arch/powerpc/kernel/perf_callchain.c

   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_counter.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  */
  29 static 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  */
  44 static 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
  61 static 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 #ifdef CONFIG_HUGETLB_PAGE
 124 #define is_huge_psize(pagesize) (HPAGE_SHIFT && mmu_huge_psizes[pagesize])
 125 #else
 126 #define is_huge_psize(pagesize) 0
 127 #endif
 128
 129 /*
 130  * On 64-bit we don't want to invoke hash_page on user addresses from
 131  * interrupt context, so if the access faults, we read the page tables
 132  * to find which page (if any) is mapped and access it directly.
 133  */
 134 static int read_user_stack_slow(void __user *ptr, void *ret, int nb)
 135 {
 136         pgd_t *pgdir;
 137         pte_t *ptep, pte;
 138         int pagesize;
 139         unsigned long addr = (unsigned long) ptr;
 140         unsigned long offset;
 141         unsigned long pfn;
 142         void *kaddr;
 143
 144         pgdir = current->mm->pgd;
 145         if (!pgdir)
 146                 return -EFAULT;
 147
 148         pagesize = get_slice_psize(current->mm, addr);
 149
 150         /* align address to page boundary */
 151         offset = addr & ((1ul << mmu_psize_defs[pagesize].shift) - 1);
 152         addr -= offset;
 153
 154         if (is_huge_psize(pagesize))
 155                 ptep = huge_pte_offset(current->mm, addr);
 156         else
 157                 ptep = find_linux_pte(pgdir, addr);
 158
 159         if (ptep == NULL)
 160                 return -EFAULT;
 161         pte = *ptep;
 162         if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER))
 163                 return -EFAULT;
 164         pfn = pte_pfn(pte);
 165         if (!page_is_ram(pfn))
 166                 return -EFAULT;
 167
 168         /* no highmem to worry about here */
 169         kaddr = pfn_to_kaddr(pfn);
 170         memcpy(ret, kaddr + offset, nb);
 171         return 0;
 172 }
 173
 174 static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
 175 {
 176         if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
 177             ((unsigned long)ptr & 7))
 178                 return -EFAULT;
 179
 180         if (!__get_user_inatomic(*ret, ptr))
 181                 return 0;
 182
 183         return read_user_stack_slow(ptr, ret, 8);
 184 }
 185
 186 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
 187 {
 188         if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
 189             ((unsigned long)ptr & 3))
 190                 return -EFAULT;
 191
 192         if (!__get_user_inatomic(*ret, ptr))
 193                 return 0;
 194
 195         return read_user_stack_slow(ptr, ret, 4);
 196 }
 197
 198 static inline int valid_user_sp(unsigned long sp, int is_64)
 199 {
 200         if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
 201                 return 0;
 202         return 1;
 203 }
 204
 205 /*
 206  * 64-bit user processes use the same stack frame for RT and non-RT signals.
 207  */
 208 struct signal_frame_64 {
 209         char            dummy[__SIGNAL_FRAMESIZE];
 210         struct ucontext uc;
 211         unsigned long   unused[2];
 212         unsigned int    tramp[6];
 213         struct siginfo  *pinfo;
 214         void            *puc;
 215         struct siginfo  info;
 216         char            abigap[288];
 217 };
 218
 219 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
 220 {
 221         if (nip == fp + offsetof(struct signal_frame_64, tramp))
 222                 return 1;
 223         if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
 224             nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
 225                 return 1;
 226         return 0;
 227 }
 228
 229 /*
 230  * Do some sanity checking on the signal frame pointed to by sp.
 231  * We check the pinfo and puc pointers in the frame.
 232  */
 233 static int sane_signal_64_frame(unsigned long sp)
 234 {
 235         struct signal_frame_64 __user *sf;
 236         unsigned long pinfo, puc;
 237
 238         sf = (struct signal_frame_64 __user *) sp;
 239         if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
 240             read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
 241                 return 0;
 242         return pinfo == (unsigned long) &sf->info &&
 243                 puc == (unsigned long) &sf->uc;
 244 }
 245
 246 static void perf_callchain_user_64(struct pt_regs *regs,
 247                                    struct perf_callchain_entry *entry)
 248 {
 249         unsigned long sp, next_sp;
 250         unsigned long next_ip;
 251         unsigned long lr;
 252         long level = 0;
 253         struct signal_frame_64 __user *sigframe;
 254         unsigned long __user *fp, *uregs;
 255
 256         next_ip = regs->nip;
 257         lr = regs->link;
 258         sp = regs->gpr[1];
 259         callchain_store(entry, PERF_CONTEXT_USER);
 260         callchain_store(entry, next_ip);
 261
 262         for (;;) {
 263                 fp = (unsigned long __user *) sp;
 264                 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
 265                         return;
 266                 if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
 267                         return;
 268
 269                 /*
 270                  * Note: the next_sp - sp >= signal frame size check
 271                  * is true when next_sp < sp, which can happen when
 272                  * transitioning from an alternate signal stack to the
 273                  * normal stack.
 274                  */
 275                 if (next_sp - sp >= sizeof(struct signal_frame_64) &&
 276                     (is_sigreturn_64_address(next_ip, sp) ||
 277                      (level <= 1 && is_sigreturn_64_address(lr, sp))) &&
 278                     sane_signal_64_frame(sp)) {
 279                         /*
 280                          * This looks like an signal frame
 281                          */
 282                         sigframe = (struct signal_frame_64 __user *) sp;
 283                         uregs = sigframe->uc.uc_mcontext.gp_regs;
 284                         if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
 285                             read_user_stack_64(&uregs[PT_LNK], &lr) ||
 286                             read_user_stack_64(&uregs[PT_R1], &sp))
 287                                 return;
 288                         level = 0;
 289                         callchain_store(entry, PERF_CONTEXT_USER);
 290                         callchain_store(entry, next_ip);
 291                         continue;
 292                 }
 293
 294                 if (level == 0)
 295                         next_ip = lr;
 296                 callchain_store(entry, next_ip);
 297                 ++level;
 298                 sp = next_sp;
 299         }
 300 }
 301
 302 static inline int current_is_64bit(void)
 303 {
 304         /*
 305          * We can't use test_thread_flag() here because we may be on an
 306          * interrupt stack, and the thread flags don't get copied over
 307          * from the thread_info on the main stack to the interrupt stack.
 308          */
 309         return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
 310 }
 311
 312 #else  /* CONFIG_PPC64 */
 313 /*
 314  * On 32-bit we just access the address and let hash_page create a
 315  * HPTE if necessary, so there is no need to fall back to reading
 316  * the page tables.  Since this is called at interrupt level,
 317  * do_page_fault() won't treat a DSI as a page fault.
 318  */
 319 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
 320 {
 321         if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
 322             ((unsigned long)ptr & 3))
 323                 return -EFAULT;
 324
 325         return __get_user_inatomic(*ret, ptr);
 326 }
 327
 328 static inline void perf_callchain_user_64(struct pt_regs *regs,
 329                                           struct perf_callchain_entry *entry)
 330 {
 331 }
 332
 333 static inline int current_is_64bit(void)
 334 {
 335         return 0;
 336 }
 337
 338 static inline int valid_user_sp(unsigned long sp, int is_64)
 339 {
 340         if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
 341                 return 0;
 342         return 1;
 343 }
 344
 345 #define __SIGNAL_FRAMESIZE32    __SIGNAL_FRAMESIZE
 346 #define sigcontext32            sigcontext
 347 #define mcontext32              mcontext
 348 #define ucontext32              ucontext
 349 #define compat_siginfo_t        struct siginfo
 350
 351 #endif /* CONFIG_PPC64 */
 352
 353 /*
 354  * Layout for non-RT signal frames
 355  */
 356 struct signal_frame_32 {
 357         char                    dummy[__SIGNAL_FRAMESIZE32];
 358         struct sigcontext32     sctx;
 359         struct mcontext32       mctx;
 360         int                     abigap[56];
 361 };
 362
 363 /*
 364  * Layout for RT signal frames
 365  */
 366 struct rt_signal_frame_32 {
 367         char                    dummy[__SIGNAL_FRAMESIZE32 + 16];
 368         compat_siginfo_t        info;
 369         struct ucontext32       uc;
 370         int                     abigap[56];
 371 };
 372
 373 static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
 374 {
 375         if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
 376                 return 1;
 377         if (vdso32_sigtramp && current->mm->context.vdso_base &&
 378             nip == current->mm->context.vdso_base + vdso32_sigtramp)
 379                 return 1;
 380         return 0;
 381 }
 382
 383 static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
 384 {
 385         if (nip == fp + offsetof(struct rt_signal_frame_32,
 386                                  uc.uc_mcontext.mc_pad))
 387                 return 1;
 388         if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
 389             nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
 390                 return 1;
 391         return 0;
 392 }
 393
 394 static int sane_signal_32_frame(unsigned int sp)
 395 {
 396         struct signal_frame_32 __user *sf;
 397         unsigned int regs;
 398
 399         sf = (struct signal_frame_32 __user *) (unsigned long) sp;
 400         if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
 401                 return 0;
 402         return regs == (unsigned long) &sf->mctx;
 403 }
 404
 405 static int sane_rt_signal_32_frame(unsigned int sp)
 406 {
 407         struct rt_signal_frame_32 __user *sf;
 408         unsigned int regs;
 409
 410         sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
 411         if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
 412                 return 0;
 413         return regs == (unsigned long) &sf->uc.uc_mcontext;
 414 }
 415
 416 static unsigned int __user *signal_frame_32_regs(unsigned int sp,
 417                                 unsigned int next_sp, unsigned int next_ip)
 418 {
 419         struct mcontext32 __user *mctx = NULL;
 420         struct signal_frame_32 __user *sf;
 421         struct rt_signal_frame_32 __user *rt_sf;
 422
 423         /*
 424          * Note: the next_sp - sp >= signal frame size check
 425          * is true when next_sp < sp, for example, when
 426          * transitioning from an alternate signal stack to the
 427          * normal stack.
 428          */
 429         if (next_sp - sp >= sizeof(struct signal_frame_32) &&
 430             is_sigreturn_32_address(next_ip, sp) &&
 431             sane_signal_32_frame(sp)) {
 432                 sf = (struct signal_frame_32 __user *) (unsigned long) sp;
 433                 mctx = &sf->mctx;
 434         }
 435
 436         if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
 437             is_rt_sigreturn_32_address(next_ip, sp) &&
 438             sane_rt_signal_32_frame(sp)) {
 439                 rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
 440                 mctx = &rt_sf->uc.uc_mcontext;
 441         }
 442
 443         if (!mctx)
 444                 return NULL;
 445         return mctx->mc_gregs;
 446 }
 447
 448 static void perf_callchain_user_32(struct pt_regs *regs,
 449                                    struct perf_callchain_entry *entry)
 450 {
 451         unsigned int sp, next_sp;
 452         unsigned int next_ip;
 453         unsigned int lr;
 454         long level = 0;
 455         unsigned int __user *fp, *uregs;
 456
 457         next_ip = regs->nip;
 458         lr = regs->link;
 459         sp = regs->gpr[1];
 460         callchain_store(entry, PERF_CONTEXT_USER);
 461         callchain_store(entry, next_ip);
 462
 463         while (entry->nr < PERF_MAX_STACK_DEPTH) {
 464                 fp = (unsigned int __user *) (unsigned long) sp;
 465                 if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
 466                         return;
 467                 if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
 468                         return;
 469
 470                 uregs = signal_frame_32_regs(sp, next_sp, next_ip);
 471                 if (!uregs && level <= 1)
 472                         uregs = signal_frame_32_regs(sp, next_sp, lr);
 473                 if (uregs) {
 474                         /*
 475                          * This looks like an signal frame, so restart
 476                          * the stack trace with the values in it.
 477                          */
 478                         if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
 479                             read_user_stack_32(&uregs[PT_LNK], &lr) ||
 480                             read_user_stack_32(&uregs[PT_R1], &sp))
 481                                 return;
 482                         level = 0;
 483                         callchain_store(entry, PERF_CONTEXT_USER);
 484                         callchain_store(entry, next_ip);
 485                         continue;
 486                 }
 487
 488                 if (level == 0)
 489                         next_ip = lr;
 490                 callchain_store(entry, next_ip);
 491                 ++level;
 492                 sp = next_sp;
 493         }
 494 }
 495
 496 /*
 497  * Since we can't get PMU interrupts inside a PMU interrupt handler,
 498  * we don't need separate irq and nmi entries here.
 499  */
 500 static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);
 501
 502 struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
 503 {
 504         struct perf_callchain_entry *entry = &__get_cpu_var(callchain);
 505
 506         entry->nr = 0;
 507
 508         if (current->pid == 0)          /* idle task? */
 509                 return entry;
 510
 511         if (!user_mode(regs)) {
 512                 perf_callchain_kernel(regs, entry);
 513                 if (current->mm)
 514                         regs = task_pt_regs(current);
 515                 else
 516                         regs = NULL;
 517         }
 518
 519         if (regs) {
 520                 if (current_is_64bit())
 521                         perf_callchain_user_64(regs, entry);
 522                 else
 523                         perf_callchain_user_32(regs, entry);
 524         }
 525
 526         return entry;
 527 }