1/*- 2 * Copyright (c) 2014 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Andrew Turner under 6 * sponsorship from the FreeBSD Foundation. 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#include <machine/asm.h> 31__FBSDID("$FreeBSD$"); 32 33ENTRY(.rtld_start) 34 mov x19, x0 /* Put ps_strings in a callee-saved register */ 35 mov x20, sp /* And the stack pointer */ 36 37 sub sp, sp, #16 /* Make room for obj_main & exit proc */ 38 39 mov x1, sp /* exit_proc */ 40 add x2, x1, #8 /* obj_main */ 41 bl _rtld /* Call the loader */ 42 mov x8, x0 /* Backup the entry point */ 43 44 ldr x2, [sp] /* Load cleanup */ 45 ldr x1, [sp, #8] /* Load obj_main */ 46 mov x0, x19 /* Restore ps_strings */ 47 mov sp, x20 /* Restore the stack pointer */ 48 br x8 /* Jump to the entry point */ 49END(.rtld_start) 50 51/* 52 * sp + 0 = &GOT[x + 3] 53 * sp + 8 = RA 54 * x16 = &GOT[2] 55 * x17 = &_rtld_bind_start 56 */ 57ENTRY(_rtld_bind_start) 58 .cfi_startproc 59 mov x17, sp 60 61 /* Save frame pointer and SP */ 62 stp x29, x30, [sp, #-16]! 63 mov x29, sp 64 .cfi_def_cfa x29, 16 65 .cfi_offset x30, -8 66 .cfi_offset x29, -16 67 68 /* Save the arguments */ 69 stp x0, x1, [sp, #-16]! 70 stp x2, x3, [sp, #-16]! 71 stp x4, x5, [sp, #-16]! 72 stp x6, x7, [sp, #-16]! 73 stp x8, xzr, [sp, #-16]! 74 75 /* Save any floating-point arguments */ 76 stp q0, q1, [sp, #-32]! 77 stp q2, q3, [sp, #-32]! 78 stp q4, q5, [sp, #-32]! 79 stp q6, q7, [sp, #-32]! 80 81 /* Calculate reloff */ 82 ldr x2, [x17, #0] /* Get the address of the entry */ 83 sub x1, x2, x16 /* Find its offset */ 84 sub x1, x1, #8 /* Adjust for x16 not being at offset 0 */ 85 /* Each rela item has 3 entriesso we need reloff = 3 * index */ 86 lsl x3, x1, #1 /* x3 = 2 * offset */ 87 add x1, x1, x3 /* x1 = x3 + offset = 3 * offset */ 88 89 /* Load obj */ 90 ldr x0, [x16, #-8] 91 92 /* Call into rtld */ 93 bl _rtld_bind 94 95 /* Backup the address to branch to */ 96 mov x16, x0 97 98 /* restore the arguments */ 99 ldp q6, q7, [sp], #32 100 ldp q4, q5, [sp], #32 101 ldp q2, q3, [sp], #32 102 ldp q0, q1, [sp], #32 103 ldp x8, xzr, [sp], #16 104 ldp x6, x7, [sp], #16 105 ldp x4, x5, [sp], #16 106 ldp x2, x3, [sp], #16 107 ldp x0, x1, [sp], #16 108 109 /* Restore frame pointer */ 110 ldp x29, xzr, [sp], #16 111 112 /* Restore link register saved by the plt code */ 113 ldp xzr, x30, [sp], #16 114 115 /* Call into the correct function */ 116 br x16 117 .cfi_endproc 118END(_rtld_bind_start) 119 120/* 121 * struct rel_tlsdesc { 122 * uint64_t resolver_fnc; 123 * uint64_t resolver_arg; 124 * 125 * 126 * uint64_t _rtld_tlsdesc_static(struct rel_tlsdesc *); 127 * 128 * Resolver function for TLS symbols resolved at load time 129 */ 130ENTRY(_rtld_tlsdesc_static) 131 .cfi_startproc 132 ldr x0, [x0, #8] 133 ret 134 .cfi_endproc 135END(_rtld_tlsdesc_static) 136 137/* 138 * uint64_t _rtld_tlsdesc_undef(void); 139 * 140 * Resolver function for weak and undefined TLS symbols 141 */ 142ENTRY(_rtld_tlsdesc_undef) 143 .cfi_startproc 144 str x1, [sp, #-16]! 145 .cfi_adjust_cfa_offset 16 146 147 mrs x1, tpidr_el0 148 ldr x0, [x0, #8] 149 sub x0, x0, x1 150 151 ldr x1, [sp], #16 152 .cfi_adjust_cfa_offset -16 153 .cfi_endproc 154 ret 155END(_rtld_tlsdesc_undef) 156 157/* 158 * uint64_t _rtld_tlsdesc_dynamic(struct rel_tlsdesc *); 159 * 160 * Resolver function for TLS symbols from dlopen() 161 */ 162ENTRY(_rtld_tlsdesc_dynamic) 163 .cfi_startproc 164 165 /* Save registers used in fast path */ 166 stp x1, x2, [sp, #(-2 * 16)]! 167 stp x3, x4, [sp, #(1 * 16)] 168 .cfi_adjust_cfa_offset 2 * 16 169 .cfi_rel_offset x1, 0 170 .cfi_rel_offset x2, 8 171 .cfi_rel_offset x3, 16 172 .cfi_rel_offset x4, 24 173 174 /* Test fastpath - inlined version of tls_get_addr_common(). */ 175 ldr x1, [x0, #8] /* tlsdesc ptr */ 176 mrs x4, tpidr_el0 177 ldr x0, [x4] /* DTV pointer */ 178 ldr x2, [x0] /* dtv[0] (generation count) */ 179 ldr x3, [x1] /* tlsdec->dtv_gen */ 180 cmp x2, x3 181 b.ne 1f /* dtv[0] != tlsdec->dtv_gen */ 182 183 ldr w2, [x1, #8] /* tlsdec->tls_index */ 184 add w2, w2, #1 185 ldr x3, [x0, w2, sxtw #3] /* dtv[tlsdesc->tls_index + 1] */ 186 cbz x3, 1f 187 188 /* Return (dtv[tlsdesc->tls_index + 1] + tlsdesc->tls_offs - tp) */ 189 ldr x2, [x1, #16] /* tlsdec->tls_offs */ 190 add x2, x2, x3 191 sub x0, x2, x4 192 /* Restore registers and return */ 193 ldp x3, x4, [sp, #(1 * 16)] 194 ldp x1, x2, [sp], #(2 * 16) 195 .cfi_adjust_cfa_offset -2 * 16 196 ret 197 198 /* 199 * Slow path 200 * return( 201 * tls_get_addr_common(tp, tlsdesc->tls_index, tlsdesc->tls_offs)); 202 * 203 */ 2041: 205 /* Save all interger registers */ 206 stp x29, x30, [sp, #-(8 * 16)]! 207 .cfi_adjust_cfa_offset 8 * 16 208 .cfi_rel_offset x29, 0 209 .cfi_rel_offset x30, 8 210 211 mov x29, sp 212 stp x5, x6, [sp, #(1 * 16)] 213 stp x7, x8, [sp, #(2 * 16)] 214 stp x9, x10, [sp, #(3 * 16)] 215 stp x11, x12, [sp, #(4 * 16)] 216 stp x13, x14, [sp, #(5 * 16)] 217 stp x15, x16, [sp, #(6 * 16)] 218 stp x17, x18, [sp, #(7 * 16)] 219 .cfi_rel_offset x5, 16 220 .cfi_rel_offset x6, 24 221 .cfi_rel_offset x7, 32 222 .cfi_rel_offset x8, 40 223 .cfi_rel_offset x9, 48 224 .cfi_rel_offset x10, 56 225 .cfi_rel_offset x11, 64 226 .cfi_rel_offset x12, 72 227 .cfi_rel_offset x13, 80 228 .cfi_rel_offset x14, 88 229 .cfi_rel_offset x15, 96 230 .cfi_rel_offset x16, 104 231 .cfi_rel_offset x17, 112 232 .cfi_rel_offset x18, 120 233 234 /* Find the tls offset */ 235 mov x0, x4 /* tp */ 236 mov x3, x1 /* tlsdesc ptr */ 237 ldr w1, [x3, #8] /* tlsdec->tls_index */ 238 ldr x2, [x3, #16] /* tlsdec->tls_offs */ 239 bl tls_get_addr_common 240 mrs x1, tpidr_el0 241 sub x0, x0, x1 242 243 /* Restore slow patch registers */ 244 ldp x17, x18, [sp, #(7 * 16)] 245 ldp x15, x16, [sp, #(6 * 16)] 246 ldp x13, x14, [sp, #(5 * 16)] 247 ldp x11, x12, [sp, #(4 * 16)] 248 ldp x9, x10, [sp, #(3 * 16)] 249 ldp x7, x8, [sp, #(2 * 16)] 250 ldp x5, x6, [sp, #(1 * 16)] 251 ldp x29, x30, [sp], #(8 * 16) 252 .cfi_adjust_cfa_offset -8 * 16 253 .cfi_restore x29 254 .cfi_restore x30 255 256 /* Restore fast path registers and return */ 257 ldp x3, x4, [sp, #16] 258 ldp x1, x2, [sp], #(2 * 16) 259 .cfi_adjust_cfa_offset -2 * 16 260 .cfi_endproc 261 ret 262END(_rtld_tlsdesc_dynamic) 263