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 * $FreeBSD$ 27 */ 28 29#include <machine/asm.h> 30#include <machine/armreg.h> 31 32 .text 33 .extern _C_LABEL(self_reloc), _C_LABEL(main) 34 .weak _DYNAMIC 35 36/* 37 * Entry point to the loader that U-Boot passes control to. 38 */ 39 .globl _start 40_start: 41 42 mrc p15, 0, ip, c1, c0, 0 43 orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE) 44 orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE) 45 mcr p15, 0, ip, c1, c0, 0 46 47 /* Save the arguments and return register before calling self_reloc */ 48 push {r0, r1, r9, lr} 49 50 /* 51 * Do self-relocation when the weak external symbol _DYNAMIC is non-NULL. 52 * When linked as a dynamic relocatable file, the linker automatically 53 * defines _DYNAMIC with a value that is the offset of the dynamic 54 * relocation info section. 55 * Note that we're still on u-boot's stack here, but the self_reloc 56 * code uses only a couple dozen bytes of stack space. 57 */ 58 adr ip, .here_off /* .here_off is a symbol whose value */ 59 ldr r0, [ip] /* is its own offset in the text seg. */ 60 sub r0, ip, r0 /* Get its pc-relative address and */ 61 ldr r1, .dynamic_off /* subtract its value and we get */ 62 teq r1, #0 /* r0 = physaddr we were loaded at. */ 63 addne r1, r1, r0 /* r1 = dynamic section physaddr. */ 64 blne _C_LABEL(self_reloc) /* Do reloc if _DYNAMIC is non-NULL. */ 65 66 /* Restore saved arguments */ 67 pop {r0, r1, r9, lr} 68 69 /* Hint where to look for the API signature */ 70 ldr ip, =uboot_address 71 str sp, [ip] 72 73 /* Save U-Boot's r8 and r9 for syscall trampoline */ 74 ldr ip, =saved_regs 75 str r8, [ip, #0] /* old gd pointer (use to hold lr) */ 76 str r9, [ip, #4] /* new gd pointer */ 77 78 /* 79 * Start loader. Save return address first (r8 is available from 80 * trampoline save). 81 */ 82 mov r8, lr 83 bl main 84 mov lr, r8 85 86 /* Restore U-Boot environment */ 87 ldr ip, =saved_regs 88 ldr r8, [ip, #0] 89 ldr r9, [ip, #4] 90 mov pc, lr 91 92 /* 93 * Data for self-relocation, in the text segment for pc-rel access. 94 */ 95.here_off: 96 .word . 97.dynamic_off: 98 .word _DYNAMIC 99 100/* 101 * syscall() 102 */ 103ENTRY(syscall) 104 /* Save caller's lr, r8 and r9 */ 105 ldr ip, =saved_regs 106 str r8, [ip, #8] 107 str r9, [ip, #12] 108 str lr, [ip, #16] 109 /* Restore U-Boot's r8 and r9 */ 110 ldr r8, [ip, #0] 111 ldr r9, [ip, #4] 112 /* Call into U-Boot */ 113 ldr lr, =return_from_syscall 114 ldr ip, =syscall_ptr 115 ldr pc, [ip] 116return_from_syscall: 117 /* Restore loader's r8, r9 and lr */ 118 ldr ip, =saved_regs 119 ldr lr, [ip, #16] 120 ldr r9, [ip, #12] 121 ldr r8, [ip, #8] 122 /* Return to caller */ 123 mov pc, lr 124 125/* 126 * Data section 127 */ 128 .data 129 .align 4 130 .globl syscall_ptr 131syscall_ptr: 132 .long 0 133 134 .globl uboot_address 135uboot_address: 136 .long 0 137 138saved_regs: 139 .long 0 /* U-Boot's r8 */ 140 .long 0 /* U-Boot's r9 */ 141 .long 0 /* Loader's r8 */ 142 .long 0 /* Loader's r9 */ 143 .long 0 /* Loader's lr */ 144