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#ifdef _ARM_ARCH_6 43 mrc p15, 0, ip, c1, c0, 0 44 orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE) 45 orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE) 46 mcr p15, 0, ip, c1, c0, 0 47#endif 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 /* Hint where to look for the API signature */ 65 ldr ip, =uboot_address 66 str sp, [ip] 67 68 /* Save U-Boot's r8 and r9 */ 69 ldr ip, =saved_regs 70 str r8, [ip, #0] 71 str r9, [ip, #4] 72 73 /* 74 * Start loader. This is basically a tail-recursion call; if main() 75 * returns, it returns to u-boot (which reports the value returned r0). 76 */ 77 b main 78 79 /* 80 * Data for self-relocation, in the text segment for pc-rel access. 81 */ 82.here_off: 83 .word . 84.dynamic_off: 85 .word _DYNAMIC 86 87/* 88 * syscall() 89 */ 90ENTRY(syscall) 91 /* Save caller's lr, r8 and r9 */ 92 ldr ip, =saved_regs 93 str r8, [ip, #8] 94 str r9, [ip, #12] 95 str lr, [ip, #16] 96 /* Restore U-Boot's r8 and r9 */ 97 ldr r8, [ip, #0] 98 ldr r9, [ip, #4] 99 /* Call into U-Boot */ 100 ldr lr, =return_from_syscall 101 ldr ip, =syscall_ptr 102 ldr pc, [ip] 103return_from_syscall: 104 /* Restore loader's r8, r9 and lr */ 105 ldr ip, =saved_regs 106 ldr lr, [ip, #16] 107 ldr r9, [ip, #12] 108 ldr r8, [ip, #8] 109 /* Return to caller */ 110 mov pc, lr 111 112/* 113 * Data section 114 */ 115 .data 116 .align 4 117 .globl syscall_ptr 118syscall_ptr: 119 .long 0 120 121 .globl uboot_address 122uboot_address: 123 .long 0 124 125saved_regs: 126 .long 0 /* U-Boot's r8 */ 127 .long 0 /* U-Boot's r9 */ 128 .long 0 /* Loader's r8 */ 129 .long 0 /* Loader's r9 */ 130 .long 0 /* Loader's lr */ 131