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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
f233f7f1 PZI |
2 | #ifndef __ASM_QSPINLOCK_PARAVIRT_H |
3 | #define __ASM_QSPINLOCK_PARAVIRT_H | |
4 | ||
d7804530 WL |
5 | /* |
6 | * For x86-64, PV_CALLEE_SAVE_REGS_THUNK() saves and restores 8 64-bit | |
7 | * registers. For i386, however, only 1 32-bit register needs to be saved | |
8 | * and restored. So an optimized version of __pv_queued_spin_unlock() is | |
9 | * hand-coded for 64-bit, but it isn't worthwhile to do it for 32-bit. | |
10 | */ | |
11 | #ifdef CONFIG_64BIT | |
12 | ||
13 | PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath); | |
14 | #define __pv_queued_spin_unlock __pv_queued_spin_unlock | |
15 | #define PV_UNLOCK "__raw_callee_save___pv_queued_spin_unlock" | |
16 | #define PV_UNLOCK_SLOWPATH "__raw_callee_save___pv_queued_spin_unlock_slowpath" | |
17 | ||
18 | /* | |
19 | * Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock | |
20 | * which combines the registers saving trunk and the body of the following | |
21 | * C code: | |
22 | * | |
23 | * void __pv_queued_spin_unlock(struct qspinlock *lock) | |
24 | * { | |
25 | * struct __qspinlock *l = (void *)lock; | |
26 | * u8 lockval = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0); | |
27 | * | |
28 | * if (likely(lockval == _Q_LOCKED_VAL)) | |
29 | * return; | |
30 | * pv_queued_spin_unlock_slowpath(lock, lockval); | |
31 | * } | |
32 | * | |
33 | * For x86-64, | |
34 | * rdi = lock (first argument) | |
35 | * rsi = lockval (second argument) | |
36 | * rdx = internal variable (set to 0) | |
37 | */ | |
38 | asm (".pushsection .text;" | |
39 | ".globl " PV_UNLOCK ";" | |
16df4ff8 | 40 | ".type " PV_UNLOCK ", @function;" |
d7804530 WL |
41 | ".align 4,0x90;" |
42 | PV_UNLOCK ": " | |
16df4ff8 | 43 | FRAME_BEGIN |
d7804530 WL |
44 | "push %rdx;" |
45 | "mov $0x1,%eax;" | |
46 | "xor %edx,%edx;" | |
47 | "lock cmpxchg %dl,(%rdi);" | |
48 | "cmp $0x1,%al;" | |
49 | "jne .slowpath;" | |
50 | "pop %rdx;" | |
16df4ff8 | 51 | FRAME_END |
d7804530 WL |
52 | "ret;" |
53 | ".slowpath: " | |
54 | "push %rsi;" | |
55 | "movzbl %al,%esi;" | |
56 | "call " PV_UNLOCK_SLOWPATH ";" | |
57 | "pop %rsi;" | |
58 | "pop %rdx;" | |
16df4ff8 | 59 | FRAME_END |
d7804530 WL |
60 | "ret;" |
61 | ".size " PV_UNLOCK ", .-" PV_UNLOCK ";" | |
62 | ".popsection"); | |
63 | ||
64 | #else /* CONFIG_64BIT */ | |
65 | ||
66 | extern void __pv_queued_spin_unlock(struct qspinlock *lock); | |
f233f7f1 PZI |
67 | PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock); |
68 | ||
d7804530 | 69 | #endif /* CONFIG_64BIT */ |
f233f7f1 | 70 | #endif |