Optimize out PTRACE_PEEKUSER with -i

strace -i was fetching PC with a separate PEEKUSER
despite having GETREGS data:

ptrace(PTRACE_GETREGS, 22331, 0, 0x8087f00) = 0
ptrace(PTRACE_PEEKUSER, 22331, 4*EIP, [0x80dd7b7]) = 0
write(3, "[080dd7b7] ioctl(0, SNDCTL_TMR_T"..., 82) = 82
ptrace(PTRACE_SYSCALL, 22331, 0, SIG_0) = 0

Now it does this:

ptrace(PTRACE_GETREGS, 22549, 0, 0x8087ea0) = 0
write(3, "[080dd7b7] ioctl(0, SNDCTL_TMR_T"..., 82) = 82
ptrace(PTRACE_SYSCALL, 22549, 0, SIG_0) = 0

Analogous improvement in sys_sigreturn() is also implemented.

* defs.h: Declare extern struct pt_regs regs for SPARC[64] and ARM.
Declare clear_regs(), get_regs() and get_regs_error flag variable.
* strace.c (trace): Call get_regs(pid) as soon as we know the tcb
and that it is stopped.
* syscall.c (get_regs): New function. Used to fetch registers early,
just after tracee has stopped.
(printcall): Move it here from util.c. Use global regs.REG data,
if available on the arch, instead of re-fetching it.
(get_scno): Use global regs.REG data.
(get_syscall_result): Likewise.
* signal.c (sys_sigreturn): Likewise.
* util.c (printcall): Moved to syscall.c.

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

1 files changed, 0 insertions, 15 deletions

diff --git a/signal.c b/signal.c
index c77758f..878a33d 100644
--- a/signal.c
+++ b/signal.c
@@ -60,13 +60,6 @@
 # include <asm/ptrace_offsets.h>
 #endif
 
-#if defined(SPARC64)
-# undef PTRACE_GETREGS
-# define PTRACE_GETREGS PTRACE_GETREGS64
-# undef PTRACE_SETREGS
-# define PTRACE_SETREGS PTRACE_SETREGS64
-#endif
-
 #if defined(SPARC) || defined(SPARC64) || defined(MIPS)
 typedef struct {
 	struct pt_regs		si_regs;
@@ -889,11 +882,8 @@ sys_sigreturn(struct tcb *tcp)
 {
 #if defined(ARM)
 	if (entering(tcp)) {
-		struct pt_regs regs;
 		struct sigcontext_struct sc;
 		sigset_t sigm;
-		if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, (void *)&regs) == -1)
-			return 0;
 		if (umove(tcp, regs.ARM_sp, &sc) < 0)
 			return 0;
 		long_to_sigset(sc.oldmask, &sigm);
@@ -986,13 +976,8 @@ sys_sigreturn(struct tcb *tcp)
 #elif defined(SPARC) || defined(SPARC64)
 	if (entering(tcp)) {
 		long i1;
-		struct pt_regs regs;
 		m_siginfo_t si;
 		sigset_t sigm;
-		if (ptrace(PTRACE_GETREGS, tcp->pid, (char *)&regs, 0) < 0) {
-			perror_msg("%s", "sigreturn: PTRACE_GETREGS");
-			return 0;
-		}
 		i1 = regs.u_regs[U_REG_O1];
 		if (umove(tcp, i1, &si) < 0) {
 			perror_msg("%s", "sigreturn: umove");