linux-kernel - [PATCH] perf/annotate: Use architecture-agnostic register limit

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Message-ID: <20250923174236.12372-1-suchitkarunakaran@gmail.com>
Date: Tue, 23 Sep 2025 23:12:36 +0530
From: Suchit Karunakaran <suchitkarunakaran@...il.com>
To: peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	namhyung@...nel.org,
	mark.rutland@....com,
	alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org,
	irogers@...gle.com,
	adrian.hunter@...el.com,
	kan.liang@...ux.intel.com,
	linux-perf-users@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org,
	Suchit Karunakaran <suchitkarunakaran@...il.com>
Subject: [PATCH] perf/annotate: Use architecture-agnostic register limit

Remove the arch-specific guard around TYPE_STATE_MAX_REGS and define it
as 32 for all architectures. The architecture that perf is built on may
not match the architecture that produced the perf.data file, so relying
on __powerpc__ or similar is fragile. Using 32 as a fixed upper bound is
safe since it is greater than the previous maximum of 16.
Add a comment to clarify that TYPE_STATE_MAX_REGS is an arch-independent
maximum rather than a build-time choice.

Suggested-by: Ian Rogers <irogers@...gle.com>
Signed-off-by: Suchit Karunakaran <suchitkarunakaran@...il.com>
---
 tools/perf/util/annotate-data.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/annotate-data.h b/tools/perf/util/annotate-data.h
index 541fee1a5f0a..1f76885facb0 100644
--- a/tools/perf/util/annotate-data.h
+++ b/tools/perf/util/annotate-data.h
@@ -189,12 +189,15 @@ struct type_state_stack {
 	u8 kind;
 };
 
-/* FIXME: This should be arch-dependent */
-#ifdef __powerpc__
+/*
+ * Maximum number of registers tracked in type_state.
+ *
+ * This limit must cover all supported architectures, since perf
+ * may analyze perf.data files generated on systems with a different
+ * register set. Use 32 as a safe upper bound instead of relying on
+ * build-arch specific values.
+ */
 #define TYPE_STATE_MAX_REGS  32
-#else
-#define TYPE_STATE_MAX_REGS  16
-#endif
 
 /*
  * State table to maintain type info in each register and stack location.
-- 
2.51.0