linux-kernel - [PATCH v1 20/23] perf dwarf-regs: Add MIPS perf to dwarf register number mapping functions

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Message-ID: <20260117052849.2205545-21-irogers@google.com>
Date: Fri, 16 Jan 2026 21:28:46 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	James Clark <james.clark@...aro.org>, John Garry <john.g.garry@...cle.com>, 
	Will Deacon <will@...nel.org>, Leo Yan <leo.yan@...ux.dev>, Guo Ren <guoren@...nel.org>, 
	Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Shimin Guo <shimin.guo@...dio.com>, 
	Athira Rajeev <atrajeev@...ux.ibm.com>, Stephen Brennan <stephen.s.brennan@...cle.com>, 
	Howard Chu <howardchu95@...il.com>, Thomas Falcon <thomas.falcon@...el.com>, 
	Andi Kleen <ak@...ux.intel.com>, "Dr. David Alan Gilbert" <linux@...blig.org>, 
	Dmitry Vyukov <dvyukov@...gle.com>, 
	"Krzysztof Łopatowski" <krzysztof.m.lopatowski@...il.com>, Chun-Tse Shao <ctshao@...gle.com>, 
	Aditya Bodkhe <aditya.b1@...ux.ibm.com>, Haibo Xu <haibo1.xu@...el.com>, 
	Sergei Trofimovich <slyich@...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-riscv@...ts.infradead.org, 
	Mark Wielaard <mark@...mp.org>
Subject: [PATCH v1 20/23] perf dwarf-regs: Add MIPS perf to dwarf register
 number mapping functions

Despite an unused function declaration, there was no unwind-libdw for
MIPS but there is a perf_regs.h and a libdw implementation. Fill in
the pieces so hopefully MIPS unwinding with libdw works.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/dwarf-regs-arch/Build             |  1 +
 tools/perf/util/dwarf-regs-arch/dwarf-regs-mips.c | 14 ++++++++++++++
 tools/perf/util/dwarf-regs.c                      |  5 +++++
 tools/perf/util/include/dwarf-regs.h              |  1 +
 tools/perf/util/unwind-libdw.h                    |  2 --
 5 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-mips.c

diff --git a/tools/perf/util/dwarf-regs-arch/Build b/tools/perf/util/dwarf-regs-arch/Build
index 10c2af3d933a..ceb68ae86fd8 100644
--- a/tools/perf/util/dwarf-regs-arch/Build
+++ b/tools/perf/util/dwarf-regs-arch/Build
@@ -2,6 +2,7 @@ perf-util-$(CONFIG_LIBDW) += dwarf-regs-arm64.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-arm.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-csky.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-loongarch.o
+perf-util-$(CONFIG_LIBDW) += dwarf-regs-mips.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-powerpc.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-riscv.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-s390.o
diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-mips.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-mips.c
new file mode 100644
index 000000000000..3bb916b45c66
--- /dev/null
+++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-mips.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <dwarf-regs.h>
+#include "../../../arch/mips/include/uapi/asm/perf_regs.h"
+
+int __get_dwarf_regnum_for_perf_regnum_mips(int perf_regnum)
+{
+	if (perf_regnum == PERF_REG_MIPS_PC)
+		return 37;
+	if (perf_regnum < 0 || perf_regnum >= PERF_REG_MIPS_MAX)
+		return -ENOENT;
+
+	return perf_regnum;
+}
diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
index f86f76547592..797f455eba0d 100644
--- a/tools/perf/util/dwarf-regs.c
+++ b/tools/perf/util/dwarf-regs.c
@@ -179,6 +179,8 @@ static int get_libdw_frame_nregs(unsigned int machine, unsigned int flags __mayb
 		return 103;
 	case EM_LOONGARCH:
 		return 74;
+	case EM_MIPS:
+		return 71;
 	default:
 		return 0;
 	}
@@ -218,6 +220,9 @@ int get_dwarf_regnum_for_perf_regnum(int perf_regnum, unsigned int machine,
 	case EM_LOONGARCH:
 		reg = __get_dwarf_regnum_for_perf_regnum_loongarch(perf_regnum);
 		break;
+	case EM_MIPS:
+		reg = __get_dwarf_regnum_for_perf_regnum_mips(perf_regnum);
+		break;
 	default:
 		pr_err("ELF MACHINE %x is not supported.\n", machine);
 		return -ENOENT;
diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
index b95cf2d7b5b3..46a764cf322f 100644
--- a/tools/perf/util/include/dwarf-regs.h
+++ b/tools/perf/util/include/dwarf-regs.h
@@ -113,6 +113,7 @@ int __get_dwarf_regnum_for_perf_regnum_loongarch(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_powerpc(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_riscv(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_s390(int perf_regnum);
+int __get_dwarf_regnum_for_perf_regnum_mips(int perf_regnum);
 
 /*
  * get_dwarf_regnum - Returns DWARF regnum from register name
diff --git a/tools/perf/util/unwind-libdw.h b/tools/perf/util/unwind-libdw.h
index 20d63d881dff..9c5b5fcaaae8 100644
--- a/tools/perf/util/unwind-libdw.h
+++ b/tools/perf/util/unwind-libdw.h
@@ -9,8 +9,6 @@ struct machine;
 struct perf_sample;
 struct thread;
 
-bool libdw_set_initial_registers_mips(Dwfl_Thread *thread, void *arg);
-
 struct unwind_info {
 	Dwfl			*dwfl;
 	struct perf_sample      *sample;
-- 
2.52.0.457.g6b5491de43-goog