[PATCH v2 10/17] perf dso: Support BPF programs in dso__read_symbol

[Ian Rogers <irogers@google.com>]

Set the buffer to the code in the BPF linear info. This enables BPF
JIT code disassembly by LLVM and capstone. Move the disassmble_bpf
calls to disassemble_objdump so that they are only called after
falling back to the objdump option.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/disasm.c | 12 +++---
 tools/perf/util/dso.c    | 85 +++++++++++++++++++++++++---------------
 2 files changed, 60 insertions(+), 37 deletions(-)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index a9cc588a3006..99b9c21e02b0 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1500,6 +1500,12 @@ 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(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
@@ -1681,11 +1687,7 @@ 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);
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 0285904ed26d..a90799bed230 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1686,48 +1686,69 @@ 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)
 {
-	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;
-	struct find_file_offset_data data = {
-		.ip = start,
-	};
+	const u8 *buf;
+	size_t len = end - start;
 
 	*out_buf = NULL;
 	*out_buf_len = 0;
 	*is_64bit = false;
 
-	nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
-	fd = open(symfs_filename, O_RDONLY);
-	nsinfo__mountns_exit(&nsc);
-	if (fd < 0)
+	if (dso__binary_type(dso) == DSO_BINARY_TYPE__BPF_IMAGE) {
+		pr_debug("No BPF image disassembly support\n");
 		return NULL;
+	} else 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;
+		buf = (const u8 *)(uintptr_t)(info_linear->info.jited_prog_insns);
+		assert(len <= info_linear->info.jited_prog_len);
+#else
+		pr_debug("No BPF program disassembly support\n");
+		return NULL;
+#endif
+	} else {
+		struct nscookie nsc;
+		int fd;
+		ssize_t count;
+		struct find_file_offset_data data = {
+			.ip = start,
+		};
+		u8 *code_buf = 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;
+		nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
+		fd = open(symfs_filename, O_RDONLY);
+		nsinfo__mountns_exit(&nsc);
+		if (fd < 0)
+			return NULL;
 
-	*out_buf = buf;
+		if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data, is_64bit) == 0) {
+			close(fd);
+			return NULL;
+		}
+		buf = code_buf = malloc(len);
+		if (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 buf;
-
-err:
-	if (fd >= 0)
-		close(fd);
-	free(buf);
-	return NULL;
 }
-- 
2.48.0.rc2.279.g1de40edade-goog