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 10284b6a349SPeter Zijlstra lockdep_assert_irqs_disabled(); 10384b6a349SPeter Zijlstra 10424f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 10589cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 10624f1e32cSFrederic Weisbecker 10724f1e32cSFrederic Weisbecker if (!*slot) { 10824f1e32cSFrederic Weisbecker *slot = bp; 1090067f129SK.Prasad break; 1100067f129SK.Prasad } 11124f1e32cSFrederic Weisbecker } 1120067f129SK.Prasad 11324f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 11424f1e32cSFrederic Weisbecker return -EBUSY; 11524f1e32cSFrederic Weisbecker 11624f1e32cSFrederic Weisbecker set_debugreg(info->address, i); 1170a3aee0dSTejun Heo __this_cpu_write(cpu_debugreg[i], info->address); 11824f1e32cSFrederic Weisbecker 11989cbc767SChristoph Lameter dr7 = this_cpu_ptr(&cpu_dr7); 12024f1e32cSFrederic Weisbecker *dr7 |= encode_dr7(i, info->len, info->type); 12124f1e32cSFrederic Weisbecker 12284b6a349SPeter Zijlstra /* 12384b6a349SPeter Zijlstra * Ensure we first write cpu_dr7 before we set the DR7 register. 12484b6a349SPeter Zijlstra * This ensures an NMI never see cpu_dr7 0 when DR7 is not. 12584b6a349SPeter Zijlstra */ 12684b6a349SPeter Zijlstra barrier(); 12784b6a349SPeter Zijlstra 12824f1e32cSFrederic Weisbecker set_debugreg(*dr7, 7); 129d6d55f0bSJacob Shin if (info->mask) 130d6d55f0bSJacob Shin set_dr_addr_mask(info->mask, i); 13124f1e32cSFrederic Weisbecker 13224f1e32cSFrederic Weisbecker return 0; 1330067f129SK.Prasad } 1340067f129SK.Prasad 1350067f129SK.Prasad /* 13624f1e32cSFrederic Weisbecker * Uninstall the breakpoint contained in the given counter. 13724f1e32cSFrederic Weisbecker * 13824f1e32cSFrederic Weisbecker * First we search the debug address register it uses and then we disable 13924f1e32cSFrederic Weisbecker * it. 14024f1e32cSFrederic Weisbecker * 14124f1e32cSFrederic Weisbecker * Atomic: we hold the counter->ctx->lock and we only handle variables 14224f1e32cSFrederic Weisbecker * and registers local to this cpu. 1430067f129SK.Prasad */ 14424f1e32cSFrederic Weisbecker void arch_uninstall_hw_breakpoint(struct perf_event *bp) 1450067f129SK.Prasad { 14624f1e32cSFrederic Weisbecker struct arch_hw_breakpoint *info = counter_arch_bp(bp); 14784b6a349SPeter Zijlstra unsigned long dr7; 14824f1e32cSFrederic Weisbecker int i; 1490067f129SK.Prasad 15084b6a349SPeter Zijlstra lockdep_assert_irqs_disabled(); 15184b6a349SPeter Zijlstra 15224f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 15389cbc767SChristoph Lameter struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]); 15424f1e32cSFrederic Weisbecker 15524f1e32cSFrederic Weisbecker if (*slot == bp) { 15624f1e32cSFrederic Weisbecker *slot = NULL; 15724f1e32cSFrederic Weisbecker break; 15824f1e32cSFrederic Weisbecker } 15924f1e32cSFrederic Weisbecker } 16024f1e32cSFrederic Weisbecker 16124f1e32cSFrederic Weisbecker if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) 16224f1e32cSFrederic Weisbecker return; 16324f1e32cSFrederic Weisbecker 16484b6a349SPeter Zijlstra dr7 = this_cpu_read(cpu_dr7); 16584b6a349SPeter Zijlstra dr7 &= ~__encode_dr7(i, info->len, info->type); 16624f1e32cSFrederic Weisbecker 16784b6a349SPeter Zijlstra set_debugreg(dr7, 7); 168d6d55f0bSJacob Shin if (info->mask) 169d6d55f0bSJacob Shin set_dr_addr_mask(0, i); 17084b6a349SPeter Zijlstra 17184b6a349SPeter Zijlstra /* 17284b6a349SPeter Zijlstra * Ensure the write to cpu_dr7 is after we've set the DR7 register. 17384b6a349SPeter Zijlstra * This ensures an NMI never see cpu_dr7 0 when DR7 is not. 17484b6a349SPeter Zijlstra */ 17584b6a349SPeter Zijlstra barrier(); 17684b6a349SPeter Zijlstra 17784b6a349SPeter Zijlstra this_cpu_write(cpu_dr7, dr7); 1780067f129SK.Prasad } 1790067f129SK.Prasad 1808e983ff9SFrederic Weisbecker static int arch_bp_generic_len(int x86_len) 1810067f129SK.Prasad { 1828e983ff9SFrederic Weisbecker switch (x86_len) { 1838e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 1848e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_1; 1858e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 1868e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_2; 1878e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 1888e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_4; 1898e983ff9SFrederic Weisbecker #ifdef CONFIG_X86_64 1908e983ff9SFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 1918e983ff9SFrederic Weisbecker return HW_BREAKPOINT_LEN_8; 1928e983ff9SFrederic Weisbecker #endif 1938e983ff9SFrederic Weisbecker default: 1948e983ff9SFrederic Weisbecker return -EINVAL; 1958e983ff9SFrederic Weisbecker } 1960067f129SK.Prasad } 1970067f129SK.Prasad 19824f1e32cSFrederic Weisbecker int arch_bp_generic_fields(int x86_len, int x86_type, 19924f1e32cSFrederic Weisbecker int *gen_len, int *gen_type) 20024f1e32cSFrederic Weisbecker { 2018e983ff9SFrederic Weisbecker int len; 2028e983ff9SFrederic Weisbecker 20389e45aacSFrederic Weisbecker /* Type */ 20489e45aacSFrederic Weisbecker switch (x86_type) { 20589e45aacSFrederic Weisbecker case X86_BREAKPOINT_EXECUTE: 20689e45aacSFrederic Weisbecker if (x86_len != X86_BREAKPOINT_LEN_X) 20789e45aacSFrederic Weisbecker return -EINVAL; 20889e45aacSFrederic Weisbecker 20989e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_X; 21089e45aacSFrederic Weisbecker *gen_len = sizeof(long); 21189e45aacSFrederic Weisbecker return 0; 21289e45aacSFrederic Weisbecker case X86_BREAKPOINT_WRITE: 21389e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W; 21489e45aacSFrederic Weisbecker break; 21589e45aacSFrederic Weisbecker case X86_BREAKPOINT_RW: 21689e45aacSFrederic Weisbecker *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; 21789e45aacSFrederic Weisbecker break; 21889e45aacSFrederic Weisbecker default: 21989e45aacSFrederic Weisbecker return -EINVAL; 22089e45aacSFrederic Weisbecker } 22189e45aacSFrederic Weisbecker 22224f1e32cSFrederic Weisbecker /* Len */ 2238e983ff9SFrederic Weisbecker len = arch_bp_generic_len(x86_len); 2248e983ff9SFrederic Weisbecker if (len < 0) 22524f1e32cSFrederic Weisbecker return -EINVAL; 2268e983ff9SFrederic Weisbecker *gen_len = len; 22724f1e32cSFrederic Weisbecker 22824f1e32cSFrederic Weisbecker return 0; 22924f1e32cSFrederic Weisbecker } 23024f1e32cSFrederic Weisbecker 2318e983ff9SFrederic Weisbecker /* 2328e983ff9SFrederic Weisbecker * Check for virtual address in kernel space. 2338e983ff9SFrederic Weisbecker */ 2348e983ff9SFrederic Weisbecker int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw) 2358e983ff9SFrederic Weisbecker { 2368e983ff9SFrederic Weisbecker unsigned long va; 2378e983ff9SFrederic Weisbecker int len; 2388e983ff9SFrederic Weisbecker 2398e983ff9SFrederic Weisbecker va = hw->address; 2408e983ff9SFrederic Weisbecker len = arch_bp_generic_len(hw->len); 2418e983ff9SFrederic Weisbecker WARN_ON_ONCE(len < 0); 2428e983ff9SFrederic Weisbecker 2438e983ff9SFrederic Weisbecker /* 2448e983ff9SFrederic Weisbecker * We don't need to worry about va + len - 1 overflowing: 2458e983ff9SFrederic Weisbecker * we already require that va is aligned to a multiple of len. 2468e983ff9SFrederic Weisbecker */ 2478e983ff9SFrederic Weisbecker return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX); 2488e983ff9SFrederic Weisbecker } 24924f1e32cSFrederic Weisbecker 25024ae0c91SAndy Lutomirski /* 251d390e6deSLai Jiangshan * Checks whether the range [addr, end], overlaps the area [base, base + size). 252d390e6deSLai Jiangshan */ 253d390e6deSLai Jiangshan static inline bool within_area(unsigned long addr, unsigned long end, 254d390e6deSLai Jiangshan unsigned long base, unsigned long size) 255d390e6deSLai Jiangshan { 256d390e6deSLai Jiangshan return end >= base && addr < (base + size); 257d390e6deSLai Jiangshan } 258d390e6deSLai Jiangshan 259d390e6deSLai Jiangshan /* 26097417cb9SLai Jiangshan * Checks whether the range from addr to end, inclusive, overlaps the fixed 26197417cb9SLai Jiangshan * mapped CPU entry area range or other ranges used for CPU entry. 26224ae0c91SAndy Lutomirski */ 26397417cb9SLai Jiangshan static inline bool within_cpu_entry(unsigned long addr, unsigned long end) 26424ae0c91SAndy Lutomirski { 26597417cb9SLai Jiangshan int cpu; 26697417cb9SLai Jiangshan 26797417cb9SLai Jiangshan /* CPU entry erea is always used for CPU entry */ 26897417cb9SLai Jiangshan if (within_area(addr, end, CPU_ENTRY_AREA_BASE, 26997417cb9SLai Jiangshan CPU_ENTRY_AREA_TOTAL_SIZE)) 27097417cb9SLai Jiangshan return true; 27197417cb9SLai Jiangshan 272*c4bed4b9SLai Jiangshan /* 273*c4bed4b9SLai Jiangshan * When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU 274*c4bed4b9SLai Jiangshan * GSBASE value via __per_cpu_offset or pcpu_unit_offsets. 275*c4bed4b9SLai Jiangshan */ 276*c4bed4b9SLai Jiangshan #ifdef CONFIG_SMP 277*c4bed4b9SLai Jiangshan if (within_area(addr, end, (unsigned long)__per_cpu_offset, 278*c4bed4b9SLai Jiangshan sizeof(unsigned long) * nr_cpu_ids)) 279*c4bed4b9SLai Jiangshan return true; 280*c4bed4b9SLai Jiangshan #else 281*c4bed4b9SLai Jiangshan if (within_area(addr, end, (unsigned long)&pcpu_unit_offsets, 282*c4bed4b9SLai Jiangshan sizeof(pcpu_unit_offsets))) 283*c4bed4b9SLai Jiangshan return true; 284*c4bed4b9SLai Jiangshan #endif 285*c4bed4b9SLai Jiangshan 28697417cb9SLai Jiangshan for_each_possible_cpu(cpu) { 28797417cb9SLai Jiangshan /* The original rw GDT is being used after load_direct_gdt() */ 28897417cb9SLai Jiangshan if (within_area(addr, end, (unsigned long)get_cpu_gdt_rw(cpu), 28997417cb9SLai Jiangshan GDT_SIZE)) 29097417cb9SLai Jiangshan return true; 291f9fe0b89SLai Jiangshan 292f9fe0b89SLai Jiangshan /* 293f9fe0b89SLai Jiangshan * cpu_tss_rw is not directly referenced by hardware, but 294f9fe0b89SLai Jiangshan * cpu_tss_rw is also used in CPU entry code, 295f9fe0b89SLai Jiangshan */ 296f9fe0b89SLai Jiangshan if (within_area(addr, end, 297f9fe0b89SLai Jiangshan (unsigned long)&per_cpu(cpu_tss_rw, cpu), 298f9fe0b89SLai Jiangshan sizeof(struct tss_struct))) 299f9fe0b89SLai Jiangshan return true; 300fdef24dfSLai Jiangshan 301fdef24dfSLai Jiangshan /* 302fdef24dfSLai Jiangshan * cpu_tlbstate.user_pcid_flush_mask is used for CPU entry. 303fdef24dfSLai Jiangshan * If a data breakpoint on it, it will cause an unwanted #DB. 304fdef24dfSLai Jiangshan * Protect the full cpu_tlbstate structure to be sure. 305fdef24dfSLai Jiangshan */ 306fdef24dfSLai Jiangshan if (within_area(addr, end, 307fdef24dfSLai Jiangshan (unsigned long)&per_cpu(cpu_tlbstate, cpu), 308fdef24dfSLai Jiangshan sizeof(struct tlb_state))) 309fdef24dfSLai Jiangshan return true; 31097417cb9SLai Jiangshan } 31197417cb9SLai Jiangshan 31297417cb9SLai Jiangshan return false; 31324ae0c91SAndy Lutomirski } 31424ae0c91SAndy Lutomirski 315a0baf043SFrederic Weisbecker static int arch_build_bp_info(struct perf_event *bp, 316a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 317a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 31824f1e32cSFrederic Weisbecker { 31924ae0c91SAndy Lutomirski unsigned long bp_end; 32024ae0c91SAndy Lutomirski 32124ae0c91SAndy Lutomirski bp_end = attr->bp_addr + attr->bp_len - 1; 32224ae0c91SAndy Lutomirski if (bp_end < attr->bp_addr) 32324ae0c91SAndy Lutomirski return -EINVAL; 32424ae0c91SAndy Lutomirski 32524ae0c91SAndy Lutomirski /* 32697417cb9SLai Jiangshan * Prevent any breakpoint of any type that overlaps the CPU 32797417cb9SLai Jiangshan * entry area and data. This protects the IST stacks and also 32824ae0c91SAndy Lutomirski * reduces the chance that we ever find out what happens if 32924ae0c91SAndy Lutomirski * there's a data breakpoint on the GDT, IDT, or TSS. 33024ae0c91SAndy Lutomirski */ 33197417cb9SLai Jiangshan if (within_cpu_entry(attr->bp_addr, bp_end)) 33224ae0c91SAndy Lutomirski return -EINVAL; 33324ae0c91SAndy Lutomirski 334a0baf043SFrederic Weisbecker hw->address = attr->bp_addr; 335a0baf043SFrederic Weisbecker hw->mask = 0; 33624f1e32cSFrederic Weisbecker 337f7809dafSFrederic Weisbecker /* Type */ 338a0baf043SFrederic Weisbecker switch (attr->bp_type) { 339f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W: 340a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_WRITE; 341f7809dafSFrederic Weisbecker break; 342f7809dafSFrederic Weisbecker case HW_BREAKPOINT_W | HW_BREAKPOINT_R: 343a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_RW; 344f7809dafSFrederic Weisbecker break; 345f7809dafSFrederic Weisbecker case HW_BREAKPOINT_X: 346e5779e8eSAndy Lutomirski /* 347e5779e8eSAndy Lutomirski * We don't allow kernel breakpoints in places that are not 348e5779e8eSAndy Lutomirski * acceptable for kprobes. On non-kprobes kernels, we don't 349e5779e8eSAndy Lutomirski * allow kernel breakpoints at all. 350e5779e8eSAndy Lutomirski */ 351a0baf043SFrederic Weisbecker if (attr->bp_addr >= TASK_SIZE_MAX) { 352a0baf043SFrederic Weisbecker if (within_kprobe_blacklist(attr->bp_addr)) 353e5779e8eSAndy Lutomirski return -EINVAL; 354e5779e8eSAndy Lutomirski } 355e5779e8eSAndy Lutomirski 356a0baf043SFrederic Weisbecker hw->type = X86_BREAKPOINT_EXECUTE; 357f7809dafSFrederic Weisbecker /* 358f7809dafSFrederic Weisbecker * x86 inst breakpoints need to have a specific undefined len. 359f7809dafSFrederic Weisbecker * But we still need to check userspace is not trying to setup 360f7809dafSFrederic Weisbecker * an unsupported length, to get a range breakpoint for example. 361f7809dafSFrederic Weisbecker */ 362a0baf043SFrederic Weisbecker if (attr->bp_len == sizeof(long)) { 363a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_X; 364f7809dafSFrederic Weisbecker return 0; 365f7809dafSFrederic Weisbecker } 366df561f66SGustavo A. R. Silva fallthrough; 367f7809dafSFrederic Weisbecker default: 368f7809dafSFrederic Weisbecker return -EINVAL; 369f7809dafSFrederic Weisbecker } 370f7809dafSFrederic Weisbecker 37124f1e32cSFrederic Weisbecker /* Len */ 372a0baf043SFrederic Weisbecker switch (attr->bp_len) { 37324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_1: 374a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 37524f1e32cSFrederic Weisbecker break; 37624f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_2: 377a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_2; 37824f1e32cSFrederic Weisbecker break; 37924f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_4: 380a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_4; 38124f1e32cSFrederic Weisbecker break; 38224f1e32cSFrederic Weisbecker #ifdef CONFIG_X86_64 38324f1e32cSFrederic Weisbecker case HW_BREAKPOINT_LEN_8: 384a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_8; 38524f1e32cSFrederic Weisbecker break; 38624f1e32cSFrederic Weisbecker #endif 38724f1e32cSFrederic Weisbecker default: 388ab513927SAndy Lutomirski /* AMD range breakpoint */ 389a0baf043SFrederic Weisbecker if (!is_power_of_2(attr->bp_len)) 39024f1e32cSFrederic Weisbecker return -EINVAL; 391a0baf043SFrederic Weisbecker if (attr->bp_addr & (attr->bp_len - 1)) 392ab513927SAndy Lutomirski return -EINVAL; 393362f924bSBorislav Petkov 394362f924bSBorislav Petkov if (!boot_cpu_has(X86_FEATURE_BPEXT)) 395362f924bSBorislav Petkov return -EOPNOTSUPP; 396362f924bSBorislav Petkov 397ab513927SAndy Lutomirski /* 398ab513927SAndy Lutomirski * It's impossible to use a range breakpoint to fake out 399ab513927SAndy Lutomirski * user vs kernel detection because bp_len - 1 can't 400ab513927SAndy Lutomirski * have the high bit set. If we ever allow range instruction 401ab513927SAndy Lutomirski * breakpoints, then we'll have to check for kprobe-blacklisted 402ab513927SAndy Lutomirski * addresses anywhere in the range. 403ab513927SAndy Lutomirski */ 404a0baf043SFrederic Weisbecker hw->mask = attr->bp_len - 1; 405a0baf043SFrederic Weisbecker hw->len = X86_BREAKPOINT_LEN_1; 40624f1e32cSFrederic Weisbecker } 40724f1e32cSFrederic Weisbecker 40824f1e32cSFrederic Weisbecker return 0; 40924f1e32cSFrederic Weisbecker } 410d6d55f0bSJacob Shin 4110067f129SK.Prasad /* 4120067f129SK.Prasad * Validate the arch-specific HW Breakpoint register settings 4130067f129SK.Prasad */ 414a0baf043SFrederic Weisbecker int hw_breakpoint_arch_parse(struct perf_event *bp, 415a0baf043SFrederic Weisbecker const struct perf_event_attr *attr, 416a0baf043SFrederic Weisbecker struct arch_hw_breakpoint *hw) 4170067f129SK.Prasad { 4180067f129SK.Prasad unsigned int align; 41924f1e32cSFrederic Weisbecker int ret; 4200067f129SK.Prasad 42124f1e32cSFrederic Weisbecker 422a0baf043SFrederic Weisbecker ret = arch_build_bp_info(bp, attr, hw); 42324f1e32cSFrederic Weisbecker if (ret) 42424f1e32cSFrederic Weisbecker return ret; 42524f1e32cSFrederic Weisbecker 426a0baf043SFrederic Weisbecker switch (hw->len) { 42724f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_1: 4280067f129SK.Prasad align = 0; 429a0baf043SFrederic Weisbecker if (hw->mask) 430a0baf043SFrederic Weisbecker align = hw->mask; 4310067f129SK.Prasad break; 43224f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_2: 4330067f129SK.Prasad align = 1; 4340067f129SK.Prasad break; 43524f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_4: 4360067f129SK.Prasad align = 3; 4370067f129SK.Prasad break; 4380067f129SK.Prasad #ifdef CONFIG_X86_64 43924f1e32cSFrederic Weisbecker case X86_BREAKPOINT_LEN_8: 4400067f129SK.Prasad align = 7; 4410067f129SK.Prasad break; 4420067f129SK.Prasad #endif 4430067f129SK.Prasad default: 444d6d55f0bSJacob Shin WARN_ON_ONCE(1); 445e898e69dSNathan Chancellor return -EINVAL; 4460067f129SK.Prasad } 4470067f129SK.Prasad 44884d71092SFrederic Weisbecker /* 4490067f129SK.Prasad * Check that the low-order bits of the address are appropriate 4500067f129SK.Prasad * for the alignment implied by len. 4510067f129SK.Prasad */ 452a0baf043SFrederic Weisbecker if (hw->address & align) 4530067f129SK.Prasad return -EINVAL; 4540067f129SK.Prasad 4550067f129SK.Prasad return 0; 4560067f129SK.Prasad } 4570067f129SK.Prasad 45824f1e32cSFrederic Weisbecker /* 45924f1e32cSFrederic Weisbecker * Release the user breakpoints used by ptrace 46024f1e32cSFrederic Weisbecker */ 46124f1e32cSFrederic Weisbecker void flush_ptrace_hw_breakpoint(struct task_struct *tsk) 4620067f129SK.Prasad { 4630067f129SK.Prasad int i; 46424f1e32cSFrederic Weisbecker struct thread_struct *t = &tsk->thread; 4650067f129SK.Prasad 46624f1e32cSFrederic Weisbecker for (i = 0; i < HBP_NUM; i++) { 46724f1e32cSFrederic Weisbecker unregister_hw_breakpoint(t->ptrace_bps[i]); 46824f1e32cSFrederic Weisbecker t->ptrace_bps[i] = NULL; 4690067f129SK.Prasad } 470f7da04c9SOleg Nesterov 471d53d9bc0SPeter Zijlstra t->virtual_dr6 = 0; 472f7da04c9SOleg Nesterov t->ptrace_dr7 = 0; 47324f1e32cSFrederic Weisbecker } 47424f1e32cSFrederic Weisbecker 47524f1e32cSFrederic Weisbecker void hw_breakpoint_restore(void) 47624f1e32cSFrederic Weisbecker { 4770a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); 4780a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); 4790a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); 4800a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); 481f4956cf8SPeter Zijlstra set_debugreg(DR6_RESERVED, 6); 4820a3aee0dSTejun Heo set_debugreg(__this_cpu_read(cpu_dr7), 7); 48324f1e32cSFrederic Weisbecker } 48424f1e32cSFrederic Weisbecker EXPORT_SYMBOL_GPL(hw_breakpoint_restore); 4850067f129SK.Prasad 4860067f129SK.Prasad /* 4870067f129SK.Prasad * Handle debug exception notifications. 4880067f129SK.Prasad * 4890067f129SK.Prasad * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below. 4900067f129SK.Prasad * 4910067f129SK.Prasad * NOTIFY_DONE returned if one of the following conditions is true. 4920067f129SK.Prasad * i) When the causative address is from user-space and the exception 4930067f129SK.Prasad * is a valid one, i.e. not triggered as a result of lazy debug register 4940067f129SK.Prasad * switching 4950067f129SK.Prasad * ii) When there are more bits than trap<n> set in DR6 register (such 4960067f129SK.Prasad * as BD, BS or BT) indicating that more than one debug condition is 4970067f129SK.Prasad * met and requires some more action in do_debug(). 4980067f129SK.Prasad * 4990067f129SK.Prasad * NOTIFY_STOP returned for all other cases 5000067f129SK.Prasad * 5010067f129SK.Prasad */ 5029c54b616SMasami Hiramatsu static int hw_breakpoint_handler(struct die_args *args) 5030067f129SK.Prasad { 50421d44be7SPeter Zijlstra int i, rc = NOTIFY_STOP; 50524f1e32cSFrederic Weisbecker struct perf_event *bp; 50662edab90SK.Prasad unsigned long *dr6_p; 507d53d9bc0SPeter Zijlstra unsigned long dr6; 5089ad22e16SPeter Zijlstra bool bpx; 50962edab90SK.Prasad 51062edab90SK.Prasad /* The DR6 value is pointed by args->err */ 51162edab90SK.Prasad dr6_p = (unsigned long *)ERR_PTR(args->err); 51262edab90SK.Prasad dr6 = *dr6_p; 5130067f129SK.Prasad 5140067f129SK.Prasad /* Do an early return if no trap bits are set in DR6 */ 5150067f129SK.Prasad if ((dr6 & DR_TRAP_BITS) == 0) 5160067f129SK.Prasad return NOTIFY_DONE; 5170067f129SK.Prasad 5180067f129SK.Prasad /* Handle all the breakpoints that were triggered */ 5190067f129SK.Prasad for (i = 0; i < HBP_NUM; ++i) { 5200067f129SK.Prasad if (likely(!(dr6 & (DR_TRAP0 << i)))) 5210067f129SK.Prasad continue; 52224f1e32cSFrederic Weisbecker 52321d44be7SPeter Zijlstra bp = this_cpu_read(bp_per_reg[i]); 5249ad22e16SPeter Zijlstra if (!bp) 5259ad22e16SPeter Zijlstra continue; 5269ad22e16SPeter Zijlstra 5279ad22e16SPeter Zijlstra bpx = bp->hw.info.type == X86_BREAKPOINT_EXECUTE; 5289ad22e16SPeter Zijlstra 5299ad22e16SPeter Zijlstra /* 5309ad22e16SPeter Zijlstra * TF and data breakpoints are traps and can be merged, however 5319ad22e16SPeter Zijlstra * instruction breakpoints are faults and will be raised 5329ad22e16SPeter Zijlstra * separately. 5339ad22e16SPeter Zijlstra * 5349ad22e16SPeter Zijlstra * However DR6 can indicate both TF and instruction 5359ad22e16SPeter Zijlstra * breakpoints. In that case take TF as that has precedence and 5369ad22e16SPeter Zijlstra * delay the instruction breakpoint for the next exception. 5379ad22e16SPeter Zijlstra */ 5389ad22e16SPeter Zijlstra if (bpx && (dr6 & DR_STEP)) 5399ad22e16SPeter Zijlstra continue; 5409ad22e16SPeter Zijlstra 5410067f129SK.Prasad /* 54262edab90SK.Prasad * Reset the 'i'th TRAP bit in dr6 to denote completion of 54362edab90SK.Prasad * exception handling 54462edab90SK.Prasad */ 54562edab90SK.Prasad (*dr6_p) &= ~(DR_TRAP0 << i); 5460067f129SK.Prasad 547b326e956SFrederic Weisbecker perf_bp_event(bp, args->regs); 54824f1e32cSFrederic Weisbecker 5490c4519e8SFrederic Weisbecker /* 5500c4519e8SFrederic Weisbecker * Set up resume flag to avoid breakpoint recursion when 5510c4519e8SFrederic Weisbecker * returning back to origin. 5520c4519e8SFrederic Weisbecker */ 5539ad22e16SPeter Zijlstra if (bpx) 5540c4519e8SFrederic Weisbecker args->regs->flags |= X86_EFLAGS_RF; 5550067f129SK.Prasad } 5569ad22e16SPeter Zijlstra 557e0e53db6SK.Prasad /* 558e0e53db6SK.Prasad * Further processing in do_debug() is needed for a) user-space 559e0e53db6SK.Prasad * breakpoints (to generate signals) and b) when the system has 560e0e53db6SK.Prasad * taken exception due to multiple causes 561e0e53db6SK.Prasad */ 562d53d9bc0SPeter Zijlstra if ((current->thread.virtual_dr6 & DR_TRAP_BITS) || 563e0e53db6SK.Prasad (dr6 & (~DR_TRAP_BITS))) 5640067f129SK.Prasad rc = NOTIFY_DONE; 5650067f129SK.Prasad 5660067f129SK.Prasad return rc; 5670067f129SK.Prasad } 5680067f129SK.Prasad 5690067f129SK.Prasad /* 5700067f129SK.Prasad * Handle debug exception notifications. 5710067f129SK.Prasad */ 5729c54b616SMasami Hiramatsu int hw_breakpoint_exceptions_notify( 5730067f129SK.Prasad struct notifier_block *unused, unsigned long val, void *data) 5740067f129SK.Prasad { 5750067f129SK.Prasad if (val != DIE_DEBUG) 5760067f129SK.Prasad return NOTIFY_DONE; 5770067f129SK.Prasad 5780067f129SK.Prasad return hw_breakpoint_handler(data); 5790067f129SK.Prasad } 58024f1e32cSFrederic Weisbecker 58124f1e32cSFrederic Weisbecker void hw_breakpoint_pmu_read(struct perf_event *bp) 58224f1e32cSFrederic Weisbecker { 58324f1e32cSFrederic Weisbecker /* TODO */ 58424f1e32cSFrederic Weisbecker } 585