Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1528 insertions, 0 deletions

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
new file mode 100644
index 0000000000..bdfead36b8
--- /dev/null
+++ b/tools/perf/util/dso.c
@@ -0,0 +1,1528 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/bug.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/zalloc.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#ifdef HAVE_LIBBPF_SUPPORT
+#include <bpf/libbpf.h>
+#include "bpf-event.h"
+#include "bpf-utils.h"
+#endif
+#include "compress.h"
+#include "env.h"
+#include "namespaces.h"
+#include "path.h"
+#include "map.h"
+#include "symbol.h"
+#include "srcline.h"
+#include "dso.h"
+#include "dsos.h"
+#include "machine.h"
+#include "auxtrace.h"
+#include "util.h" /* O_CLOEXEC for older systems */
+#include "debug.h"
+#include "string2.h"
+#include "vdso.h"
+
+static const char * const debuglink_paths[] = {
+	"%.0s%s",
+	"%s/%s",
+	"%s/.debug/%s",
+	"/usr/lib/debug%s/%s"
+};
+
+char dso__symtab_origin(const struct dso *dso)
+{
+	static const char origin[] = {
+		[DSO_BINARY_TYPE__KALLSYMS]			= 'k',
+		[DSO_BINARY_TYPE__VMLINUX]			= 'v',
+		[DSO_BINARY_TYPE__JAVA_JIT]			= 'j',
+		[DSO_BINARY_TYPE__DEBUGLINK]			= 'l',
+		[DSO_BINARY_TYPE__BUILD_ID_CACHE]		= 'B',
+		[DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO]	= 'D',
+		[DSO_BINARY_TYPE__FEDORA_DEBUGINFO]		= 'f',
+		[DSO_BINARY_TYPE__UBUNTU_DEBUGINFO]		= 'u',
+		[DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO]	= 'x',
+		[DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO]	= 'o',
+		[DSO_BINARY_TYPE__BUILDID_DEBUGINFO]		= 'b',
+		[DSO_BINARY_TYPE__SYSTEM_PATH_DSO]		= 'd',
+		[DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE]		= 'K',
+		[DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP]	= 'm',
+		[DSO_BINARY_TYPE__GUEST_KALLSYMS]		= 'g',
+		[DSO_BINARY_TYPE__GUEST_KMODULE]		= 'G',
+		[DSO_BINARY_TYPE__GUEST_KMODULE_COMP]		= 'M',
+		[DSO_BINARY_TYPE__GUEST_VMLINUX]		= 'V',
+	};
+
+	if (dso == NULL || dso->symtab_type == DSO_BINARY_TYPE__NOT_FOUND)
+		return '!';
+	return origin[dso->symtab_type];
+}
+
+bool dso__is_object_file(const struct dso *dso)
+{
+	switch (dso->binary_type) {
+	case DSO_BINARY_TYPE__KALLSYMS:
+	case DSO_BINARY_TYPE__GUEST_KALLSYMS:
+	case DSO_BINARY_TYPE__JAVA_JIT:
+	case DSO_BINARY_TYPE__BPF_PROG_INFO:
+	case DSO_BINARY_TYPE__BPF_IMAGE:
+	case DSO_BINARY_TYPE__OOL:
+		return false;
+	case DSO_BINARY_TYPE__VMLINUX:
+	case DSO_BINARY_TYPE__GUEST_VMLINUX:
+	case DSO_BINARY_TYPE__DEBUGLINK:
+	case DSO_BINARY_TYPE__BUILD_ID_CACHE:
+	case DSO_BINARY_TYPE__BUILD_ID_CACHE_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:
+	case DSO_BINARY_TYPE__SYSTEM_PATH_DSO:
+	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__OPENEMBEDDED_DEBUGINFO:
+	case DSO_BINARY_TYPE__NOT_FOUND:
+	default:
+		return true;
+	}
+}
+
+int dso__read_binary_type_filename(const struct dso *dso,
+				   enum dso_binary_type type,
+				   char *root_dir, char *filename, size_t size)
+{
+	char build_id_hex[SBUILD_ID_SIZE];
+	int ret = 0;
+	size_t len;
+
+	switch (type) {
+	case DSO_BINARY_TYPE__DEBUGLINK:
+	{
+		const char *last_slash;
+		char dso_dir[PATH_MAX];
+		char symfile[PATH_MAX];
+		unsigned int i;
+
+		len = __symbol__join_symfs(filename, size, dso->long_name);
+		last_slash = filename + len;
+		while (last_slash != filename && *last_slash != '/')
+			last_slash--;
+
+		strncpy(dso_dir, filename, last_slash - filename);
+		dso_dir[last_slash-filename] = '\0';
+
+		if (!is_regular_file(filename)) {
+			ret = -1;
+			break;
+		}
+
+		ret = filename__read_debuglink(filename, symfile, PATH_MAX);
+		if (ret)
+			break;
+
+		/* Check predefined locations where debug file might reside */
+		ret = -1;
+		for (i = 0; i < ARRAY_SIZE(debuglink_paths); i++) {
+			snprintf(filename, size,
+					debuglink_paths[i], dso_dir, symfile);
+			if (is_regular_file(filename)) {
+				ret = 0;
+				break;
+			}
+		}
+
+		break;
+	}
+	case DSO_BINARY_TYPE__BUILD_ID_CACHE:
+		if (dso__build_id_filename(dso, filename, size, false) == NULL)
+			ret = -1;
+		break;
+
+	case DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO:
+		if (dso__build_id_filename(dso, filename, size, true) == NULL)
+			ret = -1;
+		break;
+
+	case DSO_BINARY_TYPE__FEDORA_DEBUGINFO:
+		len = __symbol__join_symfs(filename, size, "/usr/lib/debug");
+		snprintf(filename + len, size - len, "%s.debug", dso->long_name);
+		break;
+
+	case DSO_BINARY_TYPE__UBUNTU_DEBUGINFO:
+		len = __symbol__join_symfs(filename, size, "/usr/lib/debug");
+		snprintf(filename + len, size - len, "%s", dso->long_name);
+		break;
+
+	case DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO:
+		/*
+		 * Ubuntu can mixup /usr/lib with /lib, putting debuginfo in
+		 * /usr/lib/debug/lib when it is expected to be in
+		 * /usr/lib/debug/usr/lib
+		 */
+		if (strlen(dso->long_name) < 9 ||
+		    strncmp(dso->long_name, "/usr/lib/", 9)) {
+			ret = -1;
+			break;
+		}
+		len = __symbol__join_symfs(filename, size, "/usr/lib/debug");
+		snprintf(filename + len, size - len, "%s", dso->long_name + 4);
+		break;
+
+	case DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO:
+	{
+		const char *last_slash;
+		size_t dir_size;
+
+		last_slash = dso->long_name + dso->long_name_len;
+		while (last_slash != dso->long_name && *last_slash != '/')
+			last_slash--;
+
+		len = __symbol__join_symfs(filename, size, "");
+		dir_size = last_slash - dso->long_name + 2;
+		if (dir_size > (size - len)) {
+			ret = -1;
+			break;
+		}
+		len += scnprintf(filename + len, dir_size, "%s",  dso->long_name);
+		len += scnprintf(filename + len , size - len, ".debug%s",
+								last_slash);
+		break;
+	}
+
+	case DSO_BINARY_TYPE__BUILDID_DEBUGINFO:
+		if (!dso->has_build_id) {
+			ret = -1;
+			break;
+		}
+
+		build_id__sprintf(&dso->bid, build_id_hex);
+		len = __symbol__join_symfs(filename, size, "/usr/lib/debug/.build-id/");
+		snprintf(filename + len, size - len, "%.2s/%s.debug",
+			 build_id_hex, build_id_hex + 2);
+		break;
+
+	case DSO_BINARY_TYPE__VMLINUX:
+	case DSO_BINARY_TYPE__GUEST_VMLINUX:
+	case DSO_BINARY_TYPE__SYSTEM_PATH_DSO:
+		__symbol__join_symfs(filename, size, dso->long_name);
+		break;
+
+	case DSO_BINARY_TYPE__GUEST_KMODULE:
+	case DSO_BINARY_TYPE__GUEST_KMODULE_COMP:
+		path__join3(filename, size, symbol_conf.symfs,
+			    root_dir, dso->long_name);
+		break;
+
+	case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE:
+	case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP:
+		__symbol__join_symfs(filename, size, dso->long_name);
+		break;
+
+	case DSO_BINARY_TYPE__KCORE:
+	case DSO_BINARY_TYPE__GUEST_KCORE:
+		snprintf(filename, size, "%s", dso->long_name);
+		break;
+
+	default:
+	case DSO_BINARY_TYPE__KALLSYMS:
+	case DSO_BINARY_TYPE__GUEST_KALLSYMS:
+	case DSO_BINARY_TYPE__JAVA_JIT:
+	case DSO_BINARY_TYPE__BPF_PROG_INFO:
+	case DSO_BINARY_TYPE__BPF_IMAGE:
+	case DSO_BINARY_TYPE__OOL:
+	case DSO_BINARY_TYPE__NOT_FOUND:
+		ret = -1;
+		break;
+	}
+
+	return ret;
+}
+
+enum {
+	COMP_ID__NONE = 0,
+};
+
+static const struct {
+	const char *fmt;
+	int (*decompress)(const char *input, int output);
+	bool (*is_compressed)(const char *input);
+} compressions[] = {
+	[COMP_ID__NONE] = { .fmt = NULL, },
+#ifdef HAVE_ZLIB_SUPPORT
+	{ "gz", gzip_decompress_to_file, gzip_is_compressed },
+#endif
+#ifdef HAVE_LZMA_SUPPORT
+	{ "xz", lzma_decompress_to_file, lzma_is_compressed },
+#endif
+	{ NULL, NULL, NULL },
+};
+
+static int is_supported_compression(const char *ext)
+{
+	unsigned i;
+
+	for (i = 1; compressions[i].fmt; i++) {
+		if (!strcmp(ext, compressions[i].fmt))
+			return i;
+	}
+	return COMP_ID__NONE;
+}
+
+bool is_kernel_module(const char *pathname, int cpumode)
+{
+	struct kmod_path m;
+	int mode = cpumode & PERF_RECORD_MISC_CPUMODE_MASK;
+
+	WARN_ONCE(mode != cpumode,
+		  "Internal error: passing unmasked cpumode (%x) to is_kernel_module",
+		  cpumode);
+
+	switch (mode) {
+	case PERF_RECORD_MISC_USER:
+	case PERF_RECORD_MISC_HYPERVISOR:
+	case PERF_RECORD_MISC_GUEST_USER:
+		return false;
+	/* Treat PERF_RECORD_MISC_CPUMODE_UNKNOWN as kernel */
+	default:
+		if (kmod_path__parse(&m, pathname)) {
+			pr_err("Failed to check whether %s is a kernel module or not. Assume it is.",
+					pathname);
+			return true;
+		}
+	}
+
+	return m.kmod;
+}
+
+bool dso__needs_decompress(struct dso *dso)
+{
+	return dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP ||
+		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
+}
+
+int filename__decompress(const char *name, char *pathname,
+			 size_t len, int comp, int *err)
+{
+	char tmpbuf[] = KMOD_DECOMP_NAME;
+	int fd = -1;
+
+	/*
+	 * We have proper compression id for DSO and yet the file
+	 * behind the 'name' can still be plain uncompressed object.
+	 *
+	 * The reason is behind the logic we open the DSO object files,
+	 * when we try all possible 'debug' objects until we find the
+	 * data. So even if the DSO is represented by 'krava.xz' module,
+	 * we can end up here opening ~/.debug/....23432432/debug' file
+	 * which is not compressed.
+	 *
+	 * To keep this transparent, we detect this and return the file
+	 * descriptor to the uncompressed file.
+	 */
+	if (!compressions[comp].is_compressed(name))
+		return open(name, O_RDONLY);
+
+	fd = mkstemp(tmpbuf);
+	if (fd < 0) {
+		*err = errno;
+		return -1;
+	}
+
+	if (compressions[comp].decompress(name, fd)) {
+		*err = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
+		close(fd);
+		fd = -1;
+	}
+
+	if (!pathname || (fd < 0))
+		unlink(tmpbuf);
+
+	if (pathname && (fd >= 0))
+		strlcpy(pathname, tmpbuf, len);
+
+	return fd;
+}
+
+static int decompress_kmodule(struct dso *dso, const char *name,
+			      char *pathname, size_t len)
+{
+	if (!dso__needs_decompress(dso))
+		return -1;
+
+	if (dso->comp == COMP_ID__NONE)
+		return -1;
+
+	return filename__decompress(name, pathname, len, dso->comp,
+				    &dso->load_errno);
+}
+
+int dso__decompress_kmodule_fd(struct dso *dso, const char *name)
+{
+	return decompress_kmodule(dso, name, NULL, 0);
+}
+
+int dso__decompress_kmodule_path(struct dso *dso, const char *name,
+				 char *pathname, size_t len)
+{
+	int fd = decompress_kmodule(dso, name, pathname, len);
+
+	close(fd);
+	return fd >= 0 ? 0 : -1;
+}
+
+/*
+ * Parses kernel module specified in @path and updates
+ * @m argument like:
+ *
+ *    @comp - true if @path contains supported compression suffix,
+ *            false otherwise
+ *    @kmod - true if @path contains '.ko' suffix in right position,
+ *            false otherwise
+ *    @name - if (@alloc_name && @kmod) is true, it contains strdup-ed base name
+ *            of the kernel module without suffixes, otherwise strudup-ed
+ *            base name of @path
+ *    @ext  - if (@alloc_ext && @comp) is true, it contains strdup-ed string
+ *            the compression suffix
+ *
+ * Returns 0 if there's no strdup error, -ENOMEM otherwise.
+ */
+int __kmod_path__parse(struct kmod_path *m, const char *path,
+		       bool alloc_name)
+{
+	const char *name = strrchr(path, '/');
+	const char *ext  = strrchr(path, '.');
+	bool is_simple_name = false;
+
+	memset(m, 0x0, sizeof(*m));
+	name = name ? name + 1 : path;
+
+	/*
+	 * '.' is also a valid character for module name. For example:
+	 * [aaa.bbb] is a valid module name. '[' should have higher
+	 * priority than '.ko' suffix.
+	 *
+	 * The kernel names are from machine__mmap_name. Such
+	 * name should belong to kernel itself, not kernel module.
+	 */
+	if (name[0] == '[') {
+		is_simple_name = true;
+		if ((strncmp(name, "[kernel.kallsyms]", 17) == 0) ||
+		    (strncmp(name, "[guest.kernel.kallsyms", 22) == 0) ||
+		    (strncmp(name, "[vdso]", 6) == 0) ||
+		    (strncmp(name, "[vdso32]", 8) == 0) ||
+		    (strncmp(name, "[vdsox32]", 9) == 0) ||
+		    (strncmp(name, "[vsyscall]", 10) == 0)) {
+			m->kmod = false;
+
+		} else
+			m->kmod = true;
+	}
+
+	/* No extension, just return name. */
+	if ((ext == NULL) || is_simple_name) {
+		if (alloc_name) {
+			m->name = strdup(name);
+			return m->name ? 0 : -ENOMEM;
+		}
+		return 0;
+	}
+
+	m->comp = is_supported_compression(ext + 1);
+	if (m->comp > COMP_ID__NONE)
+		ext -= 3;
+
+	/* Check .ko extension only if there's enough name left. */
+	if (ext > name)
+		m->kmod = !strncmp(ext, ".ko", 3);
+
+	if (alloc_name) {
+		if (m->kmod) {
+			if (asprintf(&m->name, "[%.*s]", (int) (ext - name), name) == -1)
+				return -ENOMEM;
+		} else {
+			if (asprintf(&m->name, "%s", name) == -1)
+				return -ENOMEM;
+		}
+
+		strreplace(m->name, '-', '_');
+	}
+
+	return 0;
+}
+
+void dso__set_module_info(struct dso *dso, struct kmod_path *m,
+			  struct machine *machine)
+{
+	if (machine__is_host(machine))
+		dso->symtab_type = DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE;
+	else
+		dso->symtab_type = DSO_BINARY_TYPE__GUEST_KMODULE;
+
+	/* _KMODULE_COMP should be next to _KMODULE */
+	if (m->kmod && m->comp) {
+		dso->symtab_type++;
+		dso->comp = m->comp;
+	}
+
+	dso__set_short_name(dso, strdup(m->name), true);
+}
+
+/*
+ * Global list of open DSOs and the counter.
+ */
+static LIST_HEAD(dso__data_open);
+static long dso__data_open_cnt;
+static pthread_mutex_t dso__data_open_lock = PTHREAD_MUTEX_INITIALIZER;
+
+static void dso__list_add(struct dso *dso)
+{
+	list_add_tail(&dso->data.open_entry, &dso__data_open);
+	dso__data_open_cnt++;
+}
+
+static void dso__list_del(struct dso *dso)
+{
+	list_del_init(&dso->data.open_entry);
+	WARN_ONCE(dso__data_open_cnt <= 0,
+		  "DSO data fd counter out of bounds.");
+	dso__data_open_cnt--;
+}
+
+static void close_first_dso(void);
+
+static int do_open(char *name)
+{
+	int fd;
+	char sbuf[STRERR_BUFSIZE];
+
+	do {
+		fd = open(name, O_RDONLY|O_CLOEXEC);
+		if (fd >= 0)
+			return fd;
+
+		pr_debug("dso open failed: %s\n",
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
+		if (!dso__data_open_cnt || errno != EMFILE)
+			break;
+
+		close_first_dso();
+	} while (1);
+
+	return -1;
+}
+
+char *dso__filename_with_chroot(const struct dso *dso, const char *filename)
+{
+	return filename_with_chroot(nsinfo__pid(dso->nsinfo), filename);
+}
+
+static int __open_dso(struct dso *dso, struct machine *machine)
+{
+	int fd = -EINVAL;
+	char *root_dir = (char *)"";
+	char *name = malloc(PATH_MAX);
+	bool decomp = false;
+
+	if (!name)
+		return -ENOMEM;
+
+	mutex_lock(&dso->lock);
+	if (machine)
+		root_dir = machine->root_dir;
+
+	if (dso__read_binary_type_filename(dso, dso->binary_type,
+					    root_dir, name, PATH_MAX))
+		goto out;
+
+	if (!is_regular_file(name)) {
+		char *new_name;
+
+		if (errno != ENOENT || dso->nsinfo == NULL)
+			goto out;
+
+		new_name = dso__filename_with_chroot(dso, name);
+		if (!new_name)
+			goto out;
+
+		free(name);
+		name = new_name;
+	}
+
+	if (dso__needs_decompress(dso)) {
+		char newpath[KMOD_DECOMP_LEN];
+		size_t len = sizeof(newpath);
+
+		if (dso__decompress_kmodule_path(dso, name, newpath, len) < 0) {
+			fd = -dso->load_errno;
+			goto out;
+		}
+
+		decomp = true;
+		strcpy(name, newpath);
+	}
+
+	fd = do_open(name);
+
+	if (decomp)
+		unlink(name);
+
+out:
+	mutex_unlock(&dso->lock);
+	free(name);
+	return fd;
+}
+
+static void check_data_close(void);
+
+/**
+ * dso_close - Open DSO data file
+ * @dso: dso object
+ *
+ * Open @dso's data file descriptor and updates
+ * list/count of open DSO objects.
+ */
+static int open_dso(struct dso *dso, struct machine *machine)
+{
+	int fd;
+	struct nscookie nsc;
+
+	if (dso->binary_type != DSO_BINARY_TYPE__BUILD_ID_CACHE) {
+		mutex_lock(&dso->lock);
+		nsinfo__mountns_enter(dso->nsinfo, &nsc);
+		mutex_unlock(&dso->lock);
+	}
+	fd = __open_dso(dso, machine);
+	if (dso->binary_type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
+		nsinfo__mountns_exit(&nsc);
+
+	if (fd >= 0) {
+		dso__list_add(dso);
+		/*
+		 * Check if we crossed the allowed number
+		 * of opened DSOs and close one if needed.
+		 */
+		check_data_close();
+	}
+
+	return fd;
+}
+
+static void close_data_fd(struct dso *dso)
+{
+	if (dso->data.fd >= 0) {
+		close(dso->data.fd);
+		dso->data.fd = -1;
+		dso->data.file_size = 0;
+		dso__list_del(dso);
+	}
+}
+
+/**
+ * dso_close - Close DSO data file
+ * @dso: dso object
+ *
+ * Close @dso's data file descriptor and updates
+ * list/count of open DSO objects.
+ */
+static void close_dso(struct dso *dso)
+{
+	close_data_fd(dso);
+}
+
+static void close_first_dso(void)
+{
+	struct dso *dso;
+
+	dso = list_first_entry(&dso__data_open, struct dso, data.open_entry);
+	close_dso(dso);
+}
+
+static rlim_t get_fd_limit(void)
+{
+	struct rlimit l;
+	rlim_t limit = 0;
+
+	/* Allow half of the current open fd limit. */
+	if (getrlimit(RLIMIT_NOFILE, &l) == 0) {
+		if (l.rlim_cur == RLIM_INFINITY)
+			limit = l.rlim_cur;
+		else
+			limit = l.rlim_cur / 2;
+	} else {
+		pr_err("failed to get fd limit\n");
+		limit = 1;
+	}
+
+	return limit;
+}
+
+static rlim_t fd_limit;
+
+/*
+ * Used only by tests/dso-data.c to reset the environment
+ * for tests. I dont expect we should change this during
+ * standard runtime.
+ */
+void reset_fd_limit(void)
+{
+	fd_limit = 0;
+}
+
+static bool may_cache_fd(void)
+{
+	if (!fd_limit)
+		fd_limit = get_fd_limit();
+
+	if (fd_limit == RLIM_INFINITY)
+		return true;
+
+	return fd_limit > (rlim_t) dso__data_open_cnt;
+}
+
+/*
+ * Check and close LRU dso if we crossed allowed limit
+ * for opened dso file descriptors. The limit is half
+ * of the RLIMIT_NOFILE files opened.
+*/
+static void check_data_close(void)
+{
+	bool cache_fd = may_cache_fd();
+
+	if (!cache_fd)
+		close_first_dso();
+}
+
+/**
+ * dso__data_close - Close DSO data file
+ * @dso: dso object
+ *
+ * External interface to close @dso's data file descriptor.
+ */
+void dso__data_close(struct dso *dso)
+{
+	pthread_mutex_lock(&dso__data_open_lock);
+	close_dso(dso);
+	pthread_mutex_unlock(&dso__data_open_lock);
+}
+
+static void try_to_open_dso(struct dso *dso, struct machine *machine)
+{
+	enum dso_binary_type binary_type_data[] = {
+		DSO_BINARY_TYPE__BUILD_ID_CACHE,
+		DSO_BINARY_TYPE__SYSTEM_PATH_DSO,
+		DSO_BINARY_TYPE__NOT_FOUND,
+	};
+	int i = 0;
+
+	if (dso->data.fd >= 0)
+		return;
+
+	if (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND) {
+		dso->data.fd = open_dso(dso, machine);
+		goto out;
+	}
+
+	do {
+		dso->binary_type = binary_type_data[i++];
+
+		dso->data.fd = open_dso(dso, machine);
+		if (dso->data.fd >= 0)
+			goto out;
+
+	} while (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND);
+out:
+	if (dso->data.fd >= 0)
+		dso->data.status = DSO_DATA_STATUS_OK;
+	else
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+}
+
+/**
+ * dso__data_get_fd - Get dso's data file descriptor
+ * @dso: dso object
+ * @machine: machine object
+ *
+ * External interface to find dso's file, open it and
+ * returns file descriptor.  It should be paired with
+ * dso__data_put_fd() if it returns non-negative value.
+ */
+int dso__data_get_fd(struct dso *dso, struct machine *machine)
+{
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+
+	if (pthread_mutex_lock(&dso__data_open_lock) < 0)
+		return -1;
+
+	try_to_open_dso(dso, machine);
+
+	if (dso->data.fd < 0)
+		pthread_mutex_unlock(&dso__data_open_lock);
+
+	return dso->data.fd;
+}
+
+void dso__data_put_fd(struct dso *dso __maybe_unused)
+{
+	pthread_mutex_unlock(&dso__data_open_lock);
+}
+
+bool dso__data_status_seen(struct dso *dso, enum dso_data_status_seen by)
+{
+	u32 flag = 1 << by;
+
+	if (dso->data.status_seen & flag)
+		return true;
+
+	dso->data.status_seen |= flag;
+
+	return false;
+}
+
+#ifdef HAVE_LIBBPF_SUPPORT
+static ssize_t bpf_read(struct dso *dso, u64 offset, char *data)
+{
+	struct bpf_prog_info_node *node;
+	ssize_t size = DSO__DATA_CACHE_SIZE;
+	u64 len;
+	u8 *buf;
+
+	node = perf_env__find_bpf_prog_info(dso->bpf_prog.env, dso->bpf_prog.id);
+	if (!node || !node->info_linear) {
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		return -1;
+	}
+
+	len = node->info_linear->info.jited_prog_len;
+	buf = (u8 *)(uintptr_t)node->info_linear->info.jited_prog_insns;
+
+	if (offset >= len)
+		return -1;
+
+	size = (ssize_t)min(len - offset, (u64)size);
+	memcpy(data, buf + offset, size);
+	return size;
+}
+
+static int bpf_size(struct dso *dso)
+{
+	struct bpf_prog_info_node *node;
+
+	node = perf_env__find_bpf_prog_info(dso->bpf_prog.env, dso->bpf_prog.id);
+	if (!node || !node->info_linear) {
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		return -1;
+	}
+
+	dso->data.file_size = node->info_linear->info.jited_prog_len;
+	return 0;
+}
+#endif // HAVE_LIBBPF_SUPPORT
+
+static void
+dso_cache__free(struct dso *dso)
+{
+	struct rb_root *root = &dso->data.cache;
+	struct rb_node *next = rb_first(root);
+
+	mutex_lock(&dso->lock);
+	while (next) {
+		struct dso_cache *cache;
+
+		cache = rb_entry(next, struct dso_cache, rb_node);
+		next = rb_next(&cache->rb_node);
+		rb_erase(&cache->rb_node, root);
+		free(cache);
+	}
+	mutex_unlock(&dso->lock);
+}
+
+static struct dso_cache *__dso_cache__find(struct dso *dso, u64 offset)
+{
+	const struct rb_root *root = &dso->data.cache;
+	struct rb_node * const *p = &root->rb_node;
+	const struct rb_node *parent = NULL;
+	struct dso_cache *cache;
+
+	while (*p != NULL) {
+		u64 end;
+
+		parent = *p;
+		cache = rb_entry(parent, struct dso_cache, rb_node);
+		end = cache->offset + DSO__DATA_CACHE_SIZE;
+
+		if (offset < cache->offset)
+			p = &(*p)->rb_left;
+		else if (offset >= end)
+			p = &(*p)->rb_right;
+		else
+			return cache;
+	}
+
+	return NULL;
+}
+
+static struct dso_cache *
+dso_cache__insert(struct dso *dso, struct dso_cache *new)
+{
+	struct rb_root *root = &dso->data.cache;
+	struct rb_node **p = &root->rb_node;
+	struct rb_node *parent = NULL;
+	struct dso_cache *cache;
+	u64 offset = new->offset;
+
+	mutex_lock(&dso->lock);
+	while (*p != NULL) {
+		u64 end;
+
+		parent = *p;
+		cache = rb_entry(parent, struct dso_cache, rb_node);
+		end = cache->offset + DSO__DATA_CACHE_SIZE;
+
+		if (offset < cache->offset)
+			p = &(*p)->rb_left;
+		else if (offset >= end)
+			p = &(*p)->rb_right;
+		else
+			goto out;
+	}
+
+	rb_link_node(&new->rb_node, parent, p);
+	rb_insert_color(&new->rb_node, root);
+
+	cache = NULL;
+out:
+	mutex_unlock(&dso->lock);
+	return cache;
+}
+
+static ssize_t dso_cache__memcpy(struct dso_cache *cache, u64 offset, u8 *data,
+				 u64 size, bool out)
+{
+	u64 cache_offset = offset - cache->offset;
+	u64 cache_size   = min(cache->size - cache_offset, size);
+
+	if (out)
+		memcpy(data, cache->data + cache_offset, cache_size);
+	else
+		memcpy(cache->data + cache_offset, data, cache_size);
+	return cache_size;
+}
+
+static ssize_t file_read(struct dso *dso, struct machine *machine,
+			 u64 offset, char *data)
+{
+	ssize_t ret;
+
+	pthread_mutex_lock(&dso__data_open_lock);
+
+	/*
+	 * dso->data.fd might be closed if other thread opened another
+	 * file (dso) due to open file limit (RLIMIT_NOFILE).
+	 */
+	try_to_open_dso(dso, machine);
+
+	if (dso->data.fd < 0) {
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		ret = -errno;
+		goto out;
+	}
+
+	ret = pread(dso->data.fd, data, DSO__DATA_CACHE_SIZE, offset);
+out:
+	pthread_mutex_unlock(&dso__data_open_lock);
+	return ret;
+}
+
+static struct dso_cache *dso_cache__populate(struct dso *dso,
+					     struct machine *machine,
+					     u64 offset, ssize_t *ret)
+{
+	u64 cache_offset = offset & DSO__DATA_CACHE_MASK;
+	struct dso_cache *cache;
+	struct dso_cache *old;
+
+	cache = zalloc(sizeof(*cache) + DSO__DATA_CACHE_SIZE);
+	if (!cache) {
+		*ret = -ENOMEM;
+		return NULL;
+	}
+#ifdef HAVE_LIBBPF_SUPPORT
+	if (dso->binary_type == DSO_BINARY_TYPE__BPF_PROG_INFO)
+		*ret = bpf_read(dso, cache_offset, cache->data);
+	else
+#endif
+	if (dso->binary_type == DSO_BINARY_TYPE__OOL)
+		*ret = DSO__DATA_CACHE_SIZE;
+	else
+		*ret = file_read(dso, machine, cache_offset, cache->data);
+
+	if (*ret <= 0) {
+		free(cache);
+		return NULL;
+	}
+
+	cache->offset = cache_offset;
+	cache->size   = *ret;
+
+	old = dso_cache__insert(dso, cache);
+	if (old) {
+		/* we lose the race */
+		free(cache);
+		cache = old;
+	}
+
+	return cache;
+}
+
+static struct dso_cache *dso_cache__find(struct dso *dso,
+					 struct machine *machine,
+					 u64 offset,
+					 ssize_t *ret)
+{
+	struct dso_cache *cache = __dso_cache__find(dso, offset);
+
+	return cache ? cache : dso_cache__populate(dso, machine, offset, ret);
+}
+
+static ssize_t dso_cache_io(struct dso *dso, struct machine *machine,
+			    u64 offset, u8 *data, ssize_t size, bool out)
+{
+	struct dso_cache *cache;
+	ssize_t ret = 0;
+
+	cache = dso_cache__find(dso, machine, offset, &ret);
+	if (!cache)
+		return ret;
+
+	return dso_cache__memcpy(cache, offset, data, size, out);
+}
+
+/*
+ * Reads and caches dso data DSO__DATA_CACHE_SIZE size chunks
+ * in the rb_tree. Any read to already cached data is served
+ * by cached data. Writes update the cache only, not the backing file.
+ */
+static ssize_t cached_io(struct dso *dso, struct machine *machine,
+			 u64 offset, u8 *data, ssize_t size, bool out)
+{
+	ssize_t r = 0;
+	u8 *p = data;
+
+	do {
+		ssize_t ret;
+
+		ret = dso_cache_io(dso, machine, offset, p, size, out);
+		if (ret < 0)
+			return ret;
+
+		/* Reached EOF, return what we have. */
+		if (!ret)
+			break;
+
+		BUG_ON(ret > size);
+
+		r      += ret;
+		p      += ret;
+		offset += ret;
+		size   -= ret;
+
+	} while (size);
+
+	return r;
+}
+
+static int file_size(struct dso *dso, struct machine *machine)
+{
+	int ret = 0;
+	struct stat st;
+	char sbuf[STRERR_BUFSIZE];
+
+	pthread_mutex_lock(&dso__data_open_lock);
+
+	/*
+	 * dso->data.fd might be closed if other thread opened another
+	 * file (dso) due to open file limit (RLIMIT_NOFILE).
+	 */
+	try_to_open_dso(dso, machine);
+
+	if (dso->data.fd < 0) {
+		ret = -errno;
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		goto out;
+	}
+
+	if (fstat(dso->data.fd, &st) < 0) {
+		ret = -errno;
+		pr_err("dso cache fstat failed: %s\n",
+		       str_error_r(errno, sbuf, sizeof(sbuf)));
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		goto out;
+	}
+	dso->data.file_size = st.st_size;
+
+out:
+	pthread_mutex_unlock(&dso__data_open_lock);
+	return ret;
+}
+
+int dso__data_file_size(struct dso *dso, struct machine *machine)
+{
+	if (dso->data.file_size)
+		return 0;
+
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+#ifdef HAVE_LIBBPF_SUPPORT
+	if (dso->binary_type == DSO_BINARY_TYPE__BPF_PROG_INFO)
+		return bpf_size(dso);
+#endif
+	return file_size(dso, machine);
+}
+
+/**
+ * dso__data_size - Return dso data size
+ * @dso: dso object
+ * @machine: machine object
+ *
+ * Return: dso data size
+ */
+off_t dso__data_size(struct dso *dso, struct machine *machine)
+{
+	if (dso__data_file_size(dso, machine))
+		return -1;
+
+	/* For now just estimate dso data size is close to file size */
+	return dso->data.file_size;
+}
+
+static ssize_t data_read_write_offset(struct dso *dso, struct machine *machine,
+				      u64 offset, u8 *data, ssize_t size,
+				      bool out)
+{
+	if (dso__data_file_size(dso, machine))
+		return -1;
+
+	/* Check the offset sanity. */
+	if (offset > dso->data.file_size)
+		return -1;
+
+	if (offset + size < offset)
+		return -1;
+
+	return cached_io(dso, machine, offset, data, size, out);
+}
+
+/**
+ * dso__data_read_offset - Read data from dso file offset
+ * @dso: dso object
+ * @machine: machine object
+ * @offset: file offset
+ * @data: buffer to store data
+ * @size: size of the @data buffer
+ *
+ * External interface to read data from dso file offset. Open
+ * dso data file and use cached_read to get the data.
+ */
+ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine,
+			      u64 offset, u8 *data, ssize_t size)
+{
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+
+	return data_read_write_offset(dso, machine, offset, data, size, true);
+}
+
+/**
+ * dso__data_read_addr - Read data from dso address
+ * @dso: dso object
+ * @machine: machine object
+ * @add: virtual memory address
+ * @data: buffer to store data
+ * @size: size of the @data buffer
+ *
+ * External interface to read data from dso address.
+ */
+ssize_t dso__data_read_addr(struct dso *dso, struct map *map,
+			    struct machine *machine, u64 addr,
+			    u8 *data, ssize_t size)
+{
+	u64 offset = map__map_ip(map, addr);
+
+	return dso__data_read_offset(dso, machine, offset, data, size);
+}
+
+/**
+ * dso__data_write_cache_offs - Write data to dso data cache at file offset
+ * @dso: dso object
+ * @machine: machine object
+ * @offset: file offset
+ * @data: buffer to write
+ * @size: size of the @data buffer
+ *
+ * Write into the dso file data cache, but do not change the file itself.
+ */
+ssize_t dso__data_write_cache_offs(struct dso *dso, struct machine *machine,
+				   u64 offset, const u8 *data_in, ssize_t size)
+{
+	u8 *data = (u8 *)data_in; /* cast away const to use same fns for r/w */
+
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+
+	return data_read_write_offset(dso, machine, offset, data, size, false);
+}
+
+/**
+ * dso__data_write_cache_addr - Write data to dso data cache at dso address
+ * @dso: dso object
+ * @machine: machine object
+ * @add: virtual memory address
+ * @data: buffer to write
+ * @size: size of the @data buffer
+ *
+ * External interface to write into the dso file data cache, but do not change
+ * the file itself.
+ */
+ssize_t dso__data_write_cache_addr(struct dso *dso, struct map *map,
+				   struct machine *machine, u64 addr,
+				   const u8 *data, ssize_t size)
+{
+	u64 offset = map__map_ip(map, addr);
+
+	return dso__data_write_cache_offs(dso, machine, offset, data, size);
+}
+
+struct map *dso__new_map(const char *name)
+{
+	struct map *map = NULL;
+	struct dso *dso = dso__new(name);
+
+	if (dso) {
+		map = map__new2(0, dso);
+		dso__put(dso);
+	}
+
+	return map;
+}
+
+struct dso *machine__findnew_kernel(struct machine *machine, const char *name,
+				    const char *short_name, int dso_type)
+{
+	/*
+	 * The kernel dso could be created by build_id processing.
+	 */
+	struct dso *dso = machine__findnew_dso(machine, name);
+
+	/*
+	 * We need to run this in all cases, since during the build_id
+	 * processing we had no idea this was the kernel dso.
+	 */
+	if (dso != NULL) {
+		dso__set_short_name(dso, short_name, false);
+		dso->kernel = dso_type;
+	}
+
+	return dso;
+}
+
+static void dso__set_long_name_id(struct dso *dso, const char *name, struct dso_id *id, bool name_allocated)
+{
+	struct rb_root *root = dso->root;
+
+	if (name == NULL)
+		return;
+
+	if (dso->long_name_allocated)
+		free((char *)dso->long_name);
+
+	if (root) {
+		rb_erase(&dso->rb_node, root);
+		/*
+		 * __dsos__findnew_link_by_longname_id() isn't guaranteed to
+		 * add it back, so a clean removal is required here.
+		 */
+		RB_CLEAR_NODE(&dso->rb_node);
+		dso->root = NULL;
+	}
+
+	dso->long_name		 = name;
+	dso->long_name_len	 = strlen(name);
+	dso->long_name_allocated = name_allocated;
+
+	if (root)
+		__dsos__findnew_link_by_longname_id(root, dso, NULL, id);
+}
+
+void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated)
+{
+	dso__set_long_name_id(dso, name, NULL, name_allocated);
+}
+
+void dso__set_short_name(struct dso *dso, const char *name, bool name_allocated)
+{
+	if (name == NULL)
+		return;
+
+	if (dso->short_name_allocated)
+		free((char *)dso->short_name);
+
+	dso->short_name		  = name;
+	dso->short_name_len	  = strlen(name);
+	dso->short_name_allocated = name_allocated;
+}
+
+int dso__name_len(const struct dso *dso)
+{
+	if (!dso)
+		return strlen("[unknown]");
+	if (verbose > 0)
+		return dso->long_name_len;
+
+	return dso->short_name_len;
+}
+
+bool dso__loaded(const struct dso *dso)
+{
+	return dso->loaded;
+}
+
+bool dso__sorted_by_name(const struct dso *dso)
+{
+	return dso->sorted_by_name;
+}
+
+void dso__set_sorted_by_name(struct dso *dso)
+{
+	dso->sorted_by_name = true;
+}
+
+struct dso *dso__new_id(const char *name, struct dso_id *id)
+{
+	struct dso *dso = calloc(1, sizeof(*dso) + strlen(name) + 1);
+
+	if (dso != NULL) {
+		strcpy(dso->name, name);
+		if (id)
+			dso->id = *id;
+		dso__set_long_name_id(dso, dso->name, id, false);
+		dso__set_short_name(dso, dso->name, false);
+		dso->symbols = RB_ROOT_CACHED;
+		dso->symbol_names = NULL;
+		dso->symbol_names_len = 0;
+		dso->data.cache = RB_ROOT;
+		dso->inlined_nodes = RB_ROOT_CACHED;
+		dso->srclines = RB_ROOT_CACHED;
+		dso->data.fd = -1;
+		dso->data.status = DSO_DATA_STATUS_UNKNOWN;
+		dso->symtab_type = DSO_BINARY_TYPE__NOT_FOUND;
+		dso->binary_type = DSO_BINARY_TYPE__NOT_FOUND;
+		dso->is_64_bit = (sizeof(void *) == 8);
+		dso->loaded = 0;
+		dso->rel = 0;
+		dso->sorted_by_name = 0;
+		dso->has_build_id = 0;
+		dso->has_srcline = 1;
+		dso->a2l_fails = 1;
+		dso->kernel = DSO_SPACE__USER;
+		dso->needs_swap = DSO_SWAP__UNSET;
+		dso->comp = COMP_ID__NONE;
+		RB_CLEAR_NODE(&dso->rb_node);
+		dso->root = NULL;
+		INIT_LIST_HEAD(&dso->node);
+		INIT_LIST_HEAD(&dso->data.open_entry);
+		mutex_init(&dso->lock);
+		refcount_set(&dso->refcnt, 1);
+	}
+
+	return dso;
+}
+
+struct dso *dso__new(const char *name)
+{
+	return dso__new_id(name, NULL);
+}
+
+void dso__delete(struct dso *dso)
+{
+	if (!RB_EMPTY_NODE(&dso->rb_node))
+		pr_err("DSO %s is still in rbtree when being deleted!\n",
+		       dso->long_name);
+
+	/* free inlines first, as they reference symbols */
+	inlines__tree_delete(&dso->inlined_nodes);
+	srcline__tree_delete(&dso->srclines);
+	symbols__delete(&dso->symbols);
+	dso->symbol_names_len = 0;
+	zfree(&dso->symbol_names);
+	if (dso->short_name_allocated) {
+		zfree((char **)&dso->short_name);
+		dso->short_name_allocated = false;
+	}
+
+	if (dso->long_name_allocated) {
+		zfree((char **)&dso->long_name);
+		dso->long_name_allocated = false;
+	}
+
+	dso__data_close(dso);
+	auxtrace_cache__free(dso->auxtrace_cache);
+	dso_cache__free(dso);
+	dso__free_a2l(dso);
+	zfree(&dso->symsrc_filename);
+	nsinfo__zput(dso->nsinfo);
+	mutex_destroy(&dso->lock);
+	free(dso);
+}
+
+struct dso *dso__get(struct dso *dso)
+{
+	if (dso)
+		refcount_inc(&dso->refcnt);
+	return dso;
+}
+
+void dso__put(struct dso *dso)
+{
+	if (dso && refcount_dec_and_test(&dso->refcnt))
+		dso__delete(dso);
+}
+
+void dso__set_build_id(struct dso *dso, struct build_id *bid)
+{
+	dso->bid = *bid;
+	dso->has_build_id = 1;
+}
+
+bool dso__build_id_equal(const struct dso *dso, struct build_id *bid)
+{
+	if (dso->bid.size > bid->size && dso->bid.size == BUILD_ID_SIZE) {
+		/*
+		 * For the backward compatibility, it allows a build-id has
+		 * trailing zeros.
+		 */
+		return !memcmp(dso->bid.data, bid->data, bid->size) &&
+			!memchr_inv(&dso->bid.data[bid->size], 0,
+				    dso->bid.size - bid->size);
+	}
+
+	return dso->bid.size == bid->size &&
+	       memcmp(dso->bid.data, bid->data, dso->bid.size) == 0;
+}
+
+void dso__read_running_kernel_build_id(struct dso *dso, struct machine *machine)
+{
+	char path[PATH_MAX];
+
+	if (machine__is_default_guest(machine))
+		return;
+	sprintf(path, "%s/sys/kernel/notes", machine->root_dir);
+	if (sysfs__read_build_id(path, &dso->bid) == 0)
+		dso->has_build_id = true;
+}
+
+int dso__kernel_module_get_build_id(struct dso *dso,
+				    const char *root_dir)
+{
+	char filename[PATH_MAX];
+	/*
+	 * kernel module short names are of the form "[module]" and
+	 * we need just "module" here.
+	 */
+	const char *name = dso->short_name + 1;
+
+	snprintf(filename, sizeof(filename),
+		 "%s/sys/module/%.*s/notes/.note.gnu.build-id",
+		 root_dir, (int)strlen(name) - 1, name);
+
+	if (sysfs__read_build_id(filename, &dso->bid) == 0)
+		dso->has_build_id = true;
+
+	return 0;
+}
+
+static size_t dso__fprintf_buildid(struct dso *dso, FILE *fp)
+{
+	char sbuild_id[SBUILD_ID_SIZE];
+
+	build_id__sprintf(&dso->bid, sbuild_id);
+	return fprintf(fp, "%s", sbuild_id);
+}
+
+size_t dso__fprintf(struct dso *dso, FILE *fp)
+{
+	struct rb_node *nd;
+	size_t ret = fprintf(fp, "dso: %s (", dso->short_name);
+
+	if (dso->short_name != dso->long_name)
+		ret += fprintf(fp, "%s, ", dso->long_name);
+	ret += fprintf(fp, "%sloaded, ", dso__loaded(dso) ? "" : "NOT ");
+	ret += dso__fprintf_buildid(dso, fp);
+	ret += fprintf(fp, ")\n");
+	for (nd = rb_first_cached(&dso->symbols); nd; nd = rb_next(nd)) {
+		struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
+		ret += symbol__fprintf(pos, fp);
+	}
+
+	return ret;
+}
+
+enum dso_type dso__type(struct dso *dso, struct machine *machine)
+{
+	int fd;
+	enum dso_type type = DSO__TYPE_UNKNOWN;
+
+	fd = dso__data_get_fd(dso, machine);
+	if (fd >= 0) {
+		type = dso__type_fd(fd);
+		dso__data_put_fd(dso);
+	}
+
+	return type;
+}
+
+int dso__strerror_load(struct dso *dso, char *buf, size_t buflen)
+{
+	int idx, errnum = dso->load_errno;
+	/*
+	 * This must have a same ordering as the enum dso_load_errno.
+	 */
+	static const char *dso_load__error_str[] = {
+	"Internal tools/perf/ library error",
+	"Invalid ELF file",
+	"Can not read build id",
+	"Mismatching build id",
+	"Decompression failure",
+	};
+
+	BUG_ON(buflen == 0);
+
+	if (errnum >= 0) {
+		const char *err = str_error_r(errnum, buf, buflen);
+
+		if (err != buf)
+			scnprintf(buf, buflen, "%s", err);
+
+		return 0;
+	}
+
+	if (errnum <  __DSO_LOAD_ERRNO__START || errnum >= __DSO_LOAD_ERRNO__END)
+		return -1;
+
+	idx = errnum - __DSO_LOAD_ERRNO__START;
+	scnprintf(buf, buflen, "%s", dso_load__error_str[idx]);
+	return 0;
+}