[RFC/PATCH 4/4] powerpc: Make syscall restart code more common
Christoph Hellwig
hch at lst.de
Sat Jun 2 20:12:39 EST 2007
On Wed, May 30, 2007 at 06:05:16PM +1000, Benjamin Herrenschmidt wrote:
> This patch moves the code in signal_32.c and signal_64.c for handling
> syscall restart into a common signal-common.h file and converge around
> a single implementation that is based on the 32 bits one, using trap, ccr
> and r3 rather than the special "result" field for deciding what to do.
>
> The "result" field is now pretty much deprecated. We still set it for
> the sake of whatever might rely on it in userland but we no longer use
> it's content.
>
> This, along with a previous patch that enables ptracers to write to
> "trap" and "orig_r3" should allow gdb to properly handle syscall
> restarting.
>
> There is only one common function for now and it's small enough so
> having it inline is fine. However, there is probably room for more
> merging of _32.c and _64.c in which case we'll probably want to
> have a common .c file and avoid inlines.
Here's an updated version to create a signal.[ch] instead. It will be
used by the signal consolidation patches I'll post now.
Index: linux-2.6/arch/powerpc/kernel/signal_32.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/signal_32.c 2007-05-31 19:29:19.000000000 +0200
+++ linux-2.6/arch/powerpc/kernel/signal_32.c 2007-06-01 22:25:51.000000000 +0200
@@ -51,6 +51,8 @@
#include <asm/pgtable.h>
#endif
+#include "signal.h"
+
#undef DEBUG_SIG
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
@@ -1156,30 +1158,8 @@ int do_signal(sigset_t *oldset, struct p
#ifdef CONFIG_PPC32
no_signal:
#endif
- if (TRAP(regs) == 0x0C00 /* System Call! */
- && regs->ccr & 0x10000000 /* error signalled */
- && ((ret = regs->gpr[3]) == ERESTARTSYS
- || ret == ERESTARTNOHAND || ret == ERESTARTNOINTR
- || ret == ERESTART_RESTARTBLOCK)) {
-
- if (signr > 0
- && (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
- || (ret == ERESTARTSYS
- && !(ka.sa.sa_flags & SA_RESTART)))) {
- /* make the system call return an EINTR error */
- regs->result = -EINTR;
- regs->gpr[3] = EINTR;
- /* note that the cr0.SO bit is already set */
- } else {
- regs->nip -= 4; /* Back up & retry system call */
- regs->result = 0;
- regs->trap = 0;
- if (ret == ERESTART_RESTARTBLOCK)
- regs->gpr[0] = __NR_restart_syscall;
- else
- regs->gpr[3] = regs->orig_gpr3;
- }
- }
+ /* Is there any syscall restart business here ? */
+ check_syscall_restart(regs, &ka, signr > 0);
if (signr == 0) {
/* No signal to deliver -- put the saved sigmask back */
Index: linux-2.6/arch/powerpc/kernel/signal_64.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/signal_64.c 2007-05-31 19:29:20.000000000 +0200
+++ linux-2.6/arch/powerpc/kernel/signal_64.c 2007-06-01 22:25:57.000000000 +0200
@@ -34,6 +34,8 @@
#include <asm/syscalls.h>
#include <asm/vdso.h>
+#include "signal.h"
+
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
@@ -463,41 +465,6 @@ static int handle_signal(unsigned long s
return ret;
}
-static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
-{
- switch ((int)regs->result) {
- case -ERESTART_RESTARTBLOCK:
- case -ERESTARTNOHAND:
- /* ERESTARTNOHAND means that the syscall should only be
- * restarted if there was no handler for the signal, and since
- * we only get here if there is a handler, we dont restart.
- */
- regs->result = -EINTR;
- regs->gpr[3] = EINTR;
- regs->ccr |= 0x10000000;
- break;
- case -ERESTARTSYS:
- /* ERESTARTSYS means to restart the syscall if there is no
- * handler or the handler was registered with SA_RESTART
- */
- if (!(ka->sa.sa_flags & SA_RESTART)) {
- regs->result = -EINTR;
- regs->gpr[3] = EINTR;
- regs->ccr |= 0x10000000;
- break;
- }
- /* fallthrough */
- case -ERESTARTNOINTR:
- /* ERESTARTNOINTR means that the syscall should be
- * called again after the signal handler returns.
- */
- regs->gpr[3] = regs->orig_gpr3;
- regs->nip -= 4;
- regs->result = 0;
- break;
- }
-}
-
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
@@ -522,13 +489,13 @@ int do_signal(sigset_t *oldset, struct p
oldset = ¤t->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+
+ /* Is there any syscall restart business here ? */
+ check_syscall_restart(regs, &ka, signr > 0);
+
if (signr > 0) {
int ret;
- /* Whee! Actually deliver the signal. */
- if (TRAP(regs) == 0x0C00)
- syscall_restart(regs, &ka);
-
/*
* Reenable the DABR before delivering the signal to
* user space. The DABR will have been cleared if it
@@ -537,6 +504,7 @@ int do_signal(sigset_t *oldset, struct p
if (current->thread.dabr)
set_dabr(current->thread.dabr);
+ /* Whee! Actually deliver the signal. */
ret = handle_signal(signr, &ka, &info, oldset, regs);
/* If a signal was successfully delivered, the saved sigmask is in
@@ -547,19 +515,6 @@ int do_signal(sigset_t *oldset, struct p
return ret;
}
- if (TRAP(regs) == 0x0C00) { /* System Call! */
- if ((int)regs->result == -ERESTARTNOHAND ||
- (int)regs->result == -ERESTARTSYS ||
- (int)regs->result == -ERESTARTNOINTR) {
- regs->gpr[3] = regs->orig_gpr3;
- regs->nip -= 4; /* Back up & retry system call */
- regs->result = 0;
- } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
- regs->gpr[0] = __NR_restart_syscall;
- regs->nip -= 4;
- regs->result = 0;
- }
- }
/* No signal to deliver -- put the saved sigmask back */
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
Index: linux-2.6/arch/powerpc/kernel/Makefile
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/Makefile 2007-06-01 22:26:00.000000000 +0200
+++ linux-2.6/arch/powerpc/kernel/Makefile 2007-06-01 22:26:11.000000000 +0200
@@ -12,7 +12,8 @@ endif
obj-y := semaphore.o cputable.o ptrace.o syscalls.o \
irq.o align.o signal_32.o pmc.o vdso.o \
- init_task.o process.o systbl.o idle.o
+ init_task.o process.o systbl.o idle.o \
+ signal.o
obj-y += vdso32/
obj-$(CONFIG_PPC64) += setup_64.o binfmt_elf32.o sys_ppc32.o \
signal_64.o ptrace32.o \
Index: linux-2.6/arch/powerpc/kernel/signal.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/arch/powerpc/kernel/signal.c 2007-06-01 22:28:16.000000000 +0200
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
+ * Extracted from signal_32.c and signal_64.c
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file README.legal in the main directory of
+ * this archive for more details.
+ */
+
+#include <linux/ptrace.h>
+#include <linux/signal.h>
+
+void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
+ int has_handler)
+{
+ unsigned long ret = regs->gpr[3];
+ int restart = 1;
+
+ /* syscall ? */
+ if (TRAP(regs) != 0x0C00)
+ return;
+
+ /* error signalled ? */
+ if (!(regs->ccr & 0x10000000))
+ return;
+
+ switch (ret) {
+ case ERESTART_RESTARTBLOCK:
+ case ERESTARTNOHAND:
+ /* ERESTARTNOHAND means that the syscall should only be
+ * restarted if there was no handler for the signal, and since
+ * we only get here if there is a handler, we dont restart.
+ */
+ restart = !has_handler;
+ break;
+ case ERESTARTSYS:
+ /* ERESTARTSYS means to restart the syscall if there is no
+ * handler or the handler was registered with SA_RESTART
+ */
+ restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
+ break;
+ case ERESTARTNOINTR:
+ /* ERESTARTNOINTR means that the syscall should be
+ * called again after the signal handler returns.
+ */
+ break;
+ default:
+ return;
+ }
+ if (restart) {
+ if (ret == ERESTART_RESTARTBLOCK)
+ regs->gpr[0] = __NR_restart_syscall;
+ else
+ regs->gpr[3] = regs->orig_gpr3;
+ regs->nip -= 4;
+ regs->result = 0;
+ } else {
+ regs->result = -EINTR;
+ regs->gpr[3] = EINTR;
+ regs->ccr |= 0x10000000;
+ }
+}
Index: linux-2.6/arch/powerpc/kernel/signal.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/arch/powerpc/kernel/signal.h 2007-06-01 22:25:26.000000000 +0200
@@ -0,0 +1,3 @@
+
+void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
+ int has_handler);
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