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/kprobes.h> 360067f129SK.Prasad #include <linux/percpu.h> 370067f129SK.Prasad #include <linux/kdebug.h> 380067f129SK.Prasad #include <linux/kernel.h> 390067f129SK.Prasad #include <linux/module.h> 400067f129SK.Prasad #include <linux/sched.h> 410067f129SK.Prasad #include <linux/init.h> 420067f129SK.Prasad #include <linux/smp.h> 430067f129SK.Prasad 440067f129SK.Prasad #include <asm/hw_breakpoint.h> 450067f129SK.Prasad #include <asm/processor.h> 460067f129SK.Prasad #include <asm/debugreg.h> 470067f129SK.Prasad 4824f1e32cSFrederic Weisbecker /* Per cpu debug control register value */ 4928b4e0d8STejun Heo DEFINE_PER_CPU(unsigned long, cpu_dr7); 5028b4e0d8STejun Heo EXPORT_PER_CPU_SYMBOL(cpu_dr7); 5124f1e32cSFrederic Weisbecker 5224f1e32cSFrederic Weisbecker /* Per cpu debug address registers values */ 5324f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); 540067f129SK.Prasad 550067f129SK.Prasad /* 5624f1e32cSFrederic Weisbecker * Stores the breakpoints currently in use on each breakpoint address 5724f1e32cSFrederic Weisbecker * register for each cpus 580067f129SK.Prasad */ 5924f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); 600067f129SK.Prasad 610067f129SK.Prasad 622c31b795SFrederic Weisbecker static inline unsigned long 632c31b795SFrederic Weisbecker __encode_dr7(int drnum, unsigned int len, unsigned int type) 642c31b795SFrederic Weisbecker { 652c31b795SFrederic Weisbecker unsigned long bp_info; 662c31b795SFrederic Weisbecker 672c31b795SFrederic Weisbecker bp_info = (len | type) & 0xf; 682c31b795SFrederic Weisbecker bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); 692c31b795SFrederic Weisbecker bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); 702c31b795SFrederic Weisbecker 712c31b795SFrederic Weisbecker return bp_info; 722c31b795SFrederic Weisbecker } 732c31b795SFrederic Weisbecker 740067f129SK.Prasad /* 750067f129SK.Prasad * Encode the length, type, Exact, and Enable bits for a particular breakpoint 760067f129SK.Prasad * as stored in debug register 7. 770067f129SK.Prasad */ 7824f1e32cSFrederic Weisbecker unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) 790067f129SK.Prasad { 802c31b795SFrederic Weisbecker return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN; 810067f129SK.Prasad } 820067f129SK.Prasad 8324f1e32cSFrederic Weisbecker /* 8424f1e32cSFrederic Weisbecker * Decode the length and type bits for a particular breakpoint as 8524f1e32cSFrederic Weisbecker * stored in debug register 7. Return the "enabled" status. 860067f129SK.Prasad */ 8724f1e32cSFrederic Weisbecker int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type) 8824f1e32cSFrederic Weisbecker { 8924f1e32cSFrederic Weisbecker int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE); 9024f1e32cSFrederic Weisbecker 9124f1e32cSFrederic Weisbecker *len = (bp_info & 0xc) | 0x40; 9224f1e32cSFrederic Weisbecker *type = (bp_info & 0x3) | 0x80; 9324f1e32cSFrederic Weisbecker 9424f1e32cSFrederic Weisbecker return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3; 950067f129SK.Prasad } 960067f129SK.Prasad 970067f129SK.Prasad /* 9824f1e32cSFrederic Weisbecker * Install a perf counter breakpoint. 9924f1e32cSFrederic Weisbecker * 10024f1e32cSFrederic Weisbecker * We seek a free debug address register and use it for this 10124f1e32cSFrederic Weisbecker * breakpoint. Eventually we enable it in the debug control register. 10224f1e32cSFrederic Weisbecker * 10324f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 10424f1e32cSFrederic Weisbecker * and registers local to this cpu. 1050067f129SK.Prasad */ 10624f1e32cSFrederic Weisbecker int arch_install_hw_breakpoint(struct perf_event *bp) 1070067f129SK.Prasad { 10824f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 10924f1e32cSFrederic Weisbecker unsigned long *dr7; 11024f1e32cSFrederic Weisbecker int i; 1110067f129SK.Prasad 11224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 11324f1e32cSFrederic Weisbecker struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); 11424f1e32cSFrederic Weisbecker 11524f1e32cSFrederic Weisbecker if (!*slot) { 11624f1e32cSFrederic Weisbecker *slot = bp; 1170067f129SK.Prasad break; 1180067f129SK.Prasad } 11924f1e32cSFrederic Weisbecker } 1200067f129SK.Prasad 12124f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 12224f1e32cSFrederic Weisbecker return -EBUSY; 12324f1e32cSFrederic Weisbecker 12424f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 1250a3aee0dSTejun Heo __this_cpu_write(cpu_debugreg[i], info->address); 12624f1e32cSFrederic Weisbecker 12728b4e0d8STejun Heo dr7 = &__get_cpu_var(cpu_dr7); 12824f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 12924f1e32cSFrederic Weisbecker 13024f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 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++) { 15124f1e32cSFrederic Weisbecker struct perf_event **slot = &__get_cpu_var(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 16228b4e0d8STejun Heo dr7 = &__get_cpu_var(cpu_dr7); 1632c31b795SFrederic Weisbecker *dr7 &= ~__encode_dr7(i, info->len, info->type); 16424f1e32cSFrederic Weisbecker 16524f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 1660067f129SK.Prasad } 1670067f129SK.Prasad 1680067f129SK.Prasad static int get_hbp_len(u8 hbp_len) 1690067f129SK.Prasad { 1700067f129SK.Prasad unsigned int len_in_bytes = 0; 1710067f129SK.Prasad 1720067f129SK.Prasad switch (hbp_len) { 17324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 1740067f129SK.Prasad len_in_bytes = 1; 1750067f129SK.Prasad break; 17624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 1770067f129SK.Prasad len_in_bytes = 2; 1780067f129SK.Prasad break; 17924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 1800067f129SK.Prasad len_in_bytes = 4; 1810067f129SK.Prasad break; 1820067f129SK.Prasad #ifdef CONFIG_X86_64 18324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 1840067f129SK.Prasad len_in_bytes = 8; 1850067f129SK.Prasad break; 1860067f129SK.Prasad #endif 1870067f129SK.Prasad } 1880067f129SK.Prasad return len_in_bytes; 1890067f129SK.Prasad } 1900067f129SK.Prasad 1910067f129SK.Prasad /* 1920067f129SK.Prasad * Check for virtual address in kernel space. 1930067f129SK.Prasad */ 194b2812d03SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct perf_event *bp) 1950067f129SK.Prasad { 1960067f129SK.Prasad unsigned int len; 197b2812d03SFrederic Weisbecker unsigned long va; 198b2812d03SFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 1990067f129SK.Prasad 200b2812d03SFrederic Weisbecker va = info->address; 201b2812d03SFrederic Weisbecker len = get_hbp_len(info->len); 2020067f129SK.Prasad 2030067f129SK.Prasad return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); 2040067f129SK.Prasad } 2050067f129SK.Prasad 20624f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 20724f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 20824f1e32cSFrederic Weisbecker { 20989e45aacSFrederic Weisbecker /* Type */ 21089e45aacSFrederic Weisbecker switch (x86_type) { 21189e45aacSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 21289e45aacSFrederic Weisbecker if (x86_len != X86_BREAKPOINT_LEN_X) 21389e45aacSFrederic Weisbecker return -EINVAL; 21489e45aacSFrederic Weisbecker 21589e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 21689e45aacSFrederic Weisbecker *gen_len = sizeof(long); 21789e45aacSFrederic Weisbecker return 0; 21889e45aacSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 21989e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 22089e45aacSFrederic Weisbecker break; 22189e45aacSFrederic Weisbecker case X86_BREAKPOINT_RW: 22289e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 22389e45aacSFrederic Weisbecker break; 22489e45aacSFrederic Weisbecker default: 22589e45aacSFrederic Weisbecker return -EINVAL; 22689e45aacSFrederic Weisbecker } 22789e45aacSFrederic Weisbecker 22824f1e32cSFrederic Weisbecker /* Len */ 22924f1e32cSFrederic Weisbecker switch (x86_len) { 23024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 23124f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_1; 23224f1e32cSFrederic Weisbecker break; 23324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 23424f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_2; 23524f1e32cSFrederic Weisbecker break; 23624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 23724f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_4; 23824f1e32cSFrederic Weisbecker break; 23924f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 24024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 24124f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_8; 24224f1e32cSFrederic Weisbecker break; 24324f1e32cSFrederic Weisbecker #endif 24424f1e32cSFrederic Weisbecker default: 24524f1e32cSFrederic Weisbecker return -EINVAL; 24624f1e32cSFrederic Weisbecker } 24724f1e32cSFrederic Weisbecker 24824f1e32cSFrederic Weisbecker return 0; 24924f1e32cSFrederic Weisbecker } 25024f1e32cSFrederic Weisbecker 25124f1e32cSFrederic Weisbecker 25224f1e32cSFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp) 25324f1e32cSFrederic Weisbecker { 25424f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 25524f1e32cSFrederic Weisbecker 25624f1e32cSFrederic Weisbecker info->address = bp->attr.bp_addr; 25724f1e32cSFrederic Weisbecker 258f7809dafSFrederic Weisbecker /* Type */ 259f7809dafSFrederic Weisbecker switch (bp->attr.bp_type) { 260f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 261f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_WRITE; 262f7809dafSFrederic Weisbecker break; 263f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 264f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_RW; 265f7809dafSFrederic Weisbecker break; 266f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 267f7809dafSFrederic Weisbecker info->type = X86_BREAKPOINT_EXECUTE; 268f7809dafSFrederic Weisbecker /* 269f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 270f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 271f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 272f7809dafSFrederic Weisbecker */ 273f7809dafSFrederic Weisbecker if (bp->attr.bp_len == sizeof(long)) { 274f7809dafSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_X; 275f7809dafSFrederic Weisbecker return 0; 276f7809dafSFrederic Weisbecker } 277f7809dafSFrederic Weisbecker default: 278f7809dafSFrederic Weisbecker return -EINVAL; 279f7809dafSFrederic Weisbecker } 280f7809dafSFrederic Weisbecker 28124f1e32cSFrederic Weisbecker /* Len */ 28224f1e32cSFrederic Weisbecker switch (bp->attr.bp_len) { 28324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 28424f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_1; 28524f1e32cSFrederic Weisbecker break; 28624f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 28724f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_2; 28824f1e32cSFrederic Weisbecker break; 28924f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 29024f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_4; 29124f1e32cSFrederic Weisbecker break; 29224f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 29324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 29424f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_8; 29524f1e32cSFrederic Weisbecker break; 29624f1e32cSFrederic Weisbecker #endif 29724f1e32cSFrederic Weisbecker default: 29824f1e32cSFrederic Weisbecker return -EINVAL; 29924f1e32cSFrederic Weisbecker } 30024f1e32cSFrederic Weisbecker 30124f1e32cSFrederic Weisbecker return 0; 30224f1e32cSFrederic Weisbecker } 3030067f129SK.Prasad /* 3040067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3050067f129SK.Prasad */ 306b2812d03SFrederic Weisbecker int arch_validate_hwbkpt_settings(struct perf_event *bp) 3070067f129SK.Prasad { 30824f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 3090067f129SK.Prasad unsigned int align; 31024f1e32cSFrederic Weisbecker int ret; 3110067f129SK.Prasad 31224f1e32cSFrederic Weisbecker 31324f1e32cSFrederic Weisbecker ret = arch_build_bp_info(bp); 31424f1e32cSFrederic Weisbecker if (ret) 31524f1e32cSFrederic Weisbecker return ret; 31624f1e32cSFrederic Weisbecker 31724f1e32cSFrederic Weisbecker ret = -EINVAL; 31824f1e32cSFrederic Weisbecker 31924f1e32cSFrederic Weisbecker switch (info->len) { 32024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3210067f129SK.Prasad align = 0; 3220067f129SK.Prasad break; 32324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3240067f129SK.Prasad align = 1; 3250067f129SK.Prasad break; 32624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3270067f129SK.Prasad align = 3; 3280067f129SK.Prasad break; 3290067f129SK.Prasad #ifdef CONFIG_X86_64 33024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3310067f129SK.Prasad align = 7; 3320067f129SK.Prasad break; 3330067f129SK.Prasad #endif 3340067f129SK.Prasad default: 3350067f129SK.Prasad return ret; 3360067f129SK.Prasad } 3370067f129SK.Prasad 33884d71092SFrederic Weisbecker /* 3390067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3400067f129SK.Prasad * for the alignment implied by len. 3410067f129SK.Prasad */ 34224f1e32cSFrederic Weisbecker if (info->address & align) 3430067f129SK.Prasad return -EINVAL; 3440067f129SK.Prasad 3450067f129SK.Prasad return 0; 3460067f129SK.Prasad } 3470067f129SK.Prasad 34824f1e32cSFrederic Weisbecker /* 3499f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 3509f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 3519f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 3529f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 3539f6b3c2cSFrederic Weisbecker * 3549f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 3559f6b3c2cSFrederic Weisbecker */ 3569f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 3579f6b3c2cSFrederic Weisbecker { 3589f6b3c2cSFrederic Weisbecker int i; 3599f6b3c2cSFrederic Weisbecker int dr7 = 0; 3609f6b3c2cSFrederic Weisbecker struct perf_event *bp; 3619f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 3629f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 3639f6b3c2cSFrederic Weisbecker 3649f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 3659f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 3669f6b3c2cSFrederic Weisbecker 3679f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 3689f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 3699f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 3709f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 3719f6b3c2cSFrederic Weisbecker } else { 3729f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 3739f6b3c2cSFrederic Weisbecker } 3749f6b3c2cSFrederic Weisbecker } 3759f6b3c2cSFrederic Weisbecker 3769f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 3779f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 3789f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 3799f6b3c2cSFrederic Weisbecker 3809f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 3819f6b3c2cSFrederic Weisbecker } 38268efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 3839f6b3c2cSFrederic Weisbecker 3849f6b3c2cSFrederic Weisbecker /* 38524f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 38624f1e32cSFrederic Weisbecker */ 38724f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 3880067f129SK.Prasad { 3890067f129SK.Prasad int i; 39024f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 3910067f129SK.Prasad 39224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 39324f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 39424f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 3950067f129SK.Prasad } 39624f1e32cSFrederic Weisbecker } 39724f1e32cSFrederic Weisbecker 39824f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 39924f1e32cSFrederic Weisbecker { 4000a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4010a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4020a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4030a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 40424f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 4050a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 40624f1e32cSFrederic Weisbecker } 40724f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4080067f129SK.Prasad 4090067f129SK.Prasad /* 4100067f129SK.Prasad * Handle debug exception notifications. 4110067f129SK.Prasad * 4120067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4130067f129SK.Prasad * 4140067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4150067f129SK.Prasad * i) When the causative address is from user-space and the exception 4160067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4170067f129SK.Prasad * switching 4180067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4190067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4200067f129SK.Prasad * met and requires some more action in do_debug(). 4210067f129SK.Prasad * 4220067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4230067f129SK.Prasad * 4240067f129SK.Prasad */ 4254555835bSJaswinder Singh Rajput static int __kprobes hw_breakpoint_handler(struct die_args *args) 4260067f129SK.Prasad { 4270067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 42824f1e32cSFrederic Weisbecker struct perf_event *bp; 42962edab90SK.Prasad unsigned long dr7, dr6; 43062edab90SK.Prasad unsigned long *dr6_p; 43162edab90SK.Prasad 43262edab90SK.Prasad /* The DR6 value is pointed by args->err */ 43362edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 43462edab90SK.Prasad dr6 = *dr6_p; 4350067f129SK.Prasad 4366c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 4376c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 4386c0aca28SFrederic Weisbecker return NOTIFY_DONE; 4396c0aca28SFrederic Weisbecker 4400067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4410067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4420067f129SK.Prasad return NOTIFY_DONE; 4430067f129SK.Prasad 4440067f129SK.Prasad get_debugreg(dr7, 7); 4450067f129SK.Prasad /* Disable breakpoints during exception handling */ 4460067f129SK.Prasad set_debugreg(0UL, 7); 4470067f129SK.Prasad /* 4480067f129SK.Prasad * Assert that local interrupts are disabled 4490067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4500067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4510067f129SK.Prasad */ 4520067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4530067f129SK.Prasad cpu = get_cpu(); 4540067f129SK.Prasad 4550067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 4560067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 4570067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 4580067f129SK.Prasad continue; 45924f1e32cSFrederic Weisbecker 4600067f129SK.Prasad /* 46124f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 46224f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 46324f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 46424f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 4650067f129SK.Prasad */ 46624f1e32cSFrederic Weisbecker rcu_read_lock(); 46724f1e32cSFrederic Weisbecker 46824f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 4690067f129SK.Prasad /* 47062edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 47162edab90SK.Prasad * exception handling 47262edab90SK.Prasad */ 47362edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 47462edab90SK.Prasad /* 4750067f129SK.Prasad * bp can be NULL due to lazy debug register switching 47624f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 4770067f129SK.Prasad */ 47824f1e32cSFrederic Weisbecker if (!bp) { 47924f1e32cSFrederic Weisbecker rcu_read_unlock(); 48024f1e32cSFrederic Weisbecker break; 48124f1e32cSFrederic Weisbecker } 4820067f129SK.Prasad 483b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 48424f1e32cSFrederic Weisbecker 4850c4519e8SFrederic Weisbecker /* 4860c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 4870c4519e8SFrederic Weisbecker * returning back to origin. 4880c4519e8SFrederic Weisbecker */ 4890c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 4900c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 4910c4519e8SFrederic Weisbecker 49224f1e32cSFrederic Weisbecker rcu_read_unlock(); 4930067f129SK.Prasad } 494e0e53db6SK.Prasad /* 495e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 496e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 497e0e53db6SK.Prasad * taken exception due to multiple causes 498e0e53db6SK.Prasad */ 499e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 500e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5010067f129SK.Prasad rc = NOTIFY_DONE; 5020067f129SK.Prasad 5030067f129SK.Prasad set_debugreg(dr7, 7); 504eadb8a09SIngo Molnar put_cpu(); 50524f1e32cSFrederic Weisbecker 5060067f129SK.Prasad return rc; 5070067f129SK.Prasad } 5080067f129SK.Prasad 5090067f129SK.Prasad /* 5100067f129SK.Prasad * Handle debug exception notifications. 5110067f129SK.Prasad */ 5120067f129SK.Prasad int __kprobes hw_breakpoint_exceptions_notify( 5130067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5140067f129SK.Prasad { 5150067f129SK.Prasad if (val != DIE_DEBUG) 5160067f129SK.Prasad return NOTIFY_DONE; 5170067f129SK.Prasad 5180067f129SK.Prasad return hw_breakpoint_handler(data); 5190067f129SK.Prasad } 52024f1e32cSFrederic Weisbecker 52124f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 52224f1e32cSFrederic Weisbecker { 52324f1e32cSFrederic Weisbecker /* TODO */ 52424f1e32cSFrederic Weisbecker } 525