1/* 2 * Performance counter callchain support - powerpc architecture code 3 * 4 * Copyright �� 2009 Paul Mackerras, IBM Corporation. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11#include <linux/kernel.h> 12#include <linux/sched.h> 13#include <linux/perf_event.h> 14#include <linux/percpu.h> 15#include <linux/uaccess.h> 16#include <linux/mm.h> 17#include <asm/ptrace.h> 18#include <asm/pgtable.h> 19#include <asm/sigcontext.h> 20#include <asm/ucontext.h> 21#include <asm/vdso.h> 22#ifdef CONFIG_PPC64 23#include "ppc32.h" 24#endif 25 26/* 27 * Store another value in a callchain_entry. 28 */ 29static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip) 30{ 31 unsigned int nr = entry->nr; 32 33 if (nr < PERF_MAX_STACK_DEPTH) { 34 entry->ip[nr] = ip; 35 entry->nr = nr + 1; 36 } 37} 38 39/* 40 * Is sp valid as the address of the next kernel stack frame after prev_sp? 41 * The next frame may be in a different stack area but should not go 42 * back down in the same stack area. 43 */ 44static int valid_next_sp(unsigned long sp, unsigned long prev_sp) 45{ 46 if (sp & 0xf) 47 return 0; /* must be 16-byte aligned */ 48 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 49 return 0; 50 if (sp >= prev_sp + STACK_FRAME_OVERHEAD) 51 return 1; 52 /* 53 * sp could decrease when we jump off an interrupt stack 54 * back to the regular process stack. 55 */ 56 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1))) 57 return 1; 58 return 0; 59} 60 61static void perf_callchain_kernel(struct pt_regs *regs, 62 struct perf_callchain_entry *entry) 63{ 64 unsigned long sp, next_sp; 65 unsigned long next_ip; 66 unsigned long lr; 67 long level = 0; 68 unsigned long *fp; 69 70 lr = regs->link; 71 sp = regs->gpr[1]; 72 callchain_store(entry, PERF_CONTEXT_KERNEL); 73 callchain_store(entry, regs->nip); 74 75 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 76 return; 77 78 for (;;) { 79 fp = (unsigned long *) sp; 80 next_sp = fp[0]; 81 82 if (next_sp == sp + STACK_INT_FRAME_SIZE && 83 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) { 84 /* 85 * This looks like an interrupt frame for an 86 * interrupt that occurred in the kernel 87 */ 88 regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD); 89 next_ip = regs->nip; 90 lr = regs->link; 91 level = 0; 92 callchain_store(entry, PERF_CONTEXT_KERNEL); 93 94 } else { 95 if (level == 0) 96 next_ip = lr; 97 else 98 next_ip = fp[STACK_FRAME_LR_SAVE]; 99 100 /* 101 * We can't tell which of the first two addresses 102 * we get are valid, but we can filter out the 103 * obviously bogus ones here. We replace them 104 * with 0 rather than removing them entirely so 105 * that userspace can tell which is which. 106 */ 107 if ((level == 1 && next_ip == lr) || 108 (level <= 1 && !kernel_text_address(next_ip))) 109 next_ip = 0; 110 111 ++level; 112 } 113 114 callchain_store(entry, next_ip); 115 if (!valid_next_sp(next_sp, sp)) 116 return; 117 sp = next_sp; 118 } 119} 120 121#ifdef CONFIG_PPC64 122/* 123 * On 64-bit we don't want to invoke hash_page on user addresses from 124 * interrupt context, so if the access faults, we read the page tables 125 * to find which page (if any) is mapped and access it directly. 126 */ 127static int read_user_stack_slow(void __user *ptr, void *ret, int nb) 128{ 129 pgd_t *pgdir; 130 pte_t *ptep, pte; 131 unsigned shift; 132 unsigned long addr = (unsigned long) ptr; 133 unsigned long offset; 134 unsigned long pfn; 135 void *kaddr; 136 137 pgdir = current->mm->pgd; 138 if (!pgdir) 139 return -EFAULT; 140 141 ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift); 142 if (!shift) 143 shift = PAGE_SHIFT; 144 145 /* align address to page boundary */ 146 offset = addr & ((1UL << shift) - 1); 147 addr -= offset; 148 149 if (ptep == NULL) 150 return -EFAULT; 151 pte = *ptep; 152 if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER)) 153 return -EFAULT; 154 pfn = pte_pfn(pte); 155 if (!page_is_ram(pfn)) 156 return -EFAULT; 157 158 /* no highmem to worry about here */ 159 kaddr = pfn_to_kaddr(pfn); 160 memcpy(ret, kaddr + offset, nb); 161 return 0; 162} 163 164static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) 165{ 166 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) || 167 ((unsigned long)ptr & 7)) 168 return -EFAULT; 169 170 if (!__get_user_inatomic(*ret, ptr)) 171 return 0; 172 173 return read_user_stack_slow(ptr, ret, 8); 174} 175 176static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) 177{ 178 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || 179 ((unsigned long)ptr & 3)) 180 return -EFAULT; 181 182 if (!__get_user_inatomic(*ret, ptr)) 183 return 0; 184 185 return read_user_stack_slow(ptr, ret, 4); 186} 187 188static inline int valid_user_sp(unsigned long sp, int is_64) 189{ 190 if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32) 191 return 0; 192 return 1; 193} 194 195/* 196 * 64-bit user processes use the same stack frame for RT and non-RT signals. 197 */ 198struct signal_frame_64 { 199 char dummy[__SIGNAL_FRAMESIZE]; 200 struct ucontext uc; 201 unsigned long unused[2]; 202 unsigned int tramp[6]; 203 struct siginfo *pinfo; 204 void *puc; 205 struct siginfo info; 206 char abigap[288]; 207}; 208 209static int is_sigreturn_64_address(unsigned long nip, unsigned long fp) 210{ 211 if (nip == fp + offsetof(struct signal_frame_64, tramp)) 212 return 1; 213 if (vdso64_rt_sigtramp && current->mm->context.vdso_base && 214 nip == current->mm->context.vdso_base + vdso64_rt_sigtramp) 215 return 1; 216 return 0; 217} 218 219/* 220 * Do some sanity checking on the signal frame pointed to by sp. 221 * We check the pinfo and puc pointers in the frame. 222 */ 223static int sane_signal_64_frame(unsigned long sp) 224{ 225 struct signal_frame_64 __user *sf; 226 unsigned long pinfo, puc; 227 228 sf = (struct signal_frame_64 __user *) sp; 229 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) || 230 read_user_stack_64((unsigned long __user *) &sf->puc, &puc)) 231 return 0; 232 return pinfo == (unsigned long) &sf->info && 233 puc == (unsigned long) &sf->uc; 234} 235 236static void perf_callchain_user_64(struct pt_regs *regs, 237 struct perf_callchain_entry *entry) 238{ 239 unsigned long sp, next_sp; 240 unsigned long next_ip; 241 unsigned long lr; 242 long level = 0; 243 struct signal_frame_64 __user *sigframe; 244 unsigned long __user *fp, *uregs; 245 246 next_ip = regs->nip; 247 lr = regs->link; 248 sp = regs->gpr[1]; 249 callchain_store(entry, PERF_CONTEXT_USER); 250 callchain_store(entry, next_ip); 251 252 for (;;) { 253 fp = (unsigned long __user *) sp; 254 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp)) 255 return; 256 if (level > 0 && read_user_stack_64(&fp[2], &next_ip)) 257 return; 258 259 /* 260 * Note: the next_sp - sp >= signal frame size check 261 * is true when next_sp < sp, which can happen when 262 * transitioning from an alternate signal stack to the 263 * normal stack. 264 */ 265 if (next_sp - sp >= sizeof(struct signal_frame_64) && 266 (is_sigreturn_64_address(next_ip, sp) || 267 (level <= 1 && is_sigreturn_64_address(lr, sp))) && 268 sane_signal_64_frame(sp)) { 269 /* 270 * This looks like an signal frame 271 */ 272 sigframe = (struct signal_frame_64 __user *) sp; 273 uregs = sigframe->uc.uc_mcontext.gp_regs; 274 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) || 275 read_user_stack_64(&uregs[PT_LNK], &lr) || 276 read_user_stack_64(&uregs[PT_R1], &sp)) 277 return; 278 level = 0; 279 callchain_store(entry, PERF_CONTEXT_USER); 280 callchain_store(entry, next_ip); 281 continue; 282 } 283 284 if (level == 0) 285 next_ip = lr; 286 callchain_store(entry, next_ip); 287 ++level; 288 sp = next_sp; 289 } 290} 291 292static inline int current_is_64bit(void) 293{ 294 /* 295 * We can't use test_thread_flag() here because we may be on an 296 * interrupt stack, and the thread flags don't get copied over 297 * from the thread_info on the main stack to the interrupt stack. 298 */ 299 return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT); 300} 301 302#else /* CONFIG_PPC64 */ 303/* 304 * On 32-bit we just access the address and let hash_page create a 305 * HPTE if necessary, so there is no need to fall back to reading 306 * the page tables. Since this is called at interrupt level, 307 * do_page_fault() won't treat a DSI as a page fault. 308 */ 309static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) 310{ 311 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || 312 ((unsigned long)ptr & 3)) 313 return -EFAULT; 314 315 return __get_user_inatomic(*ret, ptr); 316} 317 318static inline void perf_callchain_user_64(struct pt_regs *regs, 319 struct perf_callchain_entry *entry) 320{ 321} 322 323static inline int current_is_64bit(void) 324{ 325 return 0; 326} 327 328static inline int valid_user_sp(unsigned long sp, int is_64) 329{ 330 if (!sp || (sp & 7) || sp > TASK_SIZE - 32) 331 return 0; 332 return 1; 333} 334 335#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE 336#define sigcontext32 sigcontext 337#define mcontext32 mcontext 338#define ucontext32 ucontext 339#define compat_siginfo_t struct siginfo 340 341#endif /* CONFIG_PPC64 */ 342 343/* 344 * Layout for non-RT signal frames 345 */ 346struct signal_frame_32 { 347 char dummy[__SIGNAL_FRAMESIZE32]; 348 struct sigcontext32 sctx; 349 struct mcontext32 mctx; 350 int abigap[56]; 351}; 352 353/* 354 * Layout for RT signal frames 355 */ 356struct rt_signal_frame_32 { 357 char dummy[__SIGNAL_FRAMESIZE32 + 16]; 358 compat_siginfo_t info; 359 struct ucontext32 uc; 360 int abigap[56]; 361}; 362 363static int is_sigreturn_32_address(unsigned int nip, unsigned int fp) 364{ 365 if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad)) 366 return 1; 367 if (vdso32_sigtramp && current->mm->context.vdso_base && 368 nip == current->mm->context.vdso_base + vdso32_sigtramp) 369 return 1; 370 return 0; 371} 372 373static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp) 374{ 375 if (nip == fp + offsetof(struct rt_signal_frame_32, 376 uc.uc_mcontext.mc_pad)) 377 return 1; 378 if (vdso32_rt_sigtramp && current->mm->context.vdso_base && 379 nip == current->mm->context.vdso_base + vdso32_rt_sigtramp) 380 return 1; 381 return 0; 382} 383 384static int sane_signal_32_frame(unsigned int sp) 385{ 386 struct signal_frame_32 __user *sf; 387 unsigned int regs; 388 389 sf = (struct signal_frame_32 __user *) (unsigned long) sp; 390 if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s)) 391 return 0; 392 return regs == (unsigned long) &sf->mctx; 393} 394 395static int sane_rt_signal_32_frame(unsigned int sp) 396{ 397 struct rt_signal_frame_32 __user *sf; 398 unsigned int regs; 399 400 sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; 401 if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s)) 402 return 0; 403 return regs == (unsigned long) &sf->uc.uc_mcontext; 404} 405 406static unsigned int __user *signal_frame_32_regs(unsigned int sp, 407 unsigned int next_sp, unsigned int next_ip) 408{ 409 struct mcontext32 __user *mctx = NULL; 410 struct signal_frame_32 __user *sf; 411 struct rt_signal_frame_32 __user *rt_sf; 412 413 /* 414 * Note: the next_sp - sp >= signal frame size check 415 * is true when next_sp < sp, for example, when 416 * transitioning from an alternate signal stack to the 417 * normal stack. 418 */ 419 if (next_sp - sp >= sizeof(struct signal_frame_32) && 420 is_sigreturn_32_address(next_ip, sp) && 421 sane_signal_32_frame(sp)) { 422 sf = (struct signal_frame_32 __user *) (unsigned long) sp; 423 mctx = &sf->mctx; 424 } 425 426 if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) && 427 is_rt_sigreturn_32_address(next_ip, sp) && 428 sane_rt_signal_32_frame(sp)) { 429 rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; 430 mctx = &rt_sf->uc.uc_mcontext; 431 } 432 433 if (!mctx) 434 return NULL; 435 return mctx->mc_gregs; 436} 437 438static void perf_callchain_user_32(struct pt_regs *regs, 439 struct perf_callchain_entry *entry) 440{ 441 unsigned int sp, next_sp; 442 unsigned int next_ip; 443 unsigned int lr; 444 long level = 0; 445 unsigned int __user *fp, *uregs; 446 447 next_ip = regs->nip; 448 lr = regs->link; 449 sp = regs->gpr[1]; 450 callchain_store(entry, PERF_CONTEXT_USER); 451 callchain_store(entry, next_ip); 452 453 while (entry->nr < PERF_MAX_STACK_DEPTH) { 454 fp = (unsigned int __user *) (unsigned long) sp; 455 if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp)) 456 return; 457 if (level > 0 && read_user_stack_32(&fp[1], &next_ip)) 458 return; 459 460 uregs = signal_frame_32_regs(sp, next_sp, next_ip); 461 if (!uregs && level <= 1) 462 uregs = signal_frame_32_regs(sp, next_sp, lr); 463 if (uregs) { 464 /* 465 * This looks like an signal frame, so restart 466 * the stack trace with the values in it. 467 */ 468 if (read_user_stack_32(&uregs[PT_NIP], &next_ip) || 469 read_user_stack_32(&uregs[PT_LNK], &lr) || 470 read_user_stack_32(&uregs[PT_R1], &sp)) 471 return; 472 level = 0; 473 callchain_store(entry, PERF_CONTEXT_USER); 474 callchain_store(entry, next_ip); 475 continue; 476 } 477 478 if (level == 0) 479 next_ip = lr; 480 callchain_store(entry, next_ip); 481 ++level; 482 sp = next_sp; 483 } 484} 485 486/* 487 * Since we can't get PMU interrupts inside a PMU interrupt handler, 488 * we don't need separate irq and nmi entries here. 489 */ 490static DEFINE_PER_CPU(struct perf_callchain_entry, cpu_perf_callchain); 491 492struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) 493{ 494 struct perf_callchain_entry *entry = &__get_cpu_var(cpu_perf_callchain); 495 496 entry->nr = 0; 497 498 if (!user_mode(regs)) { 499 perf_callchain_kernel(regs, entry); 500 if (current->mm) 501 regs = task_pt_regs(current); 502 else 503 regs = NULL; 504 } 505 506 if (regs) { 507 if (current_is_64bit()) 508 perf_callchain_user_64(regs, entry); 509 else 510 perf_callchain_user_32(regs, entry); 511 } 512 513 return entry; 514} 515