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 <[email protected]>
Cc: Aditya Bodkhe <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Albert Ou <[email protected]>
Cc: Alexandre Ghiti <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Chun-Tse Shao <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: Haibo Xu <[email protected]>
Cc: Howard Chu <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Krzysztof Łopatowski <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Wielaard <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sergei Trofimovich <[email protected]>
Cc: Shimin Guo <[email protected]>
Cc: Stephen Brennan <[email protected]>
Cc: Thomas Falcon <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: captain5050

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

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;
+}

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;

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

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;