11a59d1b8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 25aae8a53SK.Prasad /* 35aae8a53SK.Prasad * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, 45aae8a53SK.Prasad * using the CPU's debug registers. Derived from 55aae8a53SK.Prasad * "arch/x86/kernel/hw_breakpoint.c" 65aae8a53SK.Prasad * 75aae8a53SK.Prasad * Copyright 2010 IBM Corporation 85aae8a53SK.Prasad * Author: K.Prasad <prasad@linux.vnet.ibm.com> 95aae8a53SK.Prasad */ 105aae8a53SK.Prasad 115aae8a53SK.Prasad #include <linux/hw_breakpoint.h> 125aae8a53SK.Prasad #include <linux/notifier.h> 135aae8a53SK.Prasad #include <linux/kprobes.h> 145aae8a53SK.Prasad #include <linux/percpu.h> 155aae8a53SK.Prasad #include <linux/kernel.h> 165aae8a53SK.Prasad #include <linux/sched.h> 175aae8a53SK.Prasad #include <linux/smp.h> 18c1fe190cSMichael Neuling #include <linux/debugfs.h> 19c1fe190cSMichael Neuling #include <linux/init.h> 205aae8a53SK.Prasad 215aae8a53SK.Prasad #include <asm/hw_breakpoint.h> 225aae8a53SK.Prasad #include <asm/processor.h> 235aae8a53SK.Prasad #include <asm/sstep.h> 2485ce9a5dSMichael Neuling #include <asm/debug.h> 25c1fe190cSMichael Neuling #include <asm/debugfs.h> 26c1fe190cSMichael Neuling #include <asm/hvcall.h> 277c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 285aae8a53SK.Prasad 295aae8a53SK.Prasad /* 305aae8a53SK.Prasad * Stores the breakpoints currently in use on each breakpoint address 315aae8a53SK.Prasad * register for every cpu 325aae8a53SK.Prasad */ 335aae8a53SK.Prasad static DEFINE_PER_CPU(struct perf_event *, bp_per_reg); 345aae8a53SK.Prasad 355aae8a53SK.Prasad /* 36d09ec738SPaul Mackerras * Returns total number of data or instruction breakpoints available. 37d09ec738SPaul Mackerras */ 38d09ec738SPaul Mackerras int hw_breakpoint_slots(int type) 39d09ec738SPaul Mackerras { 40d09ec738SPaul Mackerras if (type == TYPE_DATA) 41d09ec738SPaul Mackerras return HBP_NUM; 42d09ec738SPaul Mackerras return 0; /* no instruction breakpoints available */ 43d09ec738SPaul Mackerras } 44d09ec738SPaul Mackerras 45d09ec738SPaul Mackerras /* 465aae8a53SK.Prasad * Install a perf counter breakpoint. 475aae8a53SK.Prasad * 485aae8a53SK.Prasad * We seek a free debug address register and use it for this 495aae8a53SK.Prasad * breakpoint. 505aae8a53SK.Prasad * 515aae8a53SK.Prasad * Atomic: we hold the counter->ctx->lock and we only handle variables 525aae8a53SK.Prasad * and registers local to this cpu. 535aae8a53SK.Prasad */ 545aae8a53SK.Prasad int arch_install_hw_breakpoint(struct perf_event *bp) 555aae8a53SK.Prasad { 565aae8a53SK.Prasad struct arch_hw_breakpoint *info = counter_arch_bp(bp); 5769111bacSChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg); 585aae8a53SK.Prasad 595aae8a53SK.Prasad *slot = bp; 605aae8a53SK.Prasad 615aae8a53SK.Prasad /* 625aae8a53SK.Prasad * Do not install DABR values if the instruction must be single-stepped. 635aae8a53SK.Prasad * If so, DABR will be populated in single_step_dabr_instruction(). 645aae8a53SK.Prasad */ 655aae8a53SK.Prasad if (current->thread.last_hit_ubp != bp) 6621f58507SPaul Gortmaker __set_breakpoint(info); 675aae8a53SK.Prasad 685aae8a53SK.Prasad return 0; 695aae8a53SK.Prasad } 705aae8a53SK.Prasad 715aae8a53SK.Prasad /* 725aae8a53SK.Prasad * Uninstall the breakpoint contained in the given counter. 735aae8a53SK.Prasad * 745aae8a53SK.Prasad * First we search the debug address register it uses and then we disable 755aae8a53SK.Prasad * it. 765aae8a53SK.Prasad * 775aae8a53SK.Prasad * Atomic: we hold the counter->ctx->lock and we only handle variables 785aae8a53SK.Prasad * and registers local to this cpu. 795aae8a53SK.Prasad */ 805aae8a53SK.Prasad void arch_uninstall_hw_breakpoint(struct perf_event *bp) 815aae8a53SK.Prasad { 8269111bacSChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg); 835aae8a53SK.Prasad 845aae8a53SK.Prasad if (*slot != bp) { 855aae8a53SK.Prasad WARN_ONCE(1, "Can't find the breakpoint"); 865aae8a53SK.Prasad return; 875aae8a53SK.Prasad } 885aae8a53SK.Prasad 895aae8a53SK.Prasad *slot = NULL; 909422de3eSMichael Neuling hw_breakpoint_disable(); 915aae8a53SK.Prasad } 925aae8a53SK.Prasad 935aae8a53SK.Prasad /* 945aae8a53SK.Prasad * Perform cleanup of arch-specific counters during unregistration 955aae8a53SK.Prasad * of the perf-event 965aae8a53SK.Prasad */ 975aae8a53SK.Prasad void arch_unregister_hw_breakpoint(struct perf_event *bp) 985aae8a53SK.Prasad { 995aae8a53SK.Prasad /* 1005aae8a53SK.Prasad * If the breakpoint is unregistered between a hw_breakpoint_handler() 1015aae8a53SK.Prasad * and the single_step_dabr_instruction(), then cleanup the breakpoint 1025aae8a53SK.Prasad * restoration variables to prevent dangling pointers. 103fb822e60SRavi Bangoria * FIXME, this should not be using bp->ctx at all! Sayeth peterz. 1045aae8a53SK.Prasad */ 105fb822e60SRavi Bangoria if (bp->ctx && bp->ctx->task && bp->ctx->task != ((void *)-1L)) 1065aae8a53SK.Prasad bp->ctx->task->thread.last_hit_ubp = NULL; 1075aae8a53SK.Prasad } 1085aae8a53SK.Prasad 1095aae8a53SK.Prasad /* 1105aae8a53SK.Prasad * Check for virtual address in kernel space. 1115aae8a53SK.Prasad */ 1128e983ff9SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw) 1135aae8a53SK.Prasad { 1148e983ff9SFrederic Weisbecker return is_kernel_addr(hw->address); 1155aae8a53SK.Prasad } 1165aae8a53SK.Prasad 1175aae8a53SK.Prasad int arch_bp_generic_fields(int type, int *gen_bp_type) 1185aae8a53SK.Prasad { 1199422de3eSMichael Neuling *gen_bp_type = 0; 1209422de3eSMichael Neuling if (type & HW_BRK_TYPE_READ) 1219422de3eSMichael Neuling *gen_bp_type |= HW_BREAKPOINT_R; 1229422de3eSMichael Neuling if (type & HW_BRK_TYPE_WRITE) 1239422de3eSMichael Neuling *gen_bp_type |= HW_BREAKPOINT_W; 1249422de3eSMichael Neuling if (*gen_bp_type == 0) 1255aae8a53SK.Prasad return -EINVAL; 1265aae8a53SK.Prasad return 0; 1275aae8a53SK.Prasad } 1285aae8a53SK.Prasad 1295aae8a53SK.Prasad /* 130b57aeab8SRavi Bangoria * Watchpoint match range is always doubleword(8 bytes) aligned on 131b57aeab8SRavi Bangoria * powerpc. If the given range is crossing doubleword boundary, we 132b57aeab8SRavi Bangoria * need to increase the length such that next doubleword also get 133b57aeab8SRavi Bangoria * covered. Ex, 134b57aeab8SRavi Bangoria * 135b57aeab8SRavi Bangoria * address len = 6 bytes 136b57aeab8SRavi Bangoria * |=========. 137b57aeab8SRavi Bangoria * |------------v--|------v--------| 138b57aeab8SRavi Bangoria * | | | | | | | | | | | | | | | | | 139b57aeab8SRavi Bangoria * |---------------|---------------| 140b57aeab8SRavi Bangoria * <---8 bytes---> 141b57aeab8SRavi Bangoria * 142b57aeab8SRavi Bangoria * In this case, we should configure hw as: 143b57aeab8SRavi Bangoria * start_addr = address & ~HW_BREAKPOINT_ALIGN 144b57aeab8SRavi Bangoria * len = 16 bytes 145b57aeab8SRavi Bangoria * 146b57aeab8SRavi Bangoria * @start_addr and @end_addr are inclusive. 147b57aeab8SRavi Bangoria */ 148b57aeab8SRavi Bangoria static int hw_breakpoint_validate_len(struct arch_hw_breakpoint *hw) 149b57aeab8SRavi Bangoria { 150b57aeab8SRavi Bangoria u16 max_len = DABR_MAX_LEN; 151b57aeab8SRavi Bangoria u16 hw_len; 152b57aeab8SRavi Bangoria unsigned long start_addr, end_addr; 153b57aeab8SRavi Bangoria 154b57aeab8SRavi Bangoria start_addr = hw->address & ~HW_BREAKPOINT_ALIGN; 155b57aeab8SRavi Bangoria end_addr = (hw->address + hw->len - 1) | HW_BREAKPOINT_ALIGN; 156b57aeab8SRavi Bangoria hw_len = end_addr - start_addr + 1; 157b57aeab8SRavi Bangoria 158b57aeab8SRavi Bangoria if (dawr_enabled()) { 159b57aeab8SRavi Bangoria max_len = DAWR_MAX_LEN; 160b57aeab8SRavi Bangoria /* DAWR region can't cross 512 bytes boundary */ 161b57aeab8SRavi Bangoria if ((start_addr >> 9) != (end_addr >> 9)) 162b57aeab8SRavi Bangoria return -EINVAL; 163*39413ae0SChristophe Leroy } else if (IS_ENABLED(CONFIG_PPC_8xx)) { 164*39413ae0SChristophe Leroy /* 8xx can setup a range without limitation */ 165*39413ae0SChristophe Leroy max_len = U16_MAX; 166b57aeab8SRavi Bangoria } 167b57aeab8SRavi Bangoria 168b57aeab8SRavi Bangoria if (hw_len > max_len) 169b57aeab8SRavi Bangoria return -EINVAL; 170b57aeab8SRavi Bangoria 171b57aeab8SRavi Bangoria hw->hw_len = hw_len; 172b57aeab8SRavi Bangoria return 0; 173b57aeab8SRavi Bangoria } 174b57aeab8SRavi Bangoria 175b57aeab8SRavi Bangoria /* 1765aae8a53SK.Prasad * Validate the arch-specific HW Breakpoint register settings 1775aae8a53SK.Prasad */ 1785d5176baSFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 1795d5176baSFrederic Weisbecker const struct perf_event_attr *attr, 1805d5176baSFrederic Weisbecker struct arch_hw_breakpoint *hw) 1815aae8a53SK.Prasad { 182b57aeab8SRavi Bangoria int ret = -EINVAL; 1835aae8a53SK.Prasad 184b57aeab8SRavi Bangoria if (!bp || !attr->bp_len) 1855aae8a53SK.Prasad return ret; 1865aae8a53SK.Prasad 1875d5176baSFrederic Weisbecker hw->type = HW_BRK_TYPE_TRANSLATE; 1885d5176baSFrederic Weisbecker if (attr->bp_type & HW_BREAKPOINT_R) 1895d5176baSFrederic Weisbecker hw->type |= HW_BRK_TYPE_READ; 1905d5176baSFrederic Weisbecker if (attr->bp_type & HW_BREAKPOINT_W) 1915d5176baSFrederic Weisbecker hw->type |= HW_BRK_TYPE_WRITE; 1925d5176baSFrederic Weisbecker if (hw->type == HW_BRK_TYPE_TRANSLATE) 1939422de3eSMichael Neuling /* must set alteast read or write */ 1945aae8a53SK.Prasad return ret; 1955d5176baSFrederic Weisbecker if (!attr->exclude_user) 1965d5176baSFrederic Weisbecker hw->type |= HW_BRK_TYPE_USER; 1975d5176baSFrederic Weisbecker if (!attr->exclude_kernel) 1985d5176baSFrederic Weisbecker hw->type |= HW_BRK_TYPE_KERNEL; 1995d5176baSFrederic Weisbecker if (!attr->exclude_hv) 2005d5176baSFrederic Weisbecker hw->type |= HW_BRK_TYPE_HYP; 2015d5176baSFrederic Weisbecker hw->address = attr->bp_addr; 2025d5176baSFrederic Weisbecker hw->len = attr->bp_len; 2035aae8a53SK.Prasad 20485ce9a5dSMichael Neuling if (!ppc_breakpoint_available()) 20585ce9a5dSMichael Neuling return -ENODEV; 206b57aeab8SRavi Bangoria 207b57aeab8SRavi Bangoria return hw_breakpoint_validate_len(hw); 2085aae8a53SK.Prasad } 2095aae8a53SK.Prasad 2105aae8a53SK.Prasad /* 21106532a67SK.Prasad * Restores the breakpoint on the debug registers. 21206532a67SK.Prasad * Invoke this function if it is known that the execution context is 21306532a67SK.Prasad * about to change to cause loss of MSR_SE settings. 21406532a67SK.Prasad */ 21506532a67SK.Prasad void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs) 21606532a67SK.Prasad { 21706532a67SK.Prasad struct arch_hw_breakpoint *info; 21806532a67SK.Prasad 21906532a67SK.Prasad if (likely(!tsk->thread.last_hit_ubp)) 22006532a67SK.Prasad return; 22106532a67SK.Prasad 22206532a67SK.Prasad info = counter_arch_bp(tsk->thread.last_hit_ubp); 22306532a67SK.Prasad regs->msr &= ~MSR_SE; 22421f58507SPaul Gortmaker __set_breakpoint(info); 22506532a67SK.Prasad tsk->thread.last_hit_ubp = NULL; 22606532a67SK.Prasad } 22706532a67SK.Prasad 22827985b2aSRavi Bangoria static bool dar_within_range(unsigned long dar, struct arch_hw_breakpoint *info) 229bc01bdf6SRavi Bangoria { 23027985b2aSRavi Bangoria return ((info->address <= dar) && (dar - info->address < info->len)); 23127985b2aSRavi Bangoria } 232bc01bdf6SRavi Bangoria 23327985b2aSRavi Bangoria static bool 23427985b2aSRavi Bangoria dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info) 23527985b2aSRavi Bangoria { 23627985b2aSRavi Bangoria return ((dar <= info->address + info->len - 1) && 23727985b2aSRavi Bangoria (dar + size - 1 >= info->address)); 238bc01bdf6SRavi Bangoria } 239bc01bdf6SRavi Bangoria 24006532a67SK.Prasad /* 2415aae8a53SK.Prasad * Handle debug exception notifications. 2425aae8a53SK.Prasad */ 243658d029dSChristophe Leroy static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp, 24427985b2aSRavi Bangoria struct arch_hw_breakpoint *info) 245658d029dSChristophe Leroy { 246bc01bdf6SRavi Bangoria unsigned int instr = 0; 24727985b2aSRavi Bangoria int ret, type, size; 24827985b2aSRavi Bangoria struct instruction_op op; 24927985b2aSRavi Bangoria unsigned long addr = info->address; 250bc01bdf6SRavi Bangoria 251bc01bdf6SRavi Bangoria if (__get_user_inatomic(instr, (unsigned int *)regs->nip)) 252bc01bdf6SRavi Bangoria goto fail; 253bc01bdf6SRavi Bangoria 25427985b2aSRavi Bangoria ret = analyse_instr(&op, regs, instr); 25527985b2aSRavi Bangoria type = GETTYPE(op.type); 25627985b2aSRavi Bangoria size = GETSIZE(op.type); 25727985b2aSRavi Bangoria 25827985b2aSRavi Bangoria if (!ret && (type == LARX || type == STCX)) { 259bc01bdf6SRavi Bangoria printk_ratelimited("Breakpoint hit on instruction that can't be emulated." 260bc01bdf6SRavi Bangoria " Breakpoint at 0x%lx will be disabled.\n", addr); 261bc01bdf6SRavi Bangoria goto disable; 262bc01bdf6SRavi Bangoria } 263658d029dSChristophe Leroy 26427985b2aSRavi Bangoria /* 26527985b2aSRavi Bangoria * If it's extraneous event, we still need to emulate/single- 26627985b2aSRavi Bangoria * step the instruction, but we don't generate an event. 26727985b2aSRavi Bangoria */ 26827985b2aSRavi Bangoria if (size && !dar_range_overlaps(regs->dar, size, info)) 26927985b2aSRavi Bangoria info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ; 27027985b2aSRavi Bangoria 271658d029dSChristophe Leroy /* Do not emulate user-space instructions, instead single-step them */ 272658d029dSChristophe Leroy if (user_mode(regs)) { 273658d029dSChristophe Leroy current->thread.last_hit_ubp = bp; 274658d029dSChristophe Leroy regs->msr |= MSR_SE; 275658d029dSChristophe Leroy return false; 276658d029dSChristophe Leroy } 277658d029dSChristophe Leroy 278bc01bdf6SRavi Bangoria if (!emulate_step(regs, instr)) 279bc01bdf6SRavi Bangoria goto fail; 280658d029dSChristophe Leroy 281bc01bdf6SRavi Bangoria return true; 282bc01bdf6SRavi Bangoria 283bc01bdf6SRavi Bangoria fail: 284658d029dSChristophe Leroy /* 285bc01bdf6SRavi Bangoria * We've failed in reliably handling the hw-breakpoint. Unregister 286bc01bdf6SRavi Bangoria * it and throw a warning message to let the user know about it. 287658d029dSChristophe Leroy */ 288658d029dSChristophe Leroy WARN(1, "Unable to handle hardware breakpoint. Breakpoint at " 289658d029dSChristophe Leroy "0x%lx will be disabled.", addr); 290bc01bdf6SRavi Bangoria 291bc01bdf6SRavi Bangoria disable: 292658d029dSChristophe Leroy perf_event_disable_inatomic(bp); 293658d029dSChristophe Leroy return false; 294658d029dSChristophe Leroy } 295658d029dSChristophe Leroy 29603465f89SNicholas Piggin int hw_breakpoint_handler(struct die_args *args) 2975aae8a53SK.Prasad { 2985aae8a53SK.Prasad int rc = NOTIFY_STOP; 2995aae8a53SK.Prasad struct perf_event *bp; 3005aae8a53SK.Prasad struct pt_regs *regs = args->regs; 3014ad8622dSChristophe Leroy struct arch_hw_breakpoint *info; 3025aae8a53SK.Prasad 3035aae8a53SK.Prasad /* Disable breakpoints during exception handling */ 3049422de3eSMichael Neuling hw_breakpoint_disable(); 305574cb248SPaul Mackerras 3065aae8a53SK.Prasad /* 3075aae8a53SK.Prasad * The counter may be concurrently released but that can only 3085aae8a53SK.Prasad * occur from a call_rcu() path. We can then safely fetch 3095aae8a53SK.Prasad * the breakpoint, use its callback, touch its counter 3105aae8a53SK.Prasad * while we are in an rcu_read_lock() path. 3115aae8a53SK.Prasad */ 3125aae8a53SK.Prasad rcu_read_lock(); 3135aae8a53SK.Prasad 31469111bacSChristoph Lameter bp = __this_cpu_read(bp_per_reg); 315c21a493aSRavi Bangoria if (!bp) { 316c21a493aSRavi Bangoria rc = NOTIFY_DONE; 3175aae8a53SK.Prasad goto out; 318c21a493aSRavi Bangoria } 3195aae8a53SK.Prasad info = counter_arch_bp(bp); 3205aae8a53SK.Prasad 3215aae8a53SK.Prasad /* 3225aae8a53SK.Prasad * Return early after invoking user-callback function without restoring 3235aae8a53SK.Prasad * DABR if the breakpoint is from ptrace which always operates in 3245aae8a53SK.Prasad * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal 3255aae8a53SK.Prasad * generated in do_dabr(). 3265aae8a53SK.Prasad */ 327574cb248SPaul Mackerras if (bp->overflow_handler == ptrace_triggered) { 3285aae8a53SK.Prasad perf_bp_event(bp, regs); 3295aae8a53SK.Prasad rc = NOTIFY_DONE; 3305aae8a53SK.Prasad goto out; 3315aae8a53SK.Prasad } 3325aae8a53SK.Prasad 333540e07c6SMichael Neuling info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ; 33427985b2aSRavi Bangoria if (!dar_within_range(regs->dar, info)) 3359422de3eSMichael Neuling info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ; 336*39413ae0SChristophe Leroy 337*39413ae0SChristophe Leroy if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info)) 3385aae8a53SK.Prasad goto out; 3395aae8a53SK.Prasad 3405aae8a53SK.Prasad /* 3415aae8a53SK.Prasad * As a policy, the callback is invoked in a 'trigger-after-execute' 3425aae8a53SK.Prasad * fashion 3435aae8a53SK.Prasad */ 3449422de3eSMichael Neuling if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ)) 3455aae8a53SK.Prasad perf_bp_event(bp, regs); 3465aae8a53SK.Prasad 34721f58507SPaul Gortmaker __set_breakpoint(info); 3485aae8a53SK.Prasad out: 3495aae8a53SK.Prasad rcu_read_unlock(); 3505aae8a53SK.Prasad return rc; 3515aae8a53SK.Prasad } 35203465f89SNicholas Piggin NOKPROBE_SYMBOL(hw_breakpoint_handler); 3535aae8a53SK.Prasad 3545aae8a53SK.Prasad /* 3555aae8a53SK.Prasad * Handle single-step exceptions following a DABR hit. 3565aae8a53SK.Prasad */ 35703465f89SNicholas Piggin static int single_step_dabr_instruction(struct die_args *args) 3585aae8a53SK.Prasad { 3595aae8a53SK.Prasad struct pt_regs *regs = args->regs; 3605aae8a53SK.Prasad struct perf_event *bp = NULL; 3613f4693eeSMichael Neuling struct arch_hw_breakpoint *info; 3625aae8a53SK.Prasad 3635aae8a53SK.Prasad bp = current->thread.last_hit_ubp; 3645aae8a53SK.Prasad /* 3655aae8a53SK.Prasad * Check if we are single-stepping as a result of a 3665aae8a53SK.Prasad * previous HW Breakpoint exception 3675aae8a53SK.Prasad */ 3685aae8a53SK.Prasad if (!bp) 3695aae8a53SK.Prasad return NOTIFY_DONE; 3705aae8a53SK.Prasad 3713f4693eeSMichael Neuling info = counter_arch_bp(bp); 3725aae8a53SK.Prasad 3735aae8a53SK.Prasad /* 3745aae8a53SK.Prasad * We shall invoke the user-defined callback function in the single 3755aae8a53SK.Prasad * stepping handler to confirm to 'trigger-after-execute' semantics 3765aae8a53SK.Prasad */ 3779422de3eSMichael Neuling if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ)) 3785aae8a53SK.Prasad perf_bp_event(bp, regs); 3795aae8a53SK.Prasad 38021f58507SPaul Gortmaker __set_breakpoint(info); 3815aae8a53SK.Prasad current->thread.last_hit_ubp = NULL; 38276b0f133SPaul Mackerras 38376b0f133SPaul Mackerras /* 38476b0f133SPaul Mackerras * If the process was being single-stepped by ptrace, let the 38576b0f133SPaul Mackerras * other single-step actions occur (e.g. generate SIGTRAP). 38676b0f133SPaul Mackerras */ 38776b0f133SPaul Mackerras if (test_thread_flag(TIF_SINGLESTEP)) 38876b0f133SPaul Mackerras return NOTIFY_DONE; 38976b0f133SPaul Mackerras 3905aae8a53SK.Prasad return NOTIFY_STOP; 3915aae8a53SK.Prasad } 39203465f89SNicholas Piggin NOKPROBE_SYMBOL(single_step_dabr_instruction); 3935aae8a53SK.Prasad 3945aae8a53SK.Prasad /* 3955aae8a53SK.Prasad * Handle debug exception notifications. 3965aae8a53SK.Prasad */ 39703465f89SNicholas Piggin int hw_breakpoint_exceptions_notify( 3985aae8a53SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 3995aae8a53SK.Prasad { 4005aae8a53SK.Prasad int ret = NOTIFY_DONE; 4015aae8a53SK.Prasad 4025aae8a53SK.Prasad switch (val) { 4035aae8a53SK.Prasad case DIE_DABR_MATCH: 4045aae8a53SK.Prasad ret = hw_breakpoint_handler(data); 4055aae8a53SK.Prasad break; 4065aae8a53SK.Prasad case DIE_SSTEP: 4075aae8a53SK.Prasad ret = single_step_dabr_instruction(data); 4085aae8a53SK.Prasad break; 4095aae8a53SK.Prasad } 4105aae8a53SK.Prasad 4115aae8a53SK.Prasad return ret; 4125aae8a53SK.Prasad } 41303465f89SNicholas Piggin NOKPROBE_SYMBOL(hw_breakpoint_exceptions_notify); 4145aae8a53SK.Prasad 4155aae8a53SK.Prasad /* 4165aae8a53SK.Prasad * Release the user breakpoints used by ptrace 4175aae8a53SK.Prasad */ 4185aae8a53SK.Prasad void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 4195aae8a53SK.Prasad { 4205aae8a53SK.Prasad struct thread_struct *t = &tsk->thread; 4215aae8a53SK.Prasad 4225aae8a53SK.Prasad unregister_hw_breakpoint(t->ptrace_bps[0]); 4235aae8a53SK.Prasad t->ptrace_bps[0] = NULL; 4245aae8a53SK.Prasad } 4255aae8a53SK.Prasad 4265aae8a53SK.Prasad void hw_breakpoint_pmu_read(struct perf_event *bp) 4275aae8a53SK.Prasad { 4285aae8a53SK.Prasad /* TODO */ 4295aae8a53SK.Prasad } 430