/* Read-modify-write a semaphore in an arbitrary task, usually +/- 1. */
static int
stapiu_write_task_semaphore(struct task_struct* task,
unsigned long addr, unsigned short delta)
{
int count, rc = 0;
unsigned short sdt_semaphore = 0; /* NB: fixed size */
/* XXX: need to analyze possibility of race condition */
count = __access_process_vm_noflush(task, addr,
&sdt_semaphore, sizeof(sdt_semaphore), 0);
if (count != sizeof(sdt_semaphore))
rc = 1;
else {
sdt_semaphore += delta;
count = __access_process_vm_noflush(task, addr,
&sdt_semaphore, sizeof(sdt_semaphore), 1);
rc = (count == sizeof(sdt_semaphore)) ? 0 : 1;
}
return rc;
}
static int _stp_build_id_check (struct _stp_module *m,
unsigned long notes_addr,
struct task_struct *tsk)
{
int j;
for (j = 0; j < m->build_id_len; j++) {
/* Use set_fs / get_user to access conceivably invalid addresses.
* If loc2c-runtime.h were more easily usable, a deref() loop
* could do it too. */
mm_segment_t oldfs = get_fs();
int rc;
unsigned char theory, practice = 0;
#ifdef STAPCONF_PROBE_KERNEL
if (!tsk) {
theory = m->build_id_bits[j];
set_fs(KERNEL_DS);
rc = probe_kernel_read(&practice, (void*)(notes_addr + j), 1);
}
else
#endif
{
theory = m->build_id_bits[j];
set_fs (tsk ? USER_DS : KERNEL_DS);
/*
* Why check CONFIG_UTRACE here? If we're using real in-kernel
* utrace, we can always just call get_user() (since we're
* either reading kernel memory or 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 = get_user(practice, ((unsigned char*)(void*)(notes_addr + j)));
#else
if (!tsk || tsk == current) {
rc = get_user(practice, ((unsigned char*)(void*)(notes_addr + j)));
}
else {
rc = (__access_process_vm_noflush(tsk, (notes_addr + j), &practice,
1, 0) != 1);
}
#endif
}
set_fs(oldfs);
if (rc || (theory != practice)) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,27)
_stp_error ("Build-id mismatch [man error::buildid]: \"%s\" byte %d (0x%02x vs 0x%02x) address %#lx rc %d\n",
m->path, j, theory, practice, notes_addr, rc);
return 1;
#else
/* This branch is a surrogate for kernels affected by Fedora bug
* #465873. */
_stp_warn (KERN_WARNING
"Build-id mismatch [man error::buildid]: \"%s\" byte %d (0x%02x vs 0x%02x) rc %d\n",
m->path, j, theory, practice, rc);
#endif
break;
} /* end mismatch */
} /* end per-byte check loop */
return 0;
}
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[0] == '/'
&& m->num_sections == 1
&& strncmp(m->name, "vdso", 4) == 0)
{
unsigned long notes_addr;
int all_ok = 1;
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,
"vdso", found);
dbug_task_vma(1,"found vdso: %s\n", found->path);
}
}
#endif /* STAPCONF_MM_CONTEXT_VDSO */
}
