Optimize sigreturn handling

* signal.c (sys_sigreturn): move stack pointer variables,
and for SPARC and MIPS, stack pointer and sigmask reading code
into "if (entering) ..." block, because it is only needed
in this branch; load tcp->u_arg[1] into sigmask for display
_after_ we know for sure u_arg[1] does contain valid sigmask
(IOW: perform operation only when we know we will need the result)

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

diff --git a/signal.c b/signal.c
index e4ae7d4c0a0820a1723ec10fb731ea4683f6f229..85e74b576db00a1fb8c077a8a630aa8502ca9cb7 100644 (file)
--- a/signal.c
+++ b/signal.c
@@ -1233,35 +1233,30 @@ int
 sys_sigreturn(struct tcb *tcp)
 {
 #if defined(ARM)
-       struct pt_regs regs;
-       struct sigcontext_struct sc;
-
        if (entering(tcp)) {
+               struct pt_regs regs;
+               struct sigcontext_struct sc;
                tcp->u_arg[0] = 0;
-
                if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, (void *)&regs) == -1)
                        return 0;
-
                if (umove(tcp, regs.ARM_sp, &sc) < 0)
                        return 0;
-
                tcp->u_arg[0] = 1;
                tcp->u_arg[1] = sc.oldmask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(S390) || defined(S390X)
-       long usp;
-       struct sigcontext_struct sc;
-
        if (entering(tcp)) {
+               long usp;
+               struct sigcontext_struct sc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, PT_GPR15, &usp) < 0)
                        return 0;
@@ -1278,10 +1273,9 @@ sys_sigreturn(struct tcb *tcp)
        }
        return 0;
 #elif defined(I386)
-       long esp;
-       struct sigcontext_struct sc;
-
        if (entering(tcp)) {
+               long esp;
+               struct sigcontext_struct sc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, 4*UESP, &esp) < 0)
                        return 0;
@@ -1292,19 +1286,18 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(IA64)
-       struct sigcontext sc;
-       long sp;
-
        if (entering(tcp)) {
+               struct sigcontext sc;
+               long sp;
                /* offset of sigcontext in the kernel's sigframe structure: */
 #              define SIGFRAME_SC_OFFSET       0x90
                tcp->u_arg[0] = 0;
@@ -1317,20 +1310,18 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-
-               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(POWERPC)
-       long esp;
-       struct sigcontext_struct sc;
-
        if (entering(tcp)) {
+               long esp;
+               struct sigcontext_struct sc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, sizeof(unsigned long)*PT_R1, &esp) < 0)
                        return 0;
@@ -1350,19 +1341,18 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(M68K)
-       long usp;
-       struct sigcontext sc;
-
        if (entering(tcp)) {
+               long usp;
+               struct sigcontext sc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, 4*PT_USP, &usp) < 0)
                        return 0;
@@ -1373,19 +1363,18 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(ALPHA)
-       long fp;
-       struct sigcontext_struct sc;
-
        if (entering(tcp)) {
+               long fp;
+               struct sigcontext_struct sc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, REG_FP, &fp) < 0)
                        return 0;
@@ -1396,38 +1385,37 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined (SPARC) || defined (SPARC64)
-       long i1;
-       struct pt_regs regs;
-       m_siginfo_t si;
-
-       if (ptrace(PTRACE_GETREGS, tcp->pid, (char *)&regs, 0) < 0) {
-               perror("sigreturn: PTRACE_GETREGS ");
-               return 0;
-       }
        if (entering(tcp)) {
+               long i1;
+               struct pt_regs regs;
+               m_siginfo_t si;
                tcp->u_arg[0] = 0;
+               if (ptrace(PTRACE_GETREGS, tcp->pid, (char *)&regs, 0) < 0) {
+                       perror("sigreturn: PTRACE_GETREGS");
+                       return 0;
+               }
                i1 = regs.u_regs[U_REG_O1];
                if (umove(tcp, i1, &si) < 0) {
-                       perror("sigreturn: umove ");
+                       perror("sigreturn: umove");
                        return 0;
                }
                tcp->u_arg[0] = 1;
                tcp->u_arg[1] = si.si_mask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
@@ -1435,10 +1423,9 @@ sys_sigreturn(struct tcb *tcp)
 #elif defined (LINUX_MIPSN32) || defined (LINUX_MIPSN64)
        /* This decodes rt_sigreturn.  The 64-bit ABIs do not have
           sigreturn.  */
-       long sp;
-       struct ucontext uc;
-
        if (entering(tcp)) {
+               long sp;
+               struct ucontext uc;
                tcp->u_arg[0] = 0;
                if (upeek(tcp, REG_SP, &sp) < 0)
                        return 0;
@@ -1450,25 +1437,24 @@ sys_sigreturn(struct tcb *tcp)
                tcp->u_arg[1] = *(long *) &uc.uc_sigmask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(MIPS)
-       long sp;
-       struct pt_regs regs;
-       m_siginfo_t si;
-
-       if (ptrace(PTRACE_GETREGS, tcp->pid, (char *)&regs, 0) < 0) {
-               perror("sigreturn: PTRACE_GETREGS ");
-               return 0;
-       }
        if (entering(tcp)) {
+               long sp;
+               struct pt_regs regs;
+               m_siginfo_t si;
                tcp->u_arg[0] = 0;
+               if (ptrace(PTRACE_GETREGS, tcp->pid, (char *)&regs, 0) < 0) {
+                       perror("sigreturn: PTRACE_GETREGS");
+                       return 0;
+               }
                sp = regs.regs[29];
                if (umove(tcp, sp, &si) < 0)
                        return 0;
@@ -1476,22 +1462,19 @@ sys_sigreturn(struct tcb *tcp)
                tcp->u_arg[1] = si.si_mask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(CRISV10) || defined(CRISV32)
-       struct sigcontext sc;
-
        if (entering(tcp)) {
+               struct sigcontext sc;
                long regs[PT_MAX+1];
-
                tcp->u_arg[0] = 0;
-
                if (ptrace(PTRACE_GETREGS, tcp->pid, NULL, (long)regs) < 0) {
                        perror("sigreturn: PTRACE_GETREGS");
                        return 0;
@@ -1502,23 +1485,21 @@ sys_sigreturn(struct tcb *tcp)
                tcp->u_arg[1] = sc.oldmask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
-
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(TILE)
-       struct ucontext uc;
-       long sp;
-
-       /* offset of ucontext in the kernel's sigframe structure */
-#      define SIGFRAME_UC_OFFSET C_ABI_SAVE_AREA_SIZE + sizeof(struct siginfo)
-
        if (entering(tcp)) {
+               struct ucontext uc;
+               long sp;
+
+               /* offset of ucontext in the kernel's sigframe structure */
+#              define SIGFRAME_UC_OFFSET C_ABI_SAVE_AREA_SIZE + sizeof(struct siginfo)
                tcp->u_arg[0] = 0;
                if (upeek(tcp, PTREGS_OFFSET_SP, &sp) < 0)
                        return 0;
@@ -1529,24 +1510,20 @@ sys_sigreturn(struct tcb *tcp)
        }
        else {
                sigset_t sigm;
-
-               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
        return 0;
 #elif defined(MICROBLAZE)
-       struct sigcontext sc;
-
        /* TODO: Verify that this is correct...  */
        if (entering(tcp)) {
+               struct sigcontext sc;
                long sp;
-
                tcp->u_arg[0] = 0;
-
                /* Read r1, the stack pointer.  */
                if (upeek(tcp, 1 * 4, &sp) < 0)
                        return 0;
@@ -1556,10 +1533,10 @@ sys_sigreturn(struct tcb *tcp)
                tcp->u_arg[1] = sc.oldmask;
        } else {
                sigset_t sigm;
-               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
+               long_to_sigset(tcp->u_arg[1], &sigm);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }