x86/entry/32: Migrate to C exit path

This removes the hybrid asm-and-C implementation of exit work.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2baa438619ea6c027b40ec9fceacca52f09c74d09.1438378274.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index a3c307ad5ac41af1ff95399c50481e61cc38e415..b2909bf8cf7029b17f6457edcd86b6e04395e94b 100644 (file)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -256,14 +256,10 @@ ret_from_intr:
 
 ENTRY(resume_userspace)
        LOCKDEP_SYS_EXIT
-       DISABLE_INTERRUPTS(CLBR_ANY)            # make sure we don't miss an interrupt
-                                               # setting need_resched or sigpending
-                                               # between sampling and the iret
+       DISABLE_INTERRUPTS(CLBR_ANY)
        TRACE_IRQS_OFF
-       movl    TI_flags(%ebp), %ecx
-       andl    $_TIF_WORK_MASK, %ecx           # is there any work to be done on
-                                               # int/exception return?
-       jne     work_pending
+       movl    %esp, %eax
+       call    prepare_exit_to_usermode
        jmp     restore_all
 END(ret_from_exception)
 
@@ -341,7 +337,7 @@ sysenter_after_call:
        TRACE_IRQS_OFF
        movl    TI_flags(%ebp), %ecx
        testl   $_TIF_ALLWORK_MASK, %ecx
-       jnz     syscall_exit_work
+       jnz     syscall_exit_work_irqs_off
 sysenter_exit:
 /* if something modifies registers it must also disable sysexit */
        movl    PT_EIP(%esp), %edx
@@ -377,13 +373,7 @@ syscall_after_call:
        movl    %eax, PT_EAX(%esp)              # store the return value
 syscall_exit:
        LOCKDEP_SYS_EXIT
-       DISABLE_INTERRUPTS(CLBR_ANY)            # make sure we don't miss an interrupt
-                                               # setting need_resched or sigpending
-                                               # between sampling and the iret
-       TRACE_IRQS_OFF
-       movl    TI_flags(%ebp), %ecx
-       testl   $_TIF_ALLWORK_MASK, %ecx        # current->work
-       jnz     syscall_exit_work
+       jmp     syscall_exit_work
 
 restore_all:
        TRACE_IRQS_IRET
@@ -460,35 +450,6 @@ ldt_ss:
 #endif
 ENDPROC(entry_INT80_32)
 
-       # perform work that needs to be done immediately before resumption
-       ALIGN
-work_pending:
-       testb   $_TIF_NEED_RESCHED, %cl
-       jz      work_notifysig
-work_resched:
-       call    schedule
-       LOCKDEP_SYS_EXIT
-       DISABLE_INTERRUPTS(CLBR_ANY)            # make sure we don't miss an interrupt
-                                               # setting need_resched or sigpending
-                                               # between sampling and the iret
-       TRACE_IRQS_OFF
-       movl    TI_flags(%ebp), %ecx
-       andl    $_TIF_WORK_MASK, %ecx           # is there any work to be done other
-                                               # than syscall tracing?
-       jz      restore_all
-       testb   $_TIF_NEED_RESCHED, %cl
-       jnz     work_resched
-
-work_notifysig:                                        # deal with pending signals and
-                                               # notify-resume requests
-       TRACE_IRQS_ON
-       ENABLE_INTERRUPTS(CLBR_NONE)
-       movl    %esp, %eax
-       xorl    %edx, %edx
-       call    do_notify_resume
-       jmp     resume_userspace
-END(work_pending)
-
        # perform syscall exit tracing
        ALIGN
 syscall_trace_entry:
@@ -503,15 +464,14 @@ END(syscall_trace_entry)
 
        # perform syscall exit tracing
        ALIGN
-syscall_exit_work:
-       testl   $_TIF_WORK_SYSCALL_EXIT, %ecx
-       jz      work_pending
+syscall_exit_work_irqs_off:
        TRACE_IRQS_ON
-       ENABLE_INTERRUPTS(CLBR_ANY)             # could let syscall_trace_leave() call
-                                               # schedule() instead
+       ENABLE_INTERRUPTS(CLBR_ANY)
+
+syscall_exit_work:
        movl    %esp, %eax
-       call    syscall_trace_leave
-       jmp     resume_userspace
+       call    syscall_return_slowpath
+       jmp     restore_all
 END(syscall_exit_work)
 
 syscall_fault: