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 /* 231d390e6deSLai Jiangshan * Checks whether the range [addr, end], overlaps the area [base, base + size). 232d390e6deSLai Jiangshan */ 233d390e6deSLai Jiangshan static inline bool within_area(unsigned long addr, unsigned long end, 234d390e6deSLai Jiangshan unsigned long base, unsigned long size) 235d390e6deSLai Jiangshan { 236d390e6deSLai Jiangshan return end >= base && addr < (base + size); 237d390e6deSLai Jiangshan } 238d390e6deSLai Jiangshan 239d390e6deSLai Jiangshan /* 24024ae0c91SAndy Lutomirski * Checks whether the range from addr to end, inclusive, overlaps the CPU 24124ae0c91SAndy Lutomirski * entry area range. 24224ae0c91SAndy Lutomirski */ 24324ae0c91SAndy Lutomirski static inline bool within_cpu_entry_area(unsigned long addr, unsigned long end) 24424ae0c91SAndy Lutomirski { 245d390e6deSLai Jiangshan return within_area(addr, end, CPU_ENTRY_AREA_BASE, 246d390e6deSLai Jiangshan CPU_ENTRY_AREA_TOTAL_SIZE); 24724ae0c91SAndy Lutomirski } 24824ae0c91SAndy Lutomirski 249a0baf043SFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp, 250a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 251a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 25224f1e32cSFrederic Weisbecker { 25324ae0c91SAndy Lutomirski unsigned long bp_end; 25424ae0c91SAndy Lutomirski 25524ae0c91SAndy Lutomirski bp_end = attr->bp_addr + attr->bp_len - 1; 25624ae0c91SAndy Lutomirski if (bp_end < attr->bp_addr) 25724ae0c91SAndy Lutomirski return -EINVAL; 25824ae0c91SAndy Lutomirski 25924ae0c91SAndy Lutomirski /* 26024ae0c91SAndy Lutomirski * Prevent any breakpoint of any type that overlaps the 26124ae0c91SAndy Lutomirski * cpu_entry_area. This protects the IST stacks and also 26224ae0c91SAndy Lutomirski * reduces the chance that we ever find out what happens if 26324ae0c91SAndy Lutomirski * there's a data breakpoint on the GDT, IDT, or TSS. 26424ae0c91SAndy Lutomirski */ 26524ae0c91SAndy Lutomirski if (within_cpu_entry_area(attr->bp_addr, bp_end)) 26624ae0c91SAndy Lutomirski return -EINVAL; 26724ae0c91SAndy Lutomirski 268a0baf043SFrederic Weisbecker hw->address = attr->bp_addr; 269a0baf043SFrederic Weisbecker hw->mask = 0; 27024f1e32cSFrederic Weisbecker 271f7809dafSFrederic Weisbecker /* Type */ 272a0baf043SFrederic Weisbecker switch (attr->bp_type) { 273f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 274a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_WRITE; 275f7809dafSFrederic Weisbecker break; 276f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 277a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_RW; 278f7809dafSFrederic Weisbecker break; 279f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 280e5779e8eSAndy Lutomirski /* 281e5779e8eSAndy Lutomirski * We don't allow kernel breakpoints in places that are not 282e5779e8eSAndy Lutomirski * acceptable for kprobes. On non-kprobes kernels, we don't 283e5779e8eSAndy Lutomirski * allow kernel breakpoints at all. 284e5779e8eSAndy Lutomirski */ 285a0baf043SFrederic Weisbecker if (attr->bp_addr >= TASK_SIZE_MAX) { 286a0baf043SFrederic Weisbecker if (within_kprobe_blacklist(attr->bp_addr)) 287e5779e8eSAndy Lutomirski return -EINVAL; 288e5779e8eSAndy Lutomirski } 289e5779e8eSAndy Lutomirski 290a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_EXECUTE; 291f7809dafSFrederic Weisbecker /* 292f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 293f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 294f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 295f7809dafSFrederic Weisbecker */ 296a0baf043SFrederic Weisbecker if (attr->bp_len == sizeof(long)) { 297a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_X; 298f7809dafSFrederic Weisbecker return 0; 299f7809dafSFrederic Weisbecker } 3006fcebf13SGustavo A. R. Silva /* fall through */ 301f7809dafSFrederic Weisbecker default: 302f7809dafSFrederic Weisbecker return -EINVAL; 303f7809dafSFrederic Weisbecker } 304f7809dafSFrederic Weisbecker 30524f1e32cSFrederic Weisbecker /* Len */ 306a0baf043SFrederic Weisbecker switch (attr->bp_len) { 30724f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 308a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 30924f1e32cSFrederic Weisbecker break; 31024f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 311a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_2; 31224f1e32cSFrederic Weisbecker break; 31324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 314a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_4; 31524f1e32cSFrederic Weisbecker break; 31624f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 31724f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 318a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_8; 31924f1e32cSFrederic Weisbecker break; 32024f1e32cSFrederic Weisbecker #endif 32124f1e32cSFrederic Weisbecker default: 322ab513927SAndy Lutomirski /* AMD range breakpoint */ 323a0baf043SFrederic Weisbecker if (!is_power_of_2(attr->bp_len)) 32424f1e32cSFrederic Weisbecker return -EINVAL; 325a0baf043SFrederic Weisbecker if (attr->bp_addr & (attr->bp_len - 1)) 326ab513927SAndy Lutomirski return -EINVAL; 327362f924bSBorislav Petkov 328362f924bSBorislav Petkov if (!boot_cpu_has(X86_FEATURE_BPEXT)) 329362f924bSBorislav Petkov return -EOPNOTSUPP; 330362f924bSBorislav Petkov 331ab513927SAndy Lutomirski /* 332ab513927SAndy Lutomirski * It's impossible to use a range breakpoint to fake out 333ab513927SAndy Lutomirski * user vs kernel detection because bp_len - 1 can't 334ab513927SAndy Lutomirski * have the high bit set. If we ever allow range instruction 335ab513927SAndy Lutomirski * breakpoints, then we'll have to check for kprobe-blacklisted 336ab513927SAndy Lutomirski * addresses anywhere in the range. 337ab513927SAndy Lutomirski */ 338a0baf043SFrederic Weisbecker hw->mask = attr->bp_len - 1; 339a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 34024f1e32cSFrederic Weisbecker } 34124f1e32cSFrederic Weisbecker 34224f1e32cSFrederic Weisbecker return 0; 34324f1e32cSFrederic Weisbecker } 344d6d55f0bSJacob Shin 3450067f129SK.Prasad /* 3460067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3470067f129SK.Prasad */ 348a0baf043SFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 349a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 350a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 3510067f129SK.Prasad { 3520067f129SK.Prasad unsigned int align; 35324f1e32cSFrederic Weisbecker int ret; 3540067f129SK.Prasad 35524f1e32cSFrederic Weisbecker 356a0baf043SFrederic Weisbecker ret = arch_build_bp_info(bp, attr, hw); 35724f1e32cSFrederic Weisbecker if (ret) 35824f1e32cSFrederic Weisbecker return ret; 35924f1e32cSFrederic Weisbecker 360a0baf043SFrederic Weisbecker switch (hw->len) { 36124f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3620067f129SK.Prasad align = 0; 363a0baf043SFrederic Weisbecker if (hw->mask) 364a0baf043SFrederic Weisbecker align = hw->mask; 3650067f129SK.Prasad break; 36624f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 3670067f129SK.Prasad align = 1; 3680067f129SK.Prasad break; 36924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 3700067f129SK.Prasad align = 3; 3710067f129SK.Prasad break; 3720067f129SK.Prasad #ifdef CONFIG_X86_64 37324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 3740067f129SK.Prasad align = 7; 3750067f129SK.Prasad break; 3760067f129SK.Prasad #endif 3770067f129SK.Prasad default: 378d6d55f0bSJacob Shin WARN_ON_ONCE(1); 379e898e69dSNathan Chancellor return -EINVAL; 3800067f129SK.Prasad } 3810067f129SK.Prasad 38284d71092SFrederic Weisbecker /* 3830067f129SK.Prasad * Check that the low-order bits of the address are appropriate 3840067f129SK.Prasad * for the alignment implied by len. 3850067f129SK.Prasad */ 386a0baf043SFrederic Weisbecker if (hw->address & align) 3870067f129SK.Prasad return -EINVAL; 3880067f129SK.Prasad 3890067f129SK.Prasad return 0; 3900067f129SK.Prasad } 3910067f129SK.Prasad 39224f1e32cSFrederic Weisbecker /* 3939f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 3949f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 3959f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 3969f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 3979f6b3c2cSFrederic Weisbecker * 3989f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 3999f6b3c2cSFrederic Weisbecker */ 4009f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 4019f6b3c2cSFrederic Weisbecker { 4029f6b3c2cSFrederic Weisbecker int i; 4039f6b3c2cSFrederic Weisbecker int dr7 = 0; 4049f6b3c2cSFrederic Weisbecker struct perf_event *bp; 4059f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 4069f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 4079f6b3c2cSFrederic Weisbecker 4089f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 4099f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 4109f6b3c2cSFrederic Weisbecker 4119f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 4129f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 4139f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 4149f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 4159f6b3c2cSFrederic Weisbecker } else { 4169f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 4179f6b3c2cSFrederic Weisbecker } 4189f6b3c2cSFrederic Weisbecker } 4199f6b3c2cSFrederic Weisbecker 4209f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 4219f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 4229f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 4239f6b3c2cSFrederic Weisbecker 4249f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 4259f6b3c2cSFrederic Weisbecker } 42668efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 4279f6b3c2cSFrederic Weisbecker 4289f6b3c2cSFrederic Weisbecker /* 42924f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 43024f1e32cSFrederic Weisbecker */ 43124f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 4320067f129SK.Prasad { 4330067f129SK.Prasad int i; 43424f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 4350067f129SK.Prasad 43624f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 43724f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 43824f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 4390067f129SK.Prasad } 440f7da04c9SOleg Nesterov 441f7da04c9SOleg Nesterov t->debugreg6 = 0; 442f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 44324f1e32cSFrederic Weisbecker } 44424f1e32cSFrederic Weisbecker 44524f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 44624f1e32cSFrederic Weisbecker { 4470a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4480a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4490a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4500a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 45124f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 4520a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 45324f1e32cSFrederic Weisbecker } 45424f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4550067f129SK.Prasad 4560067f129SK.Prasad /* 4570067f129SK.Prasad * Handle debug exception notifications. 4580067f129SK.Prasad * 4590067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4600067f129SK.Prasad * 4610067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4620067f129SK.Prasad * i) When the causative address is from user-space and the exception 4630067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4640067f129SK.Prasad * switching 4650067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4660067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4670067f129SK.Prasad * met and requires some more action in do_debug(). 4680067f129SK.Prasad * 4690067f129SK.Prasad * NOTIFY_STOP returned for all other cases 4700067f129SK.Prasad * 4710067f129SK.Prasad */ 4729c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 4730067f129SK.Prasad { 4740067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 47524f1e32cSFrederic Weisbecker struct perf_event *bp; 4769f58fddeSPeter Zijlstra unsigned long dr6; 47762edab90SK.Prasad unsigned long *dr6_p; 47862edab90SK.Prasad 47962edab90SK.Prasad /* The DR6 value is pointed by args->err */ 48062edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 48162edab90SK.Prasad dr6 = *dr6_p; 4820067f129SK.Prasad 4836c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 4846c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 4856c0aca28SFrederic Weisbecker return NOTIFY_DONE; 4866c0aca28SFrederic Weisbecker 4870067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 4880067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 4890067f129SK.Prasad return NOTIFY_DONE; 4900067f129SK.Prasad 4910067f129SK.Prasad /* 4920067f129SK.Prasad * Assert that local interrupts are disabled 4930067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 4940067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 4950067f129SK.Prasad */ 4960067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 4970067f129SK.Prasad cpu = get_cpu(); 4980067f129SK.Prasad 4990067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 5000067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 5010067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 5020067f129SK.Prasad continue; 50324f1e32cSFrederic Weisbecker 5040067f129SK.Prasad /* 50524f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 50624f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 50724f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 50824f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 5090067f129SK.Prasad */ 51024f1e32cSFrederic Weisbecker rcu_read_lock(); 51124f1e32cSFrederic Weisbecker 51224f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 5130067f129SK.Prasad /* 51462edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 51562edab90SK.Prasad * exception handling 51662edab90SK.Prasad */ 51762edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 51862edab90SK.Prasad /* 5190067f129SK.Prasad * bp can be NULL due to lazy debug register switching 52024f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 5210067f129SK.Prasad */ 52224f1e32cSFrederic Weisbecker if (!bp) { 52324f1e32cSFrederic Weisbecker rcu_read_unlock(); 52424f1e32cSFrederic Weisbecker break; 52524f1e32cSFrederic Weisbecker } 5260067f129SK.Prasad 527b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 52824f1e32cSFrederic Weisbecker 5290c4519e8SFrederic Weisbecker /* 5300c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 5310c4519e8SFrederic Weisbecker * returning back to origin. 5320c4519e8SFrederic Weisbecker */ 5330c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 5340c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 5350c4519e8SFrederic Weisbecker 53624f1e32cSFrederic Weisbecker rcu_read_unlock(); 5370067f129SK.Prasad } 538e0e53db6SK.Prasad /* 539e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 540e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 541e0e53db6SK.Prasad * taken exception due to multiple causes 542e0e53db6SK.Prasad */ 543e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 544e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5450067f129SK.Prasad rc = NOTIFY_DONE; 5460067f129SK.Prasad 547eadb8a09SIngo Molnar put_cpu(); 54824f1e32cSFrederic Weisbecker 5490067f129SK.Prasad return rc; 5500067f129SK.Prasad } 5510067f129SK.Prasad 5520067f129SK.Prasad /* 5530067f129SK.Prasad * Handle debug exception notifications. 5540067f129SK.Prasad */ 5559c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5560067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5570067f129SK.Prasad { 5580067f129SK.Prasad if (val != DIE_DEBUG) 5590067f129SK.Prasad return NOTIFY_DONE; 5600067f129SK.Prasad 5610067f129SK.Prasad return hw_breakpoint_handler(data); 5620067f129SK.Prasad } 56324f1e32cSFrederic Weisbecker 56424f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 56524f1e32cSFrederic Weisbecker { 56624f1e32cSFrederic Weisbecker /* TODO */ 56724f1e32cSFrederic Weisbecker } 568