[PATCH] uml: SYSEMU: slight cleanup and speedup

As a follow-up to "UML Support - Ptrace: adds the host SYSEMU support, for
UML and general usage" (i.e.  uml-support-* in current mm).

Avoid unconditionally jumping to work_pending and code copying, just reuse
the already existing resume_userspace path.

One interesting note, from Charles P.  Wright, suggested that the API is
improvable with no downsides for UML (except that it will have to support
yet another host API, since dropping support for the current API, for UML,
is not reasonable from users' point of view).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
CC: Charles P. Wright <cwright@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 9a47723..abb9097 100644 (file)
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -339,18 +339,12 @@ syscall_trace_entry:
        xorl %edx,%edx
        call do_syscall_trace
        cmpl $0, %eax
-       jne syscall_skip                # ret != 0 -> running under PTRACE_SYSEMU,
+       jne resume_userspace            # 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