linux/arch/x86/include/asm/switch_to.h
Brian Gerst 616d24835e 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>
2016-08-24 12:31:50 +02:00

68 lines
1.8 KiB
C

#ifndef _ASM_X86_SWITCH_TO_H
#define _ASM_X86_SWITCH_TO_H
struct task_struct; /* one of the stranger aspects of C forward declarations */
struct task_struct *__switch_to_asm(struct task_struct *prev,
struct task_struct *next);
__visible struct task_struct *__switch_to(struct task_struct *prev,
struct task_struct *next);
struct tss_struct;
void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
struct tss_struct *tss);
/* This runs runs on the previous thread's stack. */
static inline void prepare_switch_to(struct task_struct *prev,
struct task_struct *next)
{
#ifdef CONFIG_VMAP_STACK
/*
* If we switch to a stack that has a top-level paging entry
* that is not present in the current mm, the resulting #PF will
* will be promoted to a double-fault and we'll panic. Probe
* the new stack now so that vmalloc_fault can fix up the page
* tables if needed. This can only happen if we use a stack
* in vmap space.
*
* We assume that the stack is aligned so that it never spans
* more than one top-level paging entry.
*
* To minimize cache pollution, just follow the stack pointer.
*/
READ_ONCE(*(unsigned char *)next->thread.sp);
#endif
}
asmlinkage void ret_from_fork(void);
/* data that is pointed to by thread.sp */
struct inactive_task_frame {
#ifdef CONFIG_X86_64
unsigned long r15;
unsigned long r14;
unsigned long r13;
unsigned long r12;
#else
unsigned long si;
unsigned long di;
#endif
unsigned long bx;
unsigned long bp;
unsigned long ret_addr;
};
struct fork_frame {
struct inactive_task_frame frame;
struct pt_regs regs;
};
#define switch_to(prev, next, last) \
do { \
prepare_switch_to(prev, next); \
\
((last) = __switch_to_asm((prev), (next))); \
} while (0)
#endif /* _ASM_X86_SWITCH_TO_H */