10067f129SK.Prasad /* 20067f129SK.Prasad * This program is free software; you can redistribute it and/or modify 30067f129SK.Prasad * it under the terms of the GNU General Public License as published by 40067f129SK.Prasad * the Free Software Foundation; either version 2 of the License, or 50067f129SK.Prasad * (at your option) any later version. 60067f129SK.Prasad * 70067f129SK.Prasad * This program is distributed in the hope that it will be useful, 80067f129SK.Prasad * but WITHOUT ANY WARRANTY; without even the implied warranty of 90067f129SK.Prasad * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 100067f129SK.Prasad * GNU General Public License for more details. 110067f129SK.Prasad * 120067f129SK.Prasad * You should have received a copy of the GNU General Public License 130067f129SK.Prasad * along with this program; if not, write to the Free Software 140067f129SK.Prasad * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 150067f129SK.Prasad * 160067f129SK.Prasad * Copyright (C) 2007 Alan Stern 170067f129SK.Prasad * Copyright (C) 2009 IBM Corporation 1824f1e32cSFrederic Weisbecker * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com> 19ba6909b7SK.Prasad * 20ba6909b7SK.Prasad * Authors: Alan Stern <stern@rowland.harvard.edu> 21ba6909b7SK.Prasad * K.Prasad <prasad@linux.vnet.ibm.com> 22ba6909b7SK.Prasad * Frederic Weisbecker <fweisbec@gmail.com> 230067f129SK.Prasad */ 240067f129SK.Prasad 250067f129SK.Prasad /* 260067f129SK.Prasad * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, 270067f129SK.Prasad * using the CPU's debug registers. 280067f129SK.Prasad */ 290067f129SK.Prasad 3024f1e32cSFrederic Weisbecker #include <linux/perf_event.h> 3124f1e32cSFrederic Weisbecker #include <linux/hw_breakpoint.h> 320067f129SK.Prasad #include <linux/irqflags.h> 330067f129SK.Prasad #include <linux/notifier.h> 340067f129SK.Prasad #include <linux/kallsyms.h> 350067f129SK.Prasad #include <linux/percpu.h> 360067f129SK.Prasad #include <linux/kdebug.h> 370067f129SK.Prasad #include <linux/kernel.h> 380067f129SK.Prasad #include <linux/module.h> 390067f129SK.Prasad #include <linux/sched.h> 400067f129SK.Prasad #include <linux/smp.h> 410067f129SK.Prasad 420067f129SK.Prasad #include <asm/hw_breakpoint.h> 430067f129SK.Prasad #include <asm/processor.h> 440067f129SK.Prasad #include <asm/debugreg.h> 450067f129SK.Prasad 4624f1e32cSFrederic Weisbecker /* Per cpu debug control register value */ 4728b4e0d8STejun Heo DEFINE_PER_CPU(unsigned long, cpu_dr7); 4828b4e0d8STejun Heo EXPORT_PER_CPU_SYMBOL(cpu_dr7); 4924f1e32cSFrederic Weisbecker 5024f1e32cSFrederic Weisbecker /* Per cpu debug address registers values */ 5124f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); 520067f129SK.Prasad 530067f129SK.Prasad /* 5424f1e32cSFrederic Weisbecker * Stores the breakpoints currently in use on each breakpoint address 5524f1e32cSFrederic Weisbecker * register for each cpus 560067f129SK.Prasad */ 5724f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); 580067f129SK.Prasad 590067f129SK.Prasad 602c31b795SFrederic Weisbecker static inline unsigned long 612c31b795SFrederic Weisbecker __encode_dr7(int drnum, unsigned int len, unsigned int type) 622c31b795SFrederic Weisbecker { 632c31b795SFrederic Weisbecker unsigned long bp_info; 642c31b795SFrederic Weisbecker 652c31b795SFrederic Weisbecker bp_info = (len | type) & 0xf; 662c31b795SFrederic Weisbecker bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); 672c31b795SFrederic Weisbecker bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); 682c31b795SFrederic Weisbecker 692c31b795SFrederic Weisbecker return bp_info; 702c31b795SFrederic Weisbecker } 712c31b795SFrederic Weisbecker 720067f129SK.Prasad /* 730067f129SK.Prasad * Encode the length, type, Exact, and Enable bits for a particular breakpoint 740067f129SK.Prasad * as stored in debug register 7. 750067f129SK.Prasad */ 7624f1e32cSFrederic Weisbecker unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) 770067f129SK.Prasad { 782c31b795SFrederic Weisbecker return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN; 790067f129SK.Prasad } 800067f129SK.Prasad 8124f1e32cSFrederic Weisbecker /* 8224f1e32cSFrederic Weisbecker * Decode the length and type bits for a particular breakpoint as 8324f1e32cSFrederic Weisbecker * stored in debug register 7. Return the "enabled" status. 840067f129SK.Prasad */ 8524f1e32cSFrederic Weisbecker int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type) 8624f1e32cSFrederic Weisbecker { 8724f1e32cSFrederic Weisbecker int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE); 8824f1e32cSFrederic Weisbecker 8924f1e32cSFrederic Weisbecker *len = (bp_info & 0xc) | 0x40; 9024f1e32cSFrederic Weisbecker *type = (bp_info & 0x3) | 0x80; 9124f1e32cSFrederic Weisbecker 9224f1e32cSFrederic Weisbecker return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3; 930067f129SK.Prasad } 940067f129SK.Prasad 950067f129SK.Prasad /* 9624f1e32cSFrederic Weisbecker * Install a perf counter breakpoint. 9724f1e32cSFrederic Weisbecker * 9824f1e32cSFrederic Weisbecker * We seek a free debug address register and use it for this 9924f1e32cSFrederic Weisbecker * breakpoint. Eventually we enable it in the debug control register. 10024f1e32cSFrederic Weisbecker * 10124f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 10224f1e32cSFrederic Weisbecker * and registers local to this cpu. 1030067f129SK.Prasad */ 10424f1e32cSFrederic Weisbecker int arch_install_hw_breakpoint(struct perf_event *bp) 1050067f129SK.Prasad { 10624f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 10724f1e32cSFrederic Weisbecker unsigned long *dr7; 10824f1e32cSFrederic Weisbecker int i; 1090067f129SK.Prasad 11024f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 11189cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 11224f1e32cSFrederic Weisbecker 11324f1e32cSFrederic Weisbecker if (!*slot) { 11424f1e32cSFrederic Weisbecker *slot = bp; 1150067f129SK.Prasad break; 1160067f129SK.Prasad } 11724f1e32cSFrederic Weisbecker } 1180067f129SK.Prasad 11924f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 12024f1e32cSFrederic Weisbecker return -EBUSY; 12124f1e32cSFrederic Weisbecker 12224f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 1230a3aee0dSTejun Heo __this_cpu_write(cpu_debugreg[i], info->address); 12424f1e32cSFrederic Weisbecker 12589cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 12624f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 12724f1e32cSFrederic Weisbecker 12824f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 129d6d55f0bSJacob Shin if (info->mask) 130d6d55f0bSJacob Shin set_dr_addr_mask(info->mask, i); 13124f1e32cSFrederic Weisbecker 13224f1e32cSFrederic Weisbecker return 0; 1330067f129SK.Prasad } 1340067f129SK.Prasad 1350067f129SK.Prasad /* 13624f1e32cSFrederic Weisbecker * Uninstall the breakpoint contained in the given counter. 13724f1e32cSFrederic Weisbecker * 13824f1e32cSFrederic Weisbecker * First we search the debug address register it uses and then we disable 13924f1e32cSFrederic Weisbecker * it. 14024f1e32cSFrederic Weisbecker * 14124f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 14224f1e32cSFrederic Weisbecker * and registers local to this cpu. 1430067f129SK.Prasad */ 14424f1e32cSFrederic Weisbecker void arch_uninstall_hw_breakpoint(struct perf_event *bp) 1450067f129SK.Prasad { 14624f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 14724f1e32cSFrederic Weisbecker unsigned long *dr7; 14824f1e32cSFrederic Weisbecker int i; 1490067f129SK.Prasad 15024f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 15189cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 15224f1e32cSFrederic Weisbecker 15324f1e32cSFrederic Weisbecker if (*slot == bp) { 15424f1e32cSFrederic Weisbecker *slot = NULL; 15524f1e32cSFrederic Weisbecker break; 15624f1e32cSFrederic Weisbecker } 15724f1e32cSFrederic Weisbecker } 15824f1e32cSFrederic Weisbecker 15924f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 16024f1e32cSFrederic Weisbecker return; 16124f1e32cSFrederic Weisbecker 16289cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 1632c31b795SFrederic Weisbecker *dr7 &= ~__encode_dr7(i, info->len, info->type); 16424f1e32cSFrederic Weisbecker 16524f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 166d6d55f0bSJacob Shin if (info->mask) 167d6d55f0bSJacob Shin set_dr_addr_mask(0, i); 1680067f129SK.Prasad } 1690067f129SK.Prasad 1700067f129SK.Prasad /* 1710067f129SK.Prasad * Check for virtual address in kernel space. 1720067f129SK.Prasad */ 173b2812d03SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct perf_event *bp) 1740067f129SK.Prasad { 1750067f129SK.Prasad unsigned int len; 176b2812d03SFrederic Weisbecker unsigned long va; 177b2812d03SFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 1780067f129SK.Prasad 179b2812d03SFrederic Weisbecker va = info->address; 18036748b95SJacob Shin len = bp->attr.bp_len; 1810067f129SK.Prasad 1820067f129SK.Prasad return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); 1830067f129SK.Prasad } 1840067f129SK.Prasad 18524f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 18624f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 18724f1e32cSFrederic Weisbecker { 18889e45aacSFrederic Weisbecker /* Type */ 18989e45aacSFrederic Weisbecker switch (x86_type) { 19089e45aacSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 19189e45aacSFrederic Weisbecker if (x86_len != X86_BREAKPOINT_LEN_X) 19289e45aacSFrederic Weisbecker return -EINVAL; 19389e45aacSFrederic Weisbecker 19489e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 19589e45aacSFrederic Weisbecker *gen_len = sizeof(long); 19689e45aacSFrederic Weisbecker return 0; 19789e45aacSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 19889e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 19989e45aacSFrederic Weisbecker break; 20089e45aacSFrederic Weisbecker case X86_BREAKPOINT_RW: 20189e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 20289e45aacSFrederic Weisbecker break; 20389e45aacSFrederic Weisbecker default: 20489e45aacSFrederic Weisbecker return -EINVAL; 20589e45aacSFrederic Weisbecker } 20689e45aacSFrederic Weisbecker 20724f1e32cSFrederic Weisbecker /* Len */ 20824f1e32cSFrederic Weisbecker switch (x86_len) { 20924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 21024f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_1; 21124f1e32cSFrederic Weisbecker break; 21224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 21324f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_2; 21424f1e32cSFrederic Weisbecker break; 21524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 21624f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_4; 21724f1e32cSFrederic Weisbecker break; 21824f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 21924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 22024f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_8; 22124f1e32cSFrederic Weisbecker break; 22224f1e32cSFrederic Weisbecker #endif 22324f1e32cSFrederic Weisbecker default: 22424f1e32cSFrederic Weisbecker return -EINVAL; 22524f1e32cSFrederic Weisbecker } 22624f1e32cSFrederic Weisbecker 22724f1e32cSFrederic Weisbecker return 0; 22824f1e32cSFrederic Weisbecker } 22924f1e32cSFrederic Weisbecker 23024f1e32cSFrederic Weisbecker 23124f1e32cSFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp) 23224f1e32cSFrederic Weisbecker { 23324f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 23424f1e32cSFrederic Weisbecker 23524f1e32cSFrederic Weisbecker info->address = bp->attr.bp_addr; 23624f1e32cSFrederic Weisbecker 237f7809dafSFrederic Weisbecker /* Type */ 238f7809dafSFrederic Weisbecker switch (bp->attr.bp_type) { 239f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 240f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_WRITE; 241f7809dafSFrederic Weisbecker break; 242f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 243f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_RW; 244f7809dafSFrederic Weisbecker break; 245f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 246f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_EXECUTE; 247f7809dafSFrederic Weisbecker /* 248f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 249f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 250f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 251f7809dafSFrederic Weisbecker */ 252f7809dafSFrederic Weisbecker if (bp->attr.bp_len == sizeof(long)) { 253f7809dafSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_X; 254f7809dafSFrederic Weisbecker return 0; 255f7809dafSFrederic Weisbecker } 256f7809dafSFrederic Weisbecker default: 257f7809dafSFrederic Weisbecker return -EINVAL; 258f7809dafSFrederic Weisbecker } 259f7809dafSFrederic Weisbecker 26024f1e32cSFrederic Weisbecker /* Len */ 261d6d55f0bSJacob Shin info->mask = 0; 262d6d55f0bSJacob Shin 26324f1e32cSFrederic Weisbecker switch (bp->attr.bp_len) { 26424f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 26524f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_1; 26624f1e32cSFrederic Weisbecker break; 26724f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 26824f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_2; 26924f1e32cSFrederic Weisbecker break; 27024f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 27124f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_4; 27224f1e32cSFrederic Weisbecker break; 27324f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 27424f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 27524f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_8; 27624f1e32cSFrederic Weisbecker break; 27724f1e32cSFrederic Weisbecker #endif 27824f1e32cSFrederic Weisbecker default: 279d6d55f0bSJacob Shin if (!is_power_of_2(bp->attr.bp_len)) 28024f1e32cSFrederic Weisbecker return -EINVAL; 281d6d55f0bSJacob Shin if (!cpu_has_bpext) 282d6d55f0bSJacob Shin return -EOPNOTSUPP; 283d6d55f0bSJacob Shin info->mask = bp->attr.bp_len - 1; 284d6d55f0bSJacob Shin info->len = X86_BREAKPOINT_LEN_1; 28524f1e32cSFrederic Weisbecker } 28624f1e32cSFrederic Weisbecker 28724f1e32cSFrederic Weisbecker return 0; 28824f1e32cSFrederic Weisbecker } 289d6d55f0bSJacob Shin 2900067f129SK.Prasad /* 2910067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 2920067f129SK.Prasad */ 293b2812d03SFrederic Weisbecker int arch_validate_hwbkpt_settings(struct perf_event *bp) 2940067f129SK.Prasad { 29524f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 2960067f129SK.Prasad unsigned int align; 29724f1e32cSFrederic Weisbecker int ret; 2980067f129SK.Prasad 29924f1e32cSFrederic Weisbecker 30024f1e32cSFrederic Weisbecker ret = arch_build_bp_info(bp); 30124f1e32cSFrederic Weisbecker if (ret) 30224f1e32cSFrederic Weisbecker return ret; 30324f1e32cSFrederic Weisbecker 30424f1e32cSFrederic Weisbecker switch (info->len) { 30524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3060067f129SK.Prasad align = 0; 307d6d55f0bSJacob Shin if (info->mask) 308d6d55f0bSJacob Shin align = info->mask; 3090067f129SK.Prasad break; 31024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3110067f129SK.Prasad align = 1; 3120067f129SK.Prasad break; 31324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3140067f129SK.Prasad align = 3; 3150067f129SK.Prasad break; 3160067f129SK.Prasad #ifdef CONFIG_X86_64 31724f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3180067f129SK.Prasad align = 7; 3190067f129SK.Prasad break; 3200067f129SK.Prasad #endif 3210067f129SK.Prasad default: 322d6d55f0bSJacob Shin WARN_ON_ONCE(1); 3230067f129SK.Prasad } 3240067f129SK.Prasad 32584d71092SFrederic Weisbecker /* 3260067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3270067f129SK.Prasad * for the alignment implied by len. 3280067f129SK.Prasad */ 32924f1e32cSFrederic Weisbecker if (info->address & align) 3300067f129SK.Prasad return -EINVAL; 3310067f129SK.Prasad 3320067f129SK.Prasad return 0; 3330067f129SK.Prasad } 3340067f129SK.Prasad 33524f1e32cSFrederic Weisbecker /* 3369f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 3379f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 3389f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 3399f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 3409f6b3c2cSFrederic Weisbecker * 3419f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 3429f6b3c2cSFrederic Weisbecker */ 3439f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 3449f6b3c2cSFrederic Weisbecker { 3459f6b3c2cSFrederic Weisbecker int i; 3469f6b3c2cSFrederic Weisbecker int dr7 = 0; 3479f6b3c2cSFrederic Weisbecker struct perf_event *bp; 3489f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 3499f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 3509f6b3c2cSFrederic Weisbecker 3519f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 3529f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 3539f6b3c2cSFrederic Weisbecker 3549f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 3559f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 3569f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 3579f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 3589f6b3c2cSFrederic Weisbecker } else { 3599f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 3609f6b3c2cSFrederic Weisbecker } 3619f6b3c2cSFrederic Weisbecker } 3629f6b3c2cSFrederic Weisbecker 3639f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 3649f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 3659f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 3669f6b3c2cSFrederic Weisbecker 3679f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 3689f6b3c2cSFrederic Weisbecker } 36968efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 3709f6b3c2cSFrederic Weisbecker 3719f6b3c2cSFrederic Weisbecker /* 37224f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 37324f1e32cSFrederic Weisbecker */ 37424f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 3750067f129SK.Prasad { 3760067f129SK.Prasad int i; 37724f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 3780067f129SK.Prasad 37924f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 38024f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 38124f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 3820067f129SK.Prasad } 383f7da04c9SOleg Nesterov 384f7da04c9SOleg Nesterov t->debugreg6 = 0; 385f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 38624f1e32cSFrederic Weisbecker } 38724f1e32cSFrederic Weisbecker 38824f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 38924f1e32cSFrederic Weisbecker { 3900a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 3910a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 3920a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 3930a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 39424f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 3950a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 39624f1e32cSFrederic Weisbecker } 39724f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 3980067f129SK.Prasad 3990067f129SK.Prasad /* 4000067f129SK.Prasad * Handle debug exception notifications. 4010067f129SK.Prasad * 4020067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4030067f129SK.Prasad * 4040067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4050067f129SK.Prasad * i) When the causative address is from user-space and the exception 4060067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4070067f129SK.Prasad * switching 4080067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4090067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4100067f129SK.Prasad * met and requires some more action in do_debug(). 4110067f129SK.Prasad * 4120067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4130067f129SK.Prasad * 4140067f129SK.Prasad */ 4159c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 4160067f129SK.Prasad { 4170067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 41824f1e32cSFrederic Weisbecker struct perf_event *bp; 41962edab90SK.Prasad unsigned long dr7, dr6; 42062edab90SK.Prasad unsigned long *dr6_p; 42162edab90SK.Prasad 42262edab90SK.Prasad /* The DR6 value is pointed by args->err */ 42362edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 42462edab90SK.Prasad dr6 = *dr6_p; 4250067f129SK.Prasad 4266c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 4276c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 4286c0aca28SFrederic Weisbecker return NOTIFY_DONE; 4296c0aca28SFrederic Weisbecker 4300067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4310067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4320067f129SK.Prasad return NOTIFY_DONE; 4330067f129SK.Prasad 4340067f129SK.Prasad get_debugreg(dr7, 7); 4350067f129SK.Prasad /* Disable breakpoints during exception handling */ 4360067f129SK.Prasad set_debugreg(0UL, 7); 4370067f129SK.Prasad /* 4380067f129SK.Prasad * Assert that local interrupts are disabled 4390067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4400067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4410067f129SK.Prasad */ 4420067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4430067f129SK.Prasad cpu = get_cpu(); 4440067f129SK.Prasad 4450067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 4460067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 4470067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 4480067f129SK.Prasad continue; 44924f1e32cSFrederic Weisbecker 4500067f129SK.Prasad /* 45124f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 45224f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 45324f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 45424f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 4550067f129SK.Prasad */ 45624f1e32cSFrederic Weisbecker rcu_read_lock(); 45724f1e32cSFrederic Weisbecker 45824f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 4590067f129SK.Prasad /* 46062edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 46162edab90SK.Prasad * exception handling 46262edab90SK.Prasad */ 46362edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 46462edab90SK.Prasad /* 4650067f129SK.Prasad * bp can be NULL due to lazy debug register switching 46624f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 4670067f129SK.Prasad */ 46824f1e32cSFrederic Weisbecker if (!bp) { 46924f1e32cSFrederic Weisbecker rcu_read_unlock(); 47024f1e32cSFrederic Weisbecker break; 47124f1e32cSFrederic Weisbecker } 4720067f129SK.Prasad 473b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 47424f1e32cSFrederic Weisbecker 4750c4519e8SFrederic Weisbecker /* 4760c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 4770c4519e8SFrederic Weisbecker * returning back to origin. 4780c4519e8SFrederic Weisbecker */ 4790c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 4800c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 4810c4519e8SFrederic Weisbecker 48224f1e32cSFrederic Weisbecker rcu_read_unlock(); 4830067f129SK.Prasad } 484e0e53db6SK.Prasad /* 485e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 486e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 487e0e53db6SK.Prasad * taken exception due to multiple causes 488e0e53db6SK.Prasad */ 489e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 490e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 4910067f129SK.Prasad rc = NOTIFY_DONE; 4920067f129SK.Prasad 4930067f129SK.Prasad set_debugreg(dr7, 7); 494eadb8a09SIngo Molnar put_cpu(); 49524f1e32cSFrederic Weisbecker 4960067f129SK.Prasad return rc; 4970067f129SK.Prasad } 4980067f129SK.Prasad 4990067f129SK.Prasad /* 5000067f129SK.Prasad * Handle debug exception notifications. 5010067f129SK.Prasad */ 5029c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5030067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5040067f129SK.Prasad { 5050067f129SK.Prasad if (val != DIE_DEBUG) 5060067f129SK.Prasad return NOTIFY_DONE; 5070067f129SK.Prasad 5080067f129SK.Prasad return hw_breakpoint_handler(data); 5090067f129SK.Prasad } 51024f1e32cSFrederic Weisbecker 51124f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 51224f1e32cSFrederic Weisbecker { 51324f1e32cSFrederic Weisbecker /* TODO */ 51424f1e32cSFrederic Weisbecker } 515