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perf dso: Support BPF programs in dso__read_symbol()

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Set the buffer to the code in the BPF linear info. This enables BPF
JIT code disassembly by LLVM and capstone.

Move the common but minimal disassmble_bpf_image call to
disassemble_objdump so that it is only called after falling back to the
objdump option.

Similarly move the disassmble_bpf function to disassemble_objdump and
rename to disassmble_bpf_libbfd to make it clearer that this support
relies on libbfd.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.ibm.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Collin Funk <collin.funk1@gmail.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers
2025-10-06 16:35:28 -03:00
committed by Arnaldo Carvalho de Melo
parent 9518e10c2b
commit aa04707f50
4 changed files with 83 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tools/perf/util/disasm.c
+7 -5
View File
@@ -1521,6 +1521,12 @@ static int symbol__disassemble_objdump(const char *filename, struct symbol *sym,
struct child_process objdump_process;
int err;
if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_PROG_INFO)
return symbol__disassemble_bpf_libbfd(sym, args);
if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_IMAGE)
return symbol__disassemble_bpf_image(sym, args);
err = asprintf(&command,
"%s %s%s --start-address=0x%016" PRIx64
" --stop-address=0x%016" PRIx64
@@ -1655,11 +1661,7 @@ int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
pr_debug("annotating [%p] %30s : [%p] %30s\n", dso, dso__long_name(dso), sym, sym->name);
if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_PROG_INFO) {
return symbol__disassemble_bpf(sym, args);
} else if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_IMAGE) {
return symbol__disassemble_bpf_image(sym, args);
} else if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND) {
if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND) {
return SYMBOL_ANNOTATE_ERRNO__COULDNT_DETERMINE_FILE_TYPE;
} else if (dso__is_kcore(dso)) {
kce.addr = map__rip_2objdump(map, sym->start);
tools/perf/util/dso.c
+71 -35
View File
@@ -1816,23 +1816,17 @@ static int find_file_offset(u64 start, u64 len, u64 pgoff, void *arg)
return 0;
}
const u8 *dso__read_symbol(struct dso *dso, const char *symfs_filename,
const struct map *map, const struct symbol *sym,
u8 **out_buf, u64 *out_buf_len, bool *is_64bit)
static const u8 *__dso__read_symbol(struct dso *dso, const char *symfs_filename,
u64 start, size_t len,
u8 **out_buf, u64 *out_buf_len, bool *is_64bit)
{
struct nscookie nsc;
u64 start = map__rip_2objdump(map, sym->start);
u64 end = map__rip_2objdump(map, sym->end);
int fd, count;
u8 *buf = NULL;
size_t len;
int fd;
ssize_t count;
struct find_file_offset_data data = {
.ip = start,
};
*out_buf = NULL;
*out_buf_len = 0;
*is_64bit = false;
u8 *code_buf = NULL;
nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
fd = open(symfs_filename, O_RDONLY);
@@ -1840,28 +1834,70 @@ const u8 *dso__read_symbol(struct dso *dso, const char *symfs_filename,
if (fd < 0)
return NULL;
if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data, is_64bit) == 0)
goto err;
len = end - start;
buf = malloc(len);
if (buf == NULL)
goto err;
count = pread(fd, buf, len, data.offset);
close(fd);
fd = -1;
if ((u64)count != len)
goto err;
*out_buf = buf;
*out_buf_len = len;
return buf;
err:
if (fd >= 0)
if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data, is_64bit) == 0) {
close(fd);
free(buf);
return NULL;
return NULL;
}
code_buf = malloc(len);
if (code_buf == NULL) {
close(fd);
return NULL;
}
count = pread(fd, code_buf, len, data.offset);
close(fd);
if ((u64)count != len) {
free(code_buf);
return NULL;
}
*out_buf = code_buf;
*out_buf_len = len;
return code_buf;
}
/*
* Read a symbol into memory for disassembly by a library like capstone of
* libLLVM. If memory is allocated out_buf holds it.
*/
const u8 *dso__read_symbol(struct dso *dso, const char *symfs_filename,
const struct map *map, const struct symbol *sym,
u8 **out_buf, u64 *out_buf_len, bool *is_64bit)
{
u64 start = map__rip_2objdump(map, sym->start);
u64 end = map__rip_2objdump(map, sym->end);
size_t len = end - start;
*out_buf = NULL;
*out_buf_len = 0;
*is_64bit = false;
if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_IMAGE) {
/*
* Note, there is fallback BPF image disassembly in the objdump
* version but it currently does nothing.
*/
return NULL;
}
if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_PROG_INFO) {
#ifdef HAVE_LIBBPF_SUPPORT
struct bpf_prog_info_node *info_node;
struct perf_bpil *info_linear;
*is_64bit = sizeof(void *) == sizeof(u64);
info_node = perf_env__find_bpf_prog_info(dso__bpf_prog(dso)->env,
dso__bpf_prog(dso)->id);
if (!info_node) {
errno = SYMBOL_ANNOTATE_ERRNO__BPF_MISSING_BTF;
return NULL;
}
info_linear = info_node->info_linear;
assert(len <= info_linear->info.jited_prog_len);
*out_buf_len = len;
return (const u8 *)(uintptr_t)(info_linear->info.jited_prog_insns);
#else
pr_debug("No BPF program disassembly support\n");
return NULL;
#endif
}
return __dso__read_symbol(dso, symfs_filename, start, len,
out_buf, out_buf_len, is_64bit);
}
tools/perf/util/libbfd.c
+2 -2
View File
@@ -448,8 +448,8 @@ out_close:
return err;
}
int symbol__disassemble_bpf(struct symbol *sym __maybe_unused,
struct annotate_args *args __maybe_unused)
int symbol__disassemble_bpf_libbfd(struct symbol *sym __maybe_unused,
struct annotate_args *args __maybe_unused)
{
#ifdef HAVE_LIBBPF_SUPPORT
struct annotation *notes = symbol__annotation(sym);
tools/perf/util/libbfd.h
+3 -3
View File
@@ -29,7 +29,7 @@ int libbfd__read_build_id(const char *filename, struct build_id *bid, bool block
int libbfd_filename__read_debuglink(const char *filename, char *debuglink, size_t size);
int symbol__disassemble_bpf(struct symbol *sym, struct annotate_args *args);
int symbol__disassemble_bpf_libbfd(struct symbol *sym, struct annotate_args *args);
#else // !defined(HAVE_LIBBFD_SUPPORT)
#include "annotate.h"
@@ -72,8 +72,8 @@ static inline int libbfd_filename__read_debuglink(const char *filename __always_
return -1;
}
static inline int symbol__disassemble_bpf(struct symbol *sym __always_unused,
struct annotate_args *args __always_unused)
static inline int symbol__disassemble_bpf_libbfd(struct symbol *sym __always_unused,
struct annotate_args *args __always_unused)
{
return SYMBOL_ANNOTATE_ERRNO__NO_LIBOPCODES_FOR_BPF;
}