1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2011-2012 Synopsys (www.synopsys.com) 4 * 5 * vineetg : May 2011 6 * -Adapted (from .26 to .35) 7 * -original contribution by Tim.yao@amlogic.com 8 */ 9 10 #include <linux/types.h> 11 #include <linux/perf_event.h> 12 #include <linux/ptrace.h> 13 #include <linux/uaccess.h> 14 #include <asm/disasm.h> 15 16 #ifdef CONFIG_CPU_BIG_ENDIAN 17 #define BE 1 18 #define FIRST_BYTE_16 "swap %1, %1\n swape %1, %1\n" 19 #define FIRST_BYTE_32 "swape %1, %1\n" 20 #else 21 #define BE 0 22 #define FIRST_BYTE_16 23 #define FIRST_BYTE_32 24 #endif 25 26 #define __get8_unaligned_check(val, addr, err) \ 27 __asm__( \ 28 "1: ldb.ab %1, [%2, 1]\n" \ 29 "2:\n" \ 30 " .section .fixup,\"ax\"\n" \ 31 " .align 4\n" \ 32 "3: mov %0, 1\n" \ 33 " j 2b\n" \ 34 " .previous\n" \ 35 " .section __ex_table,\"a\"\n" \ 36 " .align 4\n" \ 37 " .long 1b, 3b\n" \ 38 " .previous\n" \ 39 : "=r" (err), "=&r" (val), "=r" (addr) \ 40 : "0" (err), "2" (addr)) 41 42 #define get16_unaligned_check(val, addr) \ 43 do { \ 44 unsigned int err = 0, v, a = addr; \ 45 __get8_unaligned_check(v, a, err); \ 46 val = v << ((BE) ? 8 : 0); \ 47 __get8_unaligned_check(v, a, err); \ 48 val |= v << ((BE) ? 0 : 8); \ 49 if (err) \ 50 goto fault; \ 51 } while (0) 52 53 #define get32_unaligned_check(val, addr) \ 54 do { \ 55 unsigned int err = 0, v, a = addr; \ 56 __get8_unaligned_check(v, a, err); \ 57 val = v << ((BE) ? 24 : 0); \ 58 __get8_unaligned_check(v, a, err); \ 59 val |= v << ((BE) ? 16 : 8); \ 60 __get8_unaligned_check(v, a, err); \ 61 val |= v << ((BE) ? 8 : 16); \ 62 __get8_unaligned_check(v, a, err); \ 63 val |= v << ((BE) ? 0 : 24); \ 64 if (err) \ 65 goto fault; \ 66 } while (0) 67 68 #define put16_unaligned_check(val, addr) \ 69 do { \ 70 unsigned int err = 0, v = val, a = addr;\ 71 \ 72 __asm__( \ 73 FIRST_BYTE_16 \ 74 "1: stb.ab %1, [%2, 1]\n" \ 75 " lsr %1, %1, 8\n" \ 76 "2: stb %1, [%2]\n" \ 77 "3:\n" \ 78 " .section .fixup,\"ax\"\n" \ 79 " .align 4\n" \ 80 "4: mov %0, 1\n" \ 81 " j 3b\n" \ 82 " .previous\n" \ 83 " .section __ex_table,\"a\"\n" \ 84 " .align 4\n" \ 85 " .long 1b, 4b\n" \ 86 " .long 2b, 4b\n" \ 87 " .previous\n" \ 88 : "=r" (err), "=&r" (v), "=&r" (a) \ 89 : "0" (err), "1" (v), "2" (a)); \ 90 \ 91 if (err) \ 92 goto fault; \ 93 } while (0) 94 95 #define put32_unaligned_check(val, addr) \ 96 do { \ 97 unsigned int err = 0, v = val, a = addr;\ 98 \ 99 __asm__( \ 100 FIRST_BYTE_32 \ 101 "1: stb.ab %1, [%2, 1]\n" \ 102 " lsr %1, %1, 8\n" \ 103 "2: stb.ab %1, [%2, 1]\n" \ 104 " lsr %1, %1, 8\n" \ 105 "3: stb.ab %1, [%2, 1]\n" \ 106 " lsr %1, %1, 8\n" \ 107 "4: stb %1, [%2]\n" \ 108 "5:\n" \ 109 " .section .fixup,\"ax\"\n" \ 110 " .align 4\n" \ 111 "6: mov %0, 1\n" \ 112 " j 5b\n" \ 113 " .previous\n" \ 114 " .section __ex_table,\"a\"\n" \ 115 " .align 4\n" \ 116 " .long 1b, 6b\n" \ 117 " .long 2b, 6b\n" \ 118 " .long 3b, 6b\n" \ 119 " .long 4b, 6b\n" \ 120 " .previous\n" \ 121 : "=r" (err), "=&r" (v), "=&r" (a) \ 122 : "0" (err), "1" (v), "2" (a)); \ 123 \ 124 if (err) \ 125 goto fault; \ 126 } while (0) 127 128 /* sysctl hooks */ 129 int unaligned_enabled __read_mostly = 1; /* Enabled by default */ 130 int no_unaligned_warning __read_mostly = 1; /* Only 1 warning by default */ 131 132 static void fixup_load(struct disasm_state *state, struct pt_regs *regs, 133 struct callee_regs *cregs) 134 { 135 int val; 136 137 /* register write back */ 138 if ((state->aa == 1) || (state->aa == 2)) { 139 set_reg(state->wb_reg, state->src1 + state->src2, regs, cregs); 140 141 if (state->aa == 2) 142 state->src2 = 0; 143 } 144 145 if (state->zz == 0) { 146 get32_unaligned_check(val, state->src1 + state->src2); 147 } else { 148 get16_unaligned_check(val, state->src1 + state->src2); 149 150 if (state->x) 151 val = (val << 16) >> 16; 152 } 153 154 if (state->pref == 0) 155 set_reg(state->dest, val, regs, cregs); 156 157 return; 158 159 fault: state->fault = 1; 160 } 161 162 static void fixup_store(struct disasm_state *state, struct pt_regs *regs, 163 struct callee_regs *cregs) 164 { 165 /* register write back */ 166 if ((state->aa == 1) || (state->aa == 2)) { 167 set_reg(state->wb_reg, state->src2 + state->src3, regs, cregs); 168 169 if (state->aa == 3) 170 state->src3 = 0; 171 } else if (state->aa == 3) { 172 if (state->zz == 2) { 173 set_reg(state->wb_reg, state->src2 + (state->src3 << 1), 174 regs, cregs); 175 } else if (!state->zz) { 176 set_reg(state->wb_reg, state->src2 + (state->src3 << 2), 177 regs, cregs); 178 } else { 179 goto fault; 180 } 181 } 182 183 /* write fix-up */ 184 if (!state->zz) 185 put32_unaligned_check(state->src1, state->src2 + state->src3); 186 else 187 put16_unaligned_check(state->src1, state->src2 + state->src3); 188 189 return; 190 191 fault: state->fault = 1; 192 } 193 194 /* 195 * Handle an unaligned access 196 * Returns 0 if successfully handled, 1 if some error happened 197 */ 198 int misaligned_fixup(unsigned long address, struct pt_regs *regs, 199 struct callee_regs *cregs) 200 { 201 struct disasm_state state; 202 char buf[TASK_COMM_LEN]; 203 204 /* handle user mode only and only if enabled by sysadmin */ 205 if (!user_mode(regs) || !unaligned_enabled) 206 return 1; 207 208 if (no_unaligned_warning) { 209 pr_warn_once("%s(%d) made unaligned access which was emulated" 210 " by kernel assist\n. This can degrade application" 211 " performance significantly\n. To enable further" 212 " logging of such instances, please \n" 213 " echo 0 > /proc/sys/kernel/ignore-unaligned-usertrap\n", 214 get_task_comm(buf, current), task_pid_nr(current)); 215 } else { 216 /* Add rate limiting if it gets down to it */ 217 pr_warn("%s(%d): unaligned access to/from 0x%lx by PC: 0x%lx\n", 218 get_task_comm(buf, current), task_pid_nr(current), 219 address, regs->ret); 220 221 } 222 223 disasm_instr(regs->ret, &state, 1, regs, cregs); 224 225 if (state.fault) 226 goto fault; 227 228 /* ldb/stb should not have unaligned exception */ 229 if ((state.zz == 1) || (state.di)) 230 goto fault; 231 232 if (!state.write) 233 fixup_load(&state, regs, cregs); 234 else 235 fixup_store(&state, regs, cregs); 236 237 if (state.fault) 238 goto fault; 239 240 /* clear any remnants of delay slot */ 241 if (delay_mode(regs)) { 242 regs->ret = regs->bta & ~1U; 243 regs->status32 &= ~STATUS_DE_MASK; 244 } else { 245 regs->ret += state.instr_len; 246 247 /* handle zero-overhead-loop */ 248 if ((regs->ret == regs->lp_end) && (regs->lp_count)) { 249 regs->ret = regs->lp_start; 250 regs->lp_count--; 251 } 252 } 253 254 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, address); 255 return 0; 256 257 fault: 258 pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n", 259 state.words[0], address); 260 261 return 1; 262 } 263