1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * unaligned.c: Unaligned load/store trap handling with special 4 * cases for the kernel to do them more quickly. 5 * 6 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu) 7 * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 8 */ 9 10 11 #include <linux/kernel.h> 12 #include <linux/sched/signal.h> 13 #include <linux/mm.h> 14 #include <asm/ptrace.h> 15 #include <asm/processor.h> 16 #include <linux/uaccess.h> 17 #include <linux/smp.h> 18 #include <linux/perf_event.h> 19 20 #include <asm/setup.h> 21 22 #include "kernel.h" 23 24 enum direction { 25 load, /* ld, ldd, ldh, ldsh */ 26 store, /* st, std, sth, stsh */ 27 both, /* Swap, ldstub, etc. */ 28 fpload, 29 fpstore, 30 invalid, 31 }; 32 33 static inline enum direction decode_direction(unsigned int insn) 34 { 35 unsigned long tmp = (insn >> 21) & 1; 36 37 if(!tmp) 38 return load; 39 else { 40 if(((insn>>19)&0x3f) == 15) 41 return both; 42 else 43 return store; 44 } 45 } 46 47 /* 8 = double-word, 4 = word, 2 = half-word */ 48 static inline int decode_access_size(unsigned int insn) 49 { 50 insn = (insn >> 19) & 3; 51 52 if(!insn) 53 return 4; 54 else if(insn == 3) 55 return 8; 56 else if(insn == 2) 57 return 2; 58 else { 59 printk("Impossible unaligned trap. insn=%08x\n", insn); 60 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs); 61 return 4; /* just to keep gcc happy. */ 62 } 63 } 64 65 /* 0x400000 = signed, 0 = unsigned */ 66 static inline int decode_signedness(unsigned int insn) 67 { 68 return (insn & 0x400000); 69 } 70 71 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2, 72 unsigned int rd) 73 { 74 if(rs2 >= 16 || rs1 >= 16 || rd >= 16) { 75 /* Wheee... */ 76 __asm__ __volatile__("save %sp, -0x40, %sp\n\t" 77 "save %sp, -0x40, %sp\n\t" 78 "save %sp, -0x40, %sp\n\t" 79 "save %sp, -0x40, %sp\n\t" 80 "save %sp, -0x40, %sp\n\t" 81 "save %sp, -0x40, %sp\n\t" 82 "save %sp, -0x40, %sp\n\t" 83 "restore; restore; restore; restore;\n\t" 84 "restore; restore; restore;\n\t"); 85 } 86 } 87 88 static inline int sign_extend_imm13(int imm) 89 { 90 return imm << 19 >> 19; 91 } 92 93 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs) 94 { 95 struct reg_window32 *win; 96 97 if(reg < 16) 98 return (!reg ? 0 : regs->u_regs[reg]); 99 100 /* Ho hum, the slightly complicated case. */ 101 win = (struct reg_window32 *) regs->u_regs[UREG_FP]; 102 return win->locals[reg - 16]; /* yes, I know what this does... */ 103 } 104 105 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs) 106 { 107 struct reg_window32 __user *win; 108 unsigned long ret; 109 110 if (reg < 16) 111 return (!reg ? 0 : regs->u_regs[reg]); 112 113 /* Ho hum, the slightly complicated case. */ 114 win = (struct reg_window32 __user *) regs->u_regs[UREG_FP]; 115 116 if ((unsigned long)win & 3) 117 return -1; 118 119 if (get_user(ret, &win->locals[reg - 16])) 120 return -1; 121 122 return ret; 123 } 124 125 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs) 126 { 127 struct reg_window32 *win; 128 129 if(reg < 16) 130 return ®s->u_regs[reg]; 131 win = (struct reg_window32 *) regs->u_regs[UREG_FP]; 132 return &win->locals[reg - 16]; 133 } 134 135 static unsigned long compute_effective_address(struct pt_regs *regs, 136 unsigned int insn) 137 { 138 unsigned int rs1 = (insn >> 14) & 0x1f; 139 unsigned int rs2 = insn & 0x1f; 140 unsigned int rd = (insn >> 25) & 0x1f; 141 142 if(insn & 0x2000) { 143 maybe_flush_windows(rs1, 0, rd); 144 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn)); 145 } else { 146 maybe_flush_windows(rs1, rs2, rd); 147 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs)); 148 } 149 } 150 151 unsigned long safe_compute_effective_address(struct pt_regs *regs, 152 unsigned int insn) 153 { 154 unsigned int rs1 = (insn >> 14) & 0x1f; 155 unsigned int rs2 = insn & 0x1f; 156 unsigned int rd = (insn >> 25) & 0x1f; 157 158 if(insn & 0x2000) { 159 maybe_flush_windows(rs1, 0, rd); 160 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn)); 161 } else { 162 maybe_flush_windows(rs1, rs2, rd); 163 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs)); 164 } 165 } 166 167 /* This is just to make gcc think panic does return... */ 168 static void unaligned_panic(char *str) 169 { 170 panic("%s", str); 171 } 172 173 /* una_asm.S */ 174 extern int do_int_load(unsigned long *dest_reg, int size, 175 unsigned long *saddr, int is_signed); 176 extern int __do_int_store(unsigned long *dst_addr, int size, 177 unsigned long *src_val); 178 179 static int do_int_store(int reg_num, int size, unsigned long *dst_addr, 180 struct pt_regs *regs) 181 { 182 unsigned long zero[2] = { 0, 0 }; 183 unsigned long *src_val; 184 185 if (reg_num) 186 src_val = fetch_reg_addr(reg_num, regs); 187 else { 188 src_val = &zero[0]; 189 if (size == 8) 190 zero[1] = fetch_reg(1, regs); 191 } 192 return __do_int_store(dst_addr, size, src_val); 193 } 194 195 extern void smp_capture(void); 196 extern void smp_release(void); 197 198 static inline void advance(struct pt_regs *regs) 199 { 200 regs->pc = regs->npc; 201 regs->npc += 4; 202 } 203 204 static inline int floating_point_load_or_store_p(unsigned int insn) 205 { 206 return (insn >> 24) & 1; 207 } 208 209 static inline int ok_for_kernel(unsigned int insn) 210 { 211 return !floating_point_load_or_store_p(insn); 212 } 213 214 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn) 215 { 216 unsigned long g2 = regs->u_regs [UREG_G2]; 217 unsigned long fixup = search_extables_range(regs->pc, &g2); 218 219 if (!fixup) { 220 unsigned long address = compute_effective_address(regs, insn); 221 if(address < PAGE_SIZE) { 222 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler"); 223 } else 224 printk(KERN_ALERT "Unable to handle kernel paging request in mna handler"); 225 printk(KERN_ALERT " at virtual address %08lx\n",address); 226 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n", 227 (current->mm ? current->mm->context : 228 current->active_mm->context)); 229 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n", 230 (current->mm ? (unsigned long) current->mm->pgd : 231 (unsigned long) current->active_mm->pgd)); 232 die_if_kernel("Oops", regs); 233 /* Not reached */ 234 } 235 regs->pc = fixup; 236 regs->npc = regs->pc + 4; 237 regs->u_regs [UREG_G2] = g2; 238 } 239 240 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn) 241 { 242 enum direction dir = decode_direction(insn); 243 int size = decode_access_size(insn); 244 245 if(!ok_for_kernel(insn) || dir == both) { 246 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n", 247 regs->pc); 248 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store."); 249 } else { 250 unsigned long addr = compute_effective_address(regs, insn); 251 int err; 252 253 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr); 254 switch (dir) { 255 case load: 256 err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f), 257 regs), 258 size, (unsigned long *) addr, 259 decode_signedness(insn)); 260 break; 261 262 case store: 263 err = do_int_store(((insn>>25)&0x1f), size, 264 (unsigned long *) addr, regs); 265 break; 266 default: 267 panic("Impossible kernel unaligned trap."); 268 /* Not reached... */ 269 } 270 if (err) 271 kernel_mna_trap_fault(regs, insn); 272 else 273 advance(regs); 274 } 275 } 276 277 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn, 278 enum direction dir) 279 { 280 unsigned int reg; 281 int size = ((insn >> 19) & 3) == 3 ? 8 : 4; 282 283 if ((regs->pc | regs->npc) & 3) 284 return 0; 285 286 /* Must access_ok() in all the necessary places. */ 287 #define WINREG_ADDR(regnum) \ 288 ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum))) 289 290 reg = (insn >> 25) & 0x1f; 291 if (reg >= 16) { 292 if (!access_ok(WINREG_ADDR(reg - 16), size)) 293 return -EFAULT; 294 } 295 reg = (insn >> 14) & 0x1f; 296 if (reg >= 16) { 297 if (!access_ok(WINREG_ADDR(reg - 16), size)) 298 return -EFAULT; 299 } 300 if (!(insn & 0x2000)) { 301 reg = (insn & 0x1f); 302 if (reg >= 16) { 303 if (!access_ok(WINREG_ADDR(reg - 16), size)) 304 return -EFAULT; 305 } 306 } 307 #undef WINREG_ADDR 308 return 0; 309 } 310 311 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn) 312 { 313 send_sig_fault(SIGBUS, BUS_ADRALN, 314 (void __user *)safe_compute_effective_address(regs, insn), 315 0, current); 316 } 317 318 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn) 319 { 320 enum direction dir; 321 322 if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) || 323 (((insn >> 30) & 3) != 3)) 324 goto kill_user; 325 dir = decode_direction(insn); 326 if(!ok_for_user(regs, insn, dir)) { 327 goto kill_user; 328 } else { 329 int err, size = decode_access_size(insn); 330 unsigned long addr; 331 332 if(floating_point_load_or_store_p(insn)) { 333 printk("User FPU load/store unaligned unsupported.\n"); 334 goto kill_user; 335 } 336 337 addr = compute_effective_address(regs, insn); 338 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr); 339 switch(dir) { 340 case load: 341 err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f), 342 regs), 343 size, (unsigned long *) addr, 344 decode_signedness(insn)); 345 break; 346 347 case store: 348 err = do_int_store(((insn>>25)&0x1f), size, 349 (unsigned long *) addr, regs); 350 break; 351 352 case both: 353 /* 354 * This was supported in 2.4. However, we question 355 * the value of SWAP instruction across word boundaries. 356 */ 357 printk("Unaligned SWAP unsupported.\n"); 358 err = -EFAULT; 359 break; 360 361 default: 362 unaligned_panic("Impossible user unaligned trap."); 363 goto out; 364 } 365 if (err) 366 goto kill_user; 367 else 368 advance(regs); 369 goto out; 370 } 371 372 kill_user: 373 user_mna_trap_fault(regs, insn); 374 out: 375 ; 376 } 377