Pass addr=0 instead of 1 into restarting ptrace calls

While we are at it, fold do_ptrace into its lone caller.
We no longer set tcp->ptrace_errno = ESRCH on ESRC error in upeek.
Other code paths where ptrace fails wern't doing it, and the code which
checks tcp->ptrace_errno even assumes it is never set to ESRCH.
(It was me who added this code sometime ago, so it was my fault
that it was a bit messy)

I ran sigkill_rain test and verified that unfinished syscalls are
still handled correctly.

* util.c (ptrace_restart): Do not pass addr=1 to ptrace(), pass 0 instead.
I have no idea why we were passing 1. Ptrace documentation says
that addr parameter is ignored.
(do_ptrace): Remove this function.
(upeek): Use ptrace() instead of do_ptrace().
* defs.h: Remove do_ptrace() declaration.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/defs.h b/defs.h
index 9c3b234ce9772c586ef3a5e8d81c9b566c49e29b..1f0b7b519f49ab2cabec469787107061786ded51 100644 (file)
--- a/defs.h
+++ b/defs.h
@@ -466,7 +466,6 @@ extern void droptcb(struct tcb *);
 extern void set_sortby(const char *);
 extern void set_overhead(int);
 extern void qualify(const char *);
-extern long do_ptrace(int request, struct tcb *tcp, void *addr, void *data);
 extern int ptrace_restart(int request, struct tcb *tcp, int sig);
 extern int trace_syscall(struct tcb *);
 extern void count_syscall(struct tcb *, struct timeval *);

diff --git a/util.c b/util.c
index a7cb19c0ceb1c31576d75ebc569741bc06351123..59665b7074219b17a0dfa24e1fe04ed0f889dee7 100644 (file)
--- a/util.c
+++ b/util.c
@@ -165,31 +165,6 @@ stpcpy(char *dst, const char *src)
 }
 #endif
 
-/*
- * Generic ptrace wrapper which tracks ESRCH errors
- * by setting tcp->ptrace_errno to ESRCH.
- *
- * We assume that ESRCH indicates likely process death (SIGKILL?),
- * modulo bugs where process somehow ended up not stopped.
- * Unfortunately kernel uses ESRCH for that case too. Oh well.
- *
- * Currently used by upeek() only.
- * TODO: use this in all other ptrace() calls while decoding.
- */
-long
-do_ptrace(int request, struct tcb *tcp, void *addr, void *data)
-{
-       long l;
-
-       errno = 0;
-       l = ptrace(request, tcp->pid, addr, (long) data);
-       /* Non-ESRCH errors might be our invalid reg/mem accesses,
-        * we do not record them. */
-       if (errno == ESRCH)
-               tcp->ptrace_errno = ESRCH;
-       return l;
-}
-
 /*
  * Used when we want to unblock stopped traced process.
  * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL.
@@ -204,7 +179,7 @@ ptrace_restart(int op, struct tcb *tcp, int sig)
        const char *msg;
 
        errno = 0;
-       ptrace(op, tcp->pid, (void *) 1, (long) sig);
+       ptrace(op, tcp->pid, (void *) 0, (long) sig);
        err = errno;
        if (!err || err == ESRCH)
                return 0;
@@ -219,7 +194,7 @@ ptrace_restart(int op, struct tcb *tcp, int sig)
        if (op == PTRACE_LISTEN)
                msg = "LISTEN";
 #endif
-       perror_msg("ptrace(PTRACE_%s,pid:%d,1,sig:%d)", msg, tcp->pid, sig);
+       perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig);
        return -1;
 }
 
@@ -1011,7 +986,7 @@ upeek(struct tcb *tcp, long off, long *res)
        long val;
 
        errno = 0;
-       val = do_ptrace(PTRACE_PEEKUSER, tcp, (char *) off, 0);
+       val = ptrace(PTRACE_PEEKUSER, tcp->pid, (char *) off, 0);
        if (val == -1 && errno) {
                if (errno != ESRCH) {
                        perror_msg("upeek: PTRACE_PEEKUSER pid:%d @0x%lx)", tcp->pid, off);