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/* -*- linux-c -*-
* VMA tracking and lookup functions.
*
* Copyright (C) 2005-2019 Red Hat Inc.
* Copyright (C) 2006 Intel Corporation.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _STP_VMA_C_
#define _STP_VMA_C_
#include "sym.h"
#include "stp_string.c"
#include "task_finder_vma.c"
#include <asm/uaccess.h>
static void _stp_vma_match_vdso(struct task_struct *tsk)
{
/* vdso is arch specific */
#if defined(STAPCONF_MM_CONTEXT_VDSO) || defined(STAPCONF_MM_CONTEXT_VDSO_BASE)
int i, j;
if (tsk->mm)
{
struct _stp_module *found = NULL;
#ifdef STAPCONF_MM_CONTEXT_VDSO
unsigned long vdso_addr = (unsigned long) tsk->mm->context.vdso;
#else
unsigned long vdso_addr = tsk->mm->context.vdso_base;
#endif
dbug_task_vma(1,"tsk: %d vdso: 0x%lx\n", tsk->pid, vdso_addr);
for (i = 0; i < _stp_num_modules && found == NULL; i++) {
struct _stp_module *m = _stp_modules[i];
if (m->path
&& m->path[0] == '/'
&& m->num_sections == 1)
{
unsigned long notes_addr;
int all_ok = 1;
/* Assume that if the path's basename starts with 'vdso'
* and ends with '.so', it is the vdso.
*
* Note that this logic should match up with the logic in
* the find_vdso() function in translate.cxx. */
const char *name = strrchr(m->path, '/');
if (name)
{
const char *ext;
name++;
ext = strrchr(name, '.');
if (!ext
|| strncmp("vdso", name, 4) != 0
|| strcmp(".so", ext) != 0)
continue;
}
notes_addr = vdso_addr + m->build_id_offset;
dbug_task_vma(1,"notes_addr %s: 0x%lx + 0x%lx = 0x%lx (len: %x)\n", m->path,
vdso_addr, m->build_id_offset, notes_addr, m->build_id_len);
for (j = 0; j < m->build_id_len; j++)
{
int rc;
unsigned char b;
/*
* Why check CONFIG_UTRACE here? If we're using real
* in-kernel utrace, we can always just call
* get_user() (since tsk == current).
*
* Since we're only reading here, we can call
* __access_process_vm_noflush(), which only calls
* things that are exported.
*/
#ifdef CONFIG_UTRACE
rc = copy_from_user(&b, (void*)(notes_addr + j), 1);
#else
if (tsk == current)
{
rc = copy_from_user(&b, (void*)(notes_addr + j), 1);
}
else
{
rc = (__access_process_vm_noflush(tsk, (notes_addr + j),
&b, 1, 0) != 1);
}
#endif
if (rc || b != m->build_id_bits[j])
{
dbug_task_vma(1,"darn, not equal (rc=%d) at %d (0x%x != 0x%x)\n",
rc, j, b, m->build_id_bits[j]);
all_ok = 0;
break;
}
}
if (all_ok)
found = m;
}
}
if (found != NULL)
{
stap_add_vma_map_info(tsk, vdso_addr,
vdso_addr + found->sections[0].size, 0,
"vdso", found);
dbug_task_vma(1,"found vdso: %s\n", found->path);
}
}
#endif /* STAPCONF_MM_CONTEXT_VDSO */
}
#ifdef HAVE_TASK_FINDER
/* exec callback, will try to match vdso for new process,
will drop all vma maps for a process that disappears. */
static int _stp_vma_exec_cb(struct stap_task_finder_target *tgt,
struct task_struct *tsk,
int register_p,
int process_p)
{
dbug_task_vma(1,
"tsk %d:%d , register_p: %d, process_p: %d\n",
tsk->pid, tsk->tgid, register_p, process_p);
if (process_p)
{
if (register_p)
_stp_vma_match_vdso(tsk);
else
stap_drop_vma_maps(tsk);
}
return 0;
}
/* mmap callback, will match new vma with _stp_module or register vma name. */
static int _stp_vma_mmap_cb(struct stap_task_finder_target *tgt,
struct task_struct *tsk,
char *path, struct dentry *dentry,
unsigned long addr,
unsigned long length,
unsigned long offset,
unsigned long vm_flags)
{
int i, res;
struct _stp_module *module = NULL;
const char *name = ((dentry != NULL) ? (char *)dentry->d_name.name
: NULL);
if (path == NULL || *path == '\0') /* unknown? */
path = (char *)name; /* we'll copy this soon, in ..._add_vma_... */
dbug_task_vma(1,
"mmap_cb: tsk %d:%d path %s, addr 0x%08lx, length 0x%08lx, offset 0x%lx, flags 0x%lx\n",
tsk->pid, tsk->tgid, path, addr, length, offset, vm_flags);
// We used to be only interested in the first load of the whole module that
// is executable. But with modern enough gcc/ld.so, executables are mapped
// in more small pieces (r--p,r-xp,rw-p, instead of r-xp, rw-p). NB:
// the first section might not be executable, so there can be an offset.
//
// We register whether or not we know the module,
// so we can later lookup the name given an address for this task.
if (path != NULL &&
stap_find_vma_map_info(tsk, addr, NULL, NULL, NULL, NULL, NULL) != 0) {
for (i = 0; i < _stp_num_modules; i++) {
// PR20433: papering over possibility of NULL pointers
if (strcmp(path ?: "", _stp_modules[i]->path ?: "") == 0)
{
unsigned long vm_start = 0;
unsigned long vm_end = 0;
dbug_task_vma(1,
"vm_cb: matched path %s to module (sec: %s)\n",
path, _stp_modules[i]->sections[0].name);
module = _stp_modules[i];
/* Make sure we really don't know about this module
yet. If we do know, we might want to extend
the coverage. */
res = stap_find_vma_map_info_user(tsk->group_leader,
module,
&vm_start, &vm_end,
NULL);
if (res == -ESRCH || vm_start + offset == addr)
res = stap_add_vma_map_info(tsk->group_leader,
addr, addr + length,
offset, path, module);
else if (res == 0 && vm_end + 1 == addr)
res = stap_extend_vma_map_info(tsk->group_leader,
vm_start,
addr + length);
/* VMA entries are allocated dynamically, this is fine,
* since we are in a task_finder callback, which is in
* user context. */
if (res != 0) {
_stp_error ("Couldn't register module '%s' for pid %d (%d)\n", _stp_modules[i]->path, tsk->group_leader->pid, res);
}
return 0;
}
}
/* None of the tracked modules matched, register without,
* to make sure we can lookup the name later. Ignore errors,
* we will just report unknown when asked and tables were
* full. Restrict to target process when given to preserve
* vma_map entry slots. */
if (_stp_target == 0
|| _stp_target == tsk->group_leader->pid)
{
res = stap_add_vma_map_info(tsk->group_leader, addr,
addr + length, offset, path,
NULL);
dbug_task_vma(1,
"registered '%s' for %d (res:%d) [%lx-%lx]\n",
path, tsk->group_leader->pid,
res, addr, addr + length);
}
} else if (path != NULL) {
// Once registered, we may want to extend an earlier
// registered region. A segment might be mapped with
// different flags for different offsets. If so we want
// to record the extended range so we can address more
// precisely to module names and symbols.
res = stap_extend_vma_map_info(tsk->group_leader,
addr, addr + length);
dbug_task_vma(1,
"extended '%s' for %d (res:%d) [%lx-%lx]\n",
path, tsk->group_leader->pid,
res, addr, addr + length);
}
return 0;
}
/* munmap callback, removes vma map info. */
static int _stp_vma_munmap_cb(struct stap_task_finder_target *tgt,
struct task_struct *tsk,
unsigned long addr,
unsigned long length)
{
/* Unconditionally remove vm map info, ignore if not present. */
stap_remove_vma_map_info(tsk->group_leader, addr);
return 0;
}
#endif
/* Initializes the vma tracker. */
static int _stp_vma_init(void)
{
int rc = 0;
#ifdef HAVE_TASK_FINDER
static struct stap_task_finder_target vmcb = {
// NB: no .pid, no .procname filters here.
// This means that we get a system-wide mmap monitoring
// widget while the script is running. (The
// system-wideness may be restricted by stap -c or
// -x.) But this seems to be necessary if we want to
// to stack tracebacks through arbitrary shared libraries.
//
// XXX: There may be an optimization opportunity
// for executables (for which the main task-finder
// callback should be sufficient).
.pid = 0,
.procname = NULL,
.build_id_len = 0,
.purpose = "vma tracking",
.callback = &_stp_vma_exec_cb,
.mmap_callback = &_stp_vma_mmap_cb,
.munmap_callback = &_stp_vma_munmap_cb,
.mprotect_callback = NULL
};
rc = stap_initialize_vma_map ();
if (rc != 0) {
_stp_error("Couldn't initialize vma map: %d\n", rc);
return rc;
}
dbug_task_vma(1,
"registering vmcb (_stap_target: %d)\n", _stp_target);
rc = stap_register_task_finder_target (& vmcb);
if (rc != 0)
_stp_error("Couldn't register task finder target: %d\n", rc);
#endif
return rc;
}
/* Get rid of the vma tracker (memory). */
static void _stp_vma_done(void)
{
/* NB HAVE_TASK_FINDER already includes the case of CONFIG_UTRACE.
* See runtime/linux/runtime.h for more details. See also PR26123 */
#ifdef HAVE_TASK_FINDER
stap_destroy_vma_map();
#endif
}
#endif /* _STP_VMA_C_ */