mirror of
https://github.com/torvalds/linux.git
synced 2024-12-15 15:41:58 +00:00
c3b037917c
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154318.051635891@infradead.org
73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __ASM_QSPINLOCK_PARAVIRT_H
|
|
#define __ASM_QSPINLOCK_PARAVIRT_H
|
|
|
|
#include <asm/ibt.h>
|
|
|
|
/*
|
|
* For x86-64, PV_CALLEE_SAVE_REGS_THUNK() saves and restores 8 64-bit
|
|
* registers. For i386, however, only 1 32-bit register needs to be saved
|
|
* and restored. So an optimized version of __pv_queued_spin_unlock() is
|
|
* hand-coded for 64-bit, but it isn't worthwhile to do it for 32-bit.
|
|
*/
|
|
#ifdef CONFIG_64BIT
|
|
|
|
PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath);
|
|
#define __pv_queued_spin_unlock __pv_queued_spin_unlock
|
|
#define PV_UNLOCK "__raw_callee_save___pv_queued_spin_unlock"
|
|
#define PV_UNLOCK_SLOWPATH "__raw_callee_save___pv_queued_spin_unlock_slowpath"
|
|
|
|
/*
|
|
* Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock
|
|
* which combines the registers saving trunk and the body of the following
|
|
* C code:
|
|
*
|
|
* void __pv_queued_spin_unlock(struct qspinlock *lock)
|
|
* {
|
|
* u8 lockval = cmpxchg(&lock->locked, _Q_LOCKED_VAL, 0);
|
|
*
|
|
* if (likely(lockval == _Q_LOCKED_VAL))
|
|
* return;
|
|
* pv_queued_spin_unlock_slowpath(lock, lockval);
|
|
* }
|
|
*
|
|
* For x86-64,
|
|
* rdi = lock (first argument)
|
|
* rsi = lockval (second argument)
|
|
* rdx = internal variable (set to 0)
|
|
*/
|
|
asm (".pushsection .text;"
|
|
".globl " PV_UNLOCK ";"
|
|
".type " PV_UNLOCK ", @function;"
|
|
".align 4,0x90;"
|
|
PV_UNLOCK ": "
|
|
ASM_ENDBR
|
|
FRAME_BEGIN
|
|
"push %rdx;"
|
|
"mov $0x1,%eax;"
|
|
"xor %edx,%edx;"
|
|
LOCK_PREFIX "cmpxchg %dl,(%rdi);"
|
|
"cmp $0x1,%al;"
|
|
"jne .slowpath;"
|
|
"pop %rdx;"
|
|
FRAME_END
|
|
ASM_RET
|
|
".slowpath: "
|
|
"push %rsi;"
|
|
"movzbl %al,%esi;"
|
|
"call " PV_UNLOCK_SLOWPATH ";"
|
|
"pop %rsi;"
|
|
"pop %rdx;"
|
|
FRAME_END
|
|
ASM_RET
|
|
".size " PV_UNLOCK ", .-" PV_UNLOCK ";"
|
|
".popsection");
|
|
|
|
#else /* CONFIG_64BIT */
|
|
|
|
extern void __pv_queued_spin_unlock(struct qspinlock *lock);
|
|
PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock);
|
|
|
|
#endif /* CONFIG_64BIT */
|
|
#endif
|