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/*
* This file is based on a patch submitted by Mark Wielaard <mjw@redhat.com>
* to ltrace project:
* https://anonscm.debian.org/cgit/collab-maint/ltrace.git/commit/?id=dfefa9f057857735a073ea655f5cb34351032c8e
*
* It was re-licensed for strace by the original author:
* https://lists.strace.io/pipermail/strace-devel/2018-March/008063.html
*
* Copyright (c) 2014-2018 Mark Wielaard <mjw@redhat.com>
* Copyright (c) 2018 Masatake YAMATO <yamato@redhat.com>
* Copyright (c) 2018 The strace developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#include "unwind.h"
#include "mmap_notify.h"
#include <elfutils/libdwfl.h>
struct ctx {
Dwfl *dwfl;
unsigned int last_proc_updating;
};
static unsigned int mapping_generation;
static void
update_mapping_generation(struct tcb *tcp, void *unused)
{
mapping_generation++;
}
static void
init(void)
{
mmap_notify_register_client(update_mapping_generation, NULL);
}
static void *
tcb_init(struct tcb *tcp)
{
static const Dwfl_Callbacks proc_callbacks = {
.find_elf = dwfl_linux_proc_find_elf,
.find_debuginfo = dwfl_standard_find_debuginfo
};
Dwfl *dwfl = dwfl_begin(&proc_callbacks);
if (dwfl == NULL) {
error_msg("dwfl_begin: %s", dwfl_errmsg(-1));
return NULL;
}
int r = dwfl_linux_proc_attach(dwfl, tcp->pid, true);
if (r) {
const char *msg = NULL;
if (r < 0)
msg = dwfl_errmsg(-1);
else if (r > 0)
msg = strerror(r);
error_msg("dwfl_linux_proc_attach returned an error"
" for process %d: %s", tcp->pid, msg);
dwfl_end(dwfl);
return NULL;
}
struct ctx *ctx = xmalloc(sizeof(*ctx));
ctx->dwfl = dwfl;
ctx->last_proc_updating = 0;
return ctx;
}
static void
tcb_fin(struct tcb *tcp)
{
struct ctx *ctx = tcp->unwind_ctx;
if (ctx) {
dwfl_end(ctx->dwfl);
free(ctx);
}
}
static void
flush_cache_maybe(struct tcb *tcp)
{
struct ctx *ctx = tcp->unwind_ctx;
if (!ctx)
return;
if (ctx->last_proc_updating == mapping_generation)
return;
int r = dwfl_linux_proc_report(ctx->dwfl, tcp->pid);
if (r < 0)
error_msg("dwfl_linux_proc_report returned an error"
" for pid %d: %s", tcp->pid, dwfl_errmsg(-1));
else if (r > 0)
error_msg("dwfl_linux_proc_report returned an error"
" for pid %d", tcp->pid);
else if (dwfl_report_end(ctx->dwfl, NULL, NULL) != 0)
error_msg("dwfl_report_end returned an error"
" for pid %d: %s", tcp->pid, dwfl_errmsg(-1));
ctx->last_proc_updating = mapping_generation;
}
struct frame_user_data {
unwind_call_action_fn call_action;
unwind_error_action_fn error_action;
void *data;
int stack_depth;
};
static int
frame_callback(Dwfl_Frame *state, void *arg)
{
struct frame_user_data *user_data = arg;
Dwarf_Addr pc;
bool isactivation;
if (!dwfl_frame_pc(state, &pc, &isactivation)) {
/* Propagate the error to the caller. */
return -1;
}
if (!isactivation)
pc--;
Dwfl *dwfl = dwfl_thread_dwfl(dwfl_frame_thread(state));
Dwfl_Module *mod = dwfl_addrmodule(dwfl, pc);
GElf_Off off = 0;
if (mod != NULL) {
const char *modname = NULL;
const char *symname = NULL;
GElf_Sym sym;
Dwarf_Addr true_offset = pc;
modname = dwfl_module_info(mod, NULL, NULL, NULL, NULL,
NULL, NULL, NULL);
symname = dwfl_module_addrinfo(mod, pc, &off, &sym,
NULL, NULL, NULL);
dwfl_module_relocate_address(mod, &true_offset);
user_data->call_action(user_data->data, modname, symname,
off, true_offset);
}
/* Max number of frames to print reached? */
if (user_data->stack_depth-- == 0)
return DWARF_CB_ABORT;
return DWARF_CB_OK;
}
static void
tcb_walk(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data)
{
struct ctx *ctx = tcp->unwind_ctx;
if (!ctx)
return;
struct frame_user_data user_data = {
.call_action = call_action,
.error_action = error_action,
.data = data,
.stack_depth = 256,
};
flush_cache_maybe(tcp);
int r = dwfl_getthread_frames(ctx->dwfl, tcp->pid, frame_callback,
&user_data);
if (r)
error_action(data,
r < 0 ? dwfl_errmsg(-1) : "too many stack frames",
0);
}
const struct unwind_unwinder_t unwinder = {
.name = "libdw",
.init = init,
.tcb_init = tcb_init,
.tcb_fin = tcb_fin,
.tcb_walk = tcb_walk,
};
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