Thomas Gleixner | caab277 | 2019-06-03 07:44:50 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 2 | /* |
| 3 | * ARMv8 single-step debug support and mdscr context switching. |
| 4 | * |
| 5 | * Copyright (C) 2012 ARM Limited |
| 6 | * |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 7 | * Author: Will Deacon <will.deacon@arm.com> |
| 8 | */ |
| 9 | |
| 10 | #include <linux/cpu.h> |
| 11 | #include <linux/debugfs.h> |
| 12 | #include <linux/hardirq.h> |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/ptrace.h> |
Sandeepa Prabhu | 2dd0e8d | 2016-07-08 12:35:48 -0400 | [diff] [blame] | 15 | #include <linux/kprobes.h> |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 16 | #include <linux/stat.h> |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 17 | #include <linux/uaccess.h> |
Ingo Molnar | 68db0cf | 2017-02-08 18:51:37 +0100 | [diff] [blame] | 18 | #include <linux/sched/task_stack.h> |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 19 | |
Suzuki K. Poulose | 3085bb0 | 2015-10-19 14:24:54 +0100 | [diff] [blame] | 20 | #include <asm/cpufeature.h> |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 21 | #include <asm/cputype.h> |
James Morse | 65be7a1 | 2017-11-02 12:12:35 +0000 | [diff] [blame] | 22 | #include <asm/daifflags.h> |
Suzuki K. Poulose | 3085bb0 | 2015-10-19 14:24:54 +0100 | [diff] [blame] | 23 | #include <asm/debug-monitors.h> |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 24 | #include <asm/system_misc.h> |
Will Deacon | 4e829b6 | 2018-02-20 15:18:13 +0000 | [diff] [blame] | 25 | #include <asm/traps.h> |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 26 | |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 27 | /* Determine debug architecture. */ |
| 28 | u8 debug_monitors_arch(void) |
| 29 | { |
Dave Martin | 46823dd | 2017-03-23 15:14:39 +0000 | [diff] [blame] | 30 | return cpuid_feature_extract_unsigned_field(read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1), |
Suzuki K. Poulose | 3085bb0 | 2015-10-19 14:24:54 +0100 | [diff] [blame] | 31 | ID_AA64DFR0_DEBUGVER_SHIFT); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 32 | } |
| 33 | |
| 34 | /* |
| 35 | * MDSCR access routines. |
| 36 | */ |
| 37 | static void mdscr_write(u32 mdscr) |
| 38 | { |
| 39 | unsigned long flags; |
James Morse | 65be7a1 | 2017-11-02 12:12:35 +0000 | [diff] [blame] | 40 | flags = local_daif_save(); |
Mark Rutland | adf7589 | 2016-09-08 13:55:38 +0100 | [diff] [blame] | 41 | write_sysreg(mdscr, mdscr_el1); |
James Morse | 65be7a1 | 2017-11-02 12:12:35 +0000 | [diff] [blame] | 42 | local_daif_restore(flags); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 43 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 44 | NOKPROBE_SYMBOL(mdscr_write); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 45 | |
| 46 | static u32 mdscr_read(void) |
| 47 | { |
Mark Rutland | adf7589 | 2016-09-08 13:55:38 +0100 | [diff] [blame] | 48 | return read_sysreg(mdscr_el1); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 49 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 50 | NOKPROBE_SYMBOL(mdscr_read); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 51 | |
| 52 | /* |
| 53 | * Allow root to disable self-hosted debug from userspace. |
| 54 | * This is useful if you want to connect an external JTAG debugger. |
| 55 | */ |
Viresh Kumar | 621a5f7 | 2015-09-26 15:04:07 -0700 | [diff] [blame] | 56 | static bool debug_enabled = true; |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 57 | |
| 58 | static int create_debug_debugfs_entry(void) |
| 59 | { |
| 60 | debugfs_create_bool("debug_enabled", 0644, NULL, &debug_enabled); |
| 61 | return 0; |
| 62 | } |
| 63 | fs_initcall(create_debug_debugfs_entry); |
| 64 | |
| 65 | static int __init early_debug_disable(char *buf) |
| 66 | { |
Viresh Kumar | 621a5f7 | 2015-09-26 15:04:07 -0700 | [diff] [blame] | 67 | debug_enabled = false; |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 68 | return 0; |
| 69 | } |
| 70 | |
| 71 | early_param("nodebugmon", early_debug_disable); |
| 72 | |
| 73 | /* |
| 74 | * Keep track of debug users on each core. |
| 75 | * The ref counts are per-cpu so we use a local_t type. |
| 76 | */ |
Christoph Lameter | 1436c1a | 2013-10-21 13:17:08 +0100 | [diff] [blame] | 77 | static DEFINE_PER_CPU(int, mde_ref_count); |
| 78 | static DEFINE_PER_CPU(int, kde_ref_count); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 79 | |
Will Deacon | 6f883d1 | 2015-07-27 18:36:54 +0100 | [diff] [blame] | 80 | void enable_debug_monitors(enum dbg_active_el el) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 81 | { |
| 82 | u32 mdscr, enable = 0; |
| 83 | |
| 84 | WARN_ON(preemptible()); |
| 85 | |
Christoph Lameter | 1436c1a | 2013-10-21 13:17:08 +0100 | [diff] [blame] | 86 | if (this_cpu_inc_return(mde_ref_count) == 1) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 87 | enable = DBG_MDSCR_MDE; |
| 88 | |
| 89 | if (el == DBG_ACTIVE_EL1 && |
Christoph Lameter | 1436c1a | 2013-10-21 13:17:08 +0100 | [diff] [blame] | 90 | this_cpu_inc_return(kde_ref_count) == 1) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 91 | enable |= DBG_MDSCR_KDE; |
| 92 | |
| 93 | if (enable && debug_enabled) { |
| 94 | mdscr = mdscr_read(); |
| 95 | mdscr |= enable; |
| 96 | mdscr_write(mdscr); |
| 97 | } |
| 98 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 99 | NOKPROBE_SYMBOL(enable_debug_monitors); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 100 | |
Will Deacon | 6f883d1 | 2015-07-27 18:36:54 +0100 | [diff] [blame] | 101 | void disable_debug_monitors(enum dbg_active_el el) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 102 | { |
| 103 | u32 mdscr, disable = 0; |
| 104 | |
| 105 | WARN_ON(preemptible()); |
| 106 | |
Christoph Lameter | 1436c1a | 2013-10-21 13:17:08 +0100 | [diff] [blame] | 107 | if (this_cpu_dec_return(mde_ref_count) == 0) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 108 | disable = ~DBG_MDSCR_MDE; |
| 109 | |
| 110 | if (el == DBG_ACTIVE_EL1 && |
Christoph Lameter | 1436c1a | 2013-10-21 13:17:08 +0100 | [diff] [blame] | 111 | this_cpu_dec_return(kde_ref_count) == 0) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 112 | disable &= ~DBG_MDSCR_KDE; |
| 113 | |
| 114 | if (disable) { |
| 115 | mdscr = mdscr_read(); |
| 116 | mdscr &= disable; |
| 117 | mdscr_write(mdscr); |
| 118 | } |
| 119 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 120 | NOKPROBE_SYMBOL(disable_debug_monitors); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 121 | |
| 122 | /* |
| 123 | * OS lock clearing. |
| 124 | */ |
Will Deacon | e937dd5 | 2016-08-16 11:29:17 +0100 | [diff] [blame] | 125 | static int clear_os_lock(unsigned int cpu) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 126 | { |
Jean-Philippe Brucker | 6fda41b | 2019-04-08 18:17:18 +0100 | [diff] [blame] | 127 | write_sysreg(0, osdlr_el1); |
Mark Rutland | adf7589 | 2016-09-08 13:55:38 +0100 | [diff] [blame] | 128 | write_sysreg(0, oslar_el1); |
Will Deacon | e937dd5 | 2016-08-16 11:29:17 +0100 | [diff] [blame] | 129 | isb(); |
| 130 | return 0; |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 131 | } |
| 132 | |
Christophe JAILLET | 5311ebf | 2020-05-31 13:00:15 +0200 | [diff] [blame] | 133 | static int __init debug_monitors_init(void) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 134 | { |
Will Deacon | e937dd5 | 2016-08-16 11:29:17 +0100 | [diff] [blame] | 135 | return cpuhp_setup_state(CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING, |
Thomas Gleixner | 73c1b41 | 2016-12-21 20:19:54 +0100 | [diff] [blame] | 136 | "arm64/debug_monitors:starting", |
Will Deacon | e937dd5 | 2016-08-16 11:29:17 +0100 | [diff] [blame] | 137 | clear_os_lock, NULL); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 138 | } |
| 139 | postcore_initcall(debug_monitors_init); |
| 140 | |
| 141 | /* |
| 142 | * Single step API and exception handling. |
| 143 | */ |
Will Deacon | 3a5a436 | 2020-02-13 12:06:26 +0000 | [diff] [blame] | 144 | static void set_user_regs_spsr_ss(struct user_pt_regs *regs) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 145 | { |
Will Deacon | 6b68e14 | 2016-07-19 15:07:38 +0100 | [diff] [blame] | 146 | regs->pstate |= DBG_SPSR_SS; |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 147 | } |
Will Deacon | 3a5a436 | 2020-02-13 12:06:26 +0000 | [diff] [blame] | 148 | NOKPROBE_SYMBOL(set_user_regs_spsr_ss); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 149 | |
Will Deacon | 3a5a436 | 2020-02-13 12:06:26 +0000 | [diff] [blame] | 150 | static void clear_user_regs_spsr_ss(struct user_pt_regs *regs) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 151 | { |
Will Deacon | 6b68e14 | 2016-07-19 15:07:38 +0100 | [diff] [blame] | 152 | regs->pstate &= ~DBG_SPSR_SS; |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 153 | } |
Will Deacon | 3a5a436 | 2020-02-13 12:06:26 +0000 | [diff] [blame] | 154 | NOKPROBE_SYMBOL(clear_user_regs_spsr_ss); |
| 155 | |
| 156 | #define set_regs_spsr_ss(r) set_user_regs_spsr_ss(&(r)->user_regs) |
| 157 | #define clear_regs_spsr_ss(r) clear_user_regs_spsr_ss(&(r)->user_regs) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 158 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 159 | static DEFINE_SPINLOCK(debug_hook_lock); |
| 160 | static LIST_HEAD(user_step_hook); |
| 161 | static LIST_HEAD(kernel_step_hook); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 162 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 163 | static void register_debug_hook(struct list_head *node, struct list_head *list) |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 164 | { |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 165 | spin_lock(&debug_hook_lock); |
| 166 | list_add_rcu(node, list); |
| 167 | spin_unlock(&debug_hook_lock); |
| 168 | |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 169 | } |
| 170 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 171 | static void unregister_debug_hook(struct list_head *node) |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 172 | { |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 173 | spin_lock(&debug_hook_lock); |
| 174 | list_del_rcu(node); |
| 175 | spin_unlock(&debug_hook_lock); |
Yang Shi | cf0a254 | 2016-02-08 14:49:24 -0800 | [diff] [blame] | 176 | synchronize_rcu(); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 177 | } |
| 178 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 179 | void register_user_step_hook(struct step_hook *hook) |
| 180 | { |
| 181 | register_debug_hook(&hook->node, &user_step_hook); |
| 182 | } |
| 183 | |
| 184 | void unregister_user_step_hook(struct step_hook *hook) |
| 185 | { |
| 186 | unregister_debug_hook(&hook->node); |
| 187 | } |
| 188 | |
| 189 | void register_kernel_step_hook(struct step_hook *hook) |
| 190 | { |
| 191 | register_debug_hook(&hook->node, &kernel_step_hook); |
| 192 | } |
| 193 | |
| 194 | void unregister_kernel_step_hook(struct step_hook *hook) |
| 195 | { |
| 196 | unregister_debug_hook(&hook->node); |
| 197 | } |
| 198 | |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 199 | /* |
Yang Shi | 95485fd | 2015-09-18 22:09:00 +0100 | [diff] [blame] | 200 | * Call registered single step handlers |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 201 | * There is no Syndrome info to check for determining the handler. |
| 202 | * So we call all the registered handlers, until the right handler is |
| 203 | * found which returns zero. |
| 204 | */ |
| 205 | static int call_step_hook(struct pt_regs *regs, unsigned int esr) |
| 206 | { |
| 207 | struct step_hook *hook; |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 208 | struct list_head *list; |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 209 | int retval = DBG_HOOK_ERROR; |
| 210 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 211 | list = user_mode(regs) ? &user_step_hook : &kernel_step_hook; |
| 212 | |
Masami Hiramatsu | 760d8ed | 2019-07-25 17:16:25 +0900 | [diff] [blame] | 213 | /* |
| 214 | * Since single-step exception disables interrupt, this function is |
| 215 | * entirely not preemptible, and we can use rcu list safely here. |
| 216 | */ |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 217 | list_for_each_entry_rcu(hook, list, node) { |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 218 | retval = hook->fn(regs, esr); |
| 219 | if (retval == DBG_HOOK_HANDLED) |
| 220 | break; |
| 221 | } |
| 222 | |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 223 | return retval; |
| 224 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 225 | NOKPROBE_SYMBOL(call_step_hook); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 226 | |
Will Deacon | e04a28d | 2016-02-10 16:05:28 +0000 | [diff] [blame] | 227 | static void send_user_sigtrap(int si_code) |
| 228 | { |
| 229 | struct pt_regs *regs = current_pt_regs(); |
Will Deacon | e04a28d | 2016-02-10 16:05:28 +0000 | [diff] [blame] | 230 | |
| 231 | if (WARN_ON(!user_mode(regs))) |
| 232 | return; |
| 233 | |
| 234 | if (interrupts_enabled(regs)) |
| 235 | local_irq_enable(); |
| 236 | |
Eric W. Biederman | feca355 | 2018-09-22 10:26:57 +0200 | [diff] [blame] | 237 | arm64_force_sig_fault(SIGTRAP, si_code, |
| 238 | (void __user *)instruction_pointer(regs), |
| 239 | "User debug trap"); |
Will Deacon | e04a28d | 2016-02-10 16:05:28 +0000 | [diff] [blame] | 240 | } |
| 241 | |
Will Deacon | 5a9132a | 2019-02-25 12:42:26 +0000 | [diff] [blame] | 242 | static int single_step_handler(unsigned long unused, unsigned int esr, |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 243 | struct pt_regs *regs) |
| 244 | { |
Pratyush Anand | 3fb6964 | 2016-11-02 14:40:43 +0530 | [diff] [blame] | 245 | bool handler_found = false; |
| 246 | |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 247 | /* |
| 248 | * If we are stepping a pending breakpoint, call the hw_breakpoint |
| 249 | * handler first. |
| 250 | */ |
| 251 | if (!reinstall_suspended_bps(regs)) |
| 252 | return 0; |
| 253 | |
Pratyush Anand | 3fb6964 | 2016-11-02 14:40:43 +0530 | [diff] [blame] | 254 | if (!handler_found && call_step_hook(regs, esr) == DBG_HOOK_HANDLED) |
| 255 | handler_found = true; |
| 256 | |
| 257 | if (!handler_found && user_mode(regs)) { |
Will Deacon | adeb68e | 2016-09-01 13:35:02 +0100 | [diff] [blame] | 258 | send_user_sigtrap(TRAP_TRACE); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 259 | |
| 260 | /* |
| 261 | * ptrace will disable single step unless explicitly |
| 262 | * asked to re-enable it. For other clients, it makes |
| 263 | * sense to leave it enabled (i.e. rewind the controls |
| 264 | * to the active-not-pending state). |
| 265 | */ |
| 266 | user_rewind_single_step(current); |
Pratyush Anand | 3fb6964 | 2016-11-02 14:40:43 +0530 | [diff] [blame] | 267 | } else if (!handler_found) { |
| 268 | pr_warn("Unexpected kernel single-step exception at EL1\n"); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 269 | /* |
| 270 | * Re-enable stepping since we know that we will be |
| 271 | * returning to regs. |
| 272 | */ |
| 273 | set_regs_spsr_ss(regs); |
| 274 | } |
| 275 | |
| 276 | return 0; |
| 277 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 278 | NOKPROBE_SYMBOL(single_step_handler); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 279 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 280 | static LIST_HEAD(user_break_hook); |
| 281 | static LIST_HEAD(kernel_break_hook); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 282 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 283 | void register_user_break_hook(struct break_hook *hook) |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 284 | { |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 285 | register_debug_hook(&hook->node, &user_break_hook); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 286 | } |
| 287 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 288 | void unregister_user_break_hook(struct break_hook *hook) |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 289 | { |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 290 | unregister_debug_hook(&hook->node); |
| 291 | } |
| 292 | |
| 293 | void register_kernel_break_hook(struct break_hook *hook) |
| 294 | { |
| 295 | register_debug_hook(&hook->node, &kernel_break_hook); |
| 296 | } |
| 297 | |
| 298 | void unregister_kernel_break_hook(struct break_hook *hook) |
| 299 | { |
| 300 | unregister_debug_hook(&hook->node); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 301 | } |
| 302 | |
| 303 | static int call_break_hook(struct pt_regs *regs, unsigned int esr) |
| 304 | { |
| 305 | struct break_hook *hook; |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 306 | struct list_head *list; |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 307 | int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; |
| 308 | |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 309 | list = user_mode(regs) ? &user_break_hook : &kernel_break_hook; |
| 310 | |
Masami Hiramatsu | 760d8ed | 2019-07-25 17:16:25 +0900 | [diff] [blame] | 311 | /* |
| 312 | * Since brk exception disables interrupt, this function is |
| 313 | * entirely not preemptible, and we can use rcu list safely here. |
| 314 | */ |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 315 | list_for_each_entry_rcu(hook, list, node) { |
Will Deacon | 453b774 | 2019-02-26 15:06:42 +0000 | [diff] [blame] | 316 | unsigned int comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 317 | |
| 318 | if ((comment & ~hook->mask) == hook->imm) |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 319 | fn = hook->fn; |
Will Deacon | 26a04d8 | 2019-02-26 12:52:47 +0000 | [diff] [blame] | 320 | } |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 321 | |
| 322 | return fn ? fn(regs, esr) : DBG_HOOK_ERROR; |
| 323 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 324 | NOKPROBE_SYMBOL(call_break_hook); |
Sandeepa Prabhu | ee6214c | 2013-12-04 05:50:20 +0000 | [diff] [blame] | 325 | |
Will Deacon | 5a9132a | 2019-02-25 12:42:26 +0000 | [diff] [blame] | 326 | static int brk_handler(unsigned long unused, unsigned int esr, |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 327 | struct pt_regs *regs) |
| 328 | { |
Will Deacon | ab6211c | 2019-02-26 15:39:47 +0000 | [diff] [blame] | 329 | if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED) |
| 330 | return 0; |
Pratyush Anand | 53d07e218 | 2016-11-02 14:40:44 +0530 | [diff] [blame] | 331 | |
Will Deacon | ab6211c | 2019-02-26 15:39:47 +0000 | [diff] [blame] | 332 | if (user_mode(regs)) { |
Pratyush Anand | 53d07e218 | 2016-11-02 14:40:44 +0530 | [diff] [blame] | 333 | send_user_sigtrap(TRAP_BRKPT); |
Will Deacon | ab6211c | 2019-02-26 15:39:47 +0000 | [diff] [blame] | 334 | } else { |
Sandeepa Prabhu | 2dd0e8d | 2016-07-08 12:35:48 -0400 | [diff] [blame] | 335 | pr_warn("Unexpected kernel BRK exception at EL1\n"); |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 336 | return -EFAULT; |
Will Deacon | c878e0c | 2014-07-31 11:36:08 +0100 | [diff] [blame] | 337 | } |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 338 | |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 339 | return 0; |
| 340 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 341 | NOKPROBE_SYMBOL(brk_handler); |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 342 | |
| 343 | int aarch32_break_handler(struct pt_regs *regs) |
| 344 | { |
Matthew Leach | 2dacab7 | 2013-11-28 12:07:23 +0000 | [diff] [blame] | 345 | u32 arm_instr; |
| 346 | u16 thumb_instr; |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 347 | bool bp = false; |
| 348 | void __user *pc = (void __user *)instruction_pointer(regs); |
| 349 | |
| 350 | if (!compat_user_mode(regs)) |
| 351 | return -EFAULT; |
| 352 | |
| 353 | if (compat_thumb_mode(regs)) { |
| 354 | /* get 16-bit Thumb instruction */ |
Luc Van Oostenryck | a5018b0 | 2017-06-28 16:55:52 +0200 | [diff] [blame] | 355 | __le16 instr; |
| 356 | get_user(instr, (__le16 __user *)pc); |
| 357 | thumb_instr = le16_to_cpu(instr); |
Matthew Leach | 2dacab7 | 2013-11-28 12:07:23 +0000 | [diff] [blame] | 358 | if (thumb_instr == AARCH32_BREAK_THUMB2_LO) { |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 359 | /* get second half of 32-bit Thumb-2 instruction */ |
Luc Van Oostenryck | a5018b0 | 2017-06-28 16:55:52 +0200 | [diff] [blame] | 360 | get_user(instr, (__le16 __user *)(pc + 2)); |
| 361 | thumb_instr = le16_to_cpu(instr); |
Matthew Leach | 2dacab7 | 2013-11-28 12:07:23 +0000 | [diff] [blame] | 362 | bp = thumb_instr == AARCH32_BREAK_THUMB2_HI; |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 363 | } else { |
Matthew Leach | 2dacab7 | 2013-11-28 12:07:23 +0000 | [diff] [blame] | 364 | bp = thumb_instr == AARCH32_BREAK_THUMB; |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 365 | } |
| 366 | } else { |
| 367 | /* 32-bit ARM instruction */ |
Luc Van Oostenryck | a5018b0 | 2017-06-28 16:55:52 +0200 | [diff] [blame] | 368 | __le32 instr; |
| 369 | get_user(instr, (__le32 __user *)pc); |
| 370 | arm_instr = le32_to_cpu(instr); |
Matthew Leach | 2dacab7 | 2013-11-28 12:07:23 +0000 | [diff] [blame] | 371 | bp = (arm_instr & ~0xf0000000) == AARCH32_BREAK_ARM; |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 372 | } |
| 373 | |
| 374 | if (!bp) |
| 375 | return -EFAULT; |
| 376 | |
Will Deacon | e04a28d | 2016-02-10 16:05:28 +0000 | [diff] [blame] | 377 | send_user_sigtrap(TRAP_BRKPT); |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 378 | return 0; |
| 379 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 380 | NOKPROBE_SYMBOL(aarch32_break_handler); |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 381 | |
Douglas Anderson | b322c65 | 2020-05-13 16:06:37 -0700 | [diff] [blame] | 382 | void __init debug_traps_init(void) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 383 | { |
| 384 | hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP, |
Will Deacon | adeb68e | 2016-09-01 13:35:02 +0100 | [diff] [blame] | 385 | TRAP_TRACE, "single-step handler"); |
Will Deacon | 1442b6e | 2013-03-16 08:48:13 +0000 | [diff] [blame] | 386 | hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP, |
Will Deacon | 0fdb64c | 2020-09-15 15:48:09 +0100 | [diff] [blame] | 387 | TRAP_BRKPT, "BRK handler"); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 388 | } |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 389 | |
| 390 | /* Re-enable single step for syscall restarting. */ |
| 391 | void user_rewind_single_step(struct task_struct *task) |
| 392 | { |
| 393 | /* |
| 394 | * If single step is active for this thread, then set SPSR.SS |
| 395 | * to 1 to avoid returning to the active-pending state. |
| 396 | */ |
Will Deacon | 5afc785 | 2020-02-13 12:12:26 +0000 | [diff] [blame] | 397 | if (test_tsk_thread_flag(task, TIF_SINGLESTEP)) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 398 | set_regs_spsr_ss(task_pt_regs(task)); |
| 399 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 400 | NOKPROBE_SYMBOL(user_rewind_single_step); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 401 | |
| 402 | void user_fastforward_single_step(struct task_struct *task) |
| 403 | { |
Will Deacon | 5afc785 | 2020-02-13 12:12:26 +0000 | [diff] [blame] | 404 | if (test_tsk_thread_flag(task, TIF_SINGLESTEP)) |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 405 | clear_regs_spsr_ss(task_pt_regs(task)); |
| 406 | } |
| 407 | |
Will Deacon | 3a5a436 | 2020-02-13 12:06:26 +0000 | [diff] [blame] | 408 | void user_regs_reset_single_step(struct user_pt_regs *regs, |
| 409 | struct task_struct *task) |
| 410 | { |
| 411 | if (test_tsk_thread_flag(task, TIF_SINGLESTEP)) |
| 412 | set_user_regs_spsr_ss(regs); |
| 413 | else |
| 414 | clear_user_regs_spsr_ss(regs); |
| 415 | } |
| 416 | |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 417 | /* Kernel API */ |
| 418 | void kernel_enable_single_step(struct pt_regs *regs) |
| 419 | { |
| 420 | WARN_ON(!irqs_disabled()); |
| 421 | set_regs_spsr_ss(regs); |
| 422 | mdscr_write(mdscr_read() | DBG_MDSCR_SS); |
| 423 | enable_debug_monitors(DBG_ACTIVE_EL1); |
| 424 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 425 | NOKPROBE_SYMBOL(kernel_enable_single_step); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 426 | |
| 427 | void kernel_disable_single_step(void) |
| 428 | { |
| 429 | WARN_ON(!irqs_disabled()); |
| 430 | mdscr_write(mdscr_read() & ~DBG_MDSCR_SS); |
| 431 | disable_debug_monitors(DBG_ACTIVE_EL1); |
| 432 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 433 | NOKPROBE_SYMBOL(kernel_disable_single_step); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 434 | |
| 435 | int kernel_active_single_step(void) |
| 436 | { |
| 437 | WARN_ON(!irqs_disabled()); |
| 438 | return mdscr_read() & DBG_MDSCR_SS; |
| 439 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 440 | NOKPROBE_SYMBOL(kernel_active_single_step); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 441 | |
| 442 | /* ptrace API */ |
| 443 | void user_enable_single_step(struct task_struct *task) |
| 444 | { |
Will Deacon | 3a402a7 | 2016-08-26 11:36:39 +0100 | [diff] [blame] | 445 | struct thread_info *ti = task_thread_info(task); |
| 446 | |
| 447 | if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP)) |
| 448 | set_regs_spsr_ss(task_pt_regs(task)); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 449 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 450 | NOKPROBE_SYMBOL(user_enable_single_step); |
Will Deacon | 478fcb2 | 2012-03-05 11:49:33 +0000 | [diff] [blame] | 451 | |
| 452 | void user_disable_single_step(struct task_struct *task) |
| 453 | { |
| 454 | clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP); |
| 455 | } |
Pratyush Anand | 44b53f6 | 2016-07-08 12:35:49 -0400 | [diff] [blame] | 456 | NOKPROBE_SYMBOL(user_disable_single_step); |