11a59d1b8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 20067f129SK.Prasad /* 30067f129SK.Prasad * 40067f129SK.Prasad * Copyright (C) 2007 Alan Stern 50067f129SK.Prasad * Copyright (C) 2009 IBM Corporation 624f1e32cSFrederic Weisbecker * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com> 7ba6909b7SK.Prasad * 8ba6909b7SK.Prasad * Authors: Alan Stern <stern@rowland.harvard.edu> 9ba6909b7SK.Prasad * K.Prasad <prasad@linux.vnet.ibm.com> 10ba6909b7SK.Prasad * Frederic Weisbecker <fweisbec@gmail.com> 110067f129SK.Prasad */ 120067f129SK.Prasad 130067f129SK.Prasad /* 140067f129SK.Prasad * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, 150067f129SK.Prasad * using the CPU's debug registers. 160067f129SK.Prasad */ 170067f129SK.Prasad 1824f1e32cSFrederic Weisbecker #include <linux/perf_event.h> 1924f1e32cSFrederic Weisbecker #include <linux/hw_breakpoint.h> 200067f129SK.Prasad #include <linux/irqflags.h> 210067f129SK.Prasad #include <linux/notifier.h> 220067f129SK.Prasad #include <linux/kallsyms.h> 23e5779e8eSAndy Lutomirski #include <linux/kprobes.h> 240067f129SK.Prasad #include <linux/percpu.h> 250067f129SK.Prasad #include <linux/kdebug.h> 260067f129SK.Prasad #include <linux/kernel.h> 27186f4360SPaul Gortmaker #include <linux/export.h> 280067f129SK.Prasad #include <linux/sched.h> 290067f129SK.Prasad #include <linux/smp.h> 300067f129SK.Prasad 310067f129SK.Prasad #include <asm/hw_breakpoint.h> 320067f129SK.Prasad #include <asm/processor.h> 330067f129SK.Prasad #include <asm/debugreg.h> 34186f4360SPaul Gortmaker #include <asm/user.h> 350067f129SK.Prasad 3624f1e32cSFrederic Weisbecker /* Per cpu debug control register value */ 3728b4e0d8STejun Heo DEFINE_PER_CPU(unsigned long, cpu_dr7); 3828b4e0d8STejun Heo EXPORT_PER_CPU_SYMBOL(cpu_dr7); 3924f1e32cSFrederic Weisbecker 4024f1e32cSFrederic Weisbecker /* Per cpu debug address registers values */ 4124f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); 420067f129SK.Prasad 430067f129SK.Prasad /* 4424f1e32cSFrederic Weisbecker * Stores the breakpoints currently in use on each breakpoint address 4524f1e32cSFrederic Weisbecker * register for each cpus 460067f129SK.Prasad */ 4724f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); 480067f129SK.Prasad 490067f129SK.Prasad 502c31b795SFrederic Weisbecker static inline unsigned long 512c31b795SFrederic Weisbecker __encode_dr7(int drnum, unsigned int len, unsigned int type) 522c31b795SFrederic Weisbecker { 532c31b795SFrederic Weisbecker unsigned long bp_info; 542c31b795SFrederic Weisbecker 552c31b795SFrederic Weisbecker bp_info = (len | type) & 0xf; 562c31b795SFrederic Weisbecker bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); 572c31b795SFrederic Weisbecker bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); 582c31b795SFrederic Weisbecker 592c31b795SFrederic Weisbecker return bp_info; 602c31b795SFrederic Weisbecker } 612c31b795SFrederic Weisbecker 620067f129SK.Prasad /* 630067f129SK.Prasad * Encode the length, type, Exact, and Enable bits for a particular breakpoint 640067f129SK.Prasad * as stored in debug register 7. 650067f129SK.Prasad */ 6624f1e32cSFrederic Weisbecker unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) 670067f129SK.Prasad { 682c31b795SFrederic Weisbecker return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN; 690067f129SK.Prasad } 700067f129SK.Prasad 7124f1e32cSFrederic Weisbecker /* 7224f1e32cSFrederic Weisbecker * Decode the length and type bits for a particular breakpoint as 7324f1e32cSFrederic Weisbecker * stored in debug register 7. Return the "enabled" status. 740067f129SK.Prasad */ 7524f1e32cSFrederic Weisbecker int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type) 7624f1e32cSFrederic Weisbecker { 7724f1e32cSFrederic Weisbecker int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE); 7824f1e32cSFrederic Weisbecker 7924f1e32cSFrederic Weisbecker *len = (bp_info & 0xc) | 0x40; 8024f1e32cSFrederic Weisbecker *type = (bp_info & 0x3) | 0x80; 8124f1e32cSFrederic Weisbecker 8224f1e32cSFrederic Weisbecker return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3; 830067f129SK.Prasad } 840067f129SK.Prasad 850067f129SK.Prasad /* 8624f1e32cSFrederic Weisbecker * Install a perf counter breakpoint. 8724f1e32cSFrederic Weisbecker * 8824f1e32cSFrederic Weisbecker * We seek a free debug address register and use it for this 8924f1e32cSFrederic Weisbecker * breakpoint. Eventually we enable it in the debug control register. 9024f1e32cSFrederic Weisbecker * 9124f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 9224f1e32cSFrederic Weisbecker * and registers local to this cpu. 930067f129SK.Prasad */ 9424f1e32cSFrederic Weisbecker int arch_install_hw_breakpoint(struct perf_event *bp) 950067f129SK.Prasad { 9624f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 9724f1e32cSFrederic Weisbecker unsigned long *dr7; 9824f1e32cSFrederic Weisbecker int i; 990067f129SK.Prasad 10024f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 10189cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 10224f1e32cSFrederic Weisbecker 10324f1e32cSFrederic Weisbecker if (!*slot) { 10424f1e32cSFrederic Weisbecker *slot = bp; 1050067f129SK.Prasad break; 1060067f129SK.Prasad } 10724f1e32cSFrederic Weisbecker } 1080067f129SK.Prasad 10924f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 11024f1e32cSFrederic Weisbecker return -EBUSY; 11124f1e32cSFrederic Weisbecker 11224f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 1130a3aee0dSTejun Heo __this_cpu_write(cpu_debugreg[i], info->address); 11424f1e32cSFrederic Weisbecker 11589cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 11624f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 11724f1e32cSFrederic Weisbecker 11824f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 119d6d55f0bSJacob Shin if (info->mask) 120d6d55f0bSJacob Shin set_dr_addr_mask(info->mask, i); 12124f1e32cSFrederic Weisbecker 12224f1e32cSFrederic Weisbecker return 0; 1230067f129SK.Prasad } 1240067f129SK.Prasad 1250067f129SK.Prasad /* 12624f1e32cSFrederic Weisbecker * Uninstall the breakpoint contained in the given counter. 12724f1e32cSFrederic Weisbecker * 12824f1e32cSFrederic Weisbecker * First we search the debug address register it uses and then we disable 12924f1e32cSFrederic Weisbecker * it. 13024f1e32cSFrederic Weisbecker * 13124f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 13224f1e32cSFrederic Weisbecker * and registers local to this cpu. 1330067f129SK.Prasad */ 13424f1e32cSFrederic Weisbecker void arch_uninstall_hw_breakpoint(struct perf_event *bp) 1350067f129SK.Prasad { 13624f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 13724f1e32cSFrederic Weisbecker unsigned long *dr7; 13824f1e32cSFrederic Weisbecker int i; 1390067f129SK.Prasad 14024f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 14189cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 14224f1e32cSFrederic Weisbecker 14324f1e32cSFrederic Weisbecker if (*slot == bp) { 14424f1e32cSFrederic Weisbecker *slot = NULL; 14524f1e32cSFrederic Weisbecker break; 14624f1e32cSFrederic Weisbecker } 14724f1e32cSFrederic Weisbecker } 14824f1e32cSFrederic Weisbecker 14924f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 15024f1e32cSFrederic Weisbecker return; 15124f1e32cSFrederic Weisbecker 15289cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 1532c31b795SFrederic Weisbecker *dr7 &= ~__encode_dr7(i, info->len, info->type); 15424f1e32cSFrederic Weisbecker 15524f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 156d6d55f0bSJacob Shin if (info->mask) 157d6d55f0bSJacob Shin set_dr_addr_mask(0, i); 1580067f129SK.Prasad } 1590067f129SK.Prasad 1608e983ff9SFrederic Weisbecker static int arch_bp_generic_len(int x86_len) 1610067f129SK.Prasad { 1628e983ff9SFrederic Weisbecker switch (x86_len) { 1638e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 1648e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_1; 1658e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 1668e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_2; 1678e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 1688e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_4; 1698e983ff9SFrederic Weisbecker #ifdef CONFIG_X86_64 1708e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 1718e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_8; 1728e983ff9SFrederic Weisbecker #endif 1738e983ff9SFrederic Weisbecker default: 1748e983ff9SFrederic Weisbecker return -EINVAL; 1758e983ff9SFrederic Weisbecker } 1760067f129SK.Prasad } 1770067f129SK.Prasad 17824f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 17924f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 18024f1e32cSFrederic Weisbecker { 1818e983ff9SFrederic Weisbecker int len; 1828e983ff9SFrederic Weisbecker 18389e45aacSFrederic Weisbecker /* Type */ 18489e45aacSFrederic Weisbecker switch (x86_type) { 18589e45aacSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 18689e45aacSFrederic Weisbecker if (x86_len != X86_BREAKPOINT_LEN_X) 18789e45aacSFrederic Weisbecker return -EINVAL; 18889e45aacSFrederic Weisbecker 18989e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 19089e45aacSFrederic Weisbecker *gen_len = sizeof(long); 19189e45aacSFrederic Weisbecker return 0; 19289e45aacSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 19389e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 19489e45aacSFrederic Weisbecker break; 19589e45aacSFrederic Weisbecker case X86_BREAKPOINT_RW: 19689e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 19789e45aacSFrederic Weisbecker break; 19889e45aacSFrederic Weisbecker default: 19989e45aacSFrederic Weisbecker return -EINVAL; 20089e45aacSFrederic Weisbecker } 20189e45aacSFrederic Weisbecker 20224f1e32cSFrederic Weisbecker /* Len */ 2038e983ff9SFrederic Weisbecker len = arch_bp_generic_len(x86_len); 2048e983ff9SFrederic Weisbecker if (len < 0) 20524f1e32cSFrederic Weisbecker return -EINVAL; 2068e983ff9SFrederic Weisbecker *gen_len = len; 20724f1e32cSFrederic Weisbecker 20824f1e32cSFrederic Weisbecker return 0; 20924f1e32cSFrederic Weisbecker } 21024f1e32cSFrederic Weisbecker 2118e983ff9SFrederic Weisbecker /* 2128e983ff9SFrederic Weisbecker * Check for virtual address in kernel space. 2138e983ff9SFrederic Weisbecker */ 2148e983ff9SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw) 2158e983ff9SFrederic Weisbecker { 2168e983ff9SFrederic Weisbecker unsigned long va; 2178e983ff9SFrederic Weisbecker int len; 2188e983ff9SFrederic Weisbecker 2198e983ff9SFrederic Weisbecker va = hw->address; 2208e983ff9SFrederic Weisbecker len = arch_bp_generic_len(hw->len); 2218e983ff9SFrederic Weisbecker WARN_ON_ONCE(len < 0); 2228e983ff9SFrederic Weisbecker 2238e983ff9SFrederic Weisbecker /* 2248e983ff9SFrederic Weisbecker * We don't need to worry about va + len - 1 overflowing: 2258e983ff9SFrederic Weisbecker * we already require that va is aligned to a multiple of len. 2268e983ff9SFrederic Weisbecker */ 2278e983ff9SFrederic Weisbecker return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX); 2288e983ff9SFrederic Weisbecker } 22924f1e32cSFrederic Weisbecker 230a0baf043SFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp, 231a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 232a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 23324f1e32cSFrederic Weisbecker { 234a0baf043SFrederic Weisbecker hw->address = attr->bp_addr; 235a0baf043SFrederic Weisbecker hw->mask = 0; 23624f1e32cSFrederic Weisbecker 237f7809dafSFrederic Weisbecker /* Type */ 238a0baf043SFrederic Weisbecker switch (attr->bp_type) { 239f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 240a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_WRITE; 241f7809dafSFrederic Weisbecker break; 242f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 243a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_RW; 244f7809dafSFrederic Weisbecker break; 245f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 246e5779e8eSAndy Lutomirski /* 247e5779e8eSAndy Lutomirski * We don't allow kernel breakpoints in places that are not 248e5779e8eSAndy Lutomirski * acceptable for kprobes. On non-kprobes kernels, we don't 249e5779e8eSAndy Lutomirski * allow kernel breakpoints at all. 250e5779e8eSAndy Lutomirski */ 251a0baf043SFrederic Weisbecker if (attr->bp_addr >= TASK_SIZE_MAX) { 252a0baf043SFrederic Weisbecker if (within_kprobe_blacklist(attr->bp_addr)) 253e5779e8eSAndy Lutomirski return -EINVAL; 254e5779e8eSAndy Lutomirski } 255e5779e8eSAndy Lutomirski 256a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_EXECUTE; 257f7809dafSFrederic Weisbecker /* 258f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 259f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 260f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 261f7809dafSFrederic Weisbecker */ 262a0baf043SFrederic Weisbecker if (attr->bp_len == sizeof(long)) { 263a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_X; 264f7809dafSFrederic Weisbecker return 0; 265f7809dafSFrederic Weisbecker } 2666fcebf13SGustavo A. R. Silva /* fall through */ 267f7809dafSFrederic Weisbecker default: 268f7809dafSFrederic Weisbecker return -EINVAL; 269f7809dafSFrederic Weisbecker } 270f7809dafSFrederic Weisbecker 27124f1e32cSFrederic Weisbecker /* Len */ 272a0baf043SFrederic Weisbecker switch (attr->bp_len) { 27324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 274a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 27524f1e32cSFrederic Weisbecker break; 27624f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 277a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_2; 27824f1e32cSFrederic Weisbecker break; 27924f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 280a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_4; 28124f1e32cSFrederic Weisbecker break; 28224f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 28324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 284a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_8; 28524f1e32cSFrederic Weisbecker break; 28624f1e32cSFrederic Weisbecker #endif 28724f1e32cSFrederic Weisbecker default: 288ab513927SAndy Lutomirski /* AMD range breakpoint */ 289a0baf043SFrederic Weisbecker if (!is_power_of_2(attr->bp_len)) 29024f1e32cSFrederic Weisbecker return -EINVAL; 291a0baf043SFrederic Weisbecker if (attr->bp_addr & (attr->bp_len - 1)) 292ab513927SAndy Lutomirski return -EINVAL; 293362f924bSBorislav Petkov 294362f924bSBorislav Petkov if (!boot_cpu_has(X86_FEATURE_BPEXT)) 295362f924bSBorislav Petkov return -EOPNOTSUPP; 296362f924bSBorislav Petkov 297ab513927SAndy Lutomirski /* 298ab513927SAndy Lutomirski * It's impossible to use a range breakpoint to fake out 299ab513927SAndy Lutomirski * user vs kernel detection because bp_len - 1 can't 300ab513927SAndy Lutomirski * have the high bit set. If we ever allow range instruction 301ab513927SAndy Lutomirski * breakpoints, then we'll have to check for kprobe-blacklisted 302ab513927SAndy Lutomirski * addresses anywhere in the range. 303ab513927SAndy Lutomirski */ 304a0baf043SFrederic Weisbecker hw->mask = attr->bp_len - 1; 305a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 30624f1e32cSFrederic Weisbecker } 30724f1e32cSFrederic Weisbecker 30824f1e32cSFrederic Weisbecker return 0; 30924f1e32cSFrederic Weisbecker } 310d6d55f0bSJacob Shin 3110067f129SK.Prasad /* 3120067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3130067f129SK.Prasad */ 314a0baf043SFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 315a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 316a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 3170067f129SK.Prasad { 3180067f129SK.Prasad unsigned int align; 31924f1e32cSFrederic Weisbecker int ret; 3200067f129SK.Prasad 32124f1e32cSFrederic Weisbecker 322a0baf043SFrederic Weisbecker ret = arch_build_bp_info(bp, attr, hw); 32324f1e32cSFrederic Weisbecker if (ret) 32424f1e32cSFrederic Weisbecker return ret; 32524f1e32cSFrederic Weisbecker 326a0baf043SFrederic Weisbecker switch (hw->len) { 32724f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3280067f129SK.Prasad align = 0; 329a0baf043SFrederic Weisbecker if (hw->mask) 330a0baf043SFrederic Weisbecker align = hw->mask; 3310067f129SK.Prasad break; 33224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3330067f129SK.Prasad align = 1; 3340067f129SK.Prasad break; 33524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3360067f129SK.Prasad align = 3; 3370067f129SK.Prasad break; 3380067f129SK.Prasad #ifdef CONFIG_X86_64 33924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3400067f129SK.Prasad align = 7; 3410067f129SK.Prasad break; 3420067f129SK.Prasad #endif 3430067f129SK.Prasad default: 344d6d55f0bSJacob Shin WARN_ON_ONCE(1); 345e898e69dSNathan Chancellor return -EINVAL; 3460067f129SK.Prasad } 3470067f129SK.Prasad 34884d71092SFrederic Weisbecker /* 3490067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3500067f129SK.Prasad * for the alignment implied by len. 3510067f129SK.Prasad */ 352a0baf043SFrederic Weisbecker if (hw->address & align) 3530067f129SK.Prasad return -EINVAL; 3540067f129SK.Prasad 3550067f129SK.Prasad return 0; 3560067f129SK.Prasad } 3570067f129SK.Prasad 35824f1e32cSFrederic Weisbecker /* 3599f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 3609f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 3619f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 3629f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 3639f6b3c2cSFrederic Weisbecker * 3649f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 3659f6b3c2cSFrederic Weisbecker */ 3669f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 3679f6b3c2cSFrederic Weisbecker { 3689f6b3c2cSFrederic Weisbecker int i; 3699f6b3c2cSFrederic Weisbecker int dr7 = 0; 3709f6b3c2cSFrederic Weisbecker struct perf_event *bp; 3719f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 3729f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 3739f6b3c2cSFrederic Weisbecker 3749f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 3759f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 3769f6b3c2cSFrederic Weisbecker 3779f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 3789f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 3799f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 3809f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 3819f6b3c2cSFrederic Weisbecker } else { 3829f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 3839f6b3c2cSFrederic Weisbecker } 3849f6b3c2cSFrederic Weisbecker } 3859f6b3c2cSFrederic Weisbecker 3869f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 3879f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 3889f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 3899f6b3c2cSFrederic Weisbecker 3909f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 3919f6b3c2cSFrederic Weisbecker } 39268efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 3939f6b3c2cSFrederic Weisbecker 3949f6b3c2cSFrederic Weisbecker /* 39524f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 39624f1e32cSFrederic Weisbecker */ 39724f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 3980067f129SK.Prasad { 3990067f129SK.Prasad int i; 40024f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 4010067f129SK.Prasad 40224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 40324f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 40424f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 4050067f129SK.Prasad } 406f7da04c9SOleg Nesterov 407f7da04c9SOleg Nesterov t->debugreg6 = 0; 408f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 40924f1e32cSFrederic Weisbecker } 41024f1e32cSFrederic Weisbecker 41124f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 41224f1e32cSFrederic Weisbecker { 4130a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4140a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4150a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4160a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 41724f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 4180a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 41924f1e32cSFrederic Weisbecker } 42024f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4210067f129SK.Prasad 4220067f129SK.Prasad /* 4230067f129SK.Prasad * Handle debug exception notifications. 4240067f129SK.Prasad * 4250067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4260067f129SK.Prasad * 4270067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4280067f129SK.Prasad * i) When the causative address is from user-space and the exception 4290067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4300067f129SK.Prasad * switching 4310067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4320067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4330067f129SK.Prasad * met and requires some more action in do_debug(). 4340067f129SK.Prasad * 4350067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4360067f129SK.Prasad * 4370067f129SK.Prasad */ 4389c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 4390067f129SK.Prasad { 4400067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 44124f1e32cSFrederic Weisbecker struct perf_event *bp; 44262edab90SK.Prasad unsigned long dr7, dr6; 44362edab90SK.Prasad unsigned long *dr6_p; 44462edab90SK.Prasad 44562edab90SK.Prasad /* The DR6 value is pointed by args->err */ 44662edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 44762edab90SK.Prasad dr6 = *dr6_p; 4480067f129SK.Prasad 4496c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 4506c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 4516c0aca28SFrederic Weisbecker return NOTIFY_DONE; 4526c0aca28SFrederic Weisbecker 4530067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4540067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4550067f129SK.Prasad return NOTIFY_DONE; 4560067f129SK.Prasad 4570067f129SK.Prasad get_debugreg(dr7, 7); 4580067f129SK.Prasad /* Disable breakpoints during exception handling */ 4590067f129SK.Prasad set_debugreg(0UL, 7); 4600067f129SK.Prasad /* 4610067f129SK.Prasad * Assert that local interrupts are disabled 4620067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4630067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4640067f129SK.Prasad */ 4650067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4660067f129SK.Prasad cpu = get_cpu(); 4670067f129SK.Prasad 4680067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 4690067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 4700067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 4710067f129SK.Prasad continue; 47224f1e32cSFrederic Weisbecker 4730067f129SK.Prasad /* 47424f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 47524f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 47624f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 47724f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 4780067f129SK.Prasad */ 47924f1e32cSFrederic Weisbecker rcu_read_lock(); 48024f1e32cSFrederic Weisbecker 48124f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 4820067f129SK.Prasad /* 48362edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 48462edab90SK.Prasad * exception handling 48562edab90SK.Prasad */ 48662edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 48762edab90SK.Prasad /* 4880067f129SK.Prasad * bp can be NULL due to lazy debug register switching 48924f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 4900067f129SK.Prasad */ 49124f1e32cSFrederic Weisbecker if (!bp) { 49224f1e32cSFrederic Weisbecker rcu_read_unlock(); 49324f1e32cSFrederic Weisbecker break; 49424f1e32cSFrederic Weisbecker } 4950067f129SK.Prasad 496b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 49724f1e32cSFrederic Weisbecker 4980c4519e8SFrederic Weisbecker /* 4990c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 5000c4519e8SFrederic Weisbecker * returning back to origin. 5010c4519e8SFrederic Weisbecker */ 5020c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 5030c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 5040c4519e8SFrederic Weisbecker 50524f1e32cSFrederic Weisbecker rcu_read_unlock(); 5060067f129SK.Prasad } 507e0e53db6SK.Prasad /* 508e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 509e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 510e0e53db6SK.Prasad * taken exception due to multiple causes 511e0e53db6SK.Prasad */ 512e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 513e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5140067f129SK.Prasad rc = NOTIFY_DONE; 5150067f129SK.Prasad 5160067f129SK.Prasad set_debugreg(dr7, 7); 517eadb8a09SIngo Molnar put_cpu(); 51824f1e32cSFrederic Weisbecker 5190067f129SK.Prasad return rc; 5200067f129SK.Prasad } 5210067f129SK.Prasad 5220067f129SK.Prasad /* 5230067f129SK.Prasad * Handle debug exception notifications. 5240067f129SK.Prasad */ 5259c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5260067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5270067f129SK.Prasad { 5280067f129SK.Prasad if (val != DIE_DEBUG) 5290067f129SK.Prasad return NOTIFY_DONE; 5300067f129SK.Prasad 5310067f129SK.Prasad return hw_breakpoint_handler(data); 5320067f129SK.Prasad } 53324f1e32cSFrederic Weisbecker 53424f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 53524f1e32cSFrederic Weisbecker { 53624f1e32cSFrederic Weisbecker /* TODO */ 53724f1e32cSFrederic Weisbecker } 538