[patch 1/1] UML Support - SYSEMU: slight cleanup and speedup

blaisorblade_at_yahoo.it
Date: 07/31/05

  • Next message: Manuel Lauss: "Re: 2.6.13-rc3-mm3" 
    To: akpm@osdl.org
Date:	Sun, 31 Jul 2005 20:11:31 +0200

    From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
    CC: Charles P. Wright <cwright@cs.sunysb.edu>

    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.

    About those patches, they should stay in -mm only for now - I expect to get
    them reviewed.

    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> 

    ---
 linux-2.6.git-paolo/arch/i386/kernel/entry.S |    8 +-------
 1 files changed, 1 insertion(+), 7 deletions(-)
diff -puN arch/i386/kernel/entry.S~sysemu-cleanup-speedup arch/i386/kernel/entry.S
--- linux-2.6.git/arch/i386/kernel/entry.S~sysemu-cleanup-speedup	2005-07-31 20:03:19.000000000 +0200
+++ linux-2.6.git-paolo/arch/i386/kernel/entry.S	2005-07-31 20:03:19.000000000 +0200
@@ -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
_
-
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