sched/x86: Rewrite the switch_to() code
authorBrian Gerst <brgerst@gmail.com>
Sat, 13 Aug 2016 16:38:19 +0000 (12:38 -0400)
committerIngo Molnar <mingo@kernel.org>
Wed, 24 Aug 2016 10:31:41 +0000 (12:31 +0200)
commit0100301bfdf56a2a370c7157b5ab0fbf9313e1cd
treef8a339f20fb486a1ebe029d1c409e94c9bf8d67a
parent7b32aeadbc95d4a41402c1c0da6aa3ab51af4c10
sched/x86: Rewrite the switch_to() code

Move the low-level context switch code to an out-of-line asm stub instead of
using complex inline asm.  This allows constructing a new stack frame for the
child process to make it seamlessly flow to ret_from_fork without an extra
test and branch in __switch_to().  It also improves code generation for
__schedule() by using the C calling convention instead of clobbering all
registers.

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/1471106302-10159-5-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/entry/entry_32.S
arch/x86/entry/entry_64.S
arch/x86/include/asm/processor.h
arch/x86/include/asm/switch_to.h
arch/x86/include/asm/thread_info.h
arch/x86/kernel/asm-offsets.c
arch/x86/kernel/asm-offsets_32.c
arch/x86/kernel/asm-offsets_64.c
arch/x86/kernel/process_32.c
arch/x86/kernel/process_64.c
arch/x86/kernel/smpboot.c