projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 | 1 | /* |
| 69d0627a | 2 | * Code for the vDSO. This version uses the sysenter instruction. |
| 1da177e4 | 3 | * |
| 69d0627a RM |
4 | * First get the common code for the sigreturn entry points. |
| 5 | * This must come first. | |
| 1da177e4 | 6 | */ |
| 69d0627a | 7 | #include "sigreturn.S" |
| 1da177e4 | 8 | |
| 581141cb AC |
9 | /* |
| 10 | * The caller puts arg2 in %ecx, which gets pushed. The kernel will use | |
| 11 | * %ecx itself for arg2. The pushing is because the sysexit instruction | |
| 12 | * (found in entry.S) requires that we clobber %ecx with the desired %esp. | |
| 13 | * User code might expect that %ecx is unclobbered though, as it would be | |
| 14 | * for returning via the iret instruction, so we must push and pop. | |
| 15 | * | |
| 16 | * The caller puts arg3 in %edx, which the sysexit instruction requires | |
| 17 | * for %eip. Thus, exactly as for arg2, we must push and pop. | |
| 18 | * | |
| 19 | * Arg6 is different. The caller puts arg6 in %ebp. Since the sysenter | |
| 20 | * instruction clobbers %esp, the user's %esp won't even survive entry | |
| 21 | * into the kernel. We store %esp in %ebp. Code in entry.S must fetch | |
| 22 | * arg6 from the stack. | |
| be0a3912 CE |
23 | * |
| 24 | * You can not use this vsyscall for the clone() syscall because the | |
| 69d0627a | 25 | * three words on the parent stack do not get copied to the child. |
| 581141cb | 26 | */ |
| 1da177e4 LT |
27 | .text |
| 28 | .globl __kernel_vsyscall | |
| 29 | .type __kernel_vsyscall,@function | |
| 69d0627a | 30 | ALIGN |
| 1da177e4 LT |
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 | ||
| e6e5494c | 45 | /* 14: System call restart point is here! (SYSENTER_RETURN-2) */ |
| 1da177e4 LT |
46 | jmp .Lenter_kernel |
| 47 | /* 16: System call normal return point is here! */ | |
| 6c3652ef | 48 | VDSO32_SYSENTER_RETURN: /* Symbol used by sysenter.c via vdso32-syms.h */ |
| 1da177e4 LT |
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. */ | |
| cadd5164 | 87 | .byte 0x40 + (.Lpush_ecx-.LSTART_vsyscall) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
88 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 89 | .byte 0x08 /* RA at offset 8 now */ | |
| cadd5164 | 90 | .byte 0x40 + (.Lpush_edx-.Lpush_ecx) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
91 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 92 | .byte 0x0c /* RA at offset 12 now */ | |
| cadd5164 | 93 | .byte 0x40 + (.Lenter_kernel-.Lpush_edx) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
94 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 95 | .byte 0x10 /* RA at offset 16 now */ | |
| 96 | .byte 0x85, 0x04 /* DW_CFA_offset %ebp -16 */ | |
| 97 | /* Finally the epilogue. */ | |
| cadd5164 | 98 | .byte 0x40 + (.Lpop_ebp-.Lenter_kernel) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
99 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 100 | .byte 0x0c /* RA at offset 12 now */ | |
| 101 | .byte 0xc5 /* DW_CFA_restore %ebp */ | |
| cadd5164 | 102 | .byte 0x40 + (.Lpop_edx-.Lpop_ebp) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
103 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 104 | .byte 0x08 /* RA at offset 8 now */ | |
| cadd5164 | 105 | .byte 0x40 + (.Lpop_ecx-.Lpop_edx) /* DW_CFA_advance_loc */ |
| 1da177e4 LT |
106 | .byte 0x0e /* DW_CFA_def_cfa_offset */ |
| 107 | .byte 0x04 /* RA at offset 4 now */ | |
| 108 | .align 4 | |
| 109 | .LENDFDEDLSI: | |
| 110 | .previous | |
| 111 | ||
| 69d0627a RM |
112 | /* |
| 113 | * Emit a symbol with the size of this .eh_frame data, | |
| 114 | * to verify it matches the other versions. | |
| 115 | */ | |
| 116 | VDSO32_vsyscall_eh_frame_size = (.LENDFDEDLSI-.LSTARTFRAMEDLSI) |