Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull third pile of kernel_execve() patches from Al Viro:
 "The last bits of infrastructure for kernel_thread() et.al., with
  alpha/arm/x86 use of those.  Plus sanitizing the asm glue and
  do_notify_resume() on alpha, fixing the "disabled irq while running
  task_work stuff" breakage there.

  At that point the rest of kernel_thread/kernel_execve/sys_execve work
  can be done independently for different architectures.  The only
  pending bits that do depend on having all architectures converted are
  restrictred to fs/* and kernel/* - that'll obviously have to wait for
  the next cycle.

  I thought we'd have to wait for all of them done before we start
  eliminating the longjump-style insanity in kernel_execve(), but it
  turned out there's a very simple way to do that without flagday-style
  changes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
  alpha: switch to saner kernel_execve() semantics
  arm: switch to saner kernel_execve() semantics
  x86, um: convert to saner kernel_execve() semantics
  infrastructure for saner ret_from_kernel_thread semantics
  make sure that kernel_thread() callbacks call do_exit() themselves
  make sure that we always have a return path from kernel_execve()
  ppc: eeh_event should just use kthread_run()
  don't bother with kernel_thread/kernel_execve for launching linuxrc
  alpha: get rid of switch_stack argument of do_work_pending()
  alpha: don't bother passing switch_stack separately from regs
  alpha: take SIGPENDING/NOTIFY_RESUME loop into signal.c
  alpha: simplify TIF_NEED_RESCHED handling

4 files changed, 57 insertions, 80 deletions

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 7da91246e279..7a08cfb80ee8 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -21,6 +21,7 @@ config ALPHA
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_KERNEL_THREAD
+	select GENERIC_KERNEL_EXECVE
 	help
 	  The Alpha is a 64-bit general-purpose processor designed and
 	  marketed by the Digital Equipment Corporation of blessed memory,
diff --git a/arch/alpha/include/asm/unistd.h b/arch/alpha/include/asm/unistd.h
index 3cb6c1188984..7826e227e4d0 100644
--- a/arch/alpha/include/asm/unistd.h
+++ b/arch/alpha/include/asm/unistd.h
@@ -482,7 +482,6 @@
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
-#define __ARCH_WANT_KERNEL_EXECVE
 
 /* "Conditional" syscalls.  What we want is
 
diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index 2a359c9ee3cd..a7607832dd4f 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -311,7 +311,7 @@ entSys:
 
 	.align	4
 ret_from_sys_call:
-	cmovne	$26, 0, $19		/* $19 = 0 => non-restartable */
+	cmovne	$26, 0, $18		/* $18 = 0 => non-restartable */
 	ldq	$0, SP_OFF($sp)
 	and	$0, 8, $0
 	beq	$0, ret_to_kernel
@@ -320,8 +320,8 @@ ret_to_user:
 		sampling and the rti.  */
 	lda	$16, 7
 	call_pal PAL_swpipl
-	ldl	$5, TI_FLAGS($8)
-	and	$5, _TIF_WORK_MASK, $2
+	ldl	$17, TI_FLAGS($8)
+	and	$17, _TIF_WORK_MASK, $2
 	bne	$2, work_pending
 restore_all:
 	RESTORE_ALL
@@ -341,10 +341,10 @@ $syscall_error:
 	 * frame to indicate that a negative return value wasn't an
 	 * error number..
 	 */
-	ldq	$19, 0($sp)	/* old syscall nr (zero if success) */
-	beq	$19, $ret_success
+	ldq	$18, 0($sp)	/* old syscall nr (zero if success) */
+	beq	$18, $ret_success
 
-	ldq	$20, 72($sp)	/* .. and this a3 */
+	ldq	$19, 72($sp)	/* .. and this a3 */
 	subq	$31, $0, $0	/* with error in v0 */
 	addq	$31, 1, $1	/* set a3 for errno return */
 	stq	$0, 0($sp)
@@ -362,51 +362,35 @@ $ret_success:
  * Do all cleanup when returning from all interrupts and system calls.
  *
  * Arguments:
- *       $5: TI_FLAGS.
  *       $8: current.
- *      $19: The old syscall number, or zero if this is not a return
+ *      $17: TI_FLAGS.
+ *      $18: The old syscall number, or zero if this is not a return
  *           from a syscall that errored and is possibly restartable.
- *      $20: The old a3 value
+ *      $19: The old a3 value
  */
 
 	.align	4
 	.ent	work_pending
 work_pending:
-	and	$5, _TIF_NEED_RESCHED, $2
-	beq	$2, $work_notifysig
+	and	$17, _TIF_NOTIFY_RESUME | _TIF_SIGPENDING, $2
+	bne	$2, $work_notifysig
 
 $work_resched:
-	subq	$sp, 16, $sp
-	stq	$19, 0($sp)              /* save syscall nr */
-	stq	$20, 8($sp)              /* and error indication (a3) */
+	/*
+	 * We can get here only if we returned from syscall without SIGPENDING
+	 * or got through work_notifysig already.  Either case means no syscall
+	 * restarts for us, so let $18 and $19 burn.
+	 */
 	jsr	$26, schedule
-	ldq	$19, 0($sp)
-	ldq	$20, 8($sp)
-	addq	$sp, 16, $sp
-	/* Make sure need_resched and sigpending don't change between
-		sampling and the rti.  */
-	lda	$16, 7
-	call_pal PAL_swpipl
-	ldl	$5, TI_FLAGS($8)
-	and	$5, _TIF_WORK_MASK, $2
-	beq	$2, restore_all
-	and	$5, _TIF_NEED_RESCHED, $2
-	bne	$2, $work_resched
+	mov	0, $18
+	br	ret_to_user
 
 $work_notifysig:
 	mov	$sp, $16
 	bsr	$1, do_switch_stack
-	mov	$sp, $17
-	mov	$5, $18
-	mov	$19, $9		/* save old syscall number */
-	mov	$20, $10	/* save old a3 */
-	and	$5, _TIF_SIGPENDING, $2
-	cmovne	$2, 0, $9	/* we don't want double syscall restarts */
-	jsr	$26, do_notify_resume
-	mov	$9, $19
-	mov	$10, $20
+	jsr	$26, do_work_pending
 	bsr	$1, undo_switch_stack
-	br	ret_to_user
+	br	restore_all
 .end work_pending
 
 /*
@@ -454,9 +438,9 @@ $strace_success:
 
 	.align	3
 $strace_error:
-	ldq	$19, 0($sp)	/* old syscall nr (zero if success) */
-	beq	$19, $strace_success
-	ldq	$20, 72($sp)	/* .. and this a3 */
+	ldq	$18, 0($sp)	/* old syscall nr (zero if success) */
+	beq	$18, $strace_success
+	ldq	$19, 72($sp)	/* .. and this a3 */
 
 	subq	$31, $0, $0	/* with error in v0 */
 	addq	$31, 1, $1	/* set a3 for errno return */
@@ -464,11 +448,11 @@ $strace_error:
 	stq	$1, 72($sp)	/* a3 for return */
 
 	bsr	$1, do_switch_stack
-	mov	$19, $9		/* save old syscall number */
-	mov	$20, $10	/* save old a3 */
+	mov	$18, $9		/* save old syscall number */
+	mov	$19, $10	/* save old a3 */
 	jsr	$26, syscall_trace_leave
-	mov	$9, $19
-	mov	$10, $20
+	mov	$9, $18
+	mov	$10, $19
 	bsr	$1, undo_switch_stack
 
 	mov	$31, $26	/* tell "ret_from_sys_call" we can restart */
@@ -619,24 +603,9 @@ ret_from_kernel_thread:
 	mov	$9, $27
 	mov	$10, $16
 	jsr	$26, ($9)
-	ldgp	$gp, 0($26)
-	mov	$0, $16
-	mov	$31, $26
-	jmp	$31, sys_exit
-.end ret_from_kernel_thread
-
-	.globl	ret_from_kernel_execve
-	.align	4
-	.ent	ret_from_kernel_execve
-ret_from_kernel_execve:
-	mov	$16, $sp
-	/* Avoid the HAE being gratuitously wrong, to avoid restoring it.  */
-	ldq	$2, alpha_mv+HAE_CACHE
-	stq	$2, 152($sp)		/* HAE */
 	mov	$31, $19		/* to disable syscall restarts */
 	br	$31, ret_to_user
-
-.end	ret_from_kernel_execve
+.end ret_from_kernel_thread
 
 
 /*
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index a8c97d42ec8e..32575f85507d 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -298,8 +298,9 @@ get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 
 static long
 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 
-		 struct switch_stack *sw, unsigned long mask, unsigned long sp)
+		 unsigned long mask, unsigned long sp)
 {
+	struct switch_stack *sw = (struct switch_stack *)regs - 1;
 	long i, err = 0;
 
 	err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
@@ -354,7 +355,7 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 
 static int
 setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
-	    struct pt_regs *regs, struct switch_stack * sw)
+	    struct pt_regs *regs)
 {
 	unsigned long oldsp, r26, err = 0;
 	struct sigframe __user *frame;
@@ -364,7 +365,7 @@ setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		return -EFAULT;
 
-	err |= setup_sigcontext(&frame->sc, regs, sw, set->sig[0], oldsp);
+	err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 	if (err)
 		return -EFAULT;
 
@@ -401,7 +402,7 @@ setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 
 static int
 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
-	       sigset_t *set, struct pt_regs *regs, struct switch_stack * sw)
+	       sigset_t *set, struct pt_regs *regs)
 {
 	unsigned long oldsp, r26, err = 0;
 	struct rt_sigframe __user *frame;
@@ -420,7 +421,7 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 	err |= __put_user(sas_ss_flags(oldsp), &frame->uc.uc_stack.ss_flags);
 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
-	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, sw,
+	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 
 				set->sig[0], oldsp);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)
@@ -464,15 +465,15 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  */
 static inline void
 handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
-	      struct pt_regs * regs, struct switch_stack *sw)
+	      struct pt_regs * regs)
 {
 	sigset_t *oldset = sigmask_to_save();
 	int ret;
 
 	if (ka->sa.sa_flags & SA_SIGINFO)
-		ret = setup_rt_frame(sig, ka, info, oldset, regs, sw);
+		ret = setup_rt_frame(sig, ka, info, oldset, regs);
 	else
-		ret = setup_frame(sig, ka, oldset, regs, sw);
+		ret = setup_frame(sig, ka, oldset, regs);
 
 	if (ret) {
 		force_sigsegv(sig, current);
@@ -519,8 +520,7 @@ syscall_restart(unsigned long r0, unsigned long r19,
  * all (if we get here from anything but a syscall return, it will be 0)
  */
 static void
-do_signal(struct pt_regs * regs, struct switch_stack * sw,
-	  unsigned long r0, unsigned long r19)
+do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 {
 	siginfo_t info;
 	int signr;
@@ -537,7 +537,7 @@ do_signal(struct pt_regs * regs, struct switch_stack * sw,
 		/* Whee!  Actually deliver the signal.  */
 		if (r0)
 			syscall_restart(r0, r19, regs, &ka);
-		handle_signal(signr, &ka, &info, regs, sw);
+		handle_signal(signr, &ka, &info, regs);
 		if (single_stepping) 
 			ptrace_set_bpt(current); /* re-set bpt */
 		return;
@@ -568,15 +568,23 @@ do_signal(struct pt_regs * regs, struct switch_stack * sw,
 }
 
 void
-do_notify_resume(struct pt_regs *regs, struct switch_stack *sw,
-		 unsigned long thread_info_flags,
+do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 		 unsigned long r0, unsigned long r19)
 {
-	if (thread_info_flags & _TIF_SIGPENDING)
-		do_signal(regs, sw, r0, r19);
-
-	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
-		clear_thread_flag(TIF_NOTIFY_RESUME);
-		tracehook_notify_resume(regs);
-	}
+	do {
+		if (thread_flags & _TIF_NEED_RESCHED) {
+			schedule();
+		} else {
+			local_irq_enable();
+			if (thread_flags & _TIF_SIGPENDING) {
+				do_signal(regs, r0, r19);
+				r0 = 0;
+			} else {
+				clear_thread_flag(TIF_NOTIFY_RESUME);
+				tracehook_notify_resume(regs);
+			}
+		}
+		local_irq_disable();
+		thread_flags = current_thread_info()->flags;
+	} while (thread_flags & _TIF_WORK_MASK);
 }