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

25 files changed, 137 insertions, 223 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 26a28419cafc..a79a1ad8bb96 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -274,6 +274,9 @@ config ARCH_WANT_OLD_COMPAT_IPC
 config GENERIC_KERNEL_THREAD
         bool
 
+config GENERIC_KERNEL_EXECVE
+        bool
+
 config HAVE_ARCH_SECCOMP_FILTER
         bool
         help
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