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

5 files changed, 18 insertions, 40 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 42d2c35a5bb..70071b19eb9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -109,6 +109,7 @@ config X86
         select HAVE_RCU_USER_QS if X86_64
         select HAVE_IRQ_TIME_ACCOUNTING
         select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 config INSTRUCTION_DECODER
         def_bool y
diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h
index 55d155560fd..16f3fc6ebf2 100644
--- a/arch/x86/include/asm/unistd.h
+++ b/arch/x86/include/asm/unistd.h
@@ -51,7 +51,6 @@
 # define __ARCH_WANT_SYS_UTIME
 # define __ARCH_WANT_SYS_WAITPID
 # define __ARCH_WANT_SYS_EXECVE
-# define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 2c6340796fe..a1193aef6d7 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -299,12 +299,20 @@ ENTRY(ret_from_fork)
         CFI_ENDPROC
 END(ret_from_fork)
 
-ENTRY(ret_from_kernel_execve)
-        movl %eax, %esp
-        movl $0,PT_EAX(%esp)
+ENTRY(ret_from_kernel_thread)
+        CFI_STARTPROC
+        pushl_cfi %eax
+        call schedule_tail
         GET_THREAD_INFO(%ebp)
+        popl_cfi %eax
+        pushl_cfi $0x0202               # Reset kernel eflags
+        popfl_cfi
+        movl PT_EBP(%esp),%eax
+        call *PT_EBX(%esp)
+        movl $0,PT_EAX(%esp)
         jmp syscall_exit
-END(ret_from_kernel_execve)
+        CFI_ENDPROC
+ENDPROC(ret_from_kernel_thread)
 
 /*
  * Interrupt exit functions should be protected against kprobes
@@ -1015,21 +1023,6 @@ END(spurious_interrupt_bug)
  */
         .popsection
 
-ENTRY(ret_from_kernel_thread)
-        CFI_STARTPROC
-        pushl_cfi %eax
-        call schedule_tail
-        GET_THREAD_INFO(%ebp)
-        popl_cfi %eax
-        pushl_cfi $0x0202               # Reset kernel eflags
-        popfl_cfi
-        movl PT_EBP(%esp),%eax
-        call *PT_EBX(%esp)
-        call do_exit
-        ud2                     # padding for call trace
-        CFI_ENDPROC
-ENDPROC(ret_from_kernel_thread)
-
 #ifdef CONFIG_XEN
 /* Xen doesn't set %esp to be precisely what the normal sysenter
    entrypoint expects, so fix it up before using the normal path. */
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cdc790c78f3..0c58952d64e 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -563,15 +563,13 @@ ENTRY(ret_from_fork)
         jmp ret_from_sys_call                   # go to the SYSRET fastpath
 
 1:
-        subq $REST_SKIP, %rsp   # move the stack pointer back
+        subq $REST_SKIP, %rsp   # leave space for volatiles
         CFI_ADJUST_CFA_OFFSET   REST_SKIP
         movq %rbp, %rdi
         call *%rbx
-        # exit
-        mov %eax, %edi
-        call do_exit
-        ud2                     # padding for call trace
-
+        movl $0, RAX(%rsp)
+        RESTORE_REST
+        jmp int_ret_from_sys_call
         CFI_ENDPROC
 END(ret_from_fork)
 
@@ -1326,20 +1324,6 @@ bad_gs:
         jmp  2b
         .previous
 
-ENTRY(ret_from_kernel_execve)
-        movq %rdi, %rsp
-        movl $0, RAX(%rsp)
-        // RESTORE_REST
-        movq 0*8(%rsp), %r15
-        movq 1*8(%rsp), %r14
-        movq 2*8(%rsp), %r13
-        movq 3*8(%rsp), %r12
-        movq 4*8(%rsp), %rbp
-        movq 5*8(%rsp), %rbx
-        addq $(6*8), %rsp
-        jmp int_ret_from_sys_call
-END(ret_from_kernel_execve)
-
 /* Call softirq on interrupt stack. Interrupts are off. */
 ENTRY(call_softirq)
         CFI_STARTPROC
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index 30c4eec033a..9fa950df80e 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -14,6 +14,7 @@ config UML_X86
         def_bool y
         select GENERIC_FIND_FIRST_BIT
         select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 config 64BIT
         bool "64-bit kernel" if SUBARCH = "x86"