diff options
| author | Brian Gerst <brgerst@gmail.com> | 2016-08-13 12:38:20 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-08-24 12:31:50 +0200 |
| commit | 616d24835eeafa8ef3466479db028abfdfc77531 (patch) | |
| tree | 855895f0566a9c7b7b1996cbee1a384995b5a068 /arch/x86/entry/entry_32.S | |
| parent | 0100301bfdf56a2a370c7157b5ab0fbf9313e1cd (diff) | |
sched/x86: Pass kernel thread parameters in 'struct fork_frame'
Instead of setting up a fake pt_regs context, put the kernel thread
function pointer and arg into the unused callee-restored registers
of 'struct fork_frame'.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471106302-10159-6-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/entry_32.S')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index bf8f221f9c94..b75a8bcd2d23 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -240,35 +240,34 @@ END(__switch_to_asm) * A newly forked process directly context switches into this address. * * eax: prev task we switched from + * ebx: kernel thread func (NULL for user thread) + * edi: kernel thread arg */ ENTRY(ret_from_fork) pushl %eax call schedule_tail popl %eax + testl %ebx, %ebx + jnz 1f /* kernel threads are uncommon */ + +2: /* When we fork, we trace the syscall return in the child, too. */ movl %esp, %eax call syscall_return_slowpath jmp restore_all -END(ret_from_fork) - -ENTRY(ret_from_kernel_thread) - pushl %eax - call schedule_tail - popl %eax - movl PT_EBP(%esp), %eax - call *PT_EBX(%esp) - movl $0, PT_EAX(%esp) + /* kernel thread */ +1: movl %edi, %eax + call *%ebx /* - * Kernel threads return to userspace as if returning from a syscall. - * We should check whether anything actually uses this path and, if so, - * consider switching it over to ret_from_fork. + * A kernel thread is allowed to return here after successfully + * calling do_execve(). Exit to userspace to complete the execve() + * syscall. */ - movl %esp, %eax - call syscall_return_slowpath - jmp restore_all -ENDPROC(ret_from_kernel_thread) + movl $0, PT_EAX(%esp) + jmp 2b +END(ret_from_fork) /* * Return to user mode is not as complex as all this looks, |