On Fri, Mar 07, 2025 at 04:32:04PM -0800, Ian Rogers wrote:
> 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 <irog...@google.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(-)
This one, due to this having already been merged:
commit b10f74308e1305275e69ddde711ec817cc69e306
(perf-tools-next/perf-tools-next)
Author: Stephen Brennan <stephen.s.bren...@oracle.com>
Date: Fri Mar 7 15:22:03 2025 -0800
perf symbol: Support .gnu_debugdata for symbols
Needs this so that we read the e_machine from the ELF file:
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 8188ba4d432cd5ac..8d2d8bb22e077bea 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1203,6 +1203,7 @@ uint16_t dso__e_machine(struct dso *dso, struct machine
*machine)
case DSO_BINARY_TYPE__UBUNTU_DEBUGINFO:
case DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO:
case DSO_BINARY_TYPE__BUILDID_DEBUGINFO:
+ case DSO_BINARY_TYPE__GNU_DEBUGDATA:
break;
case DSO_BINARY_TYPE__NOT_FOUND:
default:
---
Continuing the review and test.
- Arnaldo
> 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
>
