CVSROOT: /cvs
Module name: src
Changes by: chel...@cvs.openbsd.org 2021/06/01 18:39:27
Modified files:
sys/kern : subr_prf.c
sys/ddb : db_command.c
sys/sys : systm.h
sys/arch/amd64/amd64: trap.c
sys/arch/alpha/include: cpu.h
sys/arch/amd64/include: cpu.h
sys/arch/arm/include: cpu.h
sys/arch/arm64/include: cpu.h
sys/arch/hppa/include: cpu.h
sys/arch/i386/include: cpu.h
sys/arch/m88k/include: cpu.h
sys/arch/mips64/include: cpu.h
sys/arch/powerpc/include: cpu.h
sys/arch/powerpc64/include: cpu.h
sys/arch/riscv64/include: cpu.h
sys/arch/sh/include: cpu.h
sys/arch/sparc64/include: cpu.h
Log message:
kernel: introduce per-CPU panic(9) message buffers
Add a 512-byte buffer (ci_panicbuf) to each cpu_info struct on each
platform for use by panic(9). The first panic on a given CPU writes
its message to this buffer. Subsequent panics on a given CPU print
the panic message to the console but do not modify the buffer. This
aids debugging in two cases:
- If 2+ CPUs panic simultaneously there is no risk of garbled messages
in the panic buffer.
- If a CPU panics and then the operator causes a second panic while
using ddb(4), the operator can still recall the first failure on
a particular CPU.
Misc. changes to support this bigger change:
- Set panicstr atomically to identify the first CPU to reach panic().
- Tweak db_show_panic_cmd() to print all panic messages across all
CPUs. Prefix the first panic with an asterisk ('*').
- Prefer db_printf() to printf() during a panic if we have it.
Apparently it disturbs less global state.
- On amd64, tweak fault() to write the local panic buffer. This needs
more work.
Prompted by bluhm@ and deraadt@. Mostly written by deraadt@.
Discussed with bluhm@, deraadt@ and kettenis@.
Borne from a discussion on tech@ about making panic(9) more MP-safe:
https://marc.info/?l=openbsd-tech&m=162086462316143&w=2
ok kettenis@, visa@, bluhm@, deraadt@
