[PATCH v1 19/23] perf dwarf-regs: Add S390 perf to dwarf register number mapping functions

Ian Rogers
2026-01-17T05:29:55Z

These functions allow the generic initial register state code in
unwind-libdw to be used. Now the non-generic code in unwind-libdw has
no uses remove it.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/dwarf-regs-arch/Build | 1 +
.../util/dwarf-regs-arch/dwarf-regs-s390.c | 53 +++++++++++++++
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-s390.c | 65 -------------------
tools/perf/util/unwind-libdw.c | 31 ++-------
tools/perf/util/unwind-libdw.h | 1 -
8 files changed, 62 insertions(+), 94 deletions(-)
create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-s390.c
delete mode 100644 tools/perf/util/unwind-libdw-arch/Build
delete mode 100644 tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c

diff --git a/tools/perf/util/dwarf-regs-arch/Build b/tools/perf/util/dwarf-regs-arch/Build
index 94e4dfceb4d1..10c2af3d933a 100644
--- a/tools/perf/util/dwarf-regs-arch/Build
+++ b/tools/perf/util/dwarf-regs-arch/Build
@@ -4,4 +4,5 @@ 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-$(CONFIG_LIBDW) += dwarf-regs-s390.o
perf-util-$(CONFIG_LIBDW) += dwarf-regs-x86.o
diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-s390.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-s390.c
new file mode 100644
index 000000000000..310a37451bdc
--- /dev/null
+++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-s390.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <dwarf-regs.h>
+#include "../../../arch/s390/include/uapi/asm/perf_regs.h"
+
+int __get_dwarf_regnum_for_perf_regnum_s390(int perf_regnum)
+{
+ static const int dwarf_s390_regnums[] = {
+ [PERF_REG_S390_R0] = 0,
+ [PERF_REG_S390_R1] = 1,
+ [PERF_REG_S390_R2] = 2,
+ [PERF_REG_S390_R3] = 3,
+ [PERF_REG_S390_R4] = 4,
+ [PERF_REG_S390_R5] = 5,
+ [PERF_REG_S390_R6] = 6,
+ [PERF_REG_S390_R7] = 7,
+ [PERF_REG_S390_R8] = 8,
+ [PERF_REG_S390_R9] = 9,
+ [PERF_REG_S390_R10] = 10,
+ [PERF_REG_S390_R11] = 11,
+ [PERF_REG_S390_R12] = 12,
+ [PERF_REG_S390_R13] = 13,
+ [PERF_REG_S390_R14] = 14,
+ [PERF_REG_S390_R15] = 15,
+ [PERF_REG_S390_FP0] = 16,
+ [PERF_REG_S390_FP1] = 20,
+ [PERF_REG_S390_FP2] = 17,
+ [PERF_REG_S390_FP3] = 21,
+ [PERF_REG_S390_FP4] = 18,
+ [PERF_REG_S390_FP5] = 22,
+ [PERF_REG_S390_FP6] = 19,
+ [PERF_REG_S390_FP7] = 23,
+ [PERF_REG_S390_FP8] = 24,
+ [PERF_REG_S390_FP9] = 28,
+ [PERF_REG_S390_FP10] = 25,
+ [PERF_REG_S390_FP11] = 29,
+ [PERF_REG_S390_FP12] = 26,
+ [PERF_REG_S390_FP13] = 30,
+ [PERF_REG_S390_FP14] = 27,
+ [PERF_REG_S390_FP15] = 31,
+ [PERF_REG_S390_MASK] = 64,
+ [PERF_REG_S390_PC] = 65,
+ };
+
+ if (perf_regnum == 0)
+ return 0;
+
+ if (perf_regnum < 0 || perf_regnum > (int)ARRAY_SIZE(dwarf_s390_regnums) ||
+ dwarf_s390_regnums[perf_regnum] == 0)
+ return -ENOENT;
+
+ return dwarf_s390_regnums[perf_regnum];
+}
diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
index 137568e15018..f86f76547592 100644
--- a/tools/perf/util/dwarf-regs.c
+++ b/tools/perf/util/dwarf-regs.c
@@ -212,6 +212,9 @@ int get_dwarf_regnum_for_perf_regnum(int perf_regnum, unsigned int machine,
case EM_RISCV:
reg = __get_dwarf_regnum_for_perf_regnum_riscv(perf_regnum);
break;
+ case EM_S390:
+ reg = __get_dwarf_regnum_for_perf_regnum_s390(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 ae76608da110..b95cf2d7b5b3 100644
--- a/tools/perf/util/include/dwarf-regs.h
+++ b/tools/perf/util/include/dwarf-regs.h
@@ -112,6 +112,7 @@ 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);
+int __get_dwarf_regnum_for_perf_regnum_s390(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
deleted file mode 100644
index 6d6e319e1201..000000000000
--- a/tools/perf/util/unwind-libdw-arch/Build
+++ /dev/null
@@ -1 +0,0 @@
-perf-util-y += unwind-libdw-s390.o
diff --git a/tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c b/tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c
deleted file mode 100644
index 1e05e9d9d95f..000000000000
--- a/tools/perf/util/unwind-libdw-arch/unwind-libdw-s390.c
+++ /dev/null
@@ -1,65 +0,0 @@
-#include <linux/kernel.h>
-#include <elfutils/libdwfl.h>
-#include "util/unwind-libdw.h"
-#include "util/perf_regs.h"
-#include "util/event.h"
-#include "util/sample.h"
-#include "../arch/s390/include/dwarf-regs-table.h"
-#include "../arch/s390/include/uapi/asm/perf_regs.h"
-
-
-bool libdw_set_initial_registers_s390(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[ARRAY_SIZE(s390_dwarf_regs)];
-
-#define REG(r) ({ \
- Dwarf_Word val = 0; \
- perf_reg_value(&val, user_regs, PERF_REG_S390_##r); \
- val; \
-})
- /*
- * For DWARF register mapping details,
- * see also perf/arch/s390/include/dwarf-regs-table.h
- */
- dwarf_regs[0] = REG(R0);
- dwarf_regs[1] = REG(R1);
- dwarf_regs[2] = REG(R2);
- dwarf_regs[3] = REG(R3);
- dwarf_regs[4] = REG(R4);
- dwarf_regs[5] = REG(R5);
- dwarf_regs[6] = REG(R6);
- dwarf_regs[7] = REG(R7);
- dwarf_regs[8] = REG(R8);
- dwarf_regs[9] = REG(R9);
- dwarf_regs[10] = REG(R10);
- dwarf_regs[11] = REG(R11);
- dwarf_regs[12] = REG(R12);
- dwarf_regs[13] = REG(R13);
- dwarf_regs[14] = REG(R14);
- dwarf_regs[15] = REG(R15);
-
- dwarf_regs[16] = REG(FP0);
- dwarf_regs[17] = REG(FP2);
- dwarf_regs[18] = REG(FP4);
- dwarf_regs[19] = REG(FP6);
- dwarf_regs[20] = REG(FP1);
- dwarf_regs[21] = REG(FP3);
- dwarf_regs[22] = REG(FP5);
- dwarf_regs[23] = REG(FP7);
- dwarf_regs[24] = REG(FP8);
- dwarf_regs[25] = REG(FP10);
- dwarf_regs[26] = REG(FP12);
- dwarf_regs[27] = REG(FP14);
- dwarf_regs[28] = REG(FP9);
- dwarf_regs[29] = REG(FP11);
- dwarf_regs[30] = REG(FP13);
- dwarf_regs[31] = REG(FP15);
-
- dwarf_regs[64] = REG(MASK);
- dwarf_regs[65] = REG(PC);
-
- dwfl_thread_state_register_pc(thread, dwarf_regs[65]);
- return dwfl_thread_state_registers(thread, 0, 32, dwarf_regs);
-}
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index b3c4380d40b6..e0321043af88 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -226,7 +226,7 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *
return true;
}

-static bool libdw_set_initial_registers_generic(Dwfl_Thread *thread, void *arg)
+static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
{
struct unwind_info *ui = arg;
struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
@@ -279,29 +279,12 @@ static bool libdw_set_initial_registers_generic(Dwfl_Thread *thread, void *arg)
return ret;
}

-#define DEFINE_DWFL_THREAD_CALLBACKS(arch) \
-static const Dwfl_Thread_Callbacks callbacks_##arch = { \
- .next_thread = next_thread, \
- .memory_read = memory_read, \
- .set_initial_registers = libdw_set_initial_registers_##arch, \
-}
-
-static const Dwfl_Thread_Callbacks callbacks_generic = {
+static const Dwfl_Thread_Callbacks callbacks = {
.next_thread = next_thread,
.memory_read = memory_read,
- .set_initial_registers = libdw_set_initial_registers_generic,
+ .set_initial_registers = libdw_set_initial_registers,
};

-DEFINE_DWFL_THREAD_CALLBACKS(s390);
-
-static const Dwfl_Thread_Callbacks *get_thread_callbacks(const char *arch)
-{
- if (!strcmp(arch, "s390"))
- return &callbacks_s390;
-
- return &callbacks_generic;
-}
-
static int
frame_callback(Dwfl_Frame *state, void *arg)
{
@@ -349,10 +332,8 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
.e_machine = e_machine,
.best_effort = best_effort
};
- const char *arch = perf_env__arch(machine->env);
Dwarf_Word ip;
int err = -EINVAL, i;
- const Dwfl_Thread_Callbacks *callbacks;

if (!data->user_regs || !data->user_regs->regs)
return -EINVAL;
@@ -375,11 +356,7 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
if (err)
goto out;

- callbacks = get_thread_callbacks(arch);
- if (!callbacks)
- goto out;
-
- err = !dwfl_attach_state(ui->dwfl, /*elf=*/NULL, thread__tid(thread), callbacks, ui);
+ err = !dwfl_attach_state(ui->dwfl, /*elf=*/NULL, thread__tid(thread), &callbacks, ui);
if (err)
goto out;

diff --git a/tools/perf/util/unwind-libdw.h b/tools/perf/util/unwind-libdw.h
index 5c23080cb6c1..20d63d881dff 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_s390(Dwfl_Thread *thread, void *arg);

struct unwind_info {
Dwfl *dwfl;
--
2.52.0.457.g6b5491de43-goog