[RFC PATCH v2 3/3] perf tools: Support sparc user register samples and dwarf unwinding
From: Stian Halseth
Date: Tue Sep 22 2026 - 16:21:23 EST
Add the sparc perf_regs tables and the EM_SPARC/EM_SPARCV9 dispatch for
register names, masks, ip/sp and the perf-to-DWARF register mapping,
plus the uapi header copy.
For libdw unwinding, seed DWARF registers 16-31 (%l0-%l7, %i0-%i7) from
the register save area at the top of the stack dump: the kernel flushes
the sampled window there, and the CFI after `save` needs %i6 and %i7 to
find the first caller. The dump base on sparc is the biased %sp, so
read words from the dump with memcpy rather than an aligned
dereference.
Signed-off-by: Stian Halseth <stian@xxxxxx>
---
tools/arch/sparc/include/uapi/asm/perf_regs.h | 33 +++++++++
tools/perf/arch/sparc/include/perf_regs.h | 18 +++++
tools/perf/check-headers.sh | 1 +
tools/perf/util/dwarf-regs-arch/Build | 1 +
.../util/dwarf-regs-arch/dwarf-regs-sparc.c | 12 ++++
tools/perf/util/dwarf-regs.c | 4 ++
tools/perf/util/include/dwarf-regs.h | 1 +
tools/perf/util/perf-regs-arch/Build | 1 +
.../util/perf-regs-arch/perf_regs_sparc.c | 69 +++++++++++++++++++
tools/perf/util/perf_regs.c | 18 +++++
tools/perf/util/perf_regs.h | 5 ++
tools/perf/util/unwind-libdw.c | 41 ++++++++++-
12 files changed, 203 insertions(+), 1 deletion(-)
create mode 100644 tools/arch/sparc/include/uapi/asm/perf_regs.h
create mode 100644 tools/perf/arch/sparc/include/perf_regs.h
create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_sparc.c
diff --git a/tools/arch/sparc/include/uapi/asm/perf_regs.h b/tools/arch/sparc/include/uapi/asm/perf_regs.h
new file mode 100644
index 000000000000..17f14335d6c0
--- /dev/null
+++ b/tools/arch/sparc/include/uapi/asm/perf_regs.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_SPARC_PERF_REGS_H
+#define _UAPI_ASM_SPARC_PERF_REGS_H
+
+/*
+ * Mirrors struct pt_regs. O6 is %sp as held in the register, i.e. biased
+ * by 2047 for a 64-bit task.
+ */
+enum perf_event_sparc_regs {
+ PERF_REG_SPARC_G0,
+ PERF_REG_SPARC_G1,
+ PERF_REG_SPARC_G2,
+ PERF_REG_SPARC_G3,
+ PERF_REG_SPARC_G4,
+ PERF_REG_SPARC_G5,
+ PERF_REG_SPARC_G6,
+ PERF_REG_SPARC_G7,
+ PERF_REG_SPARC_O0,
+ PERF_REG_SPARC_O1,
+ PERF_REG_SPARC_O2,
+ PERF_REG_SPARC_O3,
+ PERF_REG_SPARC_O4,
+ PERF_REG_SPARC_O5,
+ PERF_REG_SPARC_O6,
+ PERF_REG_SPARC_O7,
+ PERF_REG_SPARC_TSTATE,
+ PERF_REG_SPARC_PC,
+ PERF_REG_SPARC_NPC,
+ PERF_REG_SPARC_Y,
+ PERF_REG_SPARC_MAX
+};
+
+#endif /* _UAPI_ASM_SPARC_PERF_REGS_H */
diff --git a/tools/perf/arch/sparc/include/perf_regs.h b/tools/perf/arch/sparc/include/perf_regs.h
new file mode 100644
index 000000000000..493fbff9ea16
--- /dev/null
+++ b/tools/perf/arch/sparc/include/perf_regs.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_PERF_REGS_H
+#define ARCH_PERF_REGS_H
+
+#include <stdlib.h>
+#include <linux/types.h>
+#include "../../../../arch/sparc/include/uapi/asm/perf_regs.h"
+
+#define PERF_REGS_MASK ((1ULL << PERF_REG_SPARC_MAX) - 1)
+#define PERF_REGS_MAX PERF_REG_SPARC_MAX
+
+#ifdef __arch64__
+#define PERF_SAMPLE_REGS_ABI PERF_SAMPLE_REGS_ABI_64
+#else
+#define PERF_SAMPLE_REGS_ABI PERF_SAMPLE_REGS_ABI_32
+#endif
+
+#endif /* ARCH_PERF_REGS_H */
diff --git a/tools/perf/check-headers.sh b/tools/perf/check-headers.sh
index 531c0e0e84df..f144590f5082 100755
--- a/tools/perf/check-headers.sh
+++ b/tools/perf/check-headers.sh
@@ -42,6 +42,7 @@ declare -a FILES=(
"arch/mips/include/uapi/asm/perf_regs.h"
"arch/powerpc/include/uapi/asm/perf_regs.h"
"arch/s390/include/uapi/asm/perf_regs.h"
+ "arch/sparc/include/uapi/asm/perf_regs.h"
"arch/x86/include/uapi/asm/perf_regs.h"
"arch/x86/include/uapi/asm/kvm.h"
"arch/x86/include/uapi/asm/svm.h"
diff --git a/tools/perf/util/dwarf-regs-arch/Build b/tools/perf/util/dwarf-regs-arch/Build
index ceb68ae86fd8..bda944029046 100644
--- a/tools/perf/util/dwarf-regs-arch/Build
+++ b/tools/perf/util/dwarf-regs-arch/Build
@@ -6,4 +6,5 @@ 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
+perf-util-$(CONFIG_LIBDW) += dwarf-regs-sparc.o
perf-util-$(CONFIG_LIBDW) += dwarf-regs-x86.o
diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
new file mode 100644
index 000000000000..dd0c80e29764
--- /dev/null
+++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <dwarf-regs.h>
+#include "../../../arch/sparc/include/uapi/asm/perf_regs.h"
+
+int __get_dwarf_regnum_for_perf_regnum_sparc(int perf_regnum)
+{
+ if (perf_regnum < PERF_REG_SPARC_G0 || perf_regnum > PERF_REG_SPARC_O7)
+ return -ENOENT;
+
+ return perf_regnum;
+}
diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
index 797f455eba0d..df9200c31aaa 100644
--- a/tools/perf/util/dwarf-regs.c
+++ b/tools/perf/util/dwarf-regs.c
@@ -217,6 +217,10 @@ int get_dwarf_regnum_for_perf_regnum(int perf_regnum, unsigned int machine,
case EM_S390:
reg = __get_dwarf_regnum_for_perf_regnum_s390(perf_regnum);
break;
+ case EM_SPARC:
+ case EM_SPARCV9:
+ reg = __get_dwarf_regnum_for_perf_regnum_sparc(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 46a764cf322f..4a02f30c5604 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_sparc(int perf_regnum);
int __get_dwarf_regnum_for_perf_regnum_mips(int perf_regnum);
/*
diff --git a/tools/perf/util/perf-regs-arch/Build b/tools/perf/util/perf-regs-arch/Build
index be95402aa540..47220a2f2dae 100644
--- a/tools/perf/util/perf-regs-arch/Build
+++ b/tools/perf/util/perf-regs-arch/Build
@@ -6,4 +6,5 @@ perf-util-y += perf_regs_mips.o
perf-util-y += perf_regs_powerpc.o
perf-util-y += perf_regs_riscv.o
perf-util-y += perf_regs_s390.o
+perf-util-y += perf_regs_sparc.o
perf-util-y += perf_regs_x86.o
diff --git a/tools/perf/util/perf-regs-arch/perf_regs_sparc.c b/tools/perf/util/perf-regs-arch/perf_regs_sparc.c
new file mode 100644
index 000000000000..36d84ddd3a48
--- /dev/null
+++ b/tools/perf/util/perf-regs-arch/perf_regs_sparc.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "../perf_regs.h"
+#include "../../arch/sparc/include/perf_regs.h"
+
+uint64_t __perf_reg_mask_sparc(bool intr __maybe_unused)
+{
+ return PERF_REGS_MASK;
+}
+
+const char *__perf_reg_name_sparc(int id)
+{
+ switch (id) {
+ case PERF_REG_SPARC_G0:
+ return "g0";
+ case PERF_REG_SPARC_G1:
+ return "g1";
+ case PERF_REG_SPARC_G2:
+ return "g2";
+ case PERF_REG_SPARC_G3:
+ return "g3";
+ case PERF_REG_SPARC_G4:
+ return "g4";
+ case PERF_REG_SPARC_G5:
+ return "g5";
+ case PERF_REG_SPARC_G6:
+ return "g6";
+ case PERF_REG_SPARC_G7:
+ return "g7";
+ case PERF_REG_SPARC_O0:
+ return "o0";
+ case PERF_REG_SPARC_O1:
+ return "o1";
+ case PERF_REG_SPARC_O2:
+ return "o2";
+ case PERF_REG_SPARC_O3:
+ return "o3";
+ case PERF_REG_SPARC_O4:
+ return "o4";
+ case PERF_REG_SPARC_O5:
+ return "o5";
+ case PERF_REG_SPARC_O6:
+ return "sp";
+ case PERF_REG_SPARC_O7:
+ return "o7";
+ case PERF_REG_SPARC_TSTATE:
+ return "tstate";
+ case PERF_REG_SPARC_PC:
+ return "pc";
+ case PERF_REG_SPARC_NPC:
+ return "npc";
+ case PERF_REG_SPARC_Y:
+ return "y";
+ default:
+ return NULL;
+ }
+
+ return NULL;
+}
+
+uint64_t __perf_reg_ip_sparc(void)
+{
+ return PERF_REG_SPARC_PC;
+}
+
+uint64_t __perf_reg_sp_sparc(void)
+{
+ return PERF_REG_SPARC_O6;
+}
diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c
index 558c143abbab..5880b54fd7dc 100644
--- a/tools/perf/util/perf_regs.c
+++ b/tools/perf/util/perf_regs.c
@@ -68,6 +68,10 @@ uint64_t perf_intr_reg_mask(uint16_t e_machine)
case EM_S390:
mask = __perf_reg_mask_s390(/*intr=*/true);
break;
+ case EM_SPARC:
+ case EM_SPARCV9:
+ mask = __perf_reg_mask_sparc(/*intr=*/true);
+ break;
case EM_386:
case EM_X86_64:
mask = __perf_reg_mask_x86(/*intr=*/true);
@@ -111,6 +115,10 @@ uint64_t perf_user_reg_mask(uint16_t e_machine)
case EM_S390:
mask = __perf_reg_mask_s390(/*intr=*/false);
break;
+ case EM_SPARC:
+ case EM_SPARCV9:
+ mask = __perf_reg_mask_sparc(/*intr=*/false);
+ break;
case EM_386:
case EM_X86_64:
mask = __perf_reg_mask_x86(/*intr=*/false);
@@ -154,6 +162,10 @@ const char *perf_reg_name(int id, uint16_t e_machine, uint32_t e_flags)
case EM_S390:
reg_name = __perf_reg_name_s390(id);
break;
+ case EM_SPARC:
+ case EM_SPARCV9:
+ reg_name = __perf_reg_name_sparc(id);
+ break;
case EM_386:
case EM_X86_64:
reg_name = __perf_reg_name_x86(id);
@@ -215,6 +227,9 @@ uint64_t perf_arch_reg_ip(uint16_t e_machine)
return __perf_reg_ip_riscv();
case EM_S390:
return __perf_reg_ip_s390();
+ case EM_SPARC:
+ case EM_SPARCV9:
+ return __perf_reg_ip_sparc();
case EM_386:
case EM_X86_64:
return __perf_reg_ip_x86();
@@ -244,6 +259,9 @@ uint64_t perf_arch_reg_sp(uint16_t e_machine)
return __perf_reg_sp_riscv();
case EM_S390:
return __perf_reg_sp_s390();
+ case EM_SPARC:
+ case EM_SPARCV9:
+ return __perf_reg_sp_sparc();
case EM_386:
case EM_X86_64:
return __perf_reg_sp_x86();
diff --git a/tools/perf/util/perf_regs.h b/tools/perf/util/perf_regs.h
index 79be2b791509..3f453d910aa4 100644
--- a/tools/perf/util/perf_regs.h
+++ b/tools/perf/util/perf_regs.h
@@ -65,6 +65,11 @@ uint64_t __perf_reg_ip_s390(void);
uint64_t __perf_reg_sp_s390(void);
int __perf_sdt_arg_parse_op_s390(char *old_op, char **new_op);
+uint64_t __perf_reg_mask_sparc(bool intr);
+const char *__perf_reg_name_sparc(int id);
+uint64_t __perf_reg_ip_sparc(void);
+uint64_t __perf_reg_sp_sparc(void);
+
int __perf_sdt_arg_parse_op_x86(char *old_op, char **new_op);
uint64_t __perf_reg_mask_x86(bool intr);
const char *__perf_reg_name_x86(int id);
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index 63a5c2253174..62484bcd5cd3 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -4,7 +4,9 @@
#include <elfutils/libdw.h>
#include <elfutils/libdwfl.h>
#include <inttypes.h>
+#include <elf.h>
#include <errno.h>
+#include <string.h>
#include "debug.h"
#include "dso.h"
#include <dwarf-regs.h>
@@ -261,12 +263,44 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *
}
offset = addr - start;
- *result = *(Dwarf_Word *)&stack->data[offset];
+ memcpy(result, &stack->data[offset], sizeof(*result));
pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
addr, (unsigned long)*result, offset);
return true;
}
+/*
+ * The sampled window's %l and %i registers (DWARF 16-31) are not in the
+ * sample; the kernel flushed them to the register save area at the top of
+ * the dumped stack.
+ */
+static void libdw_set_sparc_window_registers(struct unwind_info *ui,
+ struct regs_dump *user_regs,
+ Dwarf_Word *dwarf_regs)
+{
+ struct stack_dump *stack = &ui->sample->user_stack;
+ bool abi64 = user_regs->abi == PERF_SAMPLE_REGS_ABI_64;
+ size_t wsize = abi64 ? sizeof(u64) : sizeof(u32);
+ u64 sp, offset = abi64 ? 2047 : 0;
+
+ if (perf_reg_value(&sp, user_regs, perf_arch_reg_sp(ui->e_machine)))
+ return;
+ if (offset + 16 * wsize > stack->size)
+ return;
+
+ for (int i = 0; i < 16; i++) {
+ const char *p = &stack->data[offset + i * wsize];
+ u32 w32;
+
+ if (abi64) {
+ memcpy(&dwarf_regs[16 + i], p, sizeof(u64));
+ } else {
+ memcpy(&w32, p, sizeof(w32));
+ dwarf_regs[16 + i] = w32;
+ }
+ }
+}
+
static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
{
struct dwfl_ui_thread_info *dwfl_ui_ti = arg;
@@ -276,6 +310,7 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
int max_dwarf_reg = 0;
bool ret;
uint16_t e_machine = ui->e_machine;
+ bool is_sparc = e_machine == EM_SPARC || e_machine == EM_SPARCV9;
int e_flags = ui->e_flags;
uint64_t ip_perf_reg = perf_arch_reg_ip(e_machine);
Dwarf_Word val = 0;
@@ -295,6 +330,8 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
max_dwarf_reg = dwarf_reg;
}
}
+ if (is_sparc && max_dwarf_reg < 31)
+ max_dwarf_reg = 31;
dwarf_regs = calloc(max_dwarf_reg + 1, sizeof(*dwarf_regs));
if (!dwarf_regs)
@@ -313,6 +350,8 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
}
}
}
+ if (is_sparc)
+ libdw_set_sparc_window_registers(ui, user_regs, dwarf_regs);
if (perf_reg_value(&val, user_regs, ip_perf_reg) == 0)
dwfl_thread_state_register_pc(thread, val);
--
2.55.0