rtld_start.S revision 1.13
1 /* $NetBSD: rtld_start.S,v 1.13 2020/05/10 06:42:38 skrll 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 Matt Fredette. 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/frame.h> 34 35 .import _GLOBAL_OFFSET_TABLE_ 36 37 ENTRY($rtld_start,HPPA_FRAME_SIZE) 38 39 /* Start stack calling convention. */ 40 copy %r3, %r1 41 copy %sp, %r3 42 stw,ma %r1, HPPA_FRAME_SIZE(%sp) 43 44 /* 45 * Save our single argument, the ps_strings pointer. We'll need this 46 * twice later: once to call _rtld, and again to transfer to the 47 * program's entry point. 48 */ 49 stw %arg0, HPPA_FRAME_ARG(0)(%r3) 50 51 /* 52 * We can't move to C until we relocate at least the 53 * Global Offset Table. Even finding the GOT is tricky 54 * without inadvertently causing the linker to make 55 * relocations for this part of the text segment. 56 */ 57 58 bl L$lpc1, %r19 59 depi 0, 31, 2, %r19 60 L$lpc1: addil L'_DYNAMIC - ($PIC_pcrel$0 - 8), %r19 61 ldo R'_DYNAMIC - ($PIC_pcrel$0 - 12)(%r1),%arg0 62 63 /* 64 * Load the absolute address of the beginning of the GOT into %r19, the 65 * shared library linkage table register, leaving it ready-to-use by 66 * the dynamic linker C code. 67 */ 68 addil L'_GLOBAL_OFFSET_TABLE_ - ($PIC_pcrel$0 - 16), %r19 69 ldo R'_GLOBAL_OFFSET_TABLE_ - ($PIC_pcrel$0 - 20)(%r1),%r19 70 71 /* 72 * The linker sets the first entry in the GOT to the unrelocated 73 * address of _DYNAMIC. Subtract this from the absolute address of 74 * _DYNAMIC to get our relocbase. 75 */ 76 ldw 0(%r19), %arg1 77 sub %arg0, %arg1, %arg1 ; %arg1 = relocbase 78 bl _rtld_relocate_nonplt_self, %rp 79 copy %arg1, %r4 ; save for later 80 81 /* 82 * Recover the ps_strings pointer, and take out the 83 * ps_argvstr member. 84 */ 85 ldw HPPA_FRAME_ARG(0)(%r3), %arg0 ; ps_strings 86 ldw 0(%arg0), %arg0 ; ps_argvstr member first in struct 87 88 /* 89 * ps_argvstr - 4 would get us a pointer to argc, comparable to the 90 * initial stack pointer on architectures where the stack grows down. 91 * Subtracting an additional eight creates the storage for obj and 92 * cleanup that _rtld needs. 93 */ 94 ldo -12(%arg0), %arg0 95 stw %arg0, HPPA_FRAME_ARG(1)(%r3) 96 97 /* Call _rtld, copying relocbase into arg1. */ 98 bl _rtld, %rp 99 copy %r4, %arg1 ; %arg1 = relocbase 100 101 /* Prepare the arguments for the entry point. */ 102 ldw HPPA_FRAME_ARG(1)(%r3), %r1 103 ldw HPPA_FRAME_ARG(0)(%r3), %arg0 ; ps_strings 104 ldw 0(%r1), %arg1 ; cleanup 105 ldw 4(%r1), %arg2 ; obj 106 107 /* End stack calling convention. */ 108 ldo HPPA_FRAME_SIZE(%r3), %sp 109 ldw,mb -HPPA_FRAME_SIZE(%sp), %r3 110 111 /* Go for it. */ 112 bv %r0(%ret0) 113 copy %r0, %rp 114 EXIT($rtld_start) 115 116 /* 117 * This does our setup for an object's GOT. %arg0 is the Obj_Entry * for the 118 * object, and %arg1 is its GOT pointer. 119 */ 120 LEAF_ENTRY(__rtld_setup_hppa_pltgot) 121 122 /* 123 * The second entry of the GOT is reserved for the dynamic linker. We 124 * put the Obj_Entry * for the object in there. 125 */ 126 stw %arg0, 4(%arg1) 127 128 /* 129 * Fill the fixup_func and fixup_ltp members of the PLT stub. This 130 * stub is inserted by the linker immediately before the GOT. We use 131 * this stub to enter our binder. 132 */ 133 134 bl L$lpc2, %arg0 135 depi 0, 31, 2, %arg0 136 L$lpc2: addil L'_rtld_bind_start - ($PIC_pcrel$0 - 8), %arg0 137 ldo R'_rtld_bind_start - ($PIC_pcrel$0 - 12)(%r1),%arg0 138 139 stw %arg0, -8(%arg1) 140 bv %r0(%rp) 141 stw %r19, -4(%arg1) 142 EXIT(__rtld_setup_hppa_pltgot) 143 144 /* 145 * In order to support lazy binding, this implementation of _rtld_bind_start is 146 * very closely tied to the shared-library call stub and the PLT stub, both 147 * inserted by the linker. 148 */ 149 150 /* 151 * This is a magic branch instruction that is used by GCC's 152 * __canonicalize_funcptr_for_compare() function to fixup relocations 153 * in order to do function pointer comparisons. 154 */ 155 156 bl _rtld_bind, %rp 157 158 ENTRY(_rtld_bind_start,HPPA_FRAME_SIZE) 159 160 /* Start stack calling convention. */ 161 copy %r3, %r1 162 copy %sp, %r3 163 164 stw,ma %r1, HPPA_FRAME_SIZE(%sp) 165 166 /* 167 * We have to save all calling convention registers that are set by the 168 * caller, because we have to restore them before transferring to the 169 * bound function. Note that this includes %ret0, %ret1, and %t1. 170 * 171 * %ret0 and %ret1 because they can have meaning on entry to a 172 * function. 173 * 174 * %t1 because it's used by libc to pass on errno values to cerror. 175 */ 176 stw %rp, HPPA_FRAME_CRP(%r3) 177 stw %arg0, HPPA_FRAME_ARG(0)(%r3) 178 stw %arg1, HPPA_FRAME_ARG(1)(%r3) 179 stw %arg2, HPPA_FRAME_ARG(2)(%r3) 180 stw %arg3, HPPA_FRAME_ARG(3)(%r3) 181 /* 0(%r3) is filled with the saved %r3 above */ 182 stw %ret0, 4(%r3) 183 stw %ret1, 8(%r3) 184 stw %t1, 12(%r3) /* %r22 */ 185 186 /* 187 * The linker PLT stub loads %r20 with (GOT - 8) for the object that 188 * needs binding done. The second entry of the GOT is reserved for the 189 * dynamic linker's use, and we previously stashed the object's 190 * Obj_Entry * there. 191 */ 192 ldw 12(%r20), %arg0 193 194 /* 195 * The linker shared-library call stub loads %r19 from the shared 196 * linkage member of the PLT entry. We previously stashed the reloff 197 * of the relocation there. 198 */ 199 copy %r19, %arg1 200 201 /* 202 * The linker PLT stub loads %r21 with the fixup_ltp word in itself. 203 * We previously stashed our %r19 value there. 204 */ 205 bl _rtld_bind, %rp 206 copy %r21, %r19 207 208 /* 209 * Our hppa version of _rtld_bind returns to us the address of the PLT 210 * entry that it fixed up. Load the function address and shared 211 * linkage for the newly bound function. 212 */ 213 ldw 0(%ret0), %r21 214 ldw 4(%ret0), %r19 215 216 /* Restore registers saved above. */ 217 ldw HPPA_FRAME_CRP(%r3), %rp 218 ldw HPPA_FRAME_ARG(0)(%r3), %arg0 219 ldw HPPA_FRAME_ARG(1)(%r3), %arg1 220 ldw HPPA_FRAME_ARG(2)(%r3), %arg2 221 ldw HPPA_FRAME_ARG(3)(%r3), %arg3 222 ldw 4(%r3), %ret0 223 ldw 8(%r3), %ret1 224 ldw 12(%r3), %t1 /* %r22 */ 225 226 /* End stack calling convention. */ 227 ldo HPPA_FRAME_SIZE(%r3), %sp 228 ldw,mb -HPPA_FRAME_SIZE(%sp), %r3 229 230 /* Transfer to the function. */ 231 bv %r0(%r21) 232 nop 233 EXIT(_rtld_bind_start) 234
Indexes created Wed Oct 22 13:09:56 GMT 2025