BCC: l...@intel.com CC: kbuild-...@lists.01.org CC: linux-ker...@vger.kernel.org TO: Dmitry Vyukov <dvyu...@google.com>
tree: https://github.com/dvyukov/linux dvyukov-perf-debugging head: 62267cd404c44bbb18a96c108839c99e7ba6f9bd commit: 62267cd404c44bbb18a96c108839c99e7ba6f9bd [1/1] perf: debugging of missed breakpoints :::::: branch date: 11 hours ago :::::: commit date: 11 hours ago config: x86_64-randconfig-m001 (https://download.01.org/0day-ci/archive/20220923/202209230922.qzcmp68z-...@intel.com/config) compiler: gcc-11 (Debian 11.3.0-5) 11.3.0 If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <l...@intel.com> | Reported-by: Dan Carpenter <dan.carpen...@oracle.com> smatch warnings: arch/x86/kernel/hw_breakpoint.c:577 hw_breakpoint_handler() error: uninitialized symbol 'info'. vim +/info +577 arch/x86/kernel/hw_breakpoint.c 0067f1297241ea K.Prasad 2009-06-01 500 0067f1297241ea K.Prasad 2009-06-01 501 /* 0067f1297241ea K.Prasad 2009-06-01 502 * Handle debug exception notifications. 0067f1297241ea K.Prasad 2009-06-01 503 * 0067f1297241ea K.Prasad 2009-06-01 504 * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 0067f1297241ea K.Prasad 2009-06-01 505 * 0067f1297241ea K.Prasad 2009-06-01 506 * NOTIFY_DONE returned if one of the following conditions is true. 0067f1297241ea K.Prasad 2009-06-01 507 * i) When the causative address is from user-space and the exception 0067f1297241ea K.Prasad 2009-06-01 508 * is a valid one, i.e. not triggered as a result of lazy debug register 0067f1297241ea K.Prasad 2009-06-01 509 * switching 0067f1297241ea K.Prasad 2009-06-01 510 * ii) When there are more bits than trap<n> set in DR6 register (such 0067f1297241ea K.Prasad 2009-06-01 511 * as BD, BS or BT) indicating that more than one debug condition is 0067f1297241ea K.Prasad 2009-06-01 512 * met and requires some more action in do_debug(). 0067f1297241ea K.Prasad 2009-06-01 513 * 0067f1297241ea K.Prasad 2009-06-01 514 * NOTIFY_STOP returned for all other cases 0067f1297241ea K.Prasad 2009-06-01 515 * 0067f1297241ea K.Prasad 2009-06-01 516 */ 9c54b6164eeb29 Masami Hiramatsu 2014-04-17 517 static int hw_breakpoint_handler(struct die_args *args) 0067f1297241ea K.Prasad 2009-06-01 518 { 21d44be7b6ff4c Peter Zijlstra 2020-09-02 519 int i, rc = NOTIFY_STOP; 24f1e32c60c45c Frederic Weisbecker 2009-09-09 520 struct perf_event *bp; 62edab9056a6cf K.Prasad 2009-06-01 521 unsigned long *dr6_p; d53d9bc0cf783e Peter Zijlstra 2020-09-02 522 unsigned long dr6; 9ad22e165994cc Peter Zijlstra 2021-01-28 523 bool bpx; 62267cd404c44b Dmitry Vyukov 2022-09-22 524 struct arch_hw_breakpoint *info; 62edab9056a6cf K.Prasad 2009-06-01 525 62edab9056a6cf K.Prasad 2009-06-01 526 /* The DR6 value is pointed by args->err */ 62edab9056a6cf K.Prasad 2009-06-01 527 dr6_p = (unsigned long *)ERR_PTR(args->err); 62edab9056a6cf K.Prasad 2009-06-01 528 dr6 = *dr6_p; 0067f1297241ea K.Prasad 2009-06-01 529 0067f1297241ea K.Prasad 2009-06-01 530 /* Do an early return if no trap bits are set in DR6 */ 62267cd404c44b Dmitry Vyukov 2022-09-22 531 if ((dr6 & DR_TRAP_BITS) == 0) { 62267cd404c44b Dmitry Vyukov 2022-09-22 532 LOG("HIT no trap bits"); 0067f1297241ea K.Prasad 2009-06-01 533 return NOTIFY_DONE; 62267cd404c44b Dmitry Vyukov 2022-09-22 534 } 0067f1297241ea K.Prasad 2009-06-01 535 0067f1297241ea K.Prasad 2009-06-01 536 /* Handle all the breakpoints that were triggered */ 0067f1297241ea K.Prasad 2009-06-01 537 for (i = 0; i < HBP_NUM; ++i) { 0067f1297241ea K.Prasad 2009-06-01 538 if (likely(!(dr6 & (DR_TRAP0 << i)))) 0067f1297241ea K.Prasad 2009-06-01 539 continue; 24f1e32c60c45c Frederic Weisbecker 2009-09-09 540 9ad22e165994cc Peter Zijlstra 2021-01-28 541 bp = this_cpu_read(bp_per_reg[i]); 9ad22e165994cc Peter Zijlstra 2021-01-28 542 if (!bp) 9ad22e165994cc Peter Zijlstra 2021-01-28 543 continue; 9ad22e165994cc Peter Zijlstra 2021-01-28 544 9ad22e165994cc Peter Zijlstra 2021-01-28 545 bpx = bp->hw.info.type == X86_BREAKPOINT_EXECUTE; 9ad22e165994cc Peter Zijlstra 2021-01-28 546 0067f1297241ea K.Prasad 2009-06-01 547 /* 9ad22e165994cc Peter Zijlstra 2021-01-28 548 * TF and data breakpoints are traps and can be merged, however 9ad22e165994cc Peter Zijlstra 2021-01-28 549 * instruction breakpoints are faults and will be raised 9ad22e165994cc Peter Zijlstra 2021-01-28 550 * separately. 9ad22e165994cc Peter Zijlstra 2021-01-28 551 * 9ad22e165994cc Peter Zijlstra 2021-01-28 552 * However DR6 can indicate both TF and instruction 9ad22e165994cc Peter Zijlstra 2021-01-28 553 * breakpoints. In that case take TF as that has precedence and 9ad22e165994cc Peter Zijlstra 2021-01-28 554 * delay the instruction breakpoint for the next exception. 0067f1297241ea K.Prasad 2009-06-01 555 */ 9ad22e165994cc Peter Zijlstra 2021-01-28 556 if (bpx && (dr6 & DR_STEP)) 9ad22e165994cc Peter Zijlstra 2021-01-28 557 continue; 24f1e32c60c45c Frederic Weisbecker 2009-09-09 558 62edab9056a6cf K.Prasad 2009-06-01 559 /* 62edab9056a6cf K.Prasad 2009-06-01 560 * Reset the 'i'th TRAP bit in dr6 to denote completion of 62edab9056a6cf K.Prasad 2009-06-01 561 * exception handling 62edab9056a6cf K.Prasad 2009-06-01 562 */ 62edab9056a6cf K.Prasad 2009-06-01 563 (*dr6_p) &= ~(DR_TRAP0 << i); 24f1e32c60c45c Frederic Weisbecker 2009-09-09 564 62267cd404c44b Dmitry Vyukov 2022-09-22 565 info = counter_arch_bp(bp); 62267cd404c44b Dmitry Vyukov 2022-09-22 566 //LOG("HIT on 0x%lx", info->address); b326e9560a28fc Frederic Weisbecker 2009-12-05 567 perf_bp_event(bp, args->regs); 0067f1297241ea K.Prasad 2009-06-01 568 0c4519e825c9e2 Frederic Weisbecker 2010-06-24 569 /* 0c4519e825c9e2 Frederic Weisbecker 2010-06-24 570 * Set up resume flag to avoid breakpoint recursion when 0c4519e825c9e2 Frederic Weisbecker 2010-06-24 571 * returning back to origin. 0c4519e825c9e2 Frederic Weisbecker 2010-06-24 572 */ 9ad22e165994cc Peter Zijlstra 2021-01-28 573 if (bpx) 0c4519e825c9e2 Frederic Weisbecker 2010-06-24 574 args->regs->flags |= X86_EFLAGS_RF; 0067f1297241ea K.Prasad 2009-06-01 575 } 9ad22e165994cc Peter Zijlstra 2021-01-28 576 62267cd404c44b Dmitry Vyukov 2022-09-22 @577 if (!info) 62267cd404c44b Dmitry Vyukov 2022-09-22 578 LOG("HIT not found"); 62267cd404c44b Dmitry Vyukov 2022-09-22 579 //LOG("HIT done"); 62267cd404c44b Dmitry Vyukov 2022-09-22 580 e0e53db6133c32 K.Prasad 2010-01-28 581 /* e0e53db6133c32 K.Prasad 2010-01-28 582 * Further processing in do_debug() is needed for a) user-space e0e53db6133c32 K.Prasad 2010-01-28 583 * breakpoints (to generate signals) and b) when the system has e0e53db6133c32 K.Prasad 2010-01-28 584 * taken exception due to multiple causes e0e53db6133c32 K.Prasad 2010-01-28 585 */ d53d9bc0cf783e Peter Zijlstra 2020-09-02 586 if ((current->thread.virtual_dr6 & DR_TRAP_BITS) || e0e53db6133c32 K.Prasad 2010-01-28 587 (dr6 & (~DR_TRAP_BITS))) 0067f1297241ea K.Prasad 2009-06-01 588 rc = NOTIFY_DONE; 0067f1297241ea K.Prasad 2009-06-01 589 0067f1297241ea K.Prasad 2009-06-01 590 return rc; 0067f1297241ea K.Prasad 2009-06-01 591 } 0067f1297241ea K.Prasad 2009-06-01 592 -- 0-DAY CI Kernel Test Service https://01.org/lkp _______________________________________________ kbuild mailing list -- kbuild@lists.01.org To unsubscribe send an email to kbuild-le...@lists.01.org
