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restore: Add restorer bootstrap mmap hint

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Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
This commit is contained in:
Cyrill Gorcunov 2011-11-06 01:49:57 +04:00
parent b69aeb9a26
commit cb7a9a524d
1 changed files with 74 additions and 10 deletions
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84
cr-restore.c
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@ -1219,9 +1219,70 @@ static int restore_all_tasks(pid_t pid)
return restore_root_task(path, pstree_fd);
}
static long restorer_vma_hint(pid_t pid, struct list_head *self_vma_list, long vma_len)
{
struct vma_area *vma_area;
long prev_vma_end, hint;
struct vma_entry vma;
char path[64];
int fd = -1, ret;
hint = -1;
/*
* Here we need some heuristics -- the VMA which restorer will
* belong to should not be unmapped, so we need to gueess out
* where to put it in.
*
* Yes, I know it's an O(n^2) algorithm, but usually there are
* not that many VMAs presented so instead of consuming memory
* better to stick with it.
*/
snprintf(path, sizeof(path), "core-%d.img", pid);
fd = open(path, O_RDONLY, CR_FD_PERM);
if (fd < 0) {
pr_perror("Can't open %s\n", path);
goto err_or_found;
}
prev_vma_end = 0;
sys_lseek(fd, GET_FILE_OFF_AFTER(struct core_entry), SEEK_SET);
while (1) {
ret = sys_read(fd, &vma, sizeof(vma));
if (ret && ret != sizeof(vma)) {
pr_perror("Can't read vma entry from %s\n", path);
goto err_or_found;
}
if (!prev_vma_end) {
prev_vma_end = vma.end;
continue;
}
if ((vma.start - prev_vma_end) > vma_len) {
list_for_each_entry(vma_area, self_vma_list, list) {
if (vma_area->vma.start <= prev_vma_end &&
vma_area->vma.end >= prev_vma_end)
goto err_or_found;
}
hint = prev_vma_end;
goto err_or_found;
} else
prev_vma_end = vma.end;
}
err_or_found:
if (fd >= 0)
close(fd);
return hint;
}
static void restorer_test(pid_t pid)
{
long code_len, vma_len, args_offset, new_sp;
long code_len, vma_len, args_offset, new_sp, hint;
void *args_rip, *exec_mem, *exec_start;
long ret;
@ -1229,7 +1290,6 @@ static void restorer_test(pid_t pid)
restorer_fcall_t restorer_fcall;
char path[64];
long prev_vma_end, cur_vma_start;
LIST_HEAD(self_vma_list);
struct vma_area *vma_area;
int fd_vmas, num;
@ -1251,6 +1311,7 @@ static void restorer_test(pid_t pid)
list_for_each_entry(vma_area, &self_vma_list, list) {
ret = write(fd_vmas, &vma_area->vma, sizeof(vma_area->vma));
if (ret != sizeof(vma_area->vma)) {
close(fd_vmas);
pr_perror("\nUnable to write vma entry (%li written)\n", num);
goto err;
}
@ -1258,6 +1319,7 @@ static void restorer_test(pid_t pid)
}
close(fd_vmas);
free_mappings(&self_vma_list);
restorer_fcall = restorer;
@ -1266,20 +1328,20 @@ static void restorer_test(pid_t pid)
code_len = round_up(code_len, 16);
vma_len = round_up(code_len + RESTORER_STACK_SIZE + RESTORER_STACK_FRAME, PAGE_SIZE);
/*
* Here we need some heuristics -- the VMA which restorer will
* belong to should not be unmapped, so we need to gueess out
* where to put it in.
*/
prev_vma_end = cur_vma_start = 0;
hint = restorer_vma_hint(pid, &self_vma_list, vma_len);
if (hint == -1) {
pr_err("No suitable area for restorer bootstrap\n");
goto err;
} else
pr_info("Found bootstrap VMA hint at: %lx\n", hint);
/* VMA we need to run restorer code */
exec_mem = mmap(0, vma_len,
exec_mem = mmap((void *)hint, vma_len,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANON, 0, 0);
if (exec_mem == MAP_FAILED) {
pr_err("Can't mmap section for restore code\n");
return;
goto err;
}
@ -1337,6 +1399,8 @@ static void restorer_test(pid_t pid)
: "rsp", "rdi", "rbx", "rax", "memory");
err:
free_mappings(&self_vma_list);
/* Just to be sure */
sys_exit(0);
}