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