srt0.S revision 1.2.20.1
1 /* $NetBSD: srt0.S,v 1.2.20.1 2010/04/30 14:39:38 uebayasi Exp $ */ 2 3 /*- 4 * Copyright (c) 2002 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Steve C. Woodford. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <machine/asm.h> 33 #include <machine/psl.h> 34 #include <powerpc/spr.h> 35 #include <powerpc/oea/spr.h> 36 37 #define STACK_SIZE 8192 38 39 /* 40 * The main entry point when loaded by PPC-Bug. 41 * 42 * There are two possible entry conditions here: 43 * 44 * 1) We were booted in `PReP' mode, either from disk or the network. 45 * In this case, we have no control over the load address so we 46 * have to relocate ourselves to the appropriate place. 47 * The firmware passes us the following registers: 48 * 49 * r1 -> Temporary stack 50 * r3 -> Residual Data 51 * r4 -> The address we were loaded to 52 * r5 -> Zero 53 * 54 * 2) We were booted over the network in Non-PReP mode. In this case, 55 * the load address is usually set using PPC-Bug's "niot" command, 56 * but we won't depend on it so relocation may be required. The 57 * firmware passes us the following registers: 58 * 59 * r1 -> Temporary stack 60 * r3 -> CLUN of the network device we booted from 61 * r4 -> DLUN of the network device we booted from 62 * r5 -> Non-zero 63 * r6 -> Base address of network device 64 * r7 -> Execution address of loaded program 65 * r8 -> Address of IP-address data structure 66 * r9 -> Pointer to start of filename string 67 * r10 -> Pointer to end+1 of filename string 68 * r11 -> Pointer to start of argument string 69 * r12 -> Pointer to end+1 of argument string 70 * 71 * The obvious way to distinguish between the two boot modes is by 72 * checking the value of r5. 73 */ 74 ENTRY(_start) 75 bl 1f 76 1: xor r0,r0,r0 77 78 /* First, switch off Instruction and Data caches. */ 79 mfspr r13,SPR_HID0 80 LDCONST(r14, HID0_DCE|HID0_ICE) 81 andc r13,r13,r14 82 sync 83 mtspr SPR_HID0,r13 84 85 86 /* 87 * All registers now available. Let's see if we need to relocate 88 */ 89 LDCONST(r13,_C_LABEL(_start)) /* Where we'd like to be */ 90 LDCONST(r14,_C_LABEL(edata)) /* End of data section */ 91 LDCONST(r15,0x3) 92 add r14,r14,r15 93 andc r14,r14,r15 /* Rounded up to the nearest 32-bits */ 94 sub r15,r14,r13 /* Our size, in bytes */ 95 mflr r16 /* Get address we were loaded to */ 96 subi r16,r16,0x4 /* Correct for branch */ 97 cmp cr0,r13,r16 /* Do we need to relocate? */ 98 beq _ASM_LABEL(clrbss) /* No relocation necessary */ 99 li r17,0x4 100 bgt 1f /* Relocate using forward copy? */ 101 102 /* Nope. Need to copy in reverse in case of overlap */ 103 mr r13,r14 /* dest -> end */ 104 add r16,r16,r15 /* src + size */ 105 subi r17,r17,0x8 /* Increment is -4 */ 106 107 /* 108 * Do the relocation 109 * r13 -> dest 110 * r15 -> number of bytes 111 * r16 -> src 112 * r17 -> Increment (+4 or -4) 113 */ 114 1: srwi r15,r15,0x2 /* Convert length to 32-bit words */ 115 mtctr r15 /* Save in counter register */ 116 117 2: lwz r15,0(r16) 118 stw r15,0(r13) 119 add r16,r16,r17 120 add r13,r13,r17 121 bdnz 2b 122 123 /* Now do an absolute jump to the relocated code */ 124 LDCONST(r13,_ASM_LABEL(clrbss)) 125 mtlr r13 126 blr 127 128 ASENTRY(clrbss) 129 LDCONST(r13,_C_LABEL(edata)) /* End of the data section */ 130 LDCONST(r14,_C_LABEL(end)) /* End of BSS */ 131 LDCONST(r15,0x3) 132 add r14,r14,r15 133 andc r14,r14,r15 /* Round-up end of BSS to 32-bits */ 134 sub r15,r14,r13 /* r15 == length of BSS */ 135 srwi r15,r15,0x2 136 mtctr r15 /* CTR == # of 32-bit words in BSS */ 137 1: stw r0,0(r13) /* Clear BSS */ 138 addi r13,r13,4 139 bdnz 1b 140 141 /* Fix up our own stack */ 142 LDCONST(r1,stack) 143 addi r1,r1,STACK_SIZE-0x10 144 LDCONST(r13,0x0f) 145 andc r1,r1,r13 146 147 /* 148 * Copy the arguments passed in from Bug into bug_bootinfo 149 * 150 * See bugsyscalls.h for details. 151 */ 152 LDCONST(r13,_C_LABEL(bug_bootinfo)) 153 stw r5,0x00(r13) 154 stw r3,0x04(r13) 155 stw r4,0x08(r13) 156 stw r6,0x0c(r13) 157 stw r7,0x10(r13) 158 stw r8,0x14(r13) 159 stw r9,0x18(r13) 160 stw r10,0x1c(r13) 161 stw r11,0x20(r13) 162 stw r12,0x24(r13) 163 164 mr r3,r13 165 bl _C_LABEL(main) /* void main(void) */ 166 /* FALLTHROUGH */ 167 168 /* 169 * Return to the debugger, either because main() returned or via panic(). 170 */ 171 ENTRY(_rtt) 172 addi r10,0,0x0063 173 sc 174 1: nop 175 b 1b 176 177 /* 178 * C code runs on this stack. 179 */ 180 .comm stack,STACK_SIZE,4 181 .comm errno,4,4 182 .comm debug,4,4 183
Indexes created Wed Oct 29 03:09:52 GMT 2025