If the tracee sets PTRACE_O_TRACEVFORK and the tracee does vfork(),
the tracee stops inside do_fork() and reports PTRACE_EVENT_VFORK.
If we need to report PTRACE_EVENT_VFORK_DONE after that, ptrace_resume()
can use ptrace_wake_up() or just report the stacked event. We need to
wake up the tracee, it should pass wait_for_completion() and then stop
and report before return to user-mode.
So. change ptrace_resume() to do set_stop_code() + utrace_control(REPORT)
like ptrace_report_clone() does, we rely on ->report_quiesce() which must
notice ptrace_event_pending() and return UTRACE_STOP.
And inow we pass this test:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <assert.h>
#define WEVENT(s) ((s & 0xFF0000) >> 16)
static unsigned long __step(int line, int pid, int o, int e)
{
int stat, cont = PTRACE_CONT;
unsigned long msg;
if (o == PTRACE_SYSCALL) {
cont = o;
} else if (o) {
assert(0 == ptrace(PTRACE_SETOPTIONS, pid, 0, o));
}
assert(0 == ptrace(cont, pid, 0, 0));
assert(waitpid(pid, &stat, __WALL) == pid);
// assert(WIFSTOPPED(stat));
// assert(WSTOPSIG(stat) == SIGTRAP);
if (!WIFSTOPPED(stat) || WSTOPSIG(stat) != SIGTRAP)
{ printf("ERR!! %3d: %06X\n", line, stat); exit(1); }
assert(WEVENT(stat) == e);
assert(0 == ptrace(PTRACE_GETEVENTMSG, pid, 0, &msg));
return msg;
}
#define step(pid, o, e) __step(__LINE__, pid, o, e)
#define T_FORK_A 0x01
#define T_FORK_Z 0x02
#define T_SYSCALL 0x04
#define T_SIGNAL 0x08
#define T_ALL (T_FORK_A | T_FORK_Z | T_SYSCALL | T_SIGNAL)
static void p_todo(int todo)
{
printf("todo: ");
#define P(n) if (todo & n) printf(#n " ")
P(T_FORK_A); P(T_FORK_Z); P(T_SYSCALL); P(T_SIGNAL);
#undef P
if (todo & ~T_ALL) printf("ERR!!!");
printf("\n");
}
static void tst(int todo)
{
int pid, cpid=-1, stat;
long msg;
p_todo(todo);
pid = fork();
if (!pid) {
int vp;
if (!(todo & T_SIGNAL))
signal(SIGCHLD, SIG_IGN);
assert(0 == ptrace(PTRACE_TRACEME, 0,0,0));
kill(getpid(), SIGSTOP);
vp = vfork();
exit(0x43);
}
assert(wait(&stat) == pid);
assert(WIFSTOPPED(stat) && WSTOPSIG(stat) == SIGSTOP);
if (todo & T_SYSCALL) {
msg = step(pid, PTRACE_SYSCALL, 0);
assert(msg == 0);
}
if (todo & T_FORK_A) {
cpid = step(pid, PTRACE_O_TRACEVFORK,
PTRACE_EVENT_VFORK);
assert(waitpid(cpid, &stat, __WALL) == cpid);
assert(WIFSTOPPED(stat));
assert(WSTOPSIG(stat) == SIGSTOP);
assert(0 == ptrace(PTRACE_CONT, cpid, 0, 0));
assert(waitpid(cpid, &stat, __WALL) == cpid);
assert(WIFEXITED(stat));
}
if (todo & T_FORK_Z) {
msg = step(pid, PTRACE_O_TRACEVFORKDONE,
PTRACE_EVENT_VFORK_DONE);
if (todo & T_FORK_A) assert(msg == cpid);
}
if (todo & T_SIGNAL) {
assert(0 == ptrace(PTRACE_CONT, pid, 0, 0));
assert(waitpid(pid, &stat, __WALL) == pid);
if (!(todo & T_FORK_A) && stat == 0x4300)
goto parent_exited_first;
assert(WIFSTOPPED(stat));
assert(WSTOPSIG(stat) == SIGCHLD);
}
if (todo & T_SYSCALL) {
msg = step(pid, PTRACE_SYSCALL, 0);
if (todo & T_FORK_A) assert(msg == cpid);
}
assert(0 == ptrace(PTRACE_CONT, pid, 0, 0));
assert(waitpid(pid, &stat, __WALL) == pid);
assert(WIFEXITED(stat));
parent_exited_first:
assert(waitpid(-1, &stat, __WALL) == -1);
assert(errno == ECHILD);
}
int main(int argc, char* argv[])
{
int todo;
if (argc > 1) {
todo = atoi(argv[1]);
tst(todo);
} else {
int todo;
for (todo = 0; todo <= T_ALL; ++todo)
tst(todo);
}
return 0;
}
---
kernel/ptrace.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- PU/kernel/ptrace.c~99_VFORK_THEN_VFORKDONE 2009-10-17 19:46:42.000000000
+0200
+++ PU/kernel/ptrace.c 2009-10-17 19:50:54.000000000 +0200
@@ -975,11 +975,21 @@ static void do_ptrace_resume(struct utra
case 0:
// XXX: JCTL stop
break;
+
+ case PTRACE_EVENT_VFORK:
+ if (context->options & PTRACE_O_TRACEVFORKDONE) {
+ set_stop_code(context, PTRACE_EVENT_VFORK_DONE);
+ utrace_control(tracee, engine, UTRACE_REPORT);
+ return;
+ }
+ break;
+
case PTRACE_EVENT_SYSCALL_ENTRY:
case PTRACE_EVENT_SYSCALL_EXIT:
if (data)
send_sig_info(data, SEND_SIG_PRIV, tracee);
break;
+
case PTRACE_EVENT_SIGNAL:
context->signr = data;
break;
