rtld_start.S revision 1.20
1 /* $NetBSD: rtld_start.S,v 1.20 2014/03/19 21:52:00 joerg Exp $ */ 2 3 /* 4 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 5 * Portions copyright 2002, 2003 Charles M. Hannum <root (at) ihack.net> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <machine/asm.h> 32 33 /* R9 contains the address of PS_STRINGS and since its caller saved, 34 * we can just use it. R6 has a backup copy of the stack pointer which 35 * we can use as well. 36 */ 37 ENTRY(_rtld_start, 0) 38 /* Allocate space on the stack for the cleanup and obj_main 39 * entries that _rtld() will provide for us. 40 */ 41 clrl %fp 42 subl2 $8,%sp 43 44 movab _DYNAMIC,%r0 45 subl3 _GLOBAL_OFFSET_TABLE_,%r0,%r10 46 pushl %r10 /* relocbase */ 47 pushl %r0 /* &_DYNAMIC */ 48 calls $2,_rtld_relocate_nonplt_self 49 50 pushl %r10 /* relocbase */ 51 pushal 4(%sp) /* sp */ 52 calls $2,_rtld /* entry = _rtld(sp, relocbase) */ 53 54 movq (%sp)+,%r7 /* grab cleanup and obj_main into %r7/%r8 */ 55 jmp 2(%r0) /* jump to entry point + 2 */ 56 END(_rtld_start) 57 58 /* 59 * Lazy binding entry point, called via PLT via JMP into pltgot[1]. 60 * SP+0: obj entry points 61 * SP+4: address to relocation index 62 * 63 * Note: Some functions rely on there not being an additional call frame; 64 * hence the `optimization' to avoid the callg opportunistically. 65 */ 66 ALTENTRY(_rtld_bind_start) 67 movab -64(%sp),%sp /* reserve some space */ 68 pushr $0x3f /* save R0-R5 */ 69 movq -8(%fp),%r0 /* get addresses of plt.got & reloc index */ 70 pushl (%r1) /* push relocation index */ 71 pushl %r0 /* push address of obj entry */ 72 calls $2,_rtld_bind 73 74 addl3 $2,%r0,%r3 /* save routine address */ 75 extzv $0,$12,(%r0),%r1 /* get entry mask */ 76 extzv $0,$12,6(%fp),%r2 /* get saved mask */ 77 cmpw %r1,%r2 /* compare them */ 78 bneq 12f /* if they are different, rebuild */ 79 movl %r3,-4(%fp) /* save routine address */ 80 popr $0x3f /* pop registers */ 81 movab 68(%sp),%sp /* restore sp */ 82 rsb /* and jump to it */ 83 84 /* 85 * We need to rebuild the callframe. Save the current one in case 86 * we might overwrite it. 87 */ 88 12: movq 4(%fp),-(%sp) /* save PSW and AP */ 89 movq 12(%fp),-(%sp) /* save FP and return address */ 90 /* 91 * Find out where this this call frame ends. 92 */ 93 movl %ap,%r0 /* get past callframe and registers */ 94 bbs $29,4(%fp),22f /* calls is easy, it's where AP is */ 95 /* 96 * Callg not so much 97 */ 98 movab 20(%fp),%r0 /* past fixed callframe */ 99 tstw %r2 /* no saved registers? */ 100 beql 22f /* none, so we are done. */ 101 movl $11,%r4 /* start with register 11 */ 102 20: bbc %r4,%r2,21f /* save this register? */ 103 addl2 $4,%r0 /* yes, adjust for saved register */ 104 21: sobgeq %r4,20b /* try next register */ 105 106 22: 107 /* 108 * First "push" the caller saved registers (if there any that 109 * need to saved.) 110 */ 111 tstw %r1 /* if there are no registers to save */ 112 beql 1f /* just push the callframe */ 113 cmpw %r1,$63 /* if there are no caller-saved registers */ 114 blequ 5f /* skip them */ 115 bbc $11,%r1,10f /* does it need to be saved? */ 116 movl %r11,-(%r0) 117 10: bbc $10,%r1,9f /* does it need to be saved? */ 118 movl %r10,-(%r0) 119 9: bbc $9,%r1,8f /* does it need to be saved? */ 120 movl %r9,-(%r0) 121 8: bbc $8,%r1,7f /* does it need to be saved? */ 122 movl %r8,-(%r0) 123 7: bbc $7,%r1,6f /* does it need to be saved? */ 124 movl %r7,-(%r0) 125 6: bbc $6,%r1,5f /* does it need to be saved? */ 126 movl %r6,-(%r0) 127 5: 128 /* 129 * r0-r5 are not normally preserved so we should be done. 130 */ 131 cmpw %r1,$63 132 bgtru 1f 133 /* 134 * For some reason, we have to preserve these. 135 */ 136 movab 16(%sp),%r2 137 bbc $5,%r1,4f /* does it need to be saved? */ 138 movl 20(%r2),-(%r0) 139 4: bbc $4,%r1,3f /* does it need to be saved? */ 140 movl 16(%r2),-(%r0) 141 3: bbc $3,%r1,2f /* does it need to be saved? */ 142 movl 12(%r2),-(%r0) 143 2: bbc $2,%r1,1f /* does it need to be saved? */ 144 movl 8(%r2),-(%r0) 145 146 /* 147 * Now we save the fixed part of the callframe. 148 */ 149 1: clrl %r4 /* clear condition handler slot */ 150 movq (%sp)+,-(%r0) /* move FP and PC into place */ 151 movq (%sp)+,-(%r0) /* move PSW/save-mask/etc + AP into place */ 152 movq %r3,-(%r0) /* move routine address + cond handle slot */ 153 addl3 $4,%r0,%fp /* get start of new callframe */ 154 insv %r1,$0,$12,6(%fp) /* insert new saved mask */ 155 popr $0x3f /* restore R0-R5 (cond flags not modified) */ 156 subl3 $4,%fp,%sp /* sp needs to be equal to fp */ 157 rsb /* and jmp to the routine */ 158 END(_rtld_bind_start) 159
Indexes created Thu Oct 02 14:10:14 GMT 2025