kernel-oops-locator

name

kernel-oops-locator

description

analyze linux kernel panic, oops, null pointer, unable to handle, or call trace text and map the likely crash site to nearby source lines using non-interactive gdb-multiarch commands against vmlinux. use when the user provides panic text, a panic log, a p-marked frame, a function+offset like foo+0x12, or asks to locate code near a crash site in a kernel tree. prefer the hardcoded ~/learn_os defaults in this skill unless the user explicitly overrides them.

Kernel Oops Locator

Use this skill for offline kernel crash source lookup, not for live breakpoint debugging.

Default environment

Unless the user explicitly overrides them, assume these defaults:

• kernel source tree: ~/learn_os/f2fs
• vmlinux path: ~/learn_os/f2fs_upstream/vmlinux
• compile commands dir: ~/learn_os/f2fs
• gdb init: ~/learn_os/.gdbinit
• debugger: /usr/bin/gdb-multiarch
• optional shell vars file: ~/learn_os/.vars.sh

Read references/default-paths.md if you need the exact defaults or an example command.

Workflow

1. Identify the input mode.

   • panic text pasted in chat: extract the best crash location.
   • panic log file: read the file content, then extract the best crash location.
   • explicit symbol: use the provided func+0xoff or absolute address directly.

2. Choose the best lookup target.

   • First choice: the frame explicitly marked (P).
   • Fallback: a PC is at ..., pc : ..., lr : ..., or RIP: style location.
   • Fallback: the first func+0xoff/0xlen in the crashing section.
   • Normalize results to func+0xoff when possible.

3. Prefer non-interactive gdb usage.

   • Do not assume terminal keyboard interaction.
   • Prefer gdb-multiarch -q -batch plus -ex commands.
   • Use scripts/make_gdb_command.py to generate the exact shell command or gdb command file text.

4. Produce readable code context.

   • Default to info line and list *location.
   • Show a readable window around the location.
   • Add disassemble /s only when the user asks for asm mixed output or when source mapping looks ambiguous.

5. Be honest about execution context.

   • If you cannot access the user’s local kernel tree from the current environment, still provide the exact command to run locally.
   • Do not pretend that the command was executed if it was not.

Preferred command shape

Default command pattern:

/usr/bin/gdb-multiarch -q -batch ~/learn_os/f2fs_upstream/vmlinux \
  -ex 'set pagination off' \
  -ex 'set confirm off' \
  -ex 'set listsize 20' \
  -ex 'directory ~/learn_os/f2fs' \
  -ex 'source ~/learn_os/.gdbinit' \
  -ex 'info line *f2fs_put_page+0x34' \
  -ex 'list *f2fs_put_page+0x34'

If the user wants a shell snippet that honors ~/learn_os/.vars.sh, prefer:

source ~/learn_os/.vars.sh && \
/usr/bin/gdb-multiarch -q -batch "$BASE/f2fs_upstream/vmlinux" \
  -ex 'set pagination off' \
  -ex 'set confirm off' \
  -ex 'set listsize 20' \
  -ex "directory $BASE/f2fs" \
  -ex "source $BASE/.gdbinit" \
  -ex 'info line *f2fs_put_page+0x34' \
  -ex 'list *f2fs_put_page+0x34'

Output expectations

When helping the user, prefer this structure:

1. picked location: the exact symbol or address chosen, and why.
2. local command: the exact non-interactive gdb command.
3. expected effect: what the command prints, such as source line mapping and nearby code.
4. fallbacks: alternate symbol candidates if the panic text is ambiguous.

Resources

• Use scripts/parse_oops_target.py to extract the best location from panic text.
• Use scripts/make_gdb_command.py to generate a ready-to-run command.
• If you want a quick no-interactive-gdb lookup (addr2line + objdump window), use scripts/symoff_lookup.sh.
• Use references/default-paths.md for the baked-in environment defaults and examples.
• For Android/Pixel kleaf builds and func+0xOFF frames, see references/aosp_kleaf_symoff_lookup.md.

Scope boundary

This skill is not primarily for target remote localhost:1234 or live attach sessions. Only discuss remote gdbstub / attach flows if the user explicitly asks to connect to a live target, qemu, kgdb, or a gdb server.