[PATCH v1 18/23] perf dwarf-regs: Add RISC-V perf to dwarf register number mapping functions

Ian Rogers
2026-01-17T05:29:53Z

These functions allow the generic initial register state code in
unwind-libdw to be used.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/dwarf-regs-arch/Build | 1 +
.../util/dwarf-regs-arch/dwarf-regs-riscv.c | 12 ++++
tools/perf/util/dwarf-regs.c | 3 +
tools/perf/util/include/dwarf-regs.h | 1 +
tools/perf/util/unwind-libdw-arch/Build | 1 -
.../unwind-libdw-arch/unwind-libdw-riscv.c | 58 -------------------
tools/perf/util/unwind-libdw.c | 5 +-
tools/perf/util/unwind-libdw.h | 1 -
8 files changed, 18 insertions(+), 64 deletions(-)
create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-riscv.c
delete mode 100644 tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c

diff --git a/tools/perf/util/dwarf-regs-arch/Build b/tools/perf/util/dwarf-regs-arch/Build
index 188359376ea5..94e4dfceb4d1 100644
--- a/tools/perf/util/dwarf-regs-arch/Build
+++ b/tools/perf/util/dwarf-regs-arch/Build
@@ -3,4 +3,5 @@ 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-powerpc.o
+perf-util-$(CONFIG_LIBDW) += dwarf-regs-riscv.o
perf-util-$(CONFIG_LIBDW) += dwarf-regs-x86.o
diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-riscv.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-riscv.c
new file mode 100644
index 000000000000..090db51aba41
--- /dev/null
+++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-riscv.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <dwarf-regs.h>
+#include "../../../arch/riscv/include/uapi/asm/perf_regs.h"
+
+int __get_dwarf_regnum_for_perf_regnum_riscv(int perf_regnum)
+{
+ if (perf_regnum < 0 || perf_regnum >= PERF_REG_RISCV_MAX)
+ return -ENOENT;
+
+ return perf_regnum;
+}
diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
index 3b1c2a436806..137568e15018 100644
--- a/tools/perf/util/dwarf-regs.c
+++ b/tools/perf/util/dwarf-regs.c
@@ -209,6 +209,9 @@ int get_dwarf_regnum_for_perf_regnum(int perf_regnum, unsigned int machine,
case EM_PPC64:
reg = __get_dwarf_regnum_for_perf_regnum_powerpc(perf_regnum);
break;
+ case EM_RISCV:
+ reg = __get_dwarf_regnum_for_perf_regnum_riscv(perf_regnum);
+ break;
case EM_LOONGARCH:
reg = __get_dwarf_regnum_for_perf_regnum_loongarch(perf_regnum);
break;
diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
index 9ebb3ba33fba..ae76608da110 100644
--- a/tools/perf/util/include/dwarf-regs.h
+++ b/tools/perf/util/include/dwarf-regs.h
@@ -111,6 +111,7 @@ int __get_dwarf_regnum_for_perf_regnum_arm64(int perf_regnum);
int __get_dwarf_regnum_for_perf_regnum_csky(int perf_regnum, unsigned int flags);
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);

/*
* get_dwarf_regnum - Returns DWARF regnum from register name
diff --git a/tools/perf/util/unwind-libdw-arch/Build b/tools/perf/util/unwind-libdw-arch/Build
index e6c97e842cd6..6d6e319e1201 100644
--- a/tools/perf/util/unwind-libdw-arch/Build
+++ b/tools/perf/util/unwind-libdw-arch/Build
@@ -1,2 +1 @@
-perf-util-y += unwind-libdw-riscv.o
perf-util-y += unwind-libdw-s390.o
diff --git a/tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c
deleted file mode 100644
index c2e2c4b6b2e0..000000000000
--- a/tools/perf/util/unwind-libdw-arch/unwind-libdw-riscv.c
+++ /dev/null
@@ -1,58 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
-
-#include <elfutils/libdwfl.h>
-#include "../arch/riscv/include/uapi/asm/perf_regs.h"
-#include "util/unwind-libdw.h"
-#include "util/perf_regs.h"
-#include "util/sample.h"
-
-bool libdw_set_initial_registers_riscv(Dwfl_Thread *thread, void *arg)
-{
- struct unwind_info *ui = arg;
- struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
- Dwarf_Word dwarf_regs[32];
-
-#define REG(r) ({ \
- Dwarf_Word val = 0; \
- perf_reg_value(&val, user_regs, PERF_REG_RISCV_##r); \
- val; \
-})
-
- dwarf_regs[0] = 0;
- dwarf_regs[1] = REG(RA);
- dwarf_regs[2] = REG(SP);
- dwarf_regs[3] = REG(GP);
- dwarf_regs[4] = REG(TP);
- dwarf_regs[5] = REG(T0);
- dwarf_regs[6] = REG(T1);
- dwarf_regs[7] = REG(T2);
- dwarf_regs[8] = REG(S0);
- dwarf_regs[9] = REG(S1);
- dwarf_regs[10] = REG(A0);
- dwarf_regs[11] = REG(A1);
- dwarf_regs[12] = REG(A2);
- dwarf_regs[13] = REG(A3);
- dwarf_regs[14] = REG(A4);
- dwarf_regs[15] = REG(A5);
- dwarf_regs[16] = REG(A6);
- dwarf_regs[17] = REG(A7);
- dwarf_regs[18] = REG(S2);
- dwarf_regs[19] = REG(S3);
- dwarf_regs[20] = REG(S4);
- dwarf_regs[21] = REG(S5);
- dwarf_regs[22] = REG(S6);
- dwarf_regs[23] = REG(S7);
- dwarf_regs[24] = REG(S8);
- dwarf_regs[25] = REG(S9);
- dwarf_regs[26] = REG(S10);
- dwarf_regs[27] = REG(S11);
- dwarf_regs[28] = REG(T3);
- dwarf_regs[29] = REG(T4);
- dwarf_regs[30] = REG(T5);
- dwarf_regs[31] = REG(T6);
- dwfl_thread_state_register_pc(thread, REG(PC));
-
- return dwfl_thread_state_registers(thread, 0, PERF_REG_RISCV_MAX,
- dwarf_regs);
-}
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index e9ba050e7ab1..b3c4380d40b6 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -292,14 +292,11 @@ static const Dwfl_Thread_Callbacks callbacks_generic = {
.set_initial_registers = libdw_set_initial_registers_generic,
};

-DEFINE_DWFL_THREAD_CALLBACKS(riscv);
DEFINE_DWFL_THREAD_CALLBACKS(s390);

static const Dwfl_Thread_Callbacks *get_thread_callbacks(const char *arch)
{
- if (!strcmp(arch, "riscv"))
- return &callbacks_riscv;
- else if (!strcmp(arch, "s390"))
+ if (!strcmp(arch, "s390"))
return &callbacks_s390;

return &callbacks_generic;
diff --git a/tools/perf/util/unwind-libdw.h b/tools/perf/util/unwind-libdw.h
index 0ec1abdabbe7..5c23080cb6c1 100644
--- a/tools/perf/util/unwind-libdw.h
+++ b/tools/perf/util/unwind-libdw.h
@@ -10,7 +10,6 @@ struct perf_sample;
struct thread;

bool libdw_set_initial_registers_mips(Dwfl_Thread *thread, void *arg);
-bool libdw_set_initial_registers_riscv(Dwfl_Thread *thread, void *arg);
bool libdw_set_initial_registers_s390(Dwfl_Thread *thread, void *arg);

struct unwind_info {
--
2.52.0.457.g6b5491de43-goog