mirror of
https://github.com/torvalds/linux.git
synced 2026-10-23 23:51:02 +02:00
9280e99d87
Let perf sample registers and dump the user stack, which is what the perf tool needs for --call-graph dwarf. The register indices follow the hardware numbering, so r0-r30 map directly to DWARF register numbers, with pc after them. r9-r15 are callee-saved and live in switch_stack rather than pt_regs, so they cannot be sampled. Without r15 an unwinder cannot recover the CFA of a first frame that uses $15 as its frame pointer. sp is not in pt_regs either: for user frames it comes from user_stack_pointer(), and for kernel frames (PERF_SAMPLE_REGS_INTR) it is the end of the trap frame, as in stacktrace.c. Software events such as context switches and tracepoints hand perf a per-CPU pt_regs filled in by perf_fetch_caller_regs() instead of a trap frame. It is not on the stack and has no room for sp, so report sp as 0 there rather than the address of the per-CPU buffer. Assisted-by: Claude:claude-opus-5-5 Acked-by: Ian Rogers <irogers@google.com> Tested-by: Magnus Lindholm <linmag7@gmail.com> Reviewed-by: Magnus Lindholm <linmag7@gmail.com> Signed-off-by: Matt Turner <mattst88@gmail.com> Link: https://lore.kernel.org/r/20261018-alpha-perf-regs-v3-v3-4-52be85332c57@gmail.com Signed-off-by: Magnus Lindholm <linmag7@gmail.com> |
||
|---|---|---|
| .. | ||
| core | ||
| debug | ||
| io/dma-contiguous | ||
| locking | ||
| perf | ||
| sched | ||
| seccomp/seccomp-filter | ||
| time | ||
| vm | ||
| arch-support.txt | ||