On Mon, 2011-08-22 at 12:21 +0200, Denys Vlasenko wrote:
> 5. Move post-execve SIGTRAP from get_scno_on_sysenter (multitude of
> places on many architectures) to a single location in
> trace_syscall_entering. This loosens the logic for some arches, since
> many of them had additional checks such as scno == 0. So maybe this last
> patch is not 100% safe. (However, on non-ancient Linux kernels we should
> never have post-execve SIGTRAP in the first place, by virtue of using
> PTRACE_O_TRACEEXEC.)
diff -d -urpN strace.4/syscall.c strace.5/syscall.c
--- strace.4/syscall.c 2011-08-22 04:01:28.851814943 +0200
+++ strace.5/syscall.c 2011-08-22 04:11:21.004866031 +0200
@@ -756,12 +756,6 @@ get_scno_on_sysenter(struct tcb *tcp)
#ifdef LINUX
# if defined(S390) || defined(S390X)
- if (tcp->flags & TCB_WAITEXECVE) {
- /* This is the post-execve SIGTRAP. */
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
if (upeek(tcp, PT_GPR2, &syscall_mode) < 0)
return -1;
@@ -845,11 +839,6 @@ get_scno_on_sysenter(struct tcb *tcp)
# elif defined (POWERPC)
if (upeek(tcp, sizeof(unsigned long)*PT_R0, &scno) < 0)
return -1;
- /* Check if this is the post-execve SIGTRAP. */
- if (scno == 0 && (tcp->flags & TCB_WAITEXECVE)) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# ifdef POWERPC64
/* TODO: speed up strace by not doing this at every syscall.
* We only need to do it after execve.
@@ -874,19 +863,10 @@ get_scno_on_sysenter(struct tcb *tcp)
}
# endif
# elif defined(AVR32)
- /*
- * Read complete register set in one go.
- */
+ /* Read complete register set in one go. */
if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, ®s) < 0)
return -1;
-
scno = regs.r8;
-
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined(BFIN)
if (upeek(tcp, PT_ORIG_P0, &scno))
return -1;
@@ -971,15 +951,8 @@ get_scno_on_sysenter(struct tcb *tcp)
if (upeek(tcp, PT_R15, &scno) < 0)
return -1;
}
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined (ARM)
- /*
- * Read complete register set in one go.
- */
+ /* Read complete register set in one go. */
if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, (void *)®s) == -1)
return -1;
@@ -987,12 +960,6 @@ get_scno_on_sysenter(struct tcb *tcp)
* We only need to grab the syscall number on syscall entry.
*/
if (regs.ARM_ip == 0) {
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
/*
* Note: we only deal with only 32-bit CPUs here.
*/
@@ -1010,14 +977,6 @@ get_scno_on_sysenter(struct tcb *tcp)
if (errno)
return -1;
- /* FIXME: bogus check? it is already done before,
- * so we never can see it here?
- */
- if (scno == 0 && (tcp->flags & TCB_WAITEXECVE)) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
/* Handle the EABI syscall convention. We do not
bother converting structures between the two
ABIs, but basic functionality should work even
@@ -1063,13 +1022,6 @@ get_scno_on_sysenter(struct tcb *tcp)
r2 = regs[REG_V0];
scno = r2;
-
- /* Check if this is the post-execve SIGTRAP. */
- if (scno == 0 && tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
if (scno < 0 || scno > nsyscalls) {
if (a3 == 0 || a3 == -1) {
if (debug)
@@ -1083,12 +1035,6 @@ get_scno_on_sysenter(struct tcb *tcp)
if (upeek(tcp, REG_V0, &scno) < 0)
return -1;
- /* Check if this is the post-execve SIGTRAP. */
- if (scno == 0 && tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
if (scno < 0 || scno > nsyscalls) {
if (a3 == 0 || a3 == -1) {
if (debug)
@@ -1099,16 +1045,9 @@ get_scno_on_sysenter(struct tcb *tcp)
# elif defined (ALPHA)
if (upeek(tcp, REG_A3, &a3) < 0)
return -1;
-
if (upeek(tcp, REG_R0, &scno) < 0)
return -1;
- /* Check if this is the post-execve SIGTRAP. */
- if (scno == 0 && tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
-
/*
* Do some sanity checks to figure out if it's
* really a syscall entry
@@ -1164,11 +1103,6 @@ get_scno_on_sysenter(struct tcb *tcp)
set_personality(1);
break;
default:
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# if defined (SPARC64)
fprintf(stderr, "syscall: unknown syscall trap %08lx %016lx\n",
trap, regs.tpc);
# else
@@ -1189,11 +1123,6 @@ get_scno_on_sysenter(struct tcb *tcp)
# elif defined(HPPA)
if (upeek(tcp, PT_GR20, &scno) < 0)
return -1;
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined(SH)
/*
* In the new syscall ABI, the system call number is in R3.
@@ -1214,34 +1143,16 @@ get_scno_on_sysenter(struct tcb *tcp)
correct_scno);
scno = correct_scno;
}
-
- /* Check if this is the post-execve SIGTRAP. */
- if (scno == 0 && tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined(SH64)
if (upeek(tcp, REG_SYSCALL, &scno) < 0)
return -1;
scno &= 0xFFFF;
-
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined(CRISV10) || defined(CRISV32)
if (upeek(tcp, 4*PT_R9, &scno) < 0)
return -1;
# elif defined(TILE)
if (upeek(tcp, PTREGS_OFFSET_REG(10), &scno) < 0)
return -1;
-
- /* Check if this is the post-execve SIGTRAP. */
- if (tcp->flags & TCB_WAITEXECVE) {
- tcp->flags &= ~TCB_WAITEXECVE;
- return 0;
- }
# elif defined(MICROBLAZE)
if (upeek(tcp, 0, &scno) < 0)
return -1;
@@ -1302,9 +1213,7 @@ get_scno_on_sysexit(struct tcb *tcp)
# if defined(S390) || defined(S390X)
# elif defined (POWERPC)
# elif defined(AVR32)
- /*
- * Read complete register set in one go.
- */
+ /* Read complete register set in one go. */
if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, ®s) < 0)
return -1;
# elif defined(BFIN)
@@ -1323,9 +1232,7 @@ get_scno_on_sysexit(struct tcb *tcp)
if (upeek(tcp, PT_R10, &r10) < 0)
return -1;
# elif defined (ARM)
- /*
- * Read complete register set in one go.
- */
+ /* Read complete register set in one go. */
if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, (void *)®s) == -1)
return -1;
# elif defined (M68K)
@@ -1513,6 +1420,7 @@ syscall_fixup(struct tcb *tcp)
== (TCB_INSYSCALL|TCB_WAITEXECVE))
&& (gpr2 == -ENOSYS || gpr2 == tcp->scno)) {
/*
+ * Return from execve.
* Fake a return value of zero. We leave the TCB_WAITEXECVE
* flag set for the post-execve SIGTRAP to see and reset.
*/
@@ -2422,6 +2330,14 @@ trace_syscall_entering(struct tcb *tcp)
{
int res, scno_good;
+#if defined TCB_WAITEXECVE
+ if (tcp->flags & TCB_WAITEXECVE) {
+ /* This is the post-execve SIGTRAP. */
+ tcp->flags &= ~TCB_WAITEXECVE;
+ return 0;
+ }
+#endif
+
scno_good = res = get_scno_on_sysenter(tcp);
if (res == 0)
return res;
@@ -2591,9 +2507,6 @@ trace_syscall_exiting(struct tcb *tcp)
if (dtime || cflag)
gettimeofday(&tv, NULL);
- /* BTW, why we don't just memorize syscall no. on entry
- * in tcp->something?
- */
scno_good = res = get_scno_on_sysexit(tcp);
if (res == 0)
return res;
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