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review.evervolv.com / android_kernel_htc_msm8960 / 6c3652efcafa6a6d795093362cb4290c84994b5c / . / arch / x86 / vdso / vdso32 / sysenter.S
blob: 109bfa394eaa32e6601802809c8c9559718ff95b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/*
2 * Code for the vsyscall page. This version uses the sysenter instruction.
3 *
4 * NOTE:
5 * 1) __kernel_vsyscall _must_ be first in this page.
6 * 2) there are alignment constraints on this stub, see vsyscall-sigreturn.S
7 * for details.
8 */
9
Albert D. Cahalan581141c2006-02-14 13:53:20 -0800[diff] [blame]10/*
11 * The caller puts arg2 in %ecx, which gets pushed. The kernel will use
12 * %ecx itself for arg2. The pushing is because the sysexit instruction
13 * (found in entry.S) requires that we clobber %ecx with the desired %esp.
14 * User code might expect that %ecx is unclobbered though, as it would be
15 * for returning via the iret instruction, so we must push and pop.
16 *
17 * The caller puts arg3 in %edx, which the sysexit instruction requires
18 * for %eip. Thus, exactly as for arg2, we must push and pop.
19 *
20 * Arg6 is different. The caller puts arg6 in %ebp. Since the sysenter
21 * instruction clobbers %esp, the user's %esp won't even survive entry
22 * into the kernel. We store %esp in %ebp. Code in entry.S must fetch
23 * arg6 from the stack.
Chuck Ebbertbe0a3912006-03-23 02:59:48 -0800[diff] [blame]24 *
25 * You can not use this vsyscall for the clone() syscall because the
26 * three dwords on the parent stack do not get copied to the child.
Albert D. Cahalan581141c2006-02-14 13:53:20 -0800[diff] [blame]27 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]28 .text
29 .globl __kernel_vsyscall
30 .type __kernel_vsyscall,@function
31__kernel_vsyscall:
32.LSTART_vsyscall:
33 push %ecx
34.Lpush_ecx:
35 push %edx
36.Lpush_edx:
37 push %ebp
38.Lenter_kernel:
39 movl %esp,%ebp
40 sysenter
41
42 /* 7: align return point with nop's to make disassembly easier */
43 .space 7,0x90
44
Ingo Molnare6e54942006-06-27 02:53:50 -0700[diff] [blame]45 /* 14: System call restart point is here! (SYSENTER_RETURN-2) */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]46 jmp .Lenter_kernel
47 /* 16: System call normal return point is here! */
Roland McGrath6c3652e2008-01-30 13:30:42 +0100[diff] [blame^]48VDSO32_SYSENTER_RETURN: /* Symbol used by sysenter.c via vdso32-syms.h */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]49 pop %ebp
50.Lpop_ebp:
51 pop %edx
52.Lpop_edx:
53 pop %ecx
54.Lpop_ecx:
55 ret
56.LEND_vsyscall:
57 .size __kernel_vsyscall,.-.LSTART_vsyscall
58 .previous
59
60 .section .eh_frame,"a",@progbits
61.LSTARTFRAMEDLSI:
62 .long .LENDCIEDLSI-.LSTARTCIEDLSI
63.LSTARTCIEDLSI:
64 .long 0 /* CIE ID */
65 .byte 1 /* Version number */
66 .string "zR" /* NUL-terminated augmentation string */
67 .uleb128 1 /* Code alignment factor */
68 .sleb128 -4 /* Data alignment factor */
69 .byte 8 /* Return address register column */
70 .uleb128 1 /* Augmentation value length */
71 .byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
72 .byte 0x0c /* DW_CFA_def_cfa */
73 .uleb128 4
74 .uleb128 4
75 .byte 0x88 /* DW_CFA_offset, column 0x8 */
76 .uleb128 1
77 .align 4
78.LENDCIEDLSI:
79 .long .LENDFDEDLSI-.LSTARTFDEDLSI /* Length FDE */
80.LSTARTFDEDLSI:
81 .long .LSTARTFDEDLSI-.LSTARTFRAMEDLSI /* CIE pointer */
82 .long .LSTART_vsyscall-. /* PC-relative start address */
83 .long .LEND_vsyscall-.LSTART_vsyscall
84 .uleb128 0
85 /* What follows are the instructions for the table generation.
86 We have to record all changes of the stack pointer. */
87 .byte 0x04 /* DW_CFA_advance_loc4 */
88 .long .Lpush_ecx-.LSTART_vsyscall
89 .byte 0x0e /* DW_CFA_def_cfa_offset */
90 .byte 0x08 /* RA at offset 8 now */
91 .byte 0x04 /* DW_CFA_advance_loc4 */
92 .long .Lpush_edx-.Lpush_ecx
93 .byte 0x0e /* DW_CFA_def_cfa_offset */
94 .byte 0x0c /* RA at offset 12 now */
95 .byte 0x04 /* DW_CFA_advance_loc4 */
96 .long .Lenter_kernel-.Lpush_edx
97 .byte 0x0e /* DW_CFA_def_cfa_offset */
98 .byte 0x10 /* RA at offset 16 now */
99 .byte 0x85, 0x04 /* DW_CFA_offset %ebp -16 */
100 /* Finally the epilogue. */
101 .byte 0x04 /* DW_CFA_advance_loc4 */
102 .long .Lpop_ebp-.Lenter_kernel
103 .byte 0x0e /* DW_CFA_def_cfa_offset */
104 .byte 0x0c /* RA at offset 12 now */
105 .byte 0xc5 /* DW_CFA_restore %ebp */
106 .byte 0x04 /* DW_CFA_advance_loc4 */
107 .long .Lpop_edx-.Lpop_ebp
108 .byte 0x0e /* DW_CFA_def_cfa_offset */
109 .byte 0x08 /* RA at offset 8 now */
110 .byte 0x04 /* DW_CFA_advance_loc4 */
111 .long .Lpop_ecx-.Lpop_edx
112 .byte 0x0e /* DW_CFA_def_cfa_offset */
113 .byte 0x04 /* RA at offset 4 now */
114 .align 4
115.LENDFDEDLSI:
116 .previous
117
118/*
119 * Get the common code for the sigreturn entry points.
120 */
Roland McGrath0c2f51a2008-01-30 13:30:42 +0100[diff] [blame]121#include "sigreturn.S"