[PATCH] Uml support: reorganize PTRACE_SYSEMU support

With this patch, we change the way we handle switching from PTRACE_SYSEMU to
PTRACE_{SINGLESTEP,SYSCALL}, to free TIF_SYSCALL_EMU from double use as a
preparation for PTRACE_SYSEMU_SINGLESTEP extension, without changing the
behavior of the host kernel.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index b389e5f3bdee..9a47723469c6 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -339,12 +339,18 @@ syscall_trace_entry:
         xorl %edx,%edx
         call do_syscall_trace
         cmpl $0, %eax
-        jne syscall_exit                # ret != 0 -> running under PTRACE_SYSEMU,
+        jne syscall_skip                # ret != 0 -> running under PTRACE_SYSEMU,
                                         # so must skip actual syscall
         movl ORIG_EAX(%esp), %eax
         cmpl $(nr_syscalls), %eax
         jnae syscall_call
         jmp syscall_exit
+syscall_skip:
+        cli                             # make sure we don't miss an interrupt
+                                        # setting need_resched or sigpending
+                                        # between sampling and the iret
+        movl TI_flags(%ebp), %ecx
+        jmp work_pending
 
         # perform syscall exit tracing
         ALIGN