Book a Demo!
CoCalc Logo Icon
StoreFeaturesDocsShareSupportNewsAboutPoliciesSign UpSign In
awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/lib/rwsem_64.S
10818 views
1
/*

2
 * x86-64 rwsem wrappers

3
 *

4
 * This interfaces the inline asm code to the slow-path

5
 * C routines. We need to save the call-clobbered regs

6
 * that the asm does not mark as clobbered, and move the

7
 * argument from %rax to %rdi.

8
 *

9
 * NOTE! We don't need to save %rax, because the functions

10
 * will always return the semaphore pointer in %rax (which

11
 * is also the input argument to these helpers)

12
 *

13
 * The following can clobber %rdx because the asm clobbers it:

14
 *   call_rwsem_down_write_failed

15
 *   call_rwsem_wake

16
 * but %rdi, %rsi, %rcx, %r8-r11 always need saving.

17
 */

18


19
#include <linux/linkage.h>

20
#include <asm/rwlock.h>

21
#include <asm/alternative-asm.h>

22
#include <asm/frame.h>

23
#include <asm/dwarf2.h>

24


25
#define save_common_regs \

26
	pushq_cfi %rdi; CFI_REL_OFFSET rdi, 0; \

27
	pushq_cfi %rsi; CFI_REL_OFFSET rsi, 0; \

28
	pushq_cfi %rcx; CFI_REL_OFFSET rcx, 0; \

29
	pushq_cfi %r8;  CFI_REL_OFFSET r8,  0; \

30
	pushq_cfi %r9;  CFI_REL_OFFSET r9,  0; \

31
	pushq_cfi %r10; CFI_REL_OFFSET r10, 0; \

32
	pushq_cfi %r11; CFI_REL_OFFSET r11, 0

33


34
#define restore_common_regs \

35
	popq_cfi %r11; CFI_RESTORE r11; \

36
	popq_cfi %r10; CFI_RESTORE r10; \

37
	popq_cfi %r9;  CFI_RESTORE r9; \

38
	popq_cfi %r8;  CFI_RESTORE r8; \

39
	popq_cfi %rcx; CFI_RESTORE rcx; \

40
	popq_cfi %rsi; CFI_RESTORE rsi; \

41
	popq_cfi %rdi; CFI_RESTORE rdi

42


43
/* Fix up special calling conventions */

44
ENTRY(call_rwsem_down_read_failed)

45
	CFI_STARTPROC

46
	save_common_regs

47
	pushq_cfi %rdx

48
	CFI_REL_OFFSET rdx, 0

49
	movq %rax,%rdi

50
	call rwsem_down_read_failed

51
	popq_cfi %rdx

52
	CFI_RESTORE rdx

53
	restore_common_regs

54
	ret

55
	CFI_ENDPROC

56
ENDPROC(call_rwsem_down_read_failed)

57


58
ENTRY(call_rwsem_down_write_failed)

59
	CFI_STARTPROC

60
	save_common_regs

61
	movq %rax,%rdi

62
	call rwsem_down_write_failed

63
	restore_common_regs

64
	ret

65
	CFI_ENDPROC

66
ENDPROC(call_rwsem_down_write_failed)

67


68
ENTRY(call_rwsem_wake)

69
	CFI_STARTPROC

70
	decl %edx	/* do nothing if still outstanding active readers */

71
	jnz 1f

72
	save_common_regs

73
	movq %rax,%rdi

74
	call rwsem_wake

75
	restore_common_regs

76
1:	ret

77
	CFI_ENDPROC

78
ENDPROC(call_rwsem_wake)

79


80
/* Fix up special calling conventions */

81
ENTRY(call_rwsem_downgrade_wake)

82
	CFI_STARTPROC

83
	save_common_regs

84
	pushq_cfi %rdx

85
	CFI_REL_OFFSET rdx, 0

86
	movq %rax,%rdi

87
	call rwsem_downgrade_wake

88
	popq_cfi %rdx

89
	CFI_RESTORE rdx

90
	restore_common_regs

91
	ret

92
	CFI_ENDPROC

93
ENDPROC(call_rwsem_downgrade_wake)

94


95