[PATCH v11 03/19] perf env, dso, thread: Add _endian variants for e_machine helpers
From: Ian Rogers
Date: Tue Jun 02 2026 - 02:27:08 EST
Add perf_arch_is_big_endian(), dso__read_e_machine_endian(),
dso__e_machine_endian(), and thread__e_machine_endian() to support
bi-endianness and cross-architecture analysis without breaking the
existing API.
These helpers allow querying the absolute endianness of a DSO or
thread, which is required for tools like Capstone that need to set the
correct disassembly mode.
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/util/dso.c | 19 ++++++++-----
tools/perf/util/dso.h | 14 ++++++++--
tools/perf/util/env.c | 16 +++++++++++
tools/perf/util/env.h | 1 +
tools/perf/util/thread.c | 58 ++++++++++++++++++++++++++++++----------
tools/perf/util/thread.h | 23 +++++++++++++++-
6 files changed, 108 insertions(+), 23 deletions(-)
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index b791e1b6b2cf..7dced896c64e 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1220,7 +1220,8 @@ static enum dso_swap_type dso_swap_type__from_elf_data(unsigned char eidata)
}
/* Reads e_machine from fd, optionally caching data in dso. */
-uint16_t dso__read_e_machine(struct dso *optional_dso, int fd, uint32_t *e_flags)
+uint16_t dso__read_e_machine_endian(struct dso *optional_dso, int fd, uint32_t *e_flags,
+ bool *is_big_endian)
{
uint16_t e_machine = EM_NONE;
unsigned char e_ident[EI_NIDENT];
@@ -1250,6 +1251,9 @@ uint16_t dso__read_e_machine(struct dso *optional_dso, int fd, uint32_t *e_flags
if (swap_type == DSO_SWAP__UNSET)
return EM_NONE; // Bad ELF data encoding.
+ if (is_big_endian)
+ *is_big_endian = (e_ident[EI_DATA] == ELFDATA2MSB);
+
/* Cache the need for swapping. */
if (optional_dso) {
assert(dso__needs_swap(optional_dso) == DSO_SWAP__UNSET ||
@@ -1288,7 +1292,8 @@ uint16_t dso__read_e_machine(struct dso *optional_dso, int fd, uint32_t *e_flags
return e_machine;
}
-uint16_t dso__e_machine(struct dso *dso, struct machine *machine, uint32_t *e_flags)
+uint16_t dso__e_machine_endian(struct dso *dso, struct machine *machine, uint32_t *e_flags,
+ bool *is_big_endian)
{
uint16_t e_machine = EM_NONE;
int fd;
@@ -1308,9 +1313,11 @@ uint16_t dso__e_machine(struct dso *dso, struct machine *machine, uint32_t *e_fl
case DSO_BINARY_TYPE__BPF_IMAGE:
case DSO_BINARY_TYPE__OOL:
case DSO_BINARY_TYPE__JAVA_JIT:
- if (e_flags)
- *e_flags = EF_HOST;
- return EM_HOST;
+ if (is_big_endian) {
+ *is_big_endian = perf_arch_is_big_endian(
+ machine && machine->env ? perf_env__arch(machine->env) : NULL);
+ }
+ return perf_env__e_machine(machine ? machine->env : NULL, e_flags);
case DSO_BINARY_TYPE__DEBUGLINK:
case DSO_BINARY_TYPE__BUILD_ID_CACHE:
case DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO:
@@ -1338,7 +1345,7 @@ uint16_t dso__e_machine(struct dso *dso, struct machine *machine, uint32_t *e_fl
try_to_open_dso(dso, machine);
fd = dso__data(dso)->fd;
if (fd >= 0)
- e_machine = dso__read_e_machine(dso, fd, e_flags);
+ e_machine = dso__read_e_machine_endian(dso, fd, e_flags, is_big_endian);
else if (e_flags)
*e_flags = 0;
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index ede691e9a249..2916b954a804 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -866,8 +866,18 @@ int dso__data_file_size(struct dso *dso, struct machine *machine);
off_t dso__data_size(struct dso *dso, struct machine *machine);
ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine,
u64 offset, u8 *data, ssize_t size);
-uint16_t dso__read_e_machine(struct dso *optional_dso, int fd, uint32_t *e_flags);
-uint16_t dso__e_machine(struct dso *dso, struct machine *machine, uint32_t *e_flags);
+uint16_t dso__read_e_machine_endian(struct dso *optional_dso, int fd, uint32_t *e_flags,
+ bool *is_big_endian);
+static inline uint16_t dso__read_e_machine(struct dso *optional_dso, int fd, uint32_t *e_flags)
+{
+ return dso__read_e_machine_endian(optional_dso, fd, e_flags, NULL);
+}
+uint16_t dso__e_machine_endian(struct dso *dso, struct machine *machine, uint32_t *e_flags,
+ bool *is_big_endian);
+static inline uint16_t dso__e_machine(struct dso *dso, struct machine *machine, uint32_t *e_flags)
+{
+ return dso__e_machine_endian(dso, machine, e_flags, NULL);
+}
ssize_t dso__data_read_addr(struct dso *dso, struct map *map,
struct machine *machine, u64 addr,
u8 *data, ssize_t size);
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index 0cd23b5fc651..fae70b07ba8d 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -342,6 +342,22 @@ int perf_env__kernel_is_64_bit(struct perf_env *env)
return env->kernel_is_64_bit;
}
+bool perf_arch_is_big_endian(const char *arch)
+{
+ if (!arch)
+ return __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__;
+
+ if (str_ends_with(arch, "_be") || !strcmp(arch, "sparc") || !strcmp(arch, "sparc64") ||
+ !strcmp(arch, "s390") || !strcmp(arch, "s390x") || !strcmp(arch, "powerpc") ||
+ !strcmp(arch, "ppc") || !strcmp(arch, "ppc64") ||
+ !strcmp(arch, "mips") || !strcmp(arch, "mips64") || !strcmp(arch, "parisc") ||
+ !strcmp(arch, "parisc64") || !strcmp(arch, "m68k") ||
+ !strcmp(arch, "armeb") || !strcmp(arch, "mipseb") || !strcmp(arch, "mips64eb"))
+ return true;
+
+ return false;
+}
+
int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
{
int i;
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index bde192fd5be5..dd9907dbc345 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -175,6 +175,7 @@ void free_cpu_domain_info(struct cpu_domain_map **cd_map, u32 schedstat_version,
void perf_env__exit(struct perf_env *env);
int perf_env__kernel_is_64_bit(struct perf_env *env);
+bool perf_arch_is_big_endian(const char *arch);
int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[]);
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index aac9cb75dcf4..ba33c0dfc18f 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -56,6 +56,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
thread__set_cpu(thread, -1);
thread__set_guest_cpu(thread, -1);
thread__set_e_machine(thread, EM_NONE);
+ thread__set_e_is_big_endian(thread, false);
thread__set_lbr_stitch_enable(thread, false);
INIT_LIST_HEAD(thread__namespaces_list(thread));
INIT_LIST_HEAD(thread__comm_list(thread));
@@ -429,7 +430,7 @@ void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
}
}
-static uint16_t read_proc_e_machine_for_pid(pid_t pid, uint32_t *e_flags)
+static uint16_t read_proc_e_machine_for_pid(pid_t pid, uint32_t *e_flags, bool *is_big_endian)
{
char path[6 /* "/proc/" */ + 11 /* max length of pid */ + 5 /* "/exe\0" */];
int fd;
@@ -438,7 +439,8 @@ static uint16_t read_proc_e_machine_for_pid(pid_t pid, uint32_t *e_flags)
snprintf(path, sizeof(path), "/proc/%d/exe", pid);
fd = open(path, O_RDONLY);
if (fd >= 0) {
- e_machine = dso__read_e_machine(/*optional_dso=*/NULL, fd, e_flags);
+ e_machine = dso__read_e_machine_endian(/*optional_dso=*/NULL, fd, e_flags,
+ is_big_endian);
close(fd);
}
return e_machine;
@@ -448,6 +450,7 @@ struct thread__e_machine_callback_args {
struct machine *machine;
uint32_t e_flags;
uint16_t e_machine;
+ bool is_big_endian;
};
static int thread__e_machine_callback(struct map *map, void *_args)
@@ -458,24 +461,38 @@ static int thread__e_machine_callback(struct map *map, void *_args)
if (!dso)
return 0; // No dso, continue search.
- args->e_machine = dso__e_machine(dso, args->machine, &args->e_flags);
+ args->e_machine =
+ dso__e_machine_endian(dso, args->machine, &args->e_flags, &args->is_big_endian);
return args->e_machine != EM_NONE ? 1 /* stop search */ : 0 /* continue search */;
}
-uint16_t thread__e_machine(struct thread *thread, struct machine *machine, uint32_t *e_flags)
+uint16_t thread__e_machine_endian(struct thread *thread, struct machine *machine, uint32_t *e_flags,
+ bool *is_big_endian)
{
pid_t tid, pid;
- uint16_t e_machine = RC_CHK_ACCESS(thread)->e_machine;
+ uint16_t e_machine;
uint32_t local_e_flags = 0;
- struct thread__e_machine_callback_args args = {
- .machine = machine,
- .e_flags = 0,
- .e_machine = EM_NONE,
- };
+ struct thread__e_machine_callback_args args;
+
+ if (!thread) {
+ if (is_big_endian) {
+ *is_big_endian = perf_arch_is_big_endian(
+ machine && machine->env ? perf_env__arch(machine->env) : NULL);
+ }
+ return perf_env__e_machine(machine ? machine->env : NULL, e_flags);
+ }
+
+ e_machine = RC_CHK_ACCESS(thread)->e_machine;
+ args.machine = machine;
+ args.e_flags = 0;
+ args.e_machine = EM_NONE;
+ args.is_big_endian = false;
if (e_machine != EM_NONE) {
if (e_flags)
*e_flags = thread__e_flags(thread);
+ if (is_big_endian)
+ *is_big_endian = thread__e_is_big_endian(thread);
return e_machine;
}
@@ -483,6 +500,7 @@ uint16_t thread__e_machine(struct thread *thread, struct machine *machine, uint3
struct maps *maps = thread__maps(thread);
machine = maps__machine(maps);
+ args.machine = machine;
}
tid = thread__tid(thread);
pid = thread__pid(thread);
@@ -490,7 +508,8 @@ uint16_t thread__e_machine(struct thread *thread, struct machine *machine, uint3
struct thread *parent = machine__findnew_thread(machine, pid, pid);
if (parent) {
- e_machine = thread__e_machine(parent, machine, &local_e_flags);
+ e_machine = thread__e_machine_endian(parent, machine, &local_e_flags,
+ &args.is_big_endian);
thread__put(parent);
goto out;
}
@@ -515,16 +534,27 @@ uint16_t thread__e_machine(struct thread *thread, struct machine *machine, uint3
is_live = !!session->data;
}
/* Read from /proc/pid/exe if live. */
- if (is_live)
- e_machine = read_proc_e_machine_for_pid(pid, &local_e_flags);
+ if (is_live) {
+ e_machine = read_proc_e_machine_for_pid(pid, &local_e_flags,
+ &args.is_big_endian);
+ } else if (machine && machine->env) {
+ /* Offline analysis: fallback to environment metadata. */
+ e_machine = perf_env__e_machine(machine->env, &local_e_flags);
+ args.is_big_endian = perf_arch_is_big_endian(perf_env__arch(machine->env));
+ }
}
out:
if (e_machine != EM_NONE) {
- thread__set_e_machine(thread, e_machine);
thread__set_e_flags(thread, local_e_flags);
+ thread__set_e_is_big_endian(thread, args.is_big_endian);
+ thread__set_e_machine(thread, e_machine);
+ if (is_big_endian)
+ *is_big_endian = args.is_big_endian;
} else {
e_machine = EM_HOST;
local_e_flags = EF_HOST;
+ if (is_big_endian)
+ *is_big_endian = (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__);
}
if (e_flags)
*e_flags = local_e_flags;
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index f5792d3e8a16..d82fce8173ae 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -69,6 +69,11 @@ DECLARE_RC_STRUCT(thread) {
* computed.
*/
uint16_t e_machine;
+ /**
+ * @e_is_big_endian: True if the ELF architecture of the thread is big endian.
+ * Valid if e_machine != EM_NONE.
+ */
+ bool e_is_big_endian;
/* LBR call stack stitch */
bool lbr_stitch_enable;
struct lbr_stitch *lbr_stitch;
@@ -311,7 +316,13 @@ static inline void thread__set_filter_entry_depth(struct thread *thread, int dep
RC_CHK_ACCESS(thread)->filter_entry_depth = depth;
}
-uint16_t thread__e_machine(struct thread *thread, struct machine *machine, uint32_t *e_flags);
+uint16_t thread__e_machine_endian(struct thread *thread, struct machine *machine, uint32_t *e_flags,
+ bool *is_big_endian);
+static inline uint16_t thread__e_machine(struct thread *thread, struct machine *machine,
+ uint32_t *e_flags)
+{
+ return thread__e_machine_endian(thread, machine, e_flags, NULL);
+}
static inline void thread__set_e_machine(struct thread *thread, uint16_t e_machine)
{
@@ -328,6 +339,16 @@ static inline void thread__set_e_flags(struct thread *thread, uint32_t e_flags)
RC_CHK_ACCESS(thread)->e_flags = e_flags;
}
+static inline bool thread__e_is_big_endian(const struct thread *thread)
+{
+ return RC_CHK_ACCESS(thread)->e_is_big_endian;
+}
+
+static inline void thread__set_e_is_big_endian(struct thread *thread, bool is_big_endian)
+{
+ RC_CHK_ACCESS(thread)->e_is_big_endian = is_big_endian;
+}
+
static inline bool thread__lbr_stitch_enable(const struct thread *thread)
{
--
2.54.0.929.g9b7fa37559-goog