Cache tcp->u_nargs in a local variable for for() loops
Loops of the form "for (i = 0; i < tcp->u_nargs; i++) ..." need to fetch tcp->u_nargs from memory on every iteration if "..." part has a function call (gcc doesn't know that tcp->u_nargs won't change). This can be sped up by putting tcp->u_nargs in a local variable, which might go into a CPU register. * syscall.c (decode_subcall): Cache tcp->u_nargs in a local variable as for() loop limit value. (syscall_enter): Likewise. Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko
parent
afc64037e2
commit
4b887a5a9a
100
syscall.c
100
syscall.c
@ -570,7 +570,7 @@ static void
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decode_subcall(struct tcb *tcp, int subcall, int nsubcalls, enum subcall_style style)
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{
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unsigned long addr, mask;
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int i;
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int i, n;
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int size = personality_wordsize[current_personality];
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switch (style) {
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@ -578,8 +578,8 @@ decode_subcall(struct tcb *tcp, int subcall, int nsubcalls, enum subcall_style s
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if (tcp->u_arg[0] < 0 || tcp->u_arg[0] >= nsubcalls)
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return;
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tcp->scno = subcall + tcp->u_arg[0];
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tcp->u_nargs = sysent[tcp->scno].nargs;
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for (i = 0; i < tcp->u_nargs; i++)
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tcp->u_nargs = n = sysent[tcp->scno].nargs;
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for (i = 0; i < n; i++)
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tcp->u_arg[i] = tcp->u_arg[i + 1];
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break;
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case deref_style:
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@ -587,7 +587,8 @@ decode_subcall(struct tcb *tcp, int subcall, int nsubcalls, enum subcall_style s
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return;
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tcp->scno = subcall + tcp->u_arg[0];
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addr = tcp->u_arg[1];
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for (i = 0; i < sysent[tcp->scno].nargs; i++) {
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tcp->u_nargs = n = sysent[tcp->scno].nargs;
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for (i = 0; i < n; i++) {
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if (size == sizeof(int)) {
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unsigned int arg;
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if (umove(tcp, addr, &arg) < 0)
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@ -604,7 +605,6 @@ decode_subcall(struct tcb *tcp, int subcall, int nsubcalls, enum subcall_style s
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abort();
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addr += size;
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}
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tcp->u_nargs = sysent[tcp->scno].nargs;
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break;
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case mask_style:
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mask = (tcp->u_arg[0] >> 8) & 0xff;
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@ -2124,12 +2124,12 @@ syscall_enter(struct tcb *tcp)
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# ifndef PT_ORIG_R3
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# define PT_ORIG_R3 34
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# endif
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, (i==0) ?
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(sizeof(unsigned long) * PT_ORIG_R3) :
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((i+PT_R3) * sizeof(unsigned long)),
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@ -2145,12 +2145,12 @@ syscall_enter(struct tcb *tcp)
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for (i = 0; i < tcp->u_nargs; i++)
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tcp->u_arg[i] = regs.u_regs[U_REG_O0 + i];
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# elif defined(HPPA)
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, PT_GR26-4*i, &tcp->u_arg[i]) < 0)
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return -1;
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}
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@ -2171,26 +2171,26 @@ syscall_enter(struct tcb *tcp)
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tcp->u_arg[4] = regs.r5;
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tcp->u_arg[5] = regs.r3;
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# elif defined(BFIN)
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int i;
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int i, nargs;
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static const int argreg[] = { PT_R0, PT_R1, PT_R2, PT_R3, PT_R4, PT_R5 };
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = ARRAY_SIZE(argreg);
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nargs = tcp->u_nargs = ARRAY_SIZE(argreg);
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for (i = 0; i < tcp->u_nargs; ++i)
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for (i = 0; i < nargs; ++i)
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if (upeek(tcp, argreg[i], &tcp->u_arg[i]) < 0)
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return -1;
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# elif defined(SH)
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int i;
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int i, nargs;
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static const int syscall_regs[] = {
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4 * (REG_REG0+4), 4 * (REG_REG0+5), 4 * (REG_REG0+6), 4 * (REG_REG0+7),
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4 * (REG_REG0 ), 4 * (REG_REG0+1), 4 * (REG_REG0+2)
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};
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tcp->u_nargs = sysent[tcp->scno].nargs;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, syscall_regs[i], &tcp->u_arg[i]) < 0)
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return -1;
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}
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@ -2207,90 +2207,90 @@ syscall_enter(struct tcb *tcp)
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assert(sysent[tcp->scno].nargs < ARRAY_SIZE(syscall_regs));
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*/
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tcp->u_nargs = sysent[tcp->scno].nargs;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, REG_GENERAL(syscall_regs[i]), &tcp->u_arg[i]) < 0)
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return -1;
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}
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# elif defined(X86_64)
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int i;
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int i, nargs;
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static const int argreg[SUPPORTED_PERSONALITIES][MAX_ARGS] = {
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{ 8 * RDI, 8 * RSI, 8 * RDX, 8 * R10, 8 * R8 , 8 * R9 }, /* x86-64 ABI */
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{ 8 * RBX, 8 * RCX, 8 * RDX, 8 * RSI, 8 * RDI, 8 * RBP } /* i386 ABI */
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};
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, argreg[current_personality][i], &tcp->u_arg[i]) < 0)
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return -1;
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}
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# elif defined(MICROBLAZE)
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = 0;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = 0;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, (5 + i) * 4, &tcp->u_arg[i]) < 0)
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return -1;
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}
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# elif defined(CRISV10) || defined(CRISV32)
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int i;
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int i, nargs;
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static const int crisregs[] = {
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4*PT_ORIG_R10, 4*PT_R11, 4*PT_R12,
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4*PT_R13 , 4*PT_MOF, 4*PT_SRP
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};
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = 0;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = 0;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, crisregs[i], &tcp->u_arg[i]) < 0)
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return -1;
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}
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# elif defined(TILE)
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; ++i) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; ++i) {
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if (upeek(tcp, PTREGS_OFFSET_REG(i), &tcp->u_arg[i]) < 0)
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return -1;
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}
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# elif defined(M68K)
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, (i < 5 ? i : i + 2)*4, &tcp->u_arg[i]) < 0)
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return -1;
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}
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# else /* Other architecture (like i386) (32bits specific) */
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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if (upeek(tcp, i*4, &tcp->u_arg[i]) < 0)
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return -1;
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}
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# endif
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#endif /* LINUX */
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#ifdef SUNOS4
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int i;
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int i, nargs;
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if (tcp->scno >= 0 && tcp->scno < nsyscalls)
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tcp->u_nargs = sysent[tcp->scno].nargs;
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nargs = tcp->u_nargs = sysent[tcp->scno].nargs;
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else
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tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < tcp->u_nargs; i++) {
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nargs = tcp->u_nargs = MAX_ARGS;
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for (i = 0; i < nargs; i++) {
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struct user *u;
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if (upeek(tcp, uoff(u_arg[0]) +
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