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> 190067f129SK.Prasad */ 200067f129SK.Prasad 210067f129SK.Prasad /* 220067f129SK.Prasad * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, 230067f129SK.Prasad * using the CPU's debug registers. 240067f129SK.Prasad */ 250067f129SK.Prasad 2624f1e32cSFrederic Weisbecker #include <linux/perf_event.h> 2724f1e32cSFrederic Weisbecker #include <linux/hw_breakpoint.h> 280067f129SK.Prasad #include <linux/irqflags.h> 290067f129SK.Prasad #include <linux/notifier.h> 300067f129SK.Prasad #include <linux/kallsyms.h> 310067f129SK.Prasad #include <linux/kprobes.h> 320067f129SK.Prasad #include <linux/percpu.h> 330067f129SK.Prasad #include <linux/kdebug.h> 340067f129SK.Prasad #include <linux/kernel.h> 350067f129SK.Prasad #include <linux/module.h> 360067f129SK.Prasad #include <linux/sched.h> 370067f129SK.Prasad #include <linux/init.h> 380067f129SK.Prasad #include <linux/smp.h> 390067f129SK.Prasad 400067f129SK.Prasad #include <asm/hw_breakpoint.h> 410067f129SK.Prasad #include <asm/processor.h> 420067f129SK.Prasad #include <asm/debugreg.h> 430067f129SK.Prasad 4424f1e32cSFrederic Weisbecker /* Per cpu debug control register value */ 4524f1e32cSFrederic Weisbecker DEFINE_PER_CPU(unsigned long, dr7); 4624f1e32cSFrederic Weisbecker 4724f1e32cSFrederic Weisbecker /* Per cpu debug address registers values */ 4824f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); 490067f129SK.Prasad 500067f129SK.Prasad /* 5124f1e32cSFrederic Weisbecker * Stores the breakpoints currently in use on each breakpoint address 5224f1e32cSFrederic Weisbecker * register for each cpus 530067f129SK.Prasad */ 5424f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); 550067f129SK.Prasad 560067f129SK.Prasad 570067f129SK.Prasad /* 580067f129SK.Prasad * Encode the length, type, Exact, and Enable bits for a particular breakpoint 590067f129SK.Prasad * as stored in debug register 7. 600067f129SK.Prasad */ 6124f1e32cSFrederic Weisbecker unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) 620067f129SK.Prasad { 630067f129SK.Prasad unsigned long bp_info; 640067f129SK.Prasad 650067f129SK.Prasad bp_info = (len | type) & 0xf; 660067f129SK.Prasad bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); 670067f129SK.Prasad bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)) | 680067f129SK.Prasad DR_GLOBAL_SLOWDOWN; 690067f129SK.Prasad return bp_info; 700067f129SK.Prasad } 710067f129SK.Prasad 7224f1e32cSFrederic Weisbecker /* 7324f1e32cSFrederic Weisbecker * Decode the length and type bits for a particular breakpoint as 7424f1e32cSFrederic Weisbecker * stored in debug register 7. Return the "enabled" status. 750067f129SK.Prasad */ 7624f1e32cSFrederic Weisbecker int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type) 7724f1e32cSFrederic Weisbecker { 7824f1e32cSFrederic Weisbecker int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE); 7924f1e32cSFrederic Weisbecker 8024f1e32cSFrederic Weisbecker *len = (bp_info & 0xc) | 0x40; 8124f1e32cSFrederic Weisbecker *type = (bp_info & 0x3) | 0x80; 8224f1e32cSFrederic Weisbecker 8324f1e32cSFrederic Weisbecker return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3; 840067f129SK.Prasad } 850067f129SK.Prasad 860067f129SK.Prasad /* 8724f1e32cSFrederic Weisbecker * Install a perf counter breakpoint. 8824f1e32cSFrederic Weisbecker * 8924f1e32cSFrederic Weisbecker * We seek a free debug address register and use it for this 9024f1e32cSFrederic Weisbecker * breakpoint. Eventually we enable it in the debug control register. 9124f1e32cSFrederic Weisbecker * 9224f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 9324f1e32cSFrederic Weisbecker * and registers local to this cpu. 940067f129SK.Prasad */ 9524f1e32cSFrederic Weisbecker int arch_install_hw_breakpoint(struct perf_event *bp) 960067f129SK.Prasad { 9724f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 9824f1e32cSFrederic Weisbecker unsigned long *dr7; 9924f1e32cSFrederic Weisbecker int i; 1000067f129SK.Prasad 10124f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 10224f1e32cSFrederic Weisbecker struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); 10324f1e32cSFrederic Weisbecker 10424f1e32cSFrederic Weisbecker if (!*slot) { 10524f1e32cSFrederic Weisbecker *slot = bp; 1060067f129SK.Prasad break; 1070067f129SK.Prasad } 10824f1e32cSFrederic Weisbecker } 1090067f129SK.Prasad 11024f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 11124f1e32cSFrederic Weisbecker return -EBUSY; 11224f1e32cSFrederic Weisbecker 11324f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 11424f1e32cSFrederic Weisbecker __get_cpu_var(cpu_debugreg[i]) = info->address; 11524f1e32cSFrederic Weisbecker 11624f1e32cSFrederic Weisbecker dr7 = &__get_cpu_var(dr7); 11724f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 11824f1e32cSFrederic Weisbecker 11924f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 12024f1e32cSFrederic Weisbecker 12124f1e32cSFrederic Weisbecker return 0; 1220067f129SK.Prasad } 1230067f129SK.Prasad 1240067f129SK.Prasad /* 12524f1e32cSFrederic Weisbecker * Uninstall the breakpoint contained in the given counter. 12624f1e32cSFrederic Weisbecker * 12724f1e32cSFrederic Weisbecker * First we search the debug address register it uses and then we disable 12824f1e32cSFrederic Weisbecker * it. 12924f1e32cSFrederic Weisbecker * 13024f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 13124f1e32cSFrederic Weisbecker * and registers local to this cpu. 1320067f129SK.Prasad */ 13324f1e32cSFrederic Weisbecker void arch_uninstall_hw_breakpoint(struct perf_event *bp) 1340067f129SK.Prasad { 13524f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 13624f1e32cSFrederic Weisbecker unsigned long *dr7; 13724f1e32cSFrederic Weisbecker int i; 1380067f129SK.Prasad 13924f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 14024f1e32cSFrederic Weisbecker struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]); 14124f1e32cSFrederic Weisbecker 14224f1e32cSFrederic Weisbecker if (*slot == bp) { 14324f1e32cSFrederic Weisbecker *slot = NULL; 14424f1e32cSFrederic Weisbecker break; 14524f1e32cSFrederic Weisbecker } 14624f1e32cSFrederic Weisbecker } 14724f1e32cSFrederic Weisbecker 14824f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 14924f1e32cSFrederic Weisbecker return; 15024f1e32cSFrederic Weisbecker 15124f1e32cSFrederic Weisbecker dr7 = &__get_cpu_var(dr7); 15224f1e32cSFrederic Weisbecker *dr7 &= ~encode_dr7(i, info->len, info->type); 15324f1e32cSFrederic Weisbecker 15424f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 1550067f129SK.Prasad } 1560067f129SK.Prasad 1570067f129SK.Prasad static int get_hbp_len(u8 hbp_len) 1580067f129SK.Prasad { 1590067f129SK.Prasad unsigned int len_in_bytes = 0; 1600067f129SK.Prasad 1610067f129SK.Prasad switch (hbp_len) { 16224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 1630067f129SK.Prasad len_in_bytes = 1; 1640067f129SK.Prasad break; 16524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 1660067f129SK.Prasad len_in_bytes = 2; 1670067f129SK.Prasad break; 16824f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 1690067f129SK.Prasad len_in_bytes = 4; 1700067f129SK.Prasad break; 1710067f129SK.Prasad #ifdef CONFIG_X86_64 17224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 1730067f129SK.Prasad len_in_bytes = 8; 1740067f129SK.Prasad break; 1750067f129SK.Prasad #endif 1760067f129SK.Prasad } 1770067f129SK.Prasad return len_in_bytes; 1780067f129SK.Prasad } 1790067f129SK.Prasad 1800067f129SK.Prasad /* 1810067f129SK.Prasad * Check for virtual address in user space. 1820067f129SK.Prasad */ 1830067f129SK.Prasad int arch_check_va_in_userspace(unsigned long va, u8 hbp_len) 1840067f129SK.Prasad { 1850067f129SK.Prasad unsigned int len; 1860067f129SK.Prasad 1870067f129SK.Prasad len = get_hbp_len(hbp_len); 1880067f129SK.Prasad 1890067f129SK.Prasad return (va <= TASK_SIZE - len); 1900067f129SK.Prasad } 1910067f129SK.Prasad 1920067f129SK.Prasad /* 1930067f129SK.Prasad * Check for virtual address in kernel space. 1940067f129SK.Prasad */ 1954555835bSJaswinder Singh Rajput static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len) 1960067f129SK.Prasad { 1970067f129SK.Prasad unsigned int len; 1980067f129SK.Prasad 1990067f129SK.Prasad len = get_hbp_len(hbp_len); 2000067f129SK.Prasad 2010067f129SK.Prasad return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); 2020067f129SK.Prasad } 2030067f129SK.Prasad 2040067f129SK.Prasad /* 2050067f129SK.Prasad * Store a breakpoint's encoded address, length, and type. 2060067f129SK.Prasad */ 20724f1e32cSFrederic Weisbecker static int arch_store_info(struct perf_event *bp) 2080067f129SK.Prasad { 20924f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 2100067f129SK.Prasad /* 2110067f129SK.Prasad * For kernel-addresses, either the address or symbol name can be 2120067f129SK.Prasad * specified. 2130067f129SK.Prasad */ 21424f1e32cSFrederic Weisbecker if (info->name) 21524f1e32cSFrederic Weisbecker info->address = (unsigned long) 21624f1e32cSFrederic Weisbecker kallsyms_lookup_name(info->name); 21724f1e32cSFrederic Weisbecker if (info->address) 2180067f129SK.Prasad return 0; 21924f1e32cSFrederic Weisbecker 2200067f129SK.Prasad return -EINVAL; 2210067f129SK.Prasad } 2220067f129SK.Prasad 22324f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 22424f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 22524f1e32cSFrederic Weisbecker { 22624f1e32cSFrederic Weisbecker /* Len */ 22724f1e32cSFrederic Weisbecker switch (x86_len) { 22824f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 22924f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_1; 23024f1e32cSFrederic Weisbecker break; 23124f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 23224f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_2; 23324f1e32cSFrederic Weisbecker break; 23424f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 23524f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_4; 23624f1e32cSFrederic Weisbecker break; 23724f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 23824f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 23924f1e32cSFrederic Weisbecker *gen_len = HW_BREAKPOINT_LEN_8; 24024f1e32cSFrederic Weisbecker break; 24124f1e32cSFrederic Weisbecker #endif 24224f1e32cSFrederic Weisbecker default: 24324f1e32cSFrederic Weisbecker return -EINVAL; 24424f1e32cSFrederic Weisbecker } 24524f1e32cSFrederic Weisbecker 24624f1e32cSFrederic Weisbecker /* Type */ 24724f1e32cSFrederic Weisbecker switch (x86_type) { 24824f1e32cSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 24924f1e32cSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 25024f1e32cSFrederic Weisbecker break; 25124f1e32cSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 25224f1e32cSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 25324f1e32cSFrederic Weisbecker break; 25424f1e32cSFrederic Weisbecker case X86_BREAKPOINT_RW: 25524f1e32cSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 25624f1e32cSFrederic Weisbecker break; 25724f1e32cSFrederic Weisbecker default: 25824f1e32cSFrederic Weisbecker return -EINVAL; 25924f1e32cSFrederic Weisbecker } 26024f1e32cSFrederic Weisbecker 26124f1e32cSFrederic Weisbecker return 0; 26224f1e32cSFrederic Weisbecker } 26324f1e32cSFrederic Weisbecker 26424f1e32cSFrederic Weisbecker 26524f1e32cSFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp) 26624f1e32cSFrederic Weisbecker { 26724f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 26824f1e32cSFrederic Weisbecker 26924f1e32cSFrederic Weisbecker info->address = bp->attr.bp_addr; 27024f1e32cSFrederic Weisbecker 27124f1e32cSFrederic Weisbecker /* Len */ 27224f1e32cSFrederic Weisbecker switch (bp->attr.bp_len) { 27324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 27424f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_1; 27524f1e32cSFrederic Weisbecker break; 27624f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 27724f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_2; 27824f1e32cSFrederic Weisbecker break; 27924f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 28024f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_4; 28124f1e32cSFrederic Weisbecker break; 28224f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 28324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 28424f1e32cSFrederic Weisbecker info->len = X86_BREAKPOINT_LEN_8; 28524f1e32cSFrederic Weisbecker break; 28624f1e32cSFrederic Weisbecker #endif 28724f1e32cSFrederic Weisbecker default: 28824f1e32cSFrederic Weisbecker return -EINVAL; 28924f1e32cSFrederic Weisbecker } 29024f1e32cSFrederic Weisbecker 29124f1e32cSFrederic Weisbecker /* Type */ 29224f1e32cSFrederic Weisbecker switch (bp->attr.bp_type) { 29324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_W: 29424f1e32cSFrederic Weisbecker info->type = X86_BREAKPOINT_WRITE; 29524f1e32cSFrederic Weisbecker break; 29624f1e32cSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 29724f1e32cSFrederic Weisbecker info->type = X86_BREAKPOINT_RW; 29824f1e32cSFrederic Weisbecker break; 29924f1e32cSFrederic Weisbecker case HW_BREAKPOINT_X: 30024f1e32cSFrederic Weisbecker info->type = X86_BREAKPOINT_EXECUTE; 30124f1e32cSFrederic Weisbecker break; 30224f1e32cSFrederic Weisbecker default: 30324f1e32cSFrederic Weisbecker return -EINVAL; 30424f1e32cSFrederic Weisbecker } 30524f1e32cSFrederic Weisbecker 30624f1e32cSFrederic Weisbecker return 0; 30724f1e32cSFrederic Weisbecker } 3080067f129SK.Prasad /* 3090067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3100067f129SK.Prasad */ 31124f1e32cSFrederic Weisbecker int arch_validate_hwbkpt_settings(struct perf_event *bp, 3120067f129SK.Prasad struct task_struct *tsk) 3130067f129SK.Prasad { 31424f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 3150067f129SK.Prasad unsigned int align; 31624f1e32cSFrederic Weisbecker int ret; 3170067f129SK.Prasad 31824f1e32cSFrederic Weisbecker 31924f1e32cSFrederic Weisbecker ret = arch_build_bp_info(bp); 32024f1e32cSFrederic Weisbecker if (ret) 32124f1e32cSFrederic Weisbecker return ret; 32224f1e32cSFrederic Weisbecker 32324f1e32cSFrederic Weisbecker ret = -EINVAL; 32424f1e32cSFrederic Weisbecker 32524f1e32cSFrederic Weisbecker if (info->type == X86_BREAKPOINT_EXECUTE) 3260067f129SK.Prasad /* 3270067f129SK.Prasad * Ptrace-refactoring code 3280067f129SK.Prasad * For now, we'll allow instruction breakpoint only for user-space 3290067f129SK.Prasad * addresses 3300067f129SK.Prasad */ 33124f1e32cSFrederic Weisbecker if ((!arch_check_va_in_userspace(info->address, info->len)) && 33224f1e32cSFrederic Weisbecker info->len != X86_BREAKPOINT_EXECUTE) 3330067f129SK.Prasad return ret; 3340067f129SK.Prasad 33524f1e32cSFrederic Weisbecker switch (info->len) { 33624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3370067f129SK.Prasad align = 0; 3380067f129SK.Prasad break; 33924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3400067f129SK.Prasad align = 1; 3410067f129SK.Prasad break; 34224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3430067f129SK.Prasad align = 3; 3440067f129SK.Prasad break; 3450067f129SK.Prasad #ifdef CONFIG_X86_64 34624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3470067f129SK.Prasad align = 7; 3480067f129SK.Prasad break; 3490067f129SK.Prasad #endif 3500067f129SK.Prasad default: 3510067f129SK.Prasad return ret; 3520067f129SK.Prasad } 3530067f129SK.Prasad 35424f1e32cSFrederic Weisbecker if (bp->callback) 35524f1e32cSFrederic Weisbecker ret = arch_store_info(bp); 3560067f129SK.Prasad 3570067f129SK.Prasad if (ret < 0) 3580067f129SK.Prasad return ret; 3590067f129SK.Prasad /* 3600067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3610067f129SK.Prasad * for the alignment implied by len. 3620067f129SK.Prasad */ 36324f1e32cSFrederic Weisbecker if (info->address & align) 3640067f129SK.Prasad return -EINVAL; 3650067f129SK.Prasad 3660067f129SK.Prasad /* Check that the virtual address is in the proper range */ 3670067f129SK.Prasad if (tsk) { 36824f1e32cSFrederic Weisbecker if (!arch_check_va_in_userspace(info->address, info->len)) 3690067f129SK.Prasad return -EFAULT; 3700067f129SK.Prasad } else { 37124f1e32cSFrederic Weisbecker if (!arch_check_va_in_kernelspace(info->address, info->len)) 3720067f129SK.Prasad return -EFAULT; 3730067f129SK.Prasad } 37424f1e32cSFrederic Weisbecker 3750067f129SK.Prasad return 0; 3760067f129SK.Prasad } 3770067f129SK.Prasad 37824f1e32cSFrederic Weisbecker /* 37924f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 38024f1e32cSFrederic Weisbecker */ 38124f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 3820067f129SK.Prasad { 3830067f129SK.Prasad int i; 38424f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 3850067f129SK.Prasad 38624f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 38724f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 38824f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 3890067f129SK.Prasad } 39024f1e32cSFrederic Weisbecker } 39124f1e32cSFrederic Weisbecker 39224f1e32cSFrederic Weisbecker #ifdef CONFIG_KVM 39324f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 39424f1e32cSFrederic Weisbecker { 39524f1e32cSFrederic Weisbecker set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0); 39624f1e32cSFrederic Weisbecker set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1); 39724f1e32cSFrederic Weisbecker set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2); 39824f1e32cSFrederic Weisbecker set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3); 39924f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 40024f1e32cSFrederic Weisbecker set_debugreg(__get_cpu_var(dr7), 7); 40124f1e32cSFrederic Weisbecker } 40224f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 40324f1e32cSFrederic Weisbecker #endif 4040067f129SK.Prasad 4050067f129SK.Prasad /* 4060067f129SK.Prasad * Handle debug exception notifications. 4070067f129SK.Prasad * 4080067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4090067f129SK.Prasad * 4100067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4110067f129SK.Prasad * i) When the causative address is from user-space and the exception 4120067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4130067f129SK.Prasad * switching 4140067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4150067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4160067f129SK.Prasad * met and requires some more action in do_debug(). 4170067f129SK.Prasad * 4180067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4190067f129SK.Prasad * 4200067f129SK.Prasad */ 4214555835bSJaswinder Singh Rajput static int __kprobes hw_breakpoint_handler(struct die_args *args) 4220067f129SK.Prasad { 4230067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 42424f1e32cSFrederic Weisbecker struct perf_event *bp; 42562edab90SK.Prasad unsigned long dr7, dr6; 42662edab90SK.Prasad unsigned long *dr6_p; 42762edab90SK.Prasad 42862edab90SK.Prasad /* The DR6 value is pointed by args->err */ 42962edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 43062edab90SK.Prasad dr6 = *dr6_p; 4310067f129SK.Prasad 4320067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4330067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4340067f129SK.Prasad return NOTIFY_DONE; 4350067f129SK.Prasad 4360067f129SK.Prasad get_debugreg(dr7, 7); 4370067f129SK.Prasad /* Disable breakpoints during exception handling */ 4380067f129SK.Prasad set_debugreg(0UL, 7); 4390067f129SK.Prasad /* 4400067f129SK.Prasad * Assert that local interrupts are disabled 4410067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4420067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4430067f129SK.Prasad */ 4440067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4450067f129SK.Prasad cpu = get_cpu(); 4460067f129SK.Prasad 4470067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 4480067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 4490067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 4500067f129SK.Prasad continue; 45124f1e32cSFrederic Weisbecker 4520067f129SK.Prasad /* 45324f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 45424f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 45524f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 45624f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 4570067f129SK.Prasad */ 45824f1e32cSFrederic Weisbecker rcu_read_lock(); 45924f1e32cSFrederic Weisbecker 46024f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 4610067f129SK.Prasad if (bp) 4620067f129SK.Prasad rc = NOTIFY_DONE; 4630067f129SK.Prasad /* 46462edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 46562edab90SK.Prasad * exception handling 46662edab90SK.Prasad */ 46762edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 46862edab90SK.Prasad /* 4690067f129SK.Prasad * bp can be NULL due to lazy debug register switching 47024f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 4710067f129SK.Prasad */ 47224f1e32cSFrederic Weisbecker if (!bp) { 47324f1e32cSFrederic Weisbecker rcu_read_unlock(); 47424f1e32cSFrederic Weisbecker break; 47524f1e32cSFrederic Weisbecker } 4760067f129SK.Prasad 47724f1e32cSFrederic Weisbecker (bp->callback)(bp, args->regs); 47824f1e32cSFrederic Weisbecker 47924f1e32cSFrederic Weisbecker rcu_read_unlock(); 4800067f129SK.Prasad } 4810067f129SK.Prasad if (dr6 & (~DR_TRAP_BITS)) 4820067f129SK.Prasad rc = NOTIFY_DONE; 4830067f129SK.Prasad 4840067f129SK.Prasad set_debugreg(dr7, 7); 485eadb8a09SIngo Molnar put_cpu(); 48624f1e32cSFrederic Weisbecker 4870067f129SK.Prasad return rc; 4880067f129SK.Prasad } 4890067f129SK.Prasad 4900067f129SK.Prasad /* 4910067f129SK.Prasad * Handle debug exception notifications. 4920067f129SK.Prasad */ 4930067f129SK.Prasad int __kprobes hw_breakpoint_exceptions_notify( 4940067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 4950067f129SK.Prasad { 4960067f129SK.Prasad if (val != DIE_DEBUG) 4970067f129SK.Prasad return NOTIFY_DONE; 4980067f129SK.Prasad 4990067f129SK.Prasad return hw_breakpoint_handler(data); 5000067f129SK.Prasad } 50124f1e32cSFrederic Weisbecker 50224f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 50324f1e32cSFrederic Weisbecker { 50424f1e32cSFrederic Weisbecker /* TODO */ 50524f1e32cSFrederic Weisbecker } 50624f1e32cSFrederic Weisbecker 50724f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_unthrottle(struct perf_event *bp) 50824f1e32cSFrederic Weisbecker { 50924f1e32cSFrederic Weisbecker /* TODO */ 51024f1e32cSFrederic Weisbecker } 511