linux-kernel - [PATCH v3 8/8] perf syscalltbl: Mask off ABI type for MIPS system calls

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Message-Id: <20250219185657.280286-9-irogers@google.com>
Date: Wed, 19 Feb 2025 10:56:57 -0800
From: Ian Rogers <irogers@...gle.com>
To: Ian Rogers <irogers@...gle.com>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>, 
	John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>, 
	James Clark <james.clark@...aro.org>, Mike Leach <mike.leach@...aro.org>, 
	Leo Yan <leo.yan@...ux.dev>, guoren <guoren@...nel.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Charlie Jenkins <charlie@...osinc.com>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Jiri Slaby <jirislaby@...nel.org>, 
	"Björn Töpel" <bjorn@...osinc.com>, Howard Chu <howardchu95@...il.com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	"linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>, linux-riscv@...ts.infradead.org, 
	linux-mips@...r.kernel.org, Arnd Bergmann <arnd@...db.de>
Subject: [PATCH v3 8/8] perf syscalltbl: Mask off ABI type for MIPS system calls

Arnd Bergmann described that MIPS system calls don't necessarily start
from 0 as an ABI prefix is applied:
https://lore.kernel.org/lkml/8ed7dfb2-1e4d-4aa4-a04b-0397a89365d1@app.fastmail.com/
When decoding the "id" (aka system call number) for MIPS ignore values
greater-than 1000.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/syscalltbl.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/syscalltbl.c b/tools/perf/util/syscalltbl.c
index db0d2b81aed1..ace66e69c1bc 100644
--- a/tools/perf/util/syscalltbl.c
+++ b/tools/perf/util/syscalltbl.c
@@ -46,6 +46,14 @@ const char *syscalltbl__name(int e_machine, int id)
 {
 	const struct syscalltbl *table = find_table(e_machine);
 
+	if (e_machine == EM_MIPS && id > 1000) {
+		/*
+		 * MIPS may encode the N32/64/O32 type in the high part of
+		 * syscall number. Mask this off if present. See the values of
+		 * __NR_N32_Linux, __NR_64_Linux, __NR_O32_Linux and __NR_Linux.
+		 */
+		id = id % 1000;
+	}
 	if (table && id >= 0 && id < table->num_to_name_len)
 		return table->num_to_name[id];
 	return NULL;
-- 
2.48.1.601.g30ceb7b040-goog