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 23024ae0c91SAndy Lutomirski /* 23124ae0c91SAndy Lutomirski * Checks whether the range from addr to end, inclusive, overlaps the CPU 23224ae0c91SAndy Lutomirski * entry area range. 23324ae0c91SAndy Lutomirski */ 23424ae0c91SAndy Lutomirski static inline bool within_cpu_entry_area(unsigned long addr, unsigned long end) 23524ae0c91SAndy Lutomirski { 23624ae0c91SAndy Lutomirski return end >= CPU_ENTRY_AREA_BASE && 23724ae0c91SAndy Lutomirski addr < (CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_TOTAL_SIZE); 23824ae0c91SAndy Lutomirski } 23924ae0c91SAndy Lutomirski 240a0baf043SFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp, 241a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 242a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 24324f1e32cSFrederic Weisbecker { 24424ae0c91SAndy Lutomirski unsigned long bp_end; 24524ae0c91SAndy Lutomirski 24624ae0c91SAndy Lutomirski bp_end = attr->bp_addr + attr->bp_len - 1; 24724ae0c91SAndy Lutomirski if (bp_end < attr->bp_addr) 24824ae0c91SAndy Lutomirski return -EINVAL; 24924ae0c91SAndy Lutomirski 25024ae0c91SAndy Lutomirski /* 25124ae0c91SAndy Lutomirski * Prevent any breakpoint of any type that overlaps the 25224ae0c91SAndy Lutomirski * cpu_entry_area. This protects the IST stacks and also 25324ae0c91SAndy Lutomirski * reduces the chance that we ever find out what happens if 25424ae0c91SAndy Lutomirski * there's a data breakpoint on the GDT, IDT, or TSS. 25524ae0c91SAndy Lutomirski */ 25624ae0c91SAndy Lutomirski if (within_cpu_entry_area(attr->bp_addr, bp_end)) 25724ae0c91SAndy Lutomirski return -EINVAL; 25824ae0c91SAndy Lutomirski 259a0baf043SFrederic Weisbecker hw->address = attr->bp_addr; 260a0baf043SFrederic Weisbecker hw->mask = 0; 26124f1e32cSFrederic Weisbecker 262f7809dafSFrederic Weisbecker /* Type */ 263a0baf043SFrederic Weisbecker switch (attr->bp_type) { 264f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 265a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_WRITE; 266f7809dafSFrederic Weisbecker break; 267f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 268a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_RW; 269f7809dafSFrederic Weisbecker break; 270f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 271e5779e8eSAndy Lutomirski /* 272e5779e8eSAndy Lutomirski * We don't allow kernel breakpoints in places that are not 273e5779e8eSAndy Lutomirski * acceptable for kprobes. On non-kprobes kernels, we don't 274e5779e8eSAndy Lutomirski * allow kernel breakpoints at all. 275e5779e8eSAndy Lutomirski */ 276a0baf043SFrederic Weisbecker if (attr->bp_addr >= TASK_SIZE_MAX) { 277a0baf043SFrederic Weisbecker if (within_kprobe_blacklist(attr->bp_addr)) 278e5779e8eSAndy Lutomirski return -EINVAL; 279e5779e8eSAndy Lutomirski } 280e5779e8eSAndy Lutomirski 281a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_EXECUTE; 282f7809dafSFrederic Weisbecker /* 283f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 284f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 285f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 286f7809dafSFrederic Weisbecker */ 287a0baf043SFrederic Weisbecker if (attr->bp_len == sizeof(long)) { 288a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_X; 289f7809dafSFrederic Weisbecker return 0; 290f7809dafSFrederic Weisbecker } 2916fcebf13SGustavo A. R. Silva /* fall through */ 292f7809dafSFrederic Weisbecker default: 293f7809dafSFrederic Weisbecker return -EINVAL; 294f7809dafSFrederic Weisbecker } 295f7809dafSFrederic Weisbecker 29624f1e32cSFrederic Weisbecker /* Len */ 297a0baf043SFrederic Weisbecker switch (attr->bp_len) { 29824f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 299a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 30024f1e32cSFrederic Weisbecker break; 30124f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 302a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_2; 30324f1e32cSFrederic Weisbecker break; 30424f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 305a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_4; 30624f1e32cSFrederic Weisbecker break; 30724f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 30824f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 309a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_8; 31024f1e32cSFrederic Weisbecker break; 31124f1e32cSFrederic Weisbecker #endif 31224f1e32cSFrederic Weisbecker default: 313ab513927SAndy Lutomirski /* AMD range breakpoint */ 314a0baf043SFrederic Weisbecker if (!is_power_of_2(attr->bp_len)) 31524f1e32cSFrederic Weisbecker return -EINVAL; 316a0baf043SFrederic Weisbecker if (attr->bp_addr & (attr->bp_len - 1)) 317ab513927SAndy Lutomirski return -EINVAL; 318362f924bSBorislav Petkov 319362f924bSBorislav Petkov if (!boot_cpu_has(X86_FEATURE_BPEXT)) 320362f924bSBorislav Petkov return -EOPNOTSUPP; 321362f924bSBorislav Petkov 322ab513927SAndy Lutomirski /* 323ab513927SAndy Lutomirski * It's impossible to use a range breakpoint to fake out 324ab513927SAndy Lutomirski * user vs kernel detection because bp_len - 1 can't 325ab513927SAndy Lutomirski * have the high bit set. If we ever allow range instruction 326ab513927SAndy Lutomirski * breakpoints, then we'll have to check for kprobe-blacklisted 327ab513927SAndy Lutomirski * addresses anywhere in the range. 328ab513927SAndy Lutomirski */ 329a0baf043SFrederic Weisbecker hw->mask = attr->bp_len - 1; 330a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 33124f1e32cSFrederic Weisbecker } 33224f1e32cSFrederic Weisbecker 33324f1e32cSFrederic Weisbecker return 0; 33424f1e32cSFrederic Weisbecker } 335d6d55f0bSJacob Shin 3360067f129SK.Prasad /* 3370067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3380067f129SK.Prasad */ 339a0baf043SFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 340a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 341a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 3420067f129SK.Prasad { 3430067f129SK.Prasad unsigned int align; 34424f1e32cSFrederic Weisbecker int ret; 3450067f129SK.Prasad 34624f1e32cSFrederic Weisbecker 347a0baf043SFrederic Weisbecker ret = arch_build_bp_info(bp, attr, hw); 34824f1e32cSFrederic Weisbecker if (ret) 34924f1e32cSFrederic Weisbecker return ret; 35024f1e32cSFrederic Weisbecker 351a0baf043SFrederic Weisbecker switch (hw->len) { 35224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3530067f129SK.Prasad align = 0; 354a0baf043SFrederic Weisbecker if (hw->mask) 355a0baf043SFrederic Weisbecker align = hw->mask; 3560067f129SK.Prasad break; 35724f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3580067f129SK.Prasad align = 1; 3590067f129SK.Prasad break; 36024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3610067f129SK.Prasad align = 3; 3620067f129SK.Prasad break; 3630067f129SK.Prasad #ifdef CONFIG_X86_64 36424f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3650067f129SK.Prasad align = 7; 3660067f129SK.Prasad break; 3670067f129SK.Prasad #endif 3680067f129SK.Prasad default: 369d6d55f0bSJacob Shin WARN_ON_ONCE(1); 370e898e69dSNathan Chancellor return -EINVAL; 3710067f129SK.Prasad } 3720067f129SK.Prasad 37384d71092SFrederic Weisbecker /* 3740067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3750067f129SK.Prasad * for the alignment implied by len. 3760067f129SK.Prasad */ 377a0baf043SFrederic Weisbecker if (hw->address & align) 3780067f129SK.Prasad return -EINVAL; 3790067f129SK.Prasad 3800067f129SK.Prasad return 0; 3810067f129SK.Prasad } 3820067f129SK.Prasad 38324f1e32cSFrederic Weisbecker /* 3849f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 3859f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 3869f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 3879f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 3889f6b3c2cSFrederic Weisbecker * 3899f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 3909f6b3c2cSFrederic Weisbecker */ 3919f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 3929f6b3c2cSFrederic Weisbecker { 3939f6b3c2cSFrederic Weisbecker int i; 3949f6b3c2cSFrederic Weisbecker int dr7 = 0; 3959f6b3c2cSFrederic Weisbecker struct perf_event *bp; 3969f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 3979f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 3989f6b3c2cSFrederic Weisbecker 3999f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 4009f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 4019f6b3c2cSFrederic Weisbecker 4029f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 4039f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 4049f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 4059f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 4069f6b3c2cSFrederic Weisbecker } else { 4079f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 4089f6b3c2cSFrederic Weisbecker } 4099f6b3c2cSFrederic Weisbecker } 4109f6b3c2cSFrederic Weisbecker 4119f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 4129f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 4139f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 4149f6b3c2cSFrederic Weisbecker 4159f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 4169f6b3c2cSFrederic Weisbecker } 41768efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 4189f6b3c2cSFrederic Weisbecker 4199f6b3c2cSFrederic Weisbecker /* 42024f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 42124f1e32cSFrederic Weisbecker */ 42224f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 4230067f129SK.Prasad { 4240067f129SK.Prasad int i; 42524f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 4260067f129SK.Prasad 42724f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 42824f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 42924f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 4300067f129SK.Prasad } 431f7da04c9SOleg Nesterov 432f7da04c9SOleg Nesterov t->debugreg6 = 0; 433f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 43424f1e32cSFrederic Weisbecker } 43524f1e32cSFrederic Weisbecker 43624f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 43724f1e32cSFrederic Weisbecker { 4380a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4390a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4400a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4410a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 44224f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 4430a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 44424f1e32cSFrederic Weisbecker } 44524f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4460067f129SK.Prasad 4470067f129SK.Prasad /* 4480067f129SK.Prasad * Handle debug exception notifications. 4490067f129SK.Prasad * 4500067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4510067f129SK.Prasad * 4520067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4530067f129SK.Prasad * i) When the causative address is from user-space and the exception 4540067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4550067f129SK.Prasad * switching 4560067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4570067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4580067f129SK.Prasad * met and requires some more action in do_debug(). 4590067f129SK.Prasad * 4600067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4610067f129SK.Prasad * 4620067f129SK.Prasad */ 4639c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 4640067f129SK.Prasad { 4650067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 46624f1e32cSFrederic Weisbecker struct perf_event *bp; 46762edab90SK.Prasad unsigned long dr7, dr6; 46862edab90SK.Prasad unsigned long *dr6_p; 46962edab90SK.Prasad 47062edab90SK.Prasad /* The DR6 value is pointed by args->err */ 47162edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 47262edab90SK.Prasad dr6 = *dr6_p; 4730067f129SK.Prasad 4746c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 4756c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 4766c0aca28SFrederic Weisbecker return NOTIFY_DONE; 4776c0aca28SFrederic Weisbecker 4780067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4790067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4800067f129SK.Prasad return NOTIFY_DONE; 4810067f129SK.Prasad 4820067f129SK.Prasad get_debugreg(dr7, 7); 4830067f129SK.Prasad /* Disable breakpoints during exception handling */ 4840067f129SK.Prasad set_debugreg(0UL, 7); 4850067f129SK.Prasad /* 4860067f129SK.Prasad * Assert that local interrupts are disabled 4870067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4880067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4890067f129SK.Prasad */ 4900067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4910067f129SK.Prasad cpu = get_cpu(); 4920067f129SK.Prasad 4930067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 4940067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 4950067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 4960067f129SK.Prasad continue; 49724f1e32cSFrederic Weisbecker 4980067f129SK.Prasad /* 49924f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 50024f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 50124f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 50224f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 5030067f129SK.Prasad */ 50424f1e32cSFrederic Weisbecker rcu_read_lock(); 50524f1e32cSFrederic Weisbecker 50624f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 5070067f129SK.Prasad /* 50862edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 50962edab90SK.Prasad * exception handling 51062edab90SK.Prasad */ 51162edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 51262edab90SK.Prasad /* 5130067f129SK.Prasad * bp can be NULL due to lazy debug register switching 51424f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 5150067f129SK.Prasad */ 51624f1e32cSFrederic Weisbecker if (!bp) { 51724f1e32cSFrederic Weisbecker rcu_read_unlock(); 51824f1e32cSFrederic Weisbecker break; 51924f1e32cSFrederic Weisbecker } 5200067f129SK.Prasad 521b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 52224f1e32cSFrederic Weisbecker 5230c4519e8SFrederic Weisbecker /* 5240c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 5250c4519e8SFrederic Weisbecker * returning back to origin. 5260c4519e8SFrederic Weisbecker */ 5270c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 5280c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 5290c4519e8SFrederic Weisbecker 53024f1e32cSFrederic Weisbecker rcu_read_unlock(); 5310067f129SK.Prasad } 532e0e53db6SK.Prasad /* 533e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 534e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 535e0e53db6SK.Prasad * taken exception due to multiple causes 536e0e53db6SK.Prasad */ 537e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 538e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5390067f129SK.Prasad rc = NOTIFY_DONE; 5400067f129SK.Prasad 5410067f129SK.Prasad set_debugreg(dr7, 7); 542eadb8a09SIngo Molnar put_cpu(); 54324f1e32cSFrederic Weisbecker 5440067f129SK.Prasad return rc; 5450067f129SK.Prasad } 5460067f129SK.Prasad 5470067f129SK.Prasad /* 5480067f129SK.Prasad * Handle debug exception notifications. 5490067f129SK.Prasad */ 5509c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5510067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5520067f129SK.Prasad { 5530067f129SK.Prasad if (val != DIE_DEBUG) 5540067f129SK.Prasad return NOTIFY_DONE; 5550067f129SK.Prasad 5560067f129SK.Prasad return hw_breakpoint_handler(data); 5570067f129SK.Prasad } 55824f1e32cSFrederic Weisbecker 55924f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 56024f1e32cSFrederic Weisbecker { 56124f1e32cSFrederic Weisbecker /* TODO */ 56224f1e32cSFrederic Weisbecker } 563