Commit aa04707f authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf dso: Support BPF programs in dso__read_symbol() 



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: default avatarIan 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9518e10c

tools/perf/util/disasm.c

+7 −5
Original line number Diff line number Diff line
@@ -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

+68 −32
Original line number Diff line number Diff line
@@ -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,

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);

	if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data, is_64bit) == 0) {

		close(fd);

	fd = -1;

		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;



	if ((u64)count != len)

		goto err;

	*out_buf = NULL;

	*out_buf_len = 0;

	*is_64bit = false;



	*out_buf = buf;

	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 buf;



err:

	if (fd >= 0)

		close(fd);

	free(buf);

		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
Original line number Diff line number Diff line
@@ -448,7 +448,7 @@ int libbfd_filename__read_debuglink(const char *filename, char *debuglink, 
	return err;

}



int symbol__disassemble_bpf(struct symbol *sym __maybe_unused,

int symbol__disassemble_bpf_libbfd(struct symbol *sym __maybe_unused,

				   struct annotate_args *args  __maybe_unused)

{

#ifdef HAVE_LIBBPF_SUPPORT

tools/perf/util/libbfd.h

+3 −3
Original line number Diff line number Diff line
@@ -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"
@@ -72,7 +72,7 @@ static inline int libbfd_filename__read_debuglink(const char *filename __always_ 
	return -1;

}



static inline int symbol__disassemble_bpf(struct symbol *sym __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;