1 /* 2 * Copyright (C) 2011-2012 Synopsys (www.synopsys.com) 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * vineetg : May 2011 9 * -Adapted (from .26 to .35) 10 * -original contribution by Tim.yao@amlogic.com 11 * 12 */ 13 14 #include <linux/types.h> 15 #include <linux/ptrace.h> 16 #include <linux/uaccess.h> 17 #include <asm/disasm.h> 18 19 #ifdef CONFIG_CPU_BIG_ENDIAN 20 #define BE 1 21 #define FIRST_BYTE_16 "swap %1, %1\n swape %1, %1\n" 22 #define FIRST_BYTE_32 "swape %1, %1\n" 23 #else 24 #define BE 0 25 #define FIRST_BYTE_16 26 #define FIRST_BYTE_32 27 #endif 28 29 #define __get8_unaligned_check(val, addr, err) \ 30 __asm__( \ 31 "1: ldb.ab %1, [%2, 1]\n" \ 32 "2:\n" \ 33 " .section .fixup,\"ax\"\n" \ 34 " .align 4\n" \ 35 "3: mov %0, 1\n" \ 36 " b 2b\n" \ 37 " .previous\n" \ 38 " .section __ex_table,\"a\"\n" \ 39 " .align 4\n" \ 40 " .long 1b, 3b\n" \ 41 " .previous\n" \ 42 : "=r" (err), "=&r" (val), "=r" (addr) \ 43 : "0" (err), "2" (addr)) 44 45 #define get16_unaligned_check(val, addr) \ 46 do { \ 47 unsigned int err = 0, v, a = addr; \ 48 __get8_unaligned_check(v, a, err); \ 49 val = v << ((BE) ? 8 : 0); \ 50 __get8_unaligned_check(v, a, err); \ 51 val |= v << ((BE) ? 0 : 8); \ 52 if (err) \ 53 goto fault; \ 54 } while (0) 55 56 #define get32_unaligned_check(val, addr) \ 57 do { \ 58 unsigned int err = 0, v, a = addr; \ 59 __get8_unaligned_check(v, a, err); \ 60 val = v << ((BE) ? 24 : 0); \ 61 __get8_unaligned_check(v, a, err); \ 62 val |= v << ((BE) ? 16 : 8); \ 63 __get8_unaligned_check(v, a, err); \ 64 val |= v << ((BE) ? 8 : 16); \ 65 __get8_unaligned_check(v, a, err); \ 66 val |= v << ((BE) ? 0 : 24); \ 67 if (err) \ 68 goto fault; \ 69 } while (0) 70 71 #define put16_unaligned_check(val, addr) \ 72 do { \ 73 unsigned int err = 0, v = val, a = addr;\ 74 \ 75 __asm__( \ 76 FIRST_BYTE_16 \ 77 "1: stb.ab %1, [%2, 1]\n" \ 78 " lsr %1, %1, 8\n" \ 79 "2: stb %1, [%2]\n" \ 80 "3:\n" \ 81 " .section .fixup,\"ax\"\n" \ 82 " .align 4\n" \ 83 "4: mov %0, 1\n" \ 84 " b 3b\n" \ 85 " .previous\n" \ 86 " .section __ex_table,\"a\"\n" \ 87 " .align 4\n" \ 88 " .long 1b, 4b\n" \ 89 " .long 2b, 4b\n" \ 90 " .previous\n" \ 91 : "=r" (err), "=&r" (v), "=&r" (a) \ 92 : "0" (err), "1" (v), "2" (a)); \ 93 \ 94 if (err) \ 95 goto fault; \ 96 } while (0) 97 98 #define put32_unaligned_check(val, addr) \ 99 do { \ 100 unsigned int err = 0, v = val, a = addr;\ 101 \ 102 __asm__( \ 103 FIRST_BYTE_32 \ 104 "1: stb.ab %1, [%2, 1]\n" \ 105 " lsr %1, %1, 8\n" \ 106 "2: stb.ab %1, [%2, 1]\n" \ 107 " lsr %1, %1, 8\n" \ 108 "3: stb.ab %1, [%2, 1]\n" \ 109 " lsr %1, %1, 8\n" \ 110 "4: stb %1, [%2]\n" \ 111 "5:\n" \ 112 " .section .fixup,\"ax\"\n" \ 113 " .align 4\n" \ 114 "6: mov %0, 1\n" \ 115 " b 5b\n" \ 116 " .previous\n" \ 117 " .section __ex_table,\"a\"\n" \ 118 " .align 4\n" \ 119 " .long 1b, 6b\n" \ 120 " .long 2b, 6b\n" \ 121 " .long 3b, 6b\n" \ 122 " .long 4b, 6b\n" \ 123 " .previous\n" \ 124 : "=r" (err), "=&r" (v), "=&r" (a) \ 125 : "0" (err), "1" (v), "2" (a)); \ 126 \ 127 if (err) \ 128 goto fault; \ 129 } while (0) 130 131 /* sysctl hooks */ 132 int unaligned_enabled __read_mostly = 1; /* Enabled by default */ 133 int no_unaligned_warning __read_mostly = 1; /* Only 1 warning by default */ 134 135 static void fixup_load(struct disasm_state *state, struct pt_regs *regs, 136 struct callee_regs *cregs) 137 { 138 int val; 139 140 /* register write back */ 141 if ((state->aa == 1) || (state->aa == 2)) { 142 set_reg(state->wb_reg, state->src1 + state->src2, regs, cregs); 143 144 if (state->aa == 2) 145 state->src2 = 0; 146 } 147 148 if (state->zz == 0) { 149 get32_unaligned_check(val, state->src1 + state->src2); 150 } else { 151 get16_unaligned_check(val, state->src1 + state->src2); 152 153 if (state->x) 154 val = (val << 16) >> 16; 155 } 156 157 if (state->pref == 0) 158 set_reg(state->dest, val, regs, cregs); 159 160 return; 161 162 fault: state->fault = 1; 163 } 164 165 static void fixup_store(struct disasm_state *state, struct pt_regs *regs, 166 struct callee_regs *cregs) 167 { 168 /* register write back */ 169 if ((state->aa == 1) || (state->aa == 2)) { 170 set_reg(state->wb_reg, state->src2 + state->src3, regs, cregs); 171 172 if (state->aa == 3) 173 state->src3 = 0; 174 } else if (state->aa == 3) { 175 if (state->zz == 2) { 176 set_reg(state->wb_reg, state->src2 + (state->src3 << 1), 177 regs, cregs); 178 } else if (!state->zz) { 179 set_reg(state->wb_reg, state->src2 + (state->src3 << 2), 180 regs, cregs); 181 } else { 182 goto fault; 183 } 184 } 185 186 /* write fix-up */ 187 if (!state->zz) 188 put32_unaligned_check(state->src1, state->src2 + state->src3); 189 else 190 put16_unaligned_check(state->src1, state->src2 + state->src3); 191 192 return; 193 194 fault: state->fault = 1; 195 } 196 197 /* 198 * Handle an unaligned access 199 * Returns 0 if successfully handled, 1 if some error happened 200 */ 201 int misaligned_fixup(unsigned long address, struct pt_regs *regs, 202 struct callee_regs *cregs) 203 { 204 struct disasm_state state; 205 char buf[TASK_COMM_LEN]; 206 207 /* handle user mode only and only if enabled by sysadmin */ 208 if (!user_mode(regs) || !unaligned_enabled) 209 return 1; 210 211 if (no_unaligned_warning) { 212 pr_warn_once("%s(%d) made unaligned access which was emulated" 213 " by kernel assist\n. This can degrade application" 214 " performance significantly\n. To enable further" 215 " logging of such instances, please \n" 216 " echo 0 > /proc/sys/kernel/ignore-unaligned-usertrap\n", 217 get_task_comm(buf, current), task_pid_nr(current)); 218 } else { 219 /* Add rate limiting if it gets down to it */ 220 pr_warn("%s(%d): unaligned access to/from 0x%lx by PC: 0x%lx\n", 221 get_task_comm(buf, current), task_pid_nr(current), 222 address, regs->ret); 223 224 } 225 226 disasm_instr(regs->ret, &state, 1, regs, cregs); 227 228 if (state.fault) 229 goto fault; 230 231 /* ldb/stb should not have unaligned exception */ 232 if ((state.zz == 1) || (state.di)) 233 goto fault; 234 235 if (!state.write) 236 fixup_load(&state, regs, cregs); 237 else 238 fixup_store(&state, regs, cregs); 239 240 if (state.fault) 241 goto fault; 242 243 if (delay_mode(regs)) { 244 regs->ret = regs->bta; 245 regs->status32 &= ~STATUS_DE_MASK; 246 } else { 247 regs->ret += state.instr_len; 248 } 249 250 return 0; 251 252 fault: 253 pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n", 254 state.words[0], address); 255 256 return 1; 257 } 258