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> 3597417cb9SLai Jiangshan #include <asm/desc.h> 36fdef24dfSLai Jiangshan #include <asm/tlbflush.h> 370067f129SK.Prasad 3824f1e32cSFrederic Weisbecker /* Per cpu debug control register value */ 3928b4e0d8STejun Heo DEFINE_PER_CPU(unsigned long, cpu_dr7); 4028b4e0d8STejun Heo EXPORT_PER_CPU_SYMBOL(cpu_dr7); 4124f1e32cSFrederic Weisbecker 4224f1e32cSFrederic Weisbecker /* Per cpu debug address registers values */ 4324f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); 440067f129SK.Prasad 450067f129SK.Prasad /* 4624f1e32cSFrederic Weisbecker * Stores the breakpoints currently in use on each breakpoint address 4724f1e32cSFrederic Weisbecker * register for each cpus 480067f129SK.Prasad */ 4924f1e32cSFrederic Weisbecker static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); 500067f129SK.Prasad 510067f129SK.Prasad 522c31b795SFrederic Weisbecker static inline unsigned long 532c31b795SFrederic Weisbecker __encode_dr7(int drnum, unsigned int len, unsigned int type) 542c31b795SFrederic Weisbecker { 552c31b795SFrederic Weisbecker unsigned long bp_info; 562c31b795SFrederic Weisbecker 572c31b795SFrederic Weisbecker bp_info = (len | type) & 0xf; 582c31b795SFrederic Weisbecker bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); 592c31b795SFrederic Weisbecker bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); 602c31b795SFrederic Weisbecker 612c31b795SFrederic Weisbecker return bp_info; 622c31b795SFrederic Weisbecker } 632c31b795SFrederic Weisbecker 640067f129SK.Prasad /* 650067f129SK.Prasad * Encode the length, type, Exact, and Enable bits for a particular breakpoint 660067f129SK.Prasad * as stored in debug register 7. 670067f129SK.Prasad */ 6824f1e32cSFrederic Weisbecker unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) 690067f129SK.Prasad { 702c31b795SFrederic Weisbecker return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN; 710067f129SK.Prasad } 720067f129SK.Prasad 7324f1e32cSFrederic Weisbecker /* 7424f1e32cSFrederic Weisbecker * Decode the length and type bits for a particular breakpoint as 7524f1e32cSFrederic Weisbecker * stored in debug register 7. Return the "enabled" status. 760067f129SK.Prasad */ 7724f1e32cSFrederic Weisbecker int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type) 7824f1e32cSFrederic Weisbecker { 7924f1e32cSFrederic Weisbecker int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE); 8024f1e32cSFrederic Weisbecker 8124f1e32cSFrederic Weisbecker *len = (bp_info & 0xc) | 0x40; 8224f1e32cSFrederic Weisbecker *type = (bp_info & 0x3) | 0x80; 8324f1e32cSFrederic Weisbecker 8424f1e32cSFrederic Weisbecker return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3; 850067f129SK.Prasad } 860067f129SK.Prasad 870067f129SK.Prasad /* 8824f1e32cSFrederic Weisbecker * Install a perf counter breakpoint. 8924f1e32cSFrederic Weisbecker * 9024f1e32cSFrederic Weisbecker * We seek a free debug address register and use it for this 9124f1e32cSFrederic Weisbecker * breakpoint. Eventually we enable it in the debug control register. 9224f1e32cSFrederic Weisbecker * 9324f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 9424f1e32cSFrederic Weisbecker * and registers local to this cpu. 950067f129SK.Prasad */ 9624f1e32cSFrederic Weisbecker int arch_install_hw_breakpoint(struct perf_event *bp) 970067f129SK.Prasad { 9824f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 9924f1e32cSFrederic Weisbecker unsigned long *dr7; 10024f1e32cSFrederic Weisbecker int i; 1010067f129SK.Prasad 10224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 10389cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 10424f1e32cSFrederic Weisbecker 10524f1e32cSFrederic Weisbecker if (!*slot) { 10624f1e32cSFrederic Weisbecker *slot = bp; 1070067f129SK.Prasad break; 1080067f129SK.Prasad } 10924f1e32cSFrederic Weisbecker } 1100067f129SK.Prasad 11124f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 11224f1e32cSFrederic Weisbecker return -EBUSY; 11324f1e32cSFrederic Weisbecker 11424f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 1150a3aee0dSTejun Heo __this_cpu_write(cpu_debugreg[i], info->address); 11624f1e32cSFrederic Weisbecker 11789cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 11824f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 11924f1e32cSFrederic Weisbecker 12024f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 121d6d55f0bSJacob Shin if (info->mask) 122d6d55f0bSJacob Shin set_dr_addr_mask(info->mask, i); 12324f1e32cSFrederic Weisbecker 12424f1e32cSFrederic Weisbecker return 0; 1250067f129SK.Prasad } 1260067f129SK.Prasad 1270067f129SK.Prasad /* 12824f1e32cSFrederic Weisbecker * Uninstall the breakpoint contained in the given counter. 12924f1e32cSFrederic Weisbecker * 13024f1e32cSFrederic Weisbecker * First we search the debug address register it uses and then we disable 13124f1e32cSFrederic Weisbecker * it. 13224f1e32cSFrederic Weisbecker * 13324f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 13424f1e32cSFrederic Weisbecker * and registers local to this cpu. 1350067f129SK.Prasad */ 13624f1e32cSFrederic Weisbecker void arch_uninstall_hw_breakpoint(struct perf_event *bp) 1370067f129SK.Prasad { 13824f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 13924f1e32cSFrederic Weisbecker unsigned long *dr7; 14024f1e32cSFrederic Weisbecker int i; 1410067f129SK.Prasad 14224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 14389cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 14424f1e32cSFrederic Weisbecker 14524f1e32cSFrederic Weisbecker if (*slot == bp) { 14624f1e32cSFrederic Weisbecker *slot = NULL; 14724f1e32cSFrederic Weisbecker break; 14824f1e32cSFrederic Weisbecker } 14924f1e32cSFrederic Weisbecker } 15024f1e32cSFrederic Weisbecker 15124f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 15224f1e32cSFrederic Weisbecker return; 15324f1e32cSFrederic Weisbecker 15489cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 1552c31b795SFrederic Weisbecker *dr7 &= ~__encode_dr7(i, info->len, info->type); 15624f1e32cSFrederic Weisbecker 15724f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 158d6d55f0bSJacob Shin if (info->mask) 159d6d55f0bSJacob Shin set_dr_addr_mask(0, i); 1600067f129SK.Prasad } 1610067f129SK.Prasad 1628e983ff9SFrederic Weisbecker static int arch_bp_generic_len(int x86_len) 1630067f129SK.Prasad { 1648e983ff9SFrederic Weisbecker switch (x86_len) { 1658e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 1668e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_1; 1678e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 1688e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_2; 1698e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 1708e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_4; 1718e983ff9SFrederic Weisbecker #ifdef CONFIG_X86_64 1728e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 1738e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_8; 1748e983ff9SFrederic Weisbecker #endif 1758e983ff9SFrederic Weisbecker default: 1768e983ff9SFrederic Weisbecker return -EINVAL; 1778e983ff9SFrederic Weisbecker } 1780067f129SK.Prasad } 1790067f129SK.Prasad 18024f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 18124f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 18224f1e32cSFrederic Weisbecker { 1838e983ff9SFrederic Weisbecker int len; 1848e983ff9SFrederic Weisbecker 18589e45aacSFrederic Weisbecker /* Type */ 18689e45aacSFrederic Weisbecker switch (x86_type) { 18789e45aacSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 18889e45aacSFrederic Weisbecker if (x86_len != X86_BREAKPOINT_LEN_X) 18989e45aacSFrederic Weisbecker return -EINVAL; 19089e45aacSFrederic Weisbecker 19189e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 19289e45aacSFrederic Weisbecker *gen_len = sizeof(long); 19389e45aacSFrederic Weisbecker return 0; 19489e45aacSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 19589e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 19689e45aacSFrederic Weisbecker break; 19789e45aacSFrederic Weisbecker case X86_BREAKPOINT_RW: 19889e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 19989e45aacSFrederic Weisbecker break; 20089e45aacSFrederic Weisbecker default: 20189e45aacSFrederic Weisbecker return -EINVAL; 20289e45aacSFrederic Weisbecker } 20389e45aacSFrederic Weisbecker 20424f1e32cSFrederic Weisbecker /* Len */ 2058e983ff9SFrederic Weisbecker len = arch_bp_generic_len(x86_len); 2068e983ff9SFrederic Weisbecker if (len < 0) 20724f1e32cSFrederic Weisbecker return -EINVAL; 2088e983ff9SFrederic Weisbecker *gen_len = len; 20924f1e32cSFrederic Weisbecker 21024f1e32cSFrederic Weisbecker return 0; 21124f1e32cSFrederic Weisbecker } 21224f1e32cSFrederic Weisbecker 2138e983ff9SFrederic Weisbecker /* 2148e983ff9SFrederic Weisbecker * Check for virtual address in kernel space. 2158e983ff9SFrederic Weisbecker */ 2168e983ff9SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw) 2178e983ff9SFrederic Weisbecker { 2188e983ff9SFrederic Weisbecker unsigned long va; 2198e983ff9SFrederic Weisbecker int len; 2208e983ff9SFrederic Weisbecker 2218e983ff9SFrederic Weisbecker va = hw->address; 2228e983ff9SFrederic Weisbecker len = arch_bp_generic_len(hw->len); 2238e983ff9SFrederic Weisbecker WARN_ON_ONCE(len < 0); 2248e983ff9SFrederic Weisbecker 2258e983ff9SFrederic Weisbecker /* 2268e983ff9SFrederic Weisbecker * We don't need to worry about va + len - 1 overflowing: 2278e983ff9SFrederic Weisbecker * we already require that va is aligned to a multiple of len. 2288e983ff9SFrederic Weisbecker */ 2298e983ff9SFrederic Weisbecker return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX); 2308e983ff9SFrederic Weisbecker } 23124f1e32cSFrederic Weisbecker 23224ae0c91SAndy Lutomirski /* 233d390e6deSLai Jiangshan * Checks whether the range [addr, end], overlaps the area [base, base + size). 234d390e6deSLai Jiangshan */ 235d390e6deSLai Jiangshan static inline bool within_area(unsigned long addr, unsigned long end, 236d390e6deSLai Jiangshan unsigned long base, unsigned long size) 237d390e6deSLai Jiangshan { 238d390e6deSLai Jiangshan return end >= base && addr < (base + size); 239d390e6deSLai Jiangshan } 240d390e6deSLai Jiangshan 241d390e6deSLai Jiangshan /* 24297417cb9SLai Jiangshan * Checks whether the range from addr to end, inclusive, overlaps the fixed 24397417cb9SLai Jiangshan * mapped CPU entry area range or other ranges used for CPU entry. 24424ae0c91SAndy Lutomirski */ 24597417cb9SLai Jiangshan static inline bool within_cpu_entry(unsigned long addr, unsigned long end) 24624ae0c91SAndy Lutomirski { 24797417cb9SLai Jiangshan int cpu; 24897417cb9SLai Jiangshan 24997417cb9SLai Jiangshan /* CPU entry erea is always used for CPU entry */ 25097417cb9SLai Jiangshan if (within_area(addr, end, CPU_ENTRY_AREA_BASE, 25197417cb9SLai Jiangshan CPU_ENTRY_AREA_TOTAL_SIZE)) 25297417cb9SLai Jiangshan return true; 25397417cb9SLai Jiangshan 25497417cb9SLai Jiangshan for_each_possible_cpu(cpu) { 25597417cb9SLai Jiangshan /* The original rw GDT is being used after load_direct_gdt() */ 25697417cb9SLai Jiangshan if (within_area(addr, end, (unsigned long)get_cpu_gdt_rw(cpu), 25797417cb9SLai Jiangshan GDT_SIZE)) 25897417cb9SLai Jiangshan return true; 259f9fe0b89SLai Jiangshan 260f9fe0b89SLai Jiangshan /* 261f9fe0b89SLai Jiangshan * cpu_tss_rw is not directly referenced by hardware, but 262f9fe0b89SLai Jiangshan * cpu_tss_rw is also used in CPU entry code, 263f9fe0b89SLai Jiangshan */ 264f9fe0b89SLai Jiangshan if (within_area(addr, end, 265f9fe0b89SLai Jiangshan (unsigned long)&per_cpu(cpu_tss_rw, cpu), 266f9fe0b89SLai Jiangshan sizeof(struct tss_struct))) 267f9fe0b89SLai Jiangshan return true; 268fdef24dfSLai Jiangshan 269fdef24dfSLai Jiangshan /* 270fdef24dfSLai Jiangshan * cpu_tlbstate.user_pcid_flush_mask is used for CPU entry. 271fdef24dfSLai Jiangshan * If a data breakpoint on it, it will cause an unwanted #DB. 272fdef24dfSLai Jiangshan * Protect the full cpu_tlbstate structure to be sure. 273fdef24dfSLai Jiangshan */ 274fdef24dfSLai Jiangshan if (within_area(addr, end, 275fdef24dfSLai Jiangshan (unsigned long)&per_cpu(cpu_tlbstate, cpu), 276fdef24dfSLai Jiangshan sizeof(struct tlb_state))) 277fdef24dfSLai Jiangshan return true; 27897417cb9SLai Jiangshan } 27997417cb9SLai Jiangshan 28097417cb9SLai Jiangshan return false; 28124ae0c91SAndy Lutomirski } 28224ae0c91SAndy Lutomirski 283a0baf043SFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp, 284a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 285a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 28624f1e32cSFrederic Weisbecker { 28724ae0c91SAndy Lutomirski unsigned long bp_end; 28824ae0c91SAndy Lutomirski 28924ae0c91SAndy Lutomirski bp_end = attr->bp_addr + attr->bp_len - 1; 29024ae0c91SAndy Lutomirski if (bp_end < attr->bp_addr) 29124ae0c91SAndy Lutomirski return -EINVAL; 29224ae0c91SAndy Lutomirski 29324ae0c91SAndy Lutomirski /* 29497417cb9SLai Jiangshan * Prevent any breakpoint of any type that overlaps the CPU 29597417cb9SLai Jiangshan * entry area and data. This protects the IST stacks and also 29624ae0c91SAndy Lutomirski * reduces the chance that we ever find out what happens if 29724ae0c91SAndy Lutomirski * there's a data breakpoint on the GDT, IDT, or TSS. 29824ae0c91SAndy Lutomirski */ 29997417cb9SLai Jiangshan if (within_cpu_entry(attr->bp_addr, bp_end)) 30024ae0c91SAndy Lutomirski return -EINVAL; 30124ae0c91SAndy Lutomirski 302a0baf043SFrederic Weisbecker hw->address = attr->bp_addr; 303a0baf043SFrederic Weisbecker hw->mask = 0; 30424f1e32cSFrederic Weisbecker 305f7809dafSFrederic Weisbecker /* Type */ 306a0baf043SFrederic Weisbecker switch (attr->bp_type) { 307f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 308a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_WRITE; 309f7809dafSFrederic Weisbecker break; 310f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 311a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_RW; 312f7809dafSFrederic Weisbecker break; 313f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 314e5779e8eSAndy Lutomirski /* 315e5779e8eSAndy Lutomirski * We don't allow kernel breakpoints in places that are not 316e5779e8eSAndy Lutomirski * acceptable for kprobes. On non-kprobes kernels, we don't 317e5779e8eSAndy Lutomirski * allow kernel breakpoints at all. 318e5779e8eSAndy Lutomirski */ 319a0baf043SFrederic Weisbecker if (attr->bp_addr >= TASK_SIZE_MAX) { 320a0baf043SFrederic Weisbecker if (within_kprobe_blacklist(attr->bp_addr)) 321e5779e8eSAndy Lutomirski return -EINVAL; 322e5779e8eSAndy Lutomirski } 323e5779e8eSAndy Lutomirski 324a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_EXECUTE; 325f7809dafSFrederic Weisbecker /* 326f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 327f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 328f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 329f7809dafSFrederic Weisbecker */ 330a0baf043SFrederic Weisbecker if (attr->bp_len == sizeof(long)) { 331a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_X; 332f7809dafSFrederic Weisbecker return 0; 333f7809dafSFrederic Weisbecker } 3346fcebf13SGustavo A. R. Silva /* fall through */ 335f7809dafSFrederic Weisbecker default: 336f7809dafSFrederic Weisbecker return -EINVAL; 337f7809dafSFrederic Weisbecker } 338f7809dafSFrederic Weisbecker 33924f1e32cSFrederic Weisbecker /* Len */ 340a0baf043SFrederic Weisbecker switch (attr->bp_len) { 34124f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 342a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 34324f1e32cSFrederic Weisbecker break; 34424f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 345a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_2; 34624f1e32cSFrederic Weisbecker break; 34724f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 348a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_4; 34924f1e32cSFrederic Weisbecker break; 35024f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 35124f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 352a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_8; 35324f1e32cSFrederic Weisbecker break; 35424f1e32cSFrederic Weisbecker #endif 35524f1e32cSFrederic Weisbecker default: 356ab513927SAndy Lutomirski /* AMD range breakpoint */ 357a0baf043SFrederic Weisbecker if (!is_power_of_2(attr->bp_len)) 35824f1e32cSFrederic Weisbecker return -EINVAL; 359a0baf043SFrederic Weisbecker if (attr->bp_addr & (attr->bp_len - 1)) 360ab513927SAndy Lutomirski return -EINVAL; 361362f924bSBorislav Petkov 362362f924bSBorislav Petkov if (!boot_cpu_has(X86_FEATURE_BPEXT)) 363362f924bSBorislav Petkov return -EOPNOTSUPP; 364362f924bSBorislav Petkov 365ab513927SAndy Lutomirski /* 366ab513927SAndy Lutomirski * It's impossible to use a range breakpoint to fake out 367ab513927SAndy Lutomirski * user vs kernel detection because bp_len - 1 can't 368ab513927SAndy Lutomirski * have the high bit set. If we ever allow range instruction 369ab513927SAndy Lutomirski * breakpoints, then we'll have to check for kprobe-blacklisted 370ab513927SAndy Lutomirski * addresses anywhere in the range. 371ab513927SAndy Lutomirski */ 372a0baf043SFrederic Weisbecker hw->mask = attr->bp_len - 1; 373a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 37424f1e32cSFrederic Weisbecker } 37524f1e32cSFrederic Weisbecker 37624f1e32cSFrederic Weisbecker return 0; 37724f1e32cSFrederic Weisbecker } 378d6d55f0bSJacob Shin 3790067f129SK.Prasad /* 3800067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 3810067f129SK.Prasad */ 382a0baf043SFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 383a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 384a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 3850067f129SK.Prasad { 3860067f129SK.Prasad unsigned int align; 38724f1e32cSFrederic Weisbecker int ret; 3880067f129SK.Prasad 38924f1e32cSFrederic Weisbecker 390a0baf043SFrederic Weisbecker ret = arch_build_bp_info(bp, attr, hw); 39124f1e32cSFrederic Weisbecker if (ret) 39224f1e32cSFrederic Weisbecker return ret; 39324f1e32cSFrederic Weisbecker 394a0baf043SFrederic Weisbecker switch (hw->len) { 39524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 3960067f129SK.Prasad align = 0; 397a0baf043SFrederic Weisbecker if (hw->mask) 398a0baf043SFrederic Weisbecker align = hw->mask; 3990067f129SK.Prasad break; 40024f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 4010067f129SK.Prasad align = 1; 4020067f129SK.Prasad break; 40324f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 4040067f129SK.Prasad align = 3; 4050067f129SK.Prasad break; 4060067f129SK.Prasad #ifdef CONFIG_X86_64 40724f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 4080067f129SK.Prasad align = 7; 4090067f129SK.Prasad break; 4100067f129SK.Prasad #endif 4110067f129SK.Prasad default: 412d6d55f0bSJacob Shin WARN_ON_ONCE(1); 413e898e69dSNathan Chancellor return -EINVAL; 4140067f129SK.Prasad } 4150067f129SK.Prasad 41684d71092SFrederic Weisbecker /* 4170067f129SK.Prasad * Check that the low-order bits of the address are appropriate 4180067f129SK.Prasad * for the alignment implied by len. 4190067f129SK.Prasad */ 420a0baf043SFrederic Weisbecker if (hw->address & align) 4210067f129SK.Prasad return -EINVAL; 4220067f129SK.Prasad 4230067f129SK.Prasad return 0; 4240067f129SK.Prasad } 4250067f129SK.Prasad 42624f1e32cSFrederic Weisbecker /* 4279f6b3c2cSFrederic Weisbecker * Dump the debug register contents to the user. 4289f6b3c2cSFrederic Weisbecker * We can't dump our per cpu values because it 4299f6b3c2cSFrederic Weisbecker * may contain cpu wide breakpoint, something that 4309f6b3c2cSFrederic Weisbecker * doesn't belong to the current task. 4319f6b3c2cSFrederic Weisbecker * 4329f6b3c2cSFrederic Weisbecker * TODO: include non-ptrace user breakpoints (perf) 4339f6b3c2cSFrederic Weisbecker */ 4349f6b3c2cSFrederic Weisbecker void aout_dump_debugregs(struct user *dump) 4359f6b3c2cSFrederic Weisbecker { 4369f6b3c2cSFrederic Weisbecker int i; 4379f6b3c2cSFrederic Weisbecker int dr7 = 0; 4389f6b3c2cSFrederic Weisbecker struct perf_event *bp; 4399f6b3c2cSFrederic Weisbecker struct arch_hw_breakpoint *info; 4409f6b3c2cSFrederic Weisbecker struct thread_struct *thread = ¤t->thread; 4419f6b3c2cSFrederic Weisbecker 4429f6b3c2cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 4439f6b3c2cSFrederic Weisbecker bp = thread->ptrace_bps[i]; 4449f6b3c2cSFrederic Weisbecker 4459f6b3c2cSFrederic Weisbecker if (bp && !bp->attr.disabled) { 4469f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = bp->attr.bp_addr; 4479f6b3c2cSFrederic Weisbecker info = counter_arch_bp(bp); 4489f6b3c2cSFrederic Weisbecker dr7 |= encode_dr7(i, info->len, info->type); 4499f6b3c2cSFrederic Weisbecker } else { 4509f6b3c2cSFrederic Weisbecker dump->u_debugreg[i] = 0; 4519f6b3c2cSFrederic Weisbecker } 4529f6b3c2cSFrederic Weisbecker } 4539f6b3c2cSFrederic Weisbecker 4549f6b3c2cSFrederic Weisbecker dump->u_debugreg[4] = 0; 4559f6b3c2cSFrederic Weisbecker dump->u_debugreg[5] = 0; 4569f6b3c2cSFrederic Weisbecker dump->u_debugreg[6] = current->thread.debugreg6; 4579f6b3c2cSFrederic Weisbecker 4589f6b3c2cSFrederic Weisbecker dump->u_debugreg[7] = dr7; 4599f6b3c2cSFrederic Weisbecker } 46068efa37dSIngo Molnar EXPORT_SYMBOL_GPL(aout_dump_debugregs); 4619f6b3c2cSFrederic Weisbecker 4629f6b3c2cSFrederic Weisbecker /* 46324f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 46424f1e32cSFrederic Weisbecker */ 46524f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 4660067f129SK.Prasad { 4670067f129SK.Prasad int i; 46824f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 4690067f129SK.Prasad 47024f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 47124f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 47224f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 4730067f129SK.Prasad } 474f7da04c9SOleg Nesterov 475f7da04c9SOleg Nesterov t->debugreg6 = 0; 476f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 47724f1e32cSFrederic Weisbecker } 47824f1e32cSFrederic Weisbecker 47924f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 48024f1e32cSFrederic Weisbecker { 4810a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4820a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4830a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4840a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 48524f1e32cSFrederic Weisbecker set_debugreg(current->thread.debugreg6, 6); 4860a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 48724f1e32cSFrederic Weisbecker } 48824f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4890067f129SK.Prasad 4900067f129SK.Prasad /* 4910067f129SK.Prasad * Handle debug exception notifications. 4920067f129SK.Prasad * 4930067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4940067f129SK.Prasad * 4950067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4960067f129SK.Prasad * i) When the causative address is from user-space and the exception 4970067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4980067f129SK.Prasad * switching 4990067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 5000067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 5010067f129SK.Prasad * met and requires some more action in do_debug(). 5020067f129SK.Prasad * 5030067f129SK.Prasad * NOTIFY_STOP returned for all other cases 5040067f129SK.Prasad * 5050067f129SK.Prasad */ 5069c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 5070067f129SK.Prasad { 5080067f129SK.Prasad int i, cpu, rc = NOTIFY_STOP; 50924f1e32cSFrederic Weisbecker struct perf_event *bp; 5109f58fddeSPeter Zijlstra unsigned long dr6; 51162edab90SK.Prasad unsigned long *dr6_p; 51262edab90SK.Prasad 51362edab90SK.Prasad /* The DR6 value is pointed by args->err */ 51462edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 51562edab90SK.Prasad dr6 = *dr6_p; 5160067f129SK.Prasad 5176c0aca28SFrederic Weisbecker /* If it's a single step, TRAP bits are random */ 5186c0aca28SFrederic Weisbecker if (dr6 & DR_STEP) 5196c0aca28SFrederic Weisbecker return NOTIFY_DONE; 5206c0aca28SFrederic Weisbecker 5210067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 5220067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 5230067f129SK.Prasad return NOTIFY_DONE; 5240067f129SK.Prasad 5250067f129SK.Prasad /* 5260067f129SK.Prasad * Assert that local interrupts are disabled 5270067f129SK.Prasad * Reset the DRn bits in the virtualized register value. 5280067f129SK.Prasad * The ptrace trigger routine will add in whatever is needed. 5290067f129SK.Prasad */ 5300067f129SK.Prasad current->thread.debugreg6 &= ~DR_TRAP_BITS; 5310067f129SK.Prasad cpu = get_cpu(); 5320067f129SK.Prasad 5330067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 5340067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 5350067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 5360067f129SK.Prasad continue; 53724f1e32cSFrederic Weisbecker 5380067f129SK.Prasad /* 53924f1e32cSFrederic Weisbecker * The counter may be concurrently released but that can only 54024f1e32cSFrederic Weisbecker * occur from a call_rcu() path. We can then safely fetch 54124f1e32cSFrederic Weisbecker * the breakpoint, use its callback, touch its counter 54224f1e32cSFrederic Weisbecker * while we are in an rcu_read_lock() path. 5430067f129SK.Prasad */ 54424f1e32cSFrederic Weisbecker rcu_read_lock(); 54524f1e32cSFrederic Weisbecker 54624f1e32cSFrederic Weisbecker bp = per_cpu(bp_per_reg[i], cpu); 5470067f129SK.Prasad /* 54862edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 54962edab90SK.Prasad * exception handling 55062edab90SK.Prasad */ 55162edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 55262edab90SK.Prasad /* 5530067f129SK.Prasad * bp can be NULL due to lazy debug register switching 55424f1e32cSFrederic Weisbecker * or due to concurrent perf counter removing. 5550067f129SK.Prasad */ 55624f1e32cSFrederic Weisbecker if (!bp) { 55724f1e32cSFrederic Weisbecker rcu_read_unlock(); 55824f1e32cSFrederic Weisbecker break; 55924f1e32cSFrederic Weisbecker } 5600067f129SK.Prasad 561b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 56224f1e32cSFrederic Weisbecker 5630c4519e8SFrederic Weisbecker /* 5640c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 5650c4519e8SFrederic Weisbecker * returning back to origin. 5660c4519e8SFrederic Weisbecker */ 5670c4519e8SFrederic Weisbecker if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE) 5680c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 5690c4519e8SFrederic Weisbecker 57024f1e32cSFrederic Weisbecker rcu_read_unlock(); 5710067f129SK.Prasad } 572e0e53db6SK.Prasad /* 573e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 574e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 575e0e53db6SK.Prasad * taken exception due to multiple causes 576e0e53db6SK.Prasad */ 577e0e53db6SK.Prasad if ((current->thread.debugreg6 & DR_TRAP_BITS) || 578e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5790067f129SK.Prasad rc = NOTIFY_DONE; 5800067f129SK.Prasad 581eadb8a09SIngo Molnar put_cpu(); 58224f1e32cSFrederic Weisbecker 5830067f129SK.Prasad return rc; 5840067f129SK.Prasad } 5850067f129SK.Prasad 5860067f129SK.Prasad /* 5870067f129SK.Prasad * Handle debug exception notifications. 5880067f129SK.Prasad */ 5899c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5900067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5910067f129SK.Prasad { 5920067f129SK.Prasad if (val != DIE_DEBUG) 5930067f129SK.Prasad return NOTIFY_DONE; 5940067f129SK.Prasad 5950067f129SK.Prasad return hw_breakpoint_handler(data); 5960067f129SK.Prasad } 59724f1e32cSFrederic Weisbecker 59824f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 59924f1e32cSFrederic Weisbecker { 60024f1e32cSFrederic Weisbecker /* TODO */ 60124f1e32cSFrederic Weisbecker } 602