1/*- 2 * Copyright (c) 2008 Semihalf, Rafal Czubak 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <machine/asm.h> 28#include <machine/armreg.h> 29 30 .text 31 .extern _C_LABEL(self_reloc), _C_LABEL(main) 32 .weak _DYNAMIC 33 34/* 35 * Entry point to the loader that U-Boot passes control to. 36 */ 37 .globl _start 38_start: 39 40 mrc p15, 0, ip, c1, c0, 0 41 orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE) 42 orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE) 43 mcr p15, 0, ip, c1, c0, 0 44 45 /* Save the arguments and return register before calling self_reloc */ 46 push {r0, r1, r9, lr} 47 48 /* 49 * Do self-relocation when the weak external symbol _DYNAMIC is non-NULL. 50 * When linked as a dynamic relocatable file, the linker automatically 51 * defines _DYNAMIC with a value that is the offset of the dynamic 52 * relocation info section. 53 * Note that we're still on u-boot's stack here, but the self_reloc 54 * code uses only a couple dozen bytes of stack space. 55 */ 56 adr ip, .here_off /* .here_off is a symbol whose value */ 57 ldr r0, [ip] /* is its own offset in the text seg. */ 58 sub r0, ip, r0 /* Get its pc-relative address and */ 59 ldr r1, .dynamic_off /* subtract its value and we get */ 60 teq r1, #0 /* r0 = physaddr we were loaded at. */ 61 addne r1, r1, r0 /* r1 = dynamic section physaddr. */ 62 blne _C_LABEL(self_reloc) /* Do reloc if _DYNAMIC is non-NULL. */ 63 64 /* Restore saved arguments */ 65 pop {r0, r1, r9, lr} 66 67 /* Hint where to look for the API signature */ 68 ldr ip, =uboot_address 69 str sp, [ip] 70 71 /* Save U-Boot's r8 and r9 for syscall trampoline */ 72 ldr ip, =saved_regs 73 str r8, [ip, #0] /* old gd pointer (use to hold lr) */ 74 str r9, [ip, #4] /* new gd pointer */ 75 76 /* 77 * Start loader. Save return address first (r8 is available from 78 * trampoline save). 79 */ 80 mov r8, lr 81 bl main 82 mov lr, r8 83 84 /* Restore U-Boot environment */ 85 ldr ip, =saved_regs 86 ldr r8, [ip, #0] 87 ldr r9, [ip, #4] 88 mov pc, lr 89 90 /* 91 * Data for self-relocation, in the text segment for pc-rel access. 92 */ 93.here_off: 94 .word . 95.dynamic_off: 96 .word _DYNAMIC 97 98/* 99 * syscall() 100 */ 101ENTRY(syscall) 102 /* Save caller's lr, r8 and r9 */ 103 ldr ip, =saved_regs 104 str r8, [ip, #8] 105 str r9, [ip, #12] 106 str lr, [ip, #16] 107 /* Restore U-Boot's r8 and r9 */ 108 ldr r8, [ip, #0] 109 ldr r9, [ip, #4] 110 /* Call into U-Boot */ 111 ldr lr, =return_from_syscall 112 ldr ip, =syscall_ptr 113 ldr pc, [ip] 114return_from_syscall: 115 /* Restore loader's r8, r9 and lr */ 116 ldr ip, =saved_regs 117 ldr lr, [ip, #16] 118 ldr r9, [ip, #12] 119 ldr r8, [ip, #8] 120 /* Return to caller */ 121 mov pc, lr 122 123/* 124 * Data section 125 */ 126 .data 127 .align 4 128 .globl syscall_ptr 129syscall_ptr: 130 .long 0 131 132 .globl uboot_address 133uboot_address: 134 .long 0 135 136saved_regs: 137 .long 0 /* U-Boot's r8 */ 138 .long 0 /* U-Boot's r9 */ 139 .long 0 /* Loader's r8 */ 140 .long 0 /* Loader's r9 */ 141 .long 0 /* Loader's lr */ 142