1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Performance counter callchain support - powerpc architecture code 4 * 5 * Copyright © 2009 Paul Mackerras, IBM Corporation. 6 */ 7 #include <linux/kernel.h> 8 #include <linux/sched.h> 9 #include <linux/perf_event.h> 10 #include <linux/percpu.h> 11 #include <linux/uaccess.h> 12 #include <linux/mm.h> 13 #include <asm/ptrace.h> 14 #include <asm/pgtable.h> 15 #include <asm/sigcontext.h> 16 #include <asm/ucontext.h> 17 #include <asm/vdso.h> 18 #ifdef CONFIG_PPC64 19 #include "../kernel/ppc32.h" 20 #endif 21 #include <asm/pte-walk.h> 22 23 24 /* 25 * Is sp valid as the address of the next kernel stack frame after prev_sp? 26 * The next frame may be in a different stack area but should not go 27 * back down in the same stack area. 28 */ 29 static int valid_next_sp(unsigned long sp, unsigned long prev_sp) 30 { 31 if (sp & 0xf) 32 return 0; /* must be 16-byte aligned */ 33 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 34 return 0; 35 if (sp >= prev_sp + STACK_FRAME_MIN_SIZE) 36 return 1; 37 /* 38 * sp could decrease when we jump off an interrupt stack 39 * back to the regular process stack. 40 */ 41 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1))) 42 return 1; 43 return 0; 44 } 45 46 void 47 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) 48 { 49 unsigned long sp, next_sp; 50 unsigned long next_ip; 51 unsigned long lr; 52 long level = 0; 53 unsigned long *fp; 54 55 lr = regs->link; 56 sp = regs->gpr[1]; 57 perf_callchain_store(entry, perf_instruction_pointer(regs)); 58 59 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 60 return; 61 62 for (;;) { 63 fp = (unsigned long *) sp; 64 next_sp = fp[0]; 65 66 if (next_sp == sp + STACK_INT_FRAME_SIZE && 67 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) { 68 /* 69 * This looks like an interrupt frame for an 70 * interrupt that occurred in the kernel 71 */ 72 regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD); 73 next_ip = regs->nip; 74 lr = regs->link; 75 level = 0; 76 perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL); 77 78 } else { 79 if (level == 0) 80 next_ip = lr; 81 else 82 next_ip = fp[STACK_FRAME_LR_SAVE]; 83 84 /* 85 * We can't tell which of the first two addresses 86 * we get are valid, but we can filter out the 87 * obviously bogus ones here. We replace them 88 * with 0 rather than removing them entirely so 89 * that userspace can tell which is which. 90 */ 91 if ((level == 1 && next_ip == lr) || 92 (level <= 1 && !kernel_text_address(next_ip))) 93 next_ip = 0; 94 95 ++level; 96 } 97 98 perf_callchain_store(entry, next_ip); 99 if (!valid_next_sp(next_sp, sp)) 100 return; 101 sp = next_sp; 102 } 103 } 104 105 #ifdef CONFIG_PPC64 106 /* 107 * On 64-bit we don't want to invoke hash_page on user addresses from 108 * interrupt context, so if the access faults, we read the page tables 109 * to find which page (if any) is mapped and access it directly. 110 */ 111 static int read_user_stack_slow(void __user *ptr, void *buf, int nb) 112 { 113 int ret = -EFAULT; 114 pgd_t *pgdir; 115 pte_t *ptep, pte; 116 unsigned shift; 117 unsigned long addr = (unsigned long) ptr; 118 unsigned long offset; 119 unsigned long pfn, flags; 120 void *kaddr; 121 122 pgdir = current->mm->pgd; 123 if (!pgdir) 124 return -EFAULT; 125 126 local_irq_save(flags); 127 ptep = find_current_mm_pte(pgdir, addr, NULL, &shift); 128 if (!ptep) 129 goto err_out; 130 if (!shift) 131 shift = PAGE_SHIFT; 132 133 /* align address to page boundary */ 134 offset = addr & ((1UL << shift) - 1); 135 136 pte = READ_ONCE(*ptep); 137 if (!pte_present(pte) || !pte_user(pte)) 138 goto err_out; 139 pfn = pte_pfn(pte); 140 if (!page_is_ram(pfn)) 141 goto err_out; 142 143 /* no highmem to worry about here */ 144 kaddr = pfn_to_kaddr(pfn); 145 memcpy(buf, kaddr + offset, nb); 146 ret = 0; 147 err_out: 148 local_irq_restore(flags); 149 return ret; 150 } 151 152 static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) 153 { 154 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) || 155 ((unsigned long)ptr & 7)) 156 return -EFAULT; 157 158 if (!probe_user_read(ret, ptr, sizeof(*ret))) 159 return 0; 160 161 return read_user_stack_slow(ptr, ret, 8); 162 } 163 164 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) 165 { 166 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || 167 ((unsigned long)ptr & 3)) 168 return -EFAULT; 169 170 if (!probe_user_read(ret, ptr, sizeof(*ret))) 171 return 0; 172 173 return read_user_stack_slow(ptr, ret, 4); 174 } 175 176 static inline int valid_user_sp(unsigned long sp, int is_64) 177 { 178 if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32) 179 return 0; 180 return 1; 181 } 182 183 /* 184 * 64-bit user processes use the same stack frame for RT and non-RT signals. 185 */ 186 struct signal_frame_64 { 187 char dummy[__SIGNAL_FRAMESIZE]; 188 struct ucontext uc; 189 unsigned long unused[2]; 190 unsigned int tramp[6]; 191 struct siginfo *pinfo; 192 void *puc; 193 struct siginfo info; 194 char abigap[288]; 195 }; 196 197 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp) 198 { 199 if (nip == fp + offsetof(struct signal_frame_64, tramp)) 200 return 1; 201 if (vdso64_rt_sigtramp && current->mm->context.vdso_base && 202 nip == current->mm->context.vdso_base + vdso64_rt_sigtramp) 203 return 1; 204 return 0; 205 } 206 207 /* 208 * Do some sanity checking on the signal frame pointed to by sp. 209 * We check the pinfo and puc pointers in the frame. 210 */ 211 static int sane_signal_64_frame(unsigned long sp) 212 { 213 struct signal_frame_64 __user *sf; 214 unsigned long pinfo, puc; 215 216 sf = (struct signal_frame_64 __user *) sp; 217 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) || 218 read_user_stack_64((unsigned long __user *) &sf->puc, &puc)) 219 return 0; 220 return pinfo == (unsigned long) &sf->info && 221 puc == (unsigned long) &sf->uc; 222 } 223 224 static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, 225 struct pt_regs *regs) 226 { 227 unsigned long sp, next_sp; 228 unsigned long next_ip; 229 unsigned long lr; 230 long level = 0; 231 struct signal_frame_64 __user *sigframe; 232 unsigned long __user *fp, *uregs; 233 234 next_ip = perf_instruction_pointer(regs); 235 lr = regs->link; 236 sp = regs->gpr[1]; 237 perf_callchain_store(entry, next_ip); 238 239 while (entry->nr < entry->max_stack) { 240 fp = (unsigned long __user *) sp; 241 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp)) 242 return; 243 if (level > 0 && read_user_stack_64(&fp[2], &next_ip)) 244 return; 245 246 /* 247 * Note: the next_sp - sp >= signal frame size check 248 * is true when next_sp < sp, which can happen when 249 * transitioning from an alternate signal stack to the 250 * normal stack. 251 */ 252 if (next_sp - sp >= sizeof(struct signal_frame_64) && 253 (is_sigreturn_64_address(next_ip, sp) || 254 (level <= 1 && is_sigreturn_64_address(lr, sp))) && 255 sane_signal_64_frame(sp)) { 256 /* 257 * This looks like an signal frame 258 */ 259 sigframe = (struct signal_frame_64 __user *) sp; 260 uregs = sigframe->uc.uc_mcontext.gp_regs; 261 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) || 262 read_user_stack_64(&uregs[PT_LNK], &lr) || 263 read_user_stack_64(&uregs[PT_R1], &sp)) 264 return; 265 level = 0; 266 perf_callchain_store_context(entry, PERF_CONTEXT_USER); 267 perf_callchain_store(entry, next_ip); 268 continue; 269 } 270 271 if (level == 0) 272 next_ip = lr; 273 perf_callchain_store(entry, next_ip); 274 ++level; 275 sp = next_sp; 276 } 277 } 278 279 #else /* CONFIG_PPC64 */ 280 /* 281 * On 32-bit we just access the address and let hash_page create a 282 * HPTE if necessary, so there is no need to fall back to reading 283 * the page tables. Since this is called at interrupt level, 284 * do_page_fault() won't treat a DSI as a page fault. 285 */ 286 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) 287 { 288 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || 289 ((unsigned long)ptr & 3)) 290 return -EFAULT; 291 292 return probe_user_read(ret, ptr, sizeof(*ret)); 293 } 294 295 static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, 296 struct pt_regs *regs) 297 { 298 } 299 300 static inline int valid_user_sp(unsigned long sp, int is_64) 301 { 302 if (!sp || (sp & 7) || sp > TASK_SIZE - 32) 303 return 0; 304 return 1; 305 } 306 307 #define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE 308 #define sigcontext32 sigcontext 309 #define mcontext32 mcontext 310 #define ucontext32 ucontext 311 #define compat_siginfo_t struct siginfo 312 313 #endif /* CONFIG_PPC64 */ 314 315 /* 316 * Layout for non-RT signal frames 317 */ 318 struct signal_frame_32 { 319 char dummy[__SIGNAL_FRAMESIZE32]; 320 struct sigcontext32 sctx; 321 struct mcontext32 mctx; 322 int abigap[56]; 323 }; 324 325 /* 326 * Layout for RT signal frames 327 */ 328 struct rt_signal_frame_32 { 329 char dummy[__SIGNAL_FRAMESIZE32 + 16]; 330 compat_siginfo_t info; 331 struct ucontext32 uc; 332 int abigap[56]; 333 }; 334 335 static int is_sigreturn_32_address(unsigned int nip, unsigned int fp) 336 { 337 if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad)) 338 return 1; 339 if (vdso32_sigtramp && current->mm->context.vdso_base && 340 nip == current->mm->context.vdso_base + vdso32_sigtramp) 341 return 1; 342 return 0; 343 } 344 345 static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp) 346 { 347 if (nip == fp + offsetof(struct rt_signal_frame_32, 348 uc.uc_mcontext.mc_pad)) 349 return 1; 350 if (vdso32_rt_sigtramp && current->mm->context.vdso_base && 351 nip == current->mm->context.vdso_base + vdso32_rt_sigtramp) 352 return 1; 353 return 0; 354 } 355 356 static int sane_signal_32_frame(unsigned int sp) 357 { 358 struct signal_frame_32 __user *sf; 359 unsigned int regs; 360 361 sf = (struct signal_frame_32 __user *) (unsigned long) sp; 362 if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s)) 363 return 0; 364 return regs == (unsigned long) &sf->mctx; 365 } 366 367 static int sane_rt_signal_32_frame(unsigned int sp) 368 { 369 struct rt_signal_frame_32 __user *sf; 370 unsigned int regs; 371 372 sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; 373 if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s)) 374 return 0; 375 return regs == (unsigned long) &sf->uc.uc_mcontext; 376 } 377 378 static unsigned int __user *signal_frame_32_regs(unsigned int sp, 379 unsigned int next_sp, unsigned int next_ip) 380 { 381 struct mcontext32 __user *mctx = NULL; 382 struct signal_frame_32 __user *sf; 383 struct rt_signal_frame_32 __user *rt_sf; 384 385 /* 386 * Note: the next_sp - sp >= signal frame size check 387 * is true when next_sp < sp, for example, when 388 * transitioning from an alternate signal stack to the 389 * normal stack. 390 */ 391 if (next_sp - sp >= sizeof(struct signal_frame_32) && 392 is_sigreturn_32_address(next_ip, sp) && 393 sane_signal_32_frame(sp)) { 394 sf = (struct signal_frame_32 __user *) (unsigned long) sp; 395 mctx = &sf->mctx; 396 } 397 398 if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) && 399 is_rt_sigreturn_32_address(next_ip, sp) && 400 sane_rt_signal_32_frame(sp)) { 401 rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; 402 mctx = &rt_sf->uc.uc_mcontext; 403 } 404 405 if (!mctx) 406 return NULL; 407 return mctx->mc_gregs; 408 } 409 410 static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry, 411 struct pt_regs *regs) 412 { 413 unsigned int sp, next_sp; 414 unsigned int next_ip; 415 unsigned int lr; 416 long level = 0; 417 unsigned int __user *fp, *uregs; 418 419 next_ip = perf_instruction_pointer(regs); 420 lr = regs->link; 421 sp = regs->gpr[1]; 422 perf_callchain_store(entry, next_ip); 423 424 while (entry->nr < entry->max_stack) { 425 fp = (unsigned int __user *) (unsigned long) sp; 426 if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp)) 427 return; 428 if (level > 0 && read_user_stack_32(&fp[1], &next_ip)) 429 return; 430 431 uregs = signal_frame_32_regs(sp, next_sp, next_ip); 432 if (!uregs && level <= 1) 433 uregs = signal_frame_32_regs(sp, next_sp, lr); 434 if (uregs) { 435 /* 436 * This looks like an signal frame, so restart 437 * the stack trace with the values in it. 438 */ 439 if (read_user_stack_32(&uregs[PT_NIP], &next_ip) || 440 read_user_stack_32(&uregs[PT_LNK], &lr) || 441 read_user_stack_32(&uregs[PT_R1], &sp)) 442 return; 443 level = 0; 444 perf_callchain_store_context(entry, PERF_CONTEXT_USER); 445 perf_callchain_store(entry, next_ip); 446 continue; 447 } 448 449 if (level == 0) 450 next_ip = lr; 451 perf_callchain_store(entry, next_ip); 452 ++level; 453 sp = next_sp; 454 } 455 } 456 457 void 458 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) 459 { 460 if (!is_32bit_task()) 461 perf_callchain_user_64(entry, regs); 462 else 463 perf_callchain_user_32(entry, regs); 464 } 465