branch v6.12.80

procfs: avoid fetching build ID while holding VMA lock

2026-02-11T12:40:18+00:00

[ Upstream commit b5cbacd7f86f4f62b8813688c8e73be94e8e1951 ]

Fix PROCMAP_QUERY to fetch optional build ID only after dropping mmap_lock
or per-VMA lock, whichever was used to lock VMA under question, to avoid
deadlock reported by syzbot:

 -> #1 (&mm->mmap_lock){++++}-{4:4}:
        __might_fault+0xed/0x170
        _copy_to_iter+0x118/0x1720
        copy_page_to_iter+0x12d/0x1e0
        filemap_read+0x720/0x10a0
        blkdev_read_iter+0x2b5/0x4e0
        vfs_read+0x7f4/0xae0
        ksys_read+0x12a/0x250
        do_syscall_64+0xcb/0xf80
        entry_SYSCALL_64_after_hwframe+0x77/0x7f

 -> #0 (&sb->s_type->i_mutex_key#8){++++}-{4:4}:
        __lock_acquire+0x1509/0x26d0
        lock_acquire+0x185/0x340
        down_read+0x98/0x490
        blkdev_read_iter+0x2a7/0x4e0
        __kernel_read+0x39a/0xa90
        freader_fetch+0x1d5/0xa80
        __build_id_parse.isra.0+0xea/0x6a0
        do_procmap_query+0xd75/0x1050
        procfs_procmap_ioctl+0x7a/0xb0
        __x64_sys_ioctl+0x18e/0x210
        do_syscall_64+0xcb/0xf80
        entry_SYSCALL_64_after_hwframe+0x77/0x7f

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   rlock(&mm->mmap_lock);
                                lock(&sb->s_type->i_mutex_key#8);
                                lock(&mm->mmap_lock);
   rlock(&sb->s_type->i_mutex_key#8);

  *** DEADLOCK ***

This seems to be exacerbated (as we haven't seen these syzbot reports
before that) by the recent:

	777a8560fd29 ("lib/buildid: use __kernel_read() for sleepable context")

To make this safe, we need to grab file refcount while VMA is still locked, but
other than that everything is pretty straightforward. Internal build_id_parse()
API assumes VMA is passed, but it only needs the underlying file reference, so
just add another variant build_id_parse_file() that expects file passed
directly.

[akpm@linux-foundation.org: fix up kerneldoc]
Link: https://lkml.kernel.org/r/20260129215340.3742283-1-andrii@kernel.org
Fixes: ed5d583a88a9 ("fs/procfs: implement efficient VMA querying API for /proc//maps")
Signed-off-by: Andrii Nakryiko 
Reported-by: 
Reviewed-by: Suren Baghdasaryan 
Tested-by: Suren Baghdasaryan 
Reviewed-by: Shakeel Butt 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Eduard Zingerman 
Cc: Hao Luo 
Cc: Jiri Olsa 
Cc: John Fastabend 
Cc: KP Singh 
Cc: Martin KaFai Lau 
Cc: Song Liu 
Cc: Stanislav Fomichev 
Cc: Yonghong Song 
Cc: 
Signed-off-by: Andrew Morton 
[ mm is local var instead of function param ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

lib/buildid: rename build_id_parse() into build_id_parse_nofault()

2024-09-11T16:58:30+00:00

Make it clear that build_id_parse() assumes that it can take no page
fault by renaming it and current few users to build_id_parse_nofault().

Also add build_id_parse() stub which for now falls back to non-sleepable
implementation, but will be changed in subsequent patches to take
advantage of sleepable context. PROCMAP_QUERY ioctl() on
/proc//maps file is using build_id_parse() and will automatically
take advantage of more reliable sleepable context implementation.

Reviewed-by: Eduard Zingerman 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/r/20240829174232.3133883-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov

crash: split vmcoreinfo exporting code out from crash_core.c

2024-02-24T01:48:22+00:00

Now move the relevant codes into separate files:
kernel/crash_reserve.c, include/linux/crash_reserve.h.

And add config item CRASH_RESERVE to control its enabling.

And also update the old ifdeffery of CONFIG_CRASH_CORE, including of
 and config item dependency on CRASH_CORE
accordingly.

And also do renaming as follows:
 - arch/xxx/kernel/{crash_core.c => vmcore_info.c}
because they are only related to vmcoreinfo exporting on x86, arm64,
riscv.

And also Remove config item CRASH_CORE, and rely on CONFIG_KEXEC_CORE to
decide if build in crash_core.c.

[yang.lee@linux.alibaba.com: remove duplicated include in vmcore_info.c]
  Link: https://lkml.kernel.org/r/20240126005744.16561-1-yang.lee@linux.alibaba.com
Link: https://lkml.kernel.org/r/20240124051254.67105-3-bhe@redhat.com
Signed-off-by: Baoquan He 
Signed-off-by: Yang Li 
Acked-by: Hari Bathini 
Cc: Al Viro 
Cc: Eric W. Biederman 
Cc: Pingfan Liu 
Cc: Klara Modin 
Cc: Michael Kelley 
Cc: Nathan Chancellor 
Cc: Stephen Rothwell 
Cc: Yang Li 
Signed-off-by: Andrew Morton

buildid: reduce header file dependencies for module

2023-10-19T01:07:57+00:00

The vmlinux decompressor code intentionally has only a limited set of
included header files, but this started running into a build failure
because of the bitmap logic needing linux/errno.h:

In file included from include/linux/cpumask.h:12,
                 from include/linux/mm_types_task.h:14,
                 from include/linux/mm_types.h:5,
                 from include/linux/buildid.h:5,
                 from include/linux/module.h:14,
                 from arch/arm/boot/compressed/../../../../lib/lz4/lz4_decompress.c:39,
                 from arch/arm/boot/compressed/../../../../lib/decompress_unlz4.c:10,
                 from arch/arm/boot/compressed/decompress.c:60:
include/linux/bitmap.h: In function 'bitmap_allocate_region':
include/linux/bitmap.h:527:25: error: 'EBUSY' undeclared (first use in this function)
  527 |                 return -EBUSY;
      |                         ^~~~~
include/linux/bitmap.h:527:25: note: each undeclared identifier is reported only once for each function it appears in
include/linux/bitmap.h: In function 'bitmap_find_free_region':
include/linux/bitmap.h:554:17: error: 'ENOMEM' undeclared (first use in this function)
  554 |         return -ENOMEM;
      |                 ^~~~~~

This is easily avoided by changing linux/buildid.h to no longer depend on
linux/mm_types.h, a header that pulls in a huge number of indirect dependencies.

Fixes: b9c957f554442 ("bitmap: move bitmap_*_region() functions to bitmap.h")
Fixes: bd7525dacd7e2 ("bpf: Move stack_map_get_build_id into lib")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Yury Norov

kdump: use vmlinux_build_id to simplify

2021-07-08T18:48:22+00:00

We can use the vmlinux_build_id array here now instead of open coding it.
This mostly consolidates code.

Link: https://lkml.kernel.org/r/20210511003845.2429846-14-swboyd@chromium.org
Signed-off-by: Stephen Boyd 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Dave Young 
Cc: Baoquan He 
Cc: Vivek Goyal 
Cc: Andy Shevchenko 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Matthew Wilcox 
Cc: Petr Mladek 
Cc: Rasmus Villemoes 
Cc: Sasha Levin 
Cc: Sergey Senozhatsky 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

dump_stack: add vmlinux build ID to stack traces

2021-07-08T18:48:22+00:00

Add the running kernel's build ID[1] to the stacktrace information header.
This makes it simpler for developers to locate the vmlinux with full
debuginfo for a particular kernel stacktrace.  Combined with
scripts/decode_stracktrace.sh, a developer can download the correct
vmlinux from a debuginfod[2] server and find the exact file and line
number for the functions plus offsets in a stacktrace.

This is especially useful for pstore crash debugging where the kernel
crashes are recorded in the pstore logs and the recovery kernel is
different or the debuginfo doesn't exist on the device due to space
concerns (the data can be large and a security concern).  The stacktrace
can be analyzed after the crash by using the build ID to find the matching
vmlinux and understand where in the function something went wrong.

Example stacktrace from lkdtm:

 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]

The hex string aa23f7a1231c229de205662d5a9e0d4c580f19a1 is the build ID,
following the kernel version number. Put it all behind a config option,
STACKTRACE_BUILD_ID, so that kernel developers can remove this
information if they decide it is too much.

Link: https://lkml.kernel.org/r/20210511003845.2429846-5-swboyd@chromium.org
Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1]
Link: https://sourceware.org/elfutils/Debuginfod.html [2]
Signed-off-by: Stephen Boyd 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Andy Shevchenko 
Cc: Matthew Wilcox 
Cc: Baoquan He 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Dave Young 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Rasmus Villemoes 
Cc: Sasha Levin 
Cc: Sergey Senozhatsky 
Cc: Thomas Gleixner 
Cc: Vivek Goyal 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

buildid: stash away kernels build ID on init

2021-07-08T18:48:22+00:00

Parse the kernel's build ID at initialization so that other code can print
a hex format string representation of the running kernel's build ID.  This
will be used in the kdump and dump_stack code so that developers can
easily locate the vmlinux debug symbols for a crash/stacktrace.

[swboyd@chromium.org: fix implicit declaration of init_vmlinux_build_id()]
  Link: https://lkml.kernel.org/r/CAE-0n51UjTbay8N9FXAyE7_aR2+ePrQnKSRJ0gbmRsXtcLBVaw@mail.gmail.com

Link: https://lkml.kernel.org/r/20210511003845.2429846-4-swboyd@chromium.org
Signed-off-by: Stephen Boyd 
Acked-by: Baoquan He 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Dave Young 
Cc: Vivek Goyal 
Cc: Andy Shevchenko 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Matthew Wilcox 
Cc: Petr Mladek 
Cc: Rasmus Villemoes 
Cc: Sasha Levin 
Cc: Sergey Senozhatsky 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

buildid: add API to parse build ID out of buffer

2021-07-08T18:48:22+00:00

Add an API that can parse the build ID out of a buffer, instead of a vma,
to support printing a kernel module's build ID for stack traces.

Link: https://lkml.kernel.org/r/20210511003845.2429846-3-swboyd@chromium.org
Signed-off-by: Stephen Boyd 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Andy Shevchenko 
Cc: Baoquan He 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Dave Young 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Matthew Wilcox 
Cc: Petr Mladek 
Cc: Rasmus Villemoes 
Cc: Sasha Levin 
Cc: Sergey Senozhatsky 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Vivek Goyal 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bpf: Add size arg to build_id_parse function

2021-01-15T03:29:58+00:00

It's possible to have other build id types (other than default SHA1).
Currently there's also ld support for MD5 build id.

Adding size argument to build_id_parse function, that returns (if defined)
size of the parsed build id, so we can recognize the build id type.

Signed-off-by: Jiri Olsa 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20210114134044.1418404-3-jolsa@kernel.org

bpf: Move stack_map_get_build_id into lib

2021-01-15T03:29:58+00:00

Moving stack_map_get_build_id into lib with
declaration in linux/buildid.h header:

  int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id);

This function returns build id for given struct vm_area_struct.
There is no functional change to stack_map_get_build_id function.

Signed-off-by: Jiri Olsa 
Signed-off-by: Alexei Starovoitov 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20210114134044.1418404-2-jolsa@kernel.org