coredump: include stacktrace of coredumps in the log message

elfutils' libdw is maintained, can read DWARF debug data and appears to
be the library of choice for generating backtraces today.

1 files changed, 200 insertions, 0 deletions

diff --git a/src/journal/stacktrace.c b/src/journal/stacktrace.c
new file mode 100644
index 0000000000..6b9d2729f5
--- /dev/null
+++ b/src/journal/stacktrace.c
@@ -0,0 +1,200 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <dwarf.h>
+#include <elfutils/libdwfl.h>
+
+#include "util.h"
+#include "macro.h"
+#include "stacktrace.h"
+
+#define FRAMES_MAX 64
+#define THREADS_MAX 64
+
+struct stack_context {
+        FILE *f;
+        Dwfl *dwfl;
+        Elf *elf;
+        unsigned n_thread;
+        unsigned n_frame;
+};
+
+static int frame_callback(Dwfl_Frame *frame, void *userdata) {
+        struct stack_context *c = userdata;
+        Dwarf_Addr pc, pc_adjusted, bias = 0;
+        _cleanup_free_ Dwarf_Die *scopes = NULL;
+        const char *fname = NULL, *symbol = NULL;
+        Dwfl_Module *module;
+        bool is_activation;
+
+        assert(frame);
+        assert(c);
+
+        if (c->n_frame >= FRAMES_MAX)
+                return DWARF_CB_ABORT;
+
+        if (!dwfl_frame_pc(frame, &pc, &is_activation))
+                return DWARF_CB_ABORT;
+
+        pc_adjusted = pc - (is_activation ? 0 : 1);
+
+        module = dwfl_addrmodule(c->dwfl, pc_adjusted);
+        if (module) {
+                Dwarf_Die *s, *cudie;
+                int n;
+
+                cudie = dwfl_module_addrdie(module, pc_adjusted, &bias);
+                if (cudie) {
+                        n = dwarf_getscopes(cudie, pc_adjusted - bias, &scopes);
+                        for (s = scopes; s < scopes + n; s++) {
+                                if (IN_SET(dwarf_tag(s), DW_TAG_subprogram, DW_TAG_inlined_subroutine, DW_TAG_entry_point)) {
+                                        Dwarf_Attribute *a, space;
+
+                                        a = dwarf_attr_integrate(s, DW_AT_MIPS_linkage_name, &space);
+                                        if (!a)
+                                                a = dwarf_attr_integrate(s, DW_AT_linkage_name, &space);
+                                        if (a)
+                                                symbol = dwarf_formstring(a);
+                                        if (!symbol)
+                                                symbol = dwarf_diename(s);
+
+                                        if (symbol)
+                                                break;
+                                }
+                        }
+                }
+
+                if (!symbol)
+                        symbol = dwfl_module_addrname(module, pc_adjusted);
+
+                fname = dwfl_module_info(module, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+        }
+
+        fprintf(c->f, "#%-2u 0x%016" PRIx64 " %s (%s)\n", c->n_frame, (uint64_t) pc, strna(symbol), strna(fname));
+        c->n_frame ++;
+
+        return DWARF_CB_OK;
+}
+
+static int thread_callback(Dwfl_Thread *thread, void *userdata) {
+        struct stack_context *c = userdata;
+        pid_t tid;
+
+        assert(thread);
+        assert(c);
+
+        if (c->n_thread >= THREADS_MAX)
+                return DWARF_CB_ABORT;
+
+        if (c->n_thread != 0)
+                fputc('\n', c->f);
+
+        c->n_frame = 0;
+
+        tid = dwfl_thread_tid(thread);
+        fprintf(c->f, "Stack trace of thread " PID_FMT ":\n", tid);
+
+        if (dwfl_thread_getframes(thread, frame_callback, c) < 0)
+                return DWARF_CB_ABORT;
+
+        c->n_thread ++;
+
+        return DWARF_CB_OK;
+}
+
+int coredump_make_stack_trace(int fd, const char *executable, char **ret) {
+
+        static const Dwfl_Callbacks callbacks = {
+                .find_elf = dwfl_build_id_find_elf,
+                .find_debuginfo = dwfl_standard_find_debuginfo,
+        };
+
+        struct stack_context c = {};
+        char *buf = NULL;
+        size_t sz = 0;
+        int r;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (lseek(fd, 0, SEEK_SET) == (off_t) -1)
+                return -errno;
+
+        c.f = open_memstream(&buf, &sz);
+        if (!c.f)
+                return -ENOMEM;
+
+        elf_version(EV_CURRENT);
+
+        c.elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+        if (!c.elf) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        c.dwfl = dwfl_begin(&callbacks);
+        if (!c.dwfl) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (dwfl_core_file_report(c.dwfl, c.elf, executable) < 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (dwfl_report_end(c.dwfl, NULL, NULL) != 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (dwfl_core_file_attach(c.dwfl, c.elf) < 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (dwfl_getthreads(c.dwfl, thread_callback, &c) < 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        fclose(c.f);
+        c.f = NULL;
+
+        *ret = buf;
+        buf = NULL;
+
+        r = 0;
+
+finish:
+        if (c.dwfl)
+                dwfl_end(c.dwfl);
+
+        if (c.elf)
+                elf_end(c.elf);
+
+        if (c.f)
+                fclose(c.f);
+
+        free(buf);
+
+        return r;
+}