#include <dwarf.h>
#include <elfutils/libdwelf.h>
#include <elfutils/libdwfl.h>
+#include <libelf.h>
#include <sys/types.h>
#include <unistd.h>
#define FRAMES_MAX 64
#define THREADS_MAX 64
+#define ELF_PACKAGE_METADATA_ID 0xcafe1a7e
struct stack_context {
FILE *f;
Elf *elf;
unsigned n_thread;
unsigned n_frame;
+ JsonVariant **package_metadata;
+ Set **modules;
};
static int frame_callback(Dwfl_Frame *frame, void *userdata) {
return DWARF_CB_OK;
}
-static int module_callback (Dwfl_Module *mod, void **userdata, const char *name, Dwarf_Addr start, void *arg)
-{
- _cleanup_free_ char *id_hex = NULL;
+static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *elf, struct stack_context *c) {
+ size_t n_program_headers;
+ int r;
+
+ assert(name);
+ assert(elf);
+ assert(c);
+
+ /* When iterating over PT_LOAD we will visit modules more than once */
+ if (set_contains(*c->modules, name))
+ return DWARF_CB_OK;
+
+ r = elf_getphdrnum(elf, &n_program_headers);
+ if (r < 0) /* Not the handle we are looking for - that's ok, skip it */
+ return DWARF_CB_OK;
+
+ /* Iterate over all program headers in that ELF object. These will have been copied by
+ * the kernel verbatim when the core file is generated. */
+ for (size_t i = 0; i < n_program_headers; ++i) {
+ size_t note_offset = 0, name_offset, desc_offset;
+ GElf_Phdr mem, *program_header;
+ GElf_Nhdr note_header;
+ Elf_Data *data;
+
+ /* Package metadata is in PT_NOTE headers. */
+ program_header = gelf_getphdr(elf, i, &mem);
+ if (!program_header || program_header->p_type != PT_NOTE)
+ continue;
+
+ /* Fortunately there is an iterator we can use to walk over the
+ * elements of a PT_NOTE program header. We are interested in the
+ * note with type. */
+ data = elf_getdata_rawchunk(elf,
+ program_header->p_offset,
+ program_header->p_filesz,
+ ELF_T_NHDR);
+
+ while (note_offset < data->d_size &&
+ (note_offset = gelf_getnote(data, note_offset, ¬e_header, &name_offset, &desc_offset)) > 0) {
+ const char *note_name = (const char *)data->d_buf + name_offset;
+ const char *payload = (const char *)data->d_buf + desc_offset;
+
+ if (note_header.n_namesz == 0 || note_header.n_descsz == 0)
+ continue;
+
+ /* Package metadata might have different owners, but the
+ * magic ID is always the same. */
+ if (note_header.n_type == ELF_PACKAGE_METADATA_ID) {
+ _cleanup_(json_variant_unrefp) JsonVariant *v = NULL, *w = NULL;
+ char *name_key = NULL;
+
+ r = json_parse(payload, 0, &v, NULL, NULL);
+ if (r < 0) {
+ log_error_errno(r, "json_parse on %s failed: %m", payload);
+ return DWARF_CB_ABORT;
+ }
+
+ /* First pretty-print to the buffer, so that the metadata goes as
+ * plaintext in the journal. */
+ fprintf(c->f, "Metadata for module %s owned by %s found: ",
+ name, note_name);
+ json_variant_dump(v, JSON_FORMAT_NEWLINE|JSON_FORMAT_PRETTY, c->f, NULL);
+ fputc('\n', c->f);
+
+ /* Secondly, if we have a build-id, merge it in the same JSON object
+ * so that it apperas all nicely together in the logs/metadata. */
+ if (id_json) {
+ r = json_variant_merge(&v, id_json);
+ if (r < 0) {
+ log_error_errno(r, "json_variant_merge of package meta with buildid failed: %m");
+ return DWARF_CB_ABORT;
+ }
+ }
+
+ /* Then we build a new object using the module name as the key, and merge it
+ * with the previous parses, so that in the end it all fits together in a single
+ * JSON blob. */
+ r = json_build(&w, JSON_BUILD_OBJECT(JSON_BUILD_PAIR(name, JSON_BUILD_VARIANT(v))));
+ if (r < 0) {
+ log_error_errno(r, "Failed to build JSON object: %m");
+ return DWARF_CB_ABORT;
+ }
+ r = json_variant_merge(c->package_metadata, w);
+ if (r < 0) {
+ log_error_errno(r, "json_variant_merge of package meta with buildid failed: %m");
+ return DWARF_CB_ABORT;
+ }
+
+ /* Finally stash the name, so we avoid double visits. */
+ name_key = strdup(name);
+ if (!name_key) {
+ log_oom();
+ return DWARF_CB_ABORT;
+ }
+ r = set_ensure_consume(c->modules, &string_hash_ops, name_key);
+ if (r < 0) {
+ log_error_errno(r, "set_ensure_consume failed: %m");
+ return DWARF_CB_ABORT;
+ }
+
+ return DWARF_CB_OK;
+ }
+ }
+ }
+
+ /* Didn't find package metadata for this module - that's ok, just go to the next. */
+ return DWARF_CB_OK;
+}
+
+static int module_callback(Dwfl_Module *mod, void **userdata, const char *name, Dwarf_Addr start, void *arg) {
+ _cleanup_(json_variant_unrefp) JsonVariant *id_json = NULL;
struct stack_context *c = arg;
- GElf_Addr id_vaddr;
+ size_t n_program_headers;
+ GElf_Addr id_vaddr, bias;
const unsigned char *id;
- int id_len;
+ int id_len, r;
+ Elf *elf;
assert(mod);
assert(c);
if (!name)
name = "(unnamed)"; /* For logging purposes */
- fprintf(c->f, "Found module %s", name);
-
/* We are iterating on each "module", which is what dwfl calls ELF objects contained in the
* core file, and extracting the build-id first and then the package metadata.
* We proceed in a best-effort fashion - not all ELF objects might contain both or either.
* The build-id is easy, as libdwfl parses it during the dwfl_core_file_report() call and
* stores it separately in an internal library struct. */
id_len = dwfl_module_build_id(mod, &id, &id_vaddr);
- if (id_len == 0) {
- fprintf(c->f, " without build-id\n");
- return DWARF_CB_OK;
+ if (id_len <= 0) {
+ /* If we don't find a build-id, note it in the journal message, and try
+ * anyway to find the package metadata. It's unlikely to have the latter
+ * without the former, but there's no hard rule. */
+ fprintf(c->f, "Found module %s without build-id\n", name);
+ } else {
+ _cleanup_free_ char *id_hex = NULL, *id_hex_prefixed = NULL;
+
+ id_hex = hexmem(id, id_len);
+ if (!id_hex) {
+ log_oom();
+ return DWARF_CB_ABORT;
+ }
+
+ fprintf(c->f, "Found module %s with build-id: %s\n", name, id_hex);
+
+ /* We will later parse package metadata json and pass it to our caller. Prepare the
+ * build-id in json format too, so that it can be appended and parsed cleanly. It
+ * will then be added as metadata to the journal message with the stack trace. */
+ id_hex_prefixed = strjoin("{\"buildid\":\"", id_hex, "\"}");
+ if (!id_hex_prefixed) {
+ log_oom();
+ return DWARF_CB_ABORT;
+ }
+ r = json_parse(id_hex_prefixed, 0, &id_json, NULL, NULL);
+ if (r < 0) {
+ log_error_errno(r, "json_parse on %s failed: %m", id_hex_prefixed);
+ return DWARF_CB_ABORT;
+ }
}
- id_hex = hexmem(id, id_len);
- if (!id_hex) {
- fprintf(c->f, "\n");
- return DWARF_CB_ABORT;
+ /* The .note.package metadata is more difficult. From the module, we need to get a reference
+ * to the ELF object first. We might be lucky and just get it from elfutils. */
+ elf = dwfl_module_getelf(mod, &bias);
+ if (elf)
+ return parse_package_metadata(name, id_json, elf, c);
+
+ /* We did not get the ELF object. That is likely because we didn't get direct
+ * access to the executable, and the version of elfutils does not yet support
+ * parsing it out of the core file directly.
+ * So fallback to manual extraction - get the PT_LOAD section from the core,
+ * and if it's the right one we can interpret it as an Elf object, and parse
+ * its notes manually. */
+
+ r = elf_getphdrnum(c->elf, &n_program_headers);
+ if (r < 0) {
+ log_warning("Could not parse number of program headers from core file: %s",
+ elf_errmsg(-1)); /* -1 retrieves the most recent error */
+ return DWARF_CB_OK;
}
- fprintf(c->f, " with build-id: %s\n", id_hex);
+ for (size_t i = 0; i < n_program_headers; ++i) {
+ GElf_Phdr mem, *program_header;
+ Elf_Data *data;
+
+ /* The core file stores the ELF files in the PT_LOAD segment .*/
+ program_header = gelf_getphdr(c->elf, i, &mem);
+ if (!program_header || program_header->p_type != PT_LOAD)
+ continue;
+
+ /* Now get a usable Elf reference, and parse the notes from it. */
+ data = elf_getdata_rawchunk(c->elf,
+ program_header->p_offset,
+ program_header->p_filesz,
+ ELF_T_NHDR);
+
+ Elf *memelf = elf_memory(data->d_buf, data->d_size);
+ if (!memelf)
+ continue;
+ r = parse_package_metadata(name, id_json, memelf, c);
+ if (r != DWARF_CB_OK)
+ return r;
+ }
return DWARF_CB_OK;
}
.find_debuginfo = dwfl_standard_find_debuginfo,
};
- struct stack_context c = {};
+ _cleanup_(json_variant_unrefp) JsonVariant *package_metadata = NULL;
+ _cleanup_(set_freep) Set *modules = NULL;
+ struct stack_context c = {
+ .package_metadata = &package_metadata,
+ .modules = &modules,
+ };
char *buf = NULL;
size_t sz = 0;
int r;
projects / thirdparty / systemd.git / commitdiff
