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Align the alpha function with the generic function signature.
The alpha function was added in commit 9280e99d87dd ("alpha: add
HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP support") while the
generic function signature was changed in commit a2c64c74c029 ("perf:
Enhance perf_reg_validate() with simd_enabled argument").
After both commits landed in Linus' tree the signatures now differ,
resulting in a build error:
arch/alpha/kernel/perf_regs.c:46:5: error: conflicting types for 'perf_reg_validate'; have 'int(u64)' {aka 'int(long long unsigned int)'}
46 | int perf_reg_validate(u64 mask)
| ^~~~~~~~~~~~~~~~~
In file included from include/linux/perf_event.h:50,
from arch/alpha/kernel/perf_regs.c:4:
include/linux/perf_regs.h:13:5: note: previous declaration of 'perf_reg_validate' with type 'int(u64, bool)' {aka 'int(long long unsigned int, _Bool)'}
13 | int perf_reg_validate(u64 mask, bool simd_enabled);
| ^~~~~~~~~~~~~~~~~
Add the missing argument.
Fixes: 742f62b63904 ("Merge tag 'alpha-for-v7.4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/lindholm/alpha")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Magnus Lindholm <linmag7@gmail.com>
Tested-by: Magnus Lindholm <linmag7@gmail.com>
Link: https://patch.msgid.link/20261021-alpha-perf_reg_validate-v1-1-a8e8cc23ea7a@linutronix.de
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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>
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