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Message-Id: <20250308003209.234114-7-irogers@google.com>
Date: Fri, 7 Mar 2025 16:32:04 -0800
From: Ian Rogers <irogers@...gle.com>
To: Ian Rogers <irogers@...gle.com>, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>,
John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>,
James Clark <james.clark@...aro.org>, Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...ux.dev>, guoren <guoren@...nel.org>,
Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>, Charlie Jenkins <charlie@...osinc.com>,
Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>,
Catalin Marinas <catalin.marinas@....com>, Jiri Slaby <jirislaby@...nel.org>,
"Björn Töpel" <bjorn@...osinc.com>, Howard Chu <howardchu95@...il.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
"linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>, linux-riscv@...ts.infradead.org,
Arnd Bergmann <arnd@...db.de>
Subject: [PATCH v5 06/11] perf dso: Add support for reading the e_machine type
for a dso
For ELF file dsos read the e_machine from the ELF header. For kernel
types assume the e_machine matches the perf tool. In other cases
return EM_NONE.
When reading from the ELF header use DSO__SWAP that may need
dso->needs_swap initializing. Factor out dso__swap_init to allow this.
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/util/dso.c | 88 ++++++++++++++++++++++++++++++++++++
tools/perf/util/dso.h | 3 ++
tools/perf/util/symbol-elf.c | 27 -----------
3 files changed, 91 insertions(+), 27 deletions(-)
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 5c6e85fdae0d..00fec1bc32bc 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1170,6 +1170,67 @@ ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine,
return data_read_write_offset(dso, machine, offset, data, size, true);
}
+uint16_t dso__e_machine(struct dso *dso, struct machine *machine)
+{
+ uint16_t e_machine = EM_NONE;
+ int fd;
+
+ switch (dso__binary_type(dso)) {
+ case DSO_BINARY_TYPE__KALLSYMS:
+ case DSO_BINARY_TYPE__GUEST_KALLSYMS:
+ case DSO_BINARY_TYPE__VMLINUX:
+ case DSO_BINARY_TYPE__GUEST_VMLINUX:
+ case DSO_BINARY_TYPE__GUEST_KMODULE:
+ case DSO_BINARY_TYPE__GUEST_KMODULE_COMP:
+ case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE:
+ case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP:
+ case DSO_BINARY_TYPE__KCORE:
+ case DSO_BINARY_TYPE__GUEST_KCORE:
+ case DSO_BINARY_TYPE__BPF_PROG_INFO:
+ case DSO_BINARY_TYPE__BPF_IMAGE:
+ case DSO_BINARY_TYPE__OOL:
+ case DSO_BINARY_TYPE__JAVA_JIT:
+ return EM_HOST;
+ case DSO_BINARY_TYPE__DEBUGLINK:
+ case DSO_BINARY_TYPE__BUILD_ID_CACHE:
+ case DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO:
+ case DSO_BINARY_TYPE__SYSTEM_PATH_DSO:
+ case DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO:
+ case DSO_BINARY_TYPE__FEDORA_DEBUGINFO:
+ case DSO_BINARY_TYPE__UBUNTU_DEBUGINFO:
+ case DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO:
+ case DSO_BINARY_TYPE__BUILDID_DEBUGINFO:
+ break;
+ case DSO_BINARY_TYPE__NOT_FOUND:
+ default:
+ return EM_NONE;
+ }
+
+ pthread_mutex_lock(&dso__data_open_lock);
+
+ /*
+ * dso__data(dso)->fd might be closed if other thread opened another
+ * file (dso) due to open file limit (RLIMIT_NOFILE).
+ */
+ try_to_open_dso(dso, machine);
+ fd = dso__data(dso)->fd;
+ if (fd >= 0) {
+ _Static_assert(offsetof(Elf32_Ehdr, e_machine) == 18, "Unexpected offset");
+ _Static_assert(offsetof(Elf64_Ehdr, e_machine) == 18, "Unexpected offset");
+ if (dso__needs_swap(dso) == DSO_SWAP__UNSET) {
+ unsigned char eidata;
+
+ if (pread(fd, &eidata, sizeof(eidata), EI_DATA) == sizeof(eidata))
+ dso__swap_init(dso, eidata);
+ }
+ if (dso__needs_swap(dso) != DSO_SWAP__UNSET &&
+ pread(fd, &e_machine, sizeof(e_machine), 18) == sizeof(e_machine))
+ e_machine = DSO__SWAP(dso, uint16_t, e_machine);
+ }
+ pthread_mutex_unlock(&dso__data_open_lock);
+ return e_machine;
+}
+
/**
* dso__data_read_addr - Read data from dso address
* @dso: dso object
@@ -1525,6 +1586,33 @@ void dso__put(struct dso *dso)
RC_CHK_PUT(dso);
}
+int dso__swap_init(struct dso *dso, unsigned char eidata)
+{
+ static unsigned int const endian = 1;
+
+ dso__set_needs_swap(dso, DSO_SWAP__NO);
+
+ switch (eidata) {
+ case ELFDATA2LSB:
+ /* We are big endian, DSO is little endian. */
+ if (*(unsigned char const *)&endian != 1)
+ dso__set_needs_swap(dso, DSO_SWAP__YES);
+ break;
+
+ case ELFDATA2MSB:
+ /* We are little endian, DSO is big endian. */
+ if (*(unsigned char const *)&endian != 0)
+ dso__set_needs_swap(dso, DSO_SWAP__YES);
+ break;
+
+ default:
+ pr_err("unrecognized DSO data encoding %d\n", eidata);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
void dso__set_build_id(struct dso *dso, struct build_id *bid)
{
RC_CHK_ACCESS(dso)->bid = *bid;
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 4aa8c3d36566..38d9e3eac501 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -730,6 +730,8 @@ bool dso__sorted_by_name(const struct dso *dso);
void dso__set_sorted_by_name(struct dso *dso);
void dso__sort_by_name(struct dso *dso);
+int dso__swap_init(struct dso *dso, unsigned char eidata);
+
void dso__set_build_id(struct dso *dso, struct build_id *bid);
bool dso__build_id_equal(const struct dso *dso, struct build_id *bid);
void dso__read_running_kernel_build_id(struct dso *dso,
@@ -818,6 +820,7 @@ 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__e_machine(struct dso *dso, struct machine *machine);
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/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 66fd1249660a..71df13a5722a 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1173,33 +1173,6 @@ int filename__read_debuglink(const char *filename, char *debuglink,
#endif
-static int dso__swap_init(struct dso *dso, unsigned char eidata)
-{
- static unsigned int const endian = 1;
-
- dso__set_needs_swap(dso, DSO_SWAP__NO);
-
- switch (eidata) {
- case ELFDATA2LSB:
- /* We are big endian, DSO is little endian. */
- if (*(unsigned char const *)&endian != 1)
- dso__set_needs_swap(dso, DSO_SWAP__YES);
- break;
-
- case ELFDATA2MSB:
- /* We are little endian, DSO is big endian. */
- if (*(unsigned char const *)&endian != 0)
- dso__set_needs_swap(dso, DSO_SWAP__YES);
- break;
-
- default:
- pr_err("unrecognized DSO data encoding %d\n", eidata);
- return -EINVAL;
- }
-
- return 0;
-}
-
bool symsrc__possibly_runtime(struct symsrc *ss)
{
return ss->dynsym || ss->opdsec;
--
2.49.0.rc0.332.g42c0ae87b1-goog
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