1 files changed, 109 insertions, 12 deletions

diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 946612029dee..2e899e940034 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -28,6 +28,7 @@
 #define FASTCALL_DECL_TAG	"bpf_fastcall"
 
 #define MAX_ROOT_IDS		16
+#define MAX_BTF_FILES		64
 
 static const char * const btf_kind_str[NR_BTF_KINDS] = {
 	[BTF_KIND_UNKN]		= "UNKNOWN",
@@ -878,6 +879,45 @@ static bool btf_is_kernel_module(__u32 btf_id)
 	return btf_info.kernel_btf && strncmp(btf_name, "vmlinux", sizeof(btf_name)) != 0;
 }
 
+static struct btf *merge_btf_files(const char **files, int nr_files,
+				   struct btf *vmlinux_base)
+{
+	struct btf *combined, *mod;
+	int ret;
+
+	combined = btf__new_empty_split(vmlinux_base);
+	if (!combined) {
+		p_err("failed to create combined BTF: %s", strerror(errno));
+		return NULL;
+	}
+
+	for (int j = 0; j < nr_files; j++) {
+		mod = btf__parse_split(files[j], vmlinux_base);
+		if (!mod) {
+			p_err("failed to load BTF from %s: %s", files[j], strerror(errno));
+			btf__free(combined);
+			return NULL;
+		}
+
+		ret = btf__add_btf(combined, mod);
+		btf__free(mod);
+		if (ret < 0) {
+			p_err("failed to merge BTF from %s: %s", files[j], strerror(-ret));
+			btf__free(combined);
+			return NULL;
+		}
+	}
+
+	ret = btf__dedup(combined, NULL);
+	if (ret) {
+		p_err("failed to dedup combined BTF: %s", strerror(-ret));
+		btf__free(combined);
+		return NULL;
+	}
+
+	return combined;
+}
+
 static int do_dump(int argc, char **argv)
 {
 	bool dump_c = false, sort_dump_c = true;
@@ -958,20 +998,76 @@ static int do_dump(int argc, char **argv)
 		NEXT_ARG();
 	} else if (is_prefix(src, "file")) {
 		const char sysfs_prefix[] = "/sys/kernel/btf/";
+		struct btf *vmlinux_base = base_btf;
+		const char *files[MAX_BTF_FILES];
+		int nr_files = 0;
 
-		if (!base_btf &&
-		    strncmp(*argv, sysfs_prefix, sizeof(sysfs_prefix) - 1) == 0 &&
-		    strcmp(*argv, sysfs_vmlinux) != 0)
-			base = get_vmlinux_btf_from_sysfs();
-
-		btf = btf__parse_split(*argv, base ?: base_btf);
-		if (!btf) {
-			err = -errno;
-			p_err("failed to load BTF from %s: %s",
-			      *argv, strerror(errno));
-			goto done;
+		/* First grab our argument, filtering out the sysfs_vmlinux. */
+		if (strcmp(*argv, sysfs_vmlinux) != 0) {
+			files[nr_files++] = *argv;
+		} else {
+			p_info("skipping %s (will be loaded as base)", *argv);
 		}
 		NEXT_ARG();
+
+		while (argc && is_prefix(*argv, "file")) {
+			NEXT_ARG();
+			if (!REQ_ARGS(1)) {
+				err = -EINVAL;
+				goto done;
+			}
+			/* Filter out any sysfs vmlinux entries. */
+			if (strcmp(*argv, sysfs_vmlinux) == 0) {
+				p_info("skipping %s (will be loaded as base)", *argv);
+				NEXT_ARG();
+				continue;
+			}
+			if (nr_files >= MAX_BTF_FILES) {
+				p_err("too many BTF files (max %d)", MAX_BTF_FILES);
+				err = -E2BIG;
+				goto done;
+			}
+			files[nr_files++] = *argv;
+			NEXT_ARG();
+		}
+
+		/* Auto-detect vmlinux base if any file is from sysfs */
+		if (!vmlinux_base) {
+			for (int j = 0; j < nr_files; j++) {
+				if (strncmp(files[j], sysfs_prefix, sizeof(sysfs_prefix) - 1) == 0) {
+					base = get_vmlinux_btf_from_sysfs();
+					vmlinux_base = base;
+					break;
+				}
+			}
+		}
+
+		/* All files were the sysfs_vmlinux, handle it like we used to */
+		if (nr_files == 0) {
+			nr_files = 1;
+			files[0] = sysfs_vmlinux;
+		}
+
+		if (nr_files == 1) {
+			btf = btf__parse_split(files[0], base ?: base_btf);
+			if (!btf) {
+				err = -errno;
+				p_err("failed to load BTF from %s: %s", files[0], strerror(errno));
+				goto done;
+			}
+		} else {
+			if (!vmlinux_base) {
+				p_err("base BTF is required when merging multiple BTF files; use -B/--base-btf or use sysfs paths");
+				err = -EINVAL;
+				goto done;
+			}
+
+			btf = merge_btf_files(files, nr_files, vmlinux_base);
+			if (!btf) {
+				err = -errno;
+				goto done;
+			}
+		}
 	} else {
 		err = -1;
 		p_err("unrecognized BTF source specifier: '%s'", src);
@@ -1445,7 +1541,8 @@ static int do_help(int argc, char **argv)
 		"       %1$s %2$s dump BTF_SRC [format FORMAT] [root_id ROOT_ID]\n"
 		"       %1$s %2$s help\n"
 		"\n"
-		"       BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n"
+		"       BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] |\n"
+		"                    file FILE [file FILE]... }\n"
 		"       FORMAT  := { raw | c [unsorted] }\n"
 		"       " HELP_SPEC_MAP "\n"
 		"       " HELP_SPEC_PROGRAM "\n"