diff options
| author | Matt Turner <mattst88@gmail.com> | 2026-10-18 10:22:04 -0400 |
|---|---|---|
| committer | Magnus Lindholm <linmag7@gmail.com> | 2026-10-18 20:09:29 +0200 |
| commit | 9280e99d87ddd8c6c7fd83f9ea1585967b3dcd60 (patch) | |
| tree | ecab6de91c4b4dea9ad37e9f7dcf4b85e42e3a3e /arch/alpha/include/uapi | |
| parent | c5280a56dc4cbcbbfd3256a0fd58071587e928b0 (diff) | |
alpha: add HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP support
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>
Diffstat (limited to 'arch/alpha/include/uapi')
| -rw-r--r-- | arch/alpha/include/uapi/asm/perf_regs.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/alpha/include/uapi/asm/perf_regs.h b/arch/alpha/include/uapi/asm/perf_regs.h new file mode 100644 index 000000000000..b6d2dcf6e184 --- /dev/null +++ b/arch/alpha/include/uapi/asm/perf_regs.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _ASM_ALPHA_PERF_REGS_H +#define _ASM_ALPHA_PERF_REGS_H + +/* + * Indices 0-30 match the hardware (and DWARF) register numbers. + * r9-r15 are not saved in pt_regs and cannot be sampled. + */ +enum perf_event_alpha_regs { + PERF_REG_ALPHA_R0, + PERF_REG_ALPHA_R1, + PERF_REG_ALPHA_R2, + PERF_REG_ALPHA_R3, + PERF_REG_ALPHA_R4, + PERF_REG_ALPHA_R5, + PERF_REG_ALPHA_R6, + PERF_REG_ALPHA_R7, + PERF_REG_ALPHA_R8, + PERF_REG_ALPHA_R9, + PERF_REG_ALPHA_R10, + PERF_REG_ALPHA_R11, + PERF_REG_ALPHA_R12, + PERF_REG_ALPHA_R13, + PERF_REG_ALPHA_R14, + PERF_REG_ALPHA_R15, + PERF_REG_ALPHA_R16, + PERF_REG_ALPHA_R17, + PERF_REG_ALPHA_R18, + PERF_REG_ALPHA_R19, + PERF_REG_ALPHA_R20, + PERF_REG_ALPHA_R21, + PERF_REG_ALPHA_R22, + PERF_REG_ALPHA_R23, + PERF_REG_ALPHA_R24, + PERF_REG_ALPHA_R25, + PERF_REG_ALPHA_R26, + PERF_REG_ALPHA_R27, + PERF_REG_ALPHA_R28, + PERF_REG_ALPHA_GP, + PERF_REG_ALPHA_SP, + PERF_REG_ALPHA_PC, + PERF_REG_ALPHA_MAX, +}; + +#endif /* _ASM_ALPHA_PERF_REGS_H */ |