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1/*
2 * ARMv8 single-step debug support and mdscr context switching.
3 *
4 * Copyright (C) 2012 ARM Limited
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Will Deacon <will.deacon@arm.com>
19 */
20
21#include <linux/cpu.h>
22#include <linux/debugfs.h>
23#include <linux/hardirq.h>
24#include <linux/init.h>
25#include <linux/ptrace.h>
26#include <linux/stat.h>
27#include <linux/uaccess.h>
28
29#include <asm/cpufeature.h>
30#include <asm/cputype.h>
31#include <asm/debug-monitors.h>
32#include <asm/system_misc.h>
33
34/* Determine debug architecture. */
35u8 debug_monitors_arch(void)
36{
37 return cpuid_feature_extract_unsigned_field(read_system_reg(SYS_ID_AA64DFR0_EL1),
38 ID_AA64DFR0_DEBUGVER_SHIFT);
39}
40
41/*
42 * MDSCR access routines.
43 */
44static void mdscr_write(u32 mdscr)
45{
46 unsigned long flags;
47 local_dbg_save(flags);
48 asm volatile("msr mdscr_el1, %0" :: "r" (mdscr));
49 local_dbg_restore(flags);
50}
51
52static u32 mdscr_read(void)
53{
54 u32 mdscr;
55 asm volatile("mrs %0, mdscr_el1" : "=r" (mdscr));
56 return mdscr;
57}
58
59/*
60 * Allow root to disable self-hosted debug from userspace.
61 * This is useful if you want to connect an external JTAG debugger.
62 */
63static bool debug_enabled = true;
64
65static int create_debug_debugfs_entry(void)
66{
67 debugfs_create_bool("debug_enabled", 0644, NULL, &debug_enabled);
68 return 0;
69}
70fs_initcall(create_debug_debugfs_entry);
71
72static int __init early_debug_disable(char *buf)
73{
74 debug_enabled = false;
75 return 0;
76}
77
78early_param("nodebugmon", early_debug_disable);
79
80/*
81 * Keep track of debug users on each core.
82 * The ref counts are per-cpu so we use a local_t type.
83 */
84static DEFINE_PER_CPU(int, mde_ref_count);
85static DEFINE_PER_CPU(int, kde_ref_count);
86
87void enable_debug_monitors(enum dbg_active_el el)
88{
89 u32 mdscr, enable = 0;
90
91 WARN_ON(preemptible());
92
93 if (this_cpu_inc_return(mde_ref_count) == 1)
94 enable = DBG_MDSCR_MDE;
95
96 if (el == DBG_ACTIVE_EL1 &&
97 this_cpu_inc_return(kde_ref_count) == 1)
98 enable |= DBG_MDSCR_KDE;
99
100 if (enable && debug_enabled) {
101 mdscr = mdscr_read();
102 mdscr |= enable;
103 mdscr_write(mdscr);
104 }
105}
106
107void disable_debug_monitors(enum dbg_active_el el)
108{
109 u32 mdscr, disable = 0;
110
111 WARN_ON(preemptible());
112
113 if (this_cpu_dec_return(mde_ref_count) == 0)
114 disable = ~DBG_MDSCR_MDE;
115
116 if (el == DBG_ACTIVE_EL1 &&
117 this_cpu_dec_return(kde_ref_count) == 0)
118 disable &= ~DBG_MDSCR_KDE;
119
120 if (disable) {
121 mdscr = mdscr_read();
122 mdscr &= disable;
123 mdscr_write(mdscr);
124 }
125}
126
127/*
128 * OS lock clearing.
129 */
130static void clear_os_lock(void *unused)
131{
132 asm volatile("msr oslar_el1, %0" : : "r" (0));
133}
134
135static int os_lock_notify(struct notifier_block *self,
136 unsigned long action, void *data)
137{
138 int cpu = (unsigned long)data;
139 if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
140 smp_call_function_single(cpu, clear_os_lock, NULL, 1);
141 return NOTIFY_OK;
142}
143
144static struct notifier_block os_lock_nb = {
145 .notifier_call = os_lock_notify,
146};
147
148static int debug_monitors_init(void)
149{
150 cpu_notifier_register_begin();
151
152 /* Clear the OS lock. */
153 on_each_cpu(clear_os_lock, NULL, 1);
154 isb();
155 local_dbg_enable();
156
157 /* Register hotplug handler. */
158 __register_cpu_notifier(&os_lock_nb);
159
160 cpu_notifier_register_done();
161 return 0;
162}
163postcore_initcall(debug_monitors_init);
164
165/*
166 * Single step API and exception handling.
167 */
168static void set_regs_spsr_ss(struct pt_regs *regs)
169{
170 unsigned long spsr;
171
172 spsr = regs->pstate;
173 spsr &= ~DBG_SPSR_SS;
174 spsr |= DBG_SPSR_SS;
175 regs->pstate = spsr;
176}
177
178static void clear_regs_spsr_ss(struct pt_regs *regs)
179{
180 unsigned long spsr;
181
182 spsr = regs->pstate;
183 spsr &= ~DBG_SPSR_SS;
184 regs->pstate = spsr;
185}
186
187/* EL1 Single Step Handler hooks */
188static LIST_HEAD(step_hook);
189static DEFINE_SPINLOCK(step_hook_lock);
190
191void register_step_hook(struct step_hook *hook)
192{
193 spin_lock(&step_hook_lock);
194 list_add_rcu(&hook->node, &step_hook);
195 spin_unlock(&step_hook_lock);
196}
197
198void unregister_step_hook(struct step_hook *hook)
199{
200 spin_lock(&step_hook_lock);
201 list_del_rcu(&hook->node);
202 spin_unlock(&step_hook_lock);
203 synchronize_rcu();
204}
205
206/*
207 * Call registered single step handlers
208 * There is no Syndrome info to check for determining the handler.
209 * So we call all the registered handlers, until the right handler is
210 * found which returns zero.
211 */
212static int call_step_hook(struct pt_regs *regs, unsigned int esr)
213{
214 struct step_hook *hook;
215 int retval = DBG_HOOK_ERROR;
216
217 rcu_read_lock();
218
219 list_for_each_entry_rcu(hook, &step_hook, node) {
220 retval = hook->fn(regs, esr);
221 if (retval == DBG_HOOK_HANDLED)
222 break;
223 }
224
225 rcu_read_unlock();
226
227 return retval;
228}
229
230static void send_user_sigtrap(int si_code)
231{
232 struct pt_regs *regs = current_pt_regs();
233 siginfo_t info = {
234 .si_signo = SIGTRAP,
235 .si_errno = 0,
236 .si_code = si_code,
237 .si_addr = (void __user *)instruction_pointer(regs),
238 };
239
240 if (WARN_ON(!user_mode(regs)))
241 return;
242
243 if (interrupts_enabled(regs))
244 local_irq_enable();
245
246 force_sig_info(SIGTRAP, &info, current);
247}
248
249static int single_step_handler(unsigned long addr, unsigned int esr,
250 struct pt_regs *regs)
251{
252 /*
253 * If we are stepping a pending breakpoint, call the hw_breakpoint
254 * handler first.
255 */
256 if (!reinstall_suspended_bps(regs))
257 return 0;
258
259 if (user_mode(regs)) {
260 send_user_sigtrap(TRAP_HWBKPT);
261
262 /*
263 * ptrace will disable single step unless explicitly
264 * asked to re-enable it. For other clients, it makes
265 * sense to leave it enabled (i.e. rewind the controls
266 * to the active-not-pending state).
267 */
268 user_rewind_single_step(current);
269 } else {
270 if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
271 return 0;
272
273 pr_warning("Unexpected kernel single-step exception at EL1\n");
274 /*
275 * Re-enable stepping since we know that we will be
276 * returning to regs.
277 */
278 set_regs_spsr_ss(regs);
279 }
280
281 return 0;
282}
283
284/*
285 * Breakpoint handler is re-entrant as another breakpoint can
286 * hit within breakpoint handler, especically in kprobes.
287 * Use reader/writer locks instead of plain spinlock.
288 */
289static LIST_HEAD(break_hook);
290static DEFINE_SPINLOCK(break_hook_lock);
291
292void register_break_hook(struct break_hook *hook)
293{
294 spin_lock(&break_hook_lock);
295 list_add_rcu(&hook->node, &break_hook);
296 spin_unlock(&break_hook_lock);
297}
298
299void unregister_break_hook(struct break_hook *hook)
300{
301 spin_lock(&break_hook_lock);
302 list_del_rcu(&hook->node);
303 spin_unlock(&break_hook_lock);
304 synchronize_rcu();
305}
306
307static int call_break_hook(struct pt_regs *regs, unsigned int esr)
308{
309 struct break_hook *hook;
310 int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL;
311
312 rcu_read_lock();
313 list_for_each_entry_rcu(hook, &break_hook, node)
314 if ((esr & hook->esr_mask) == hook->esr_val)
315 fn = hook->fn;
316 rcu_read_unlock();
317
318 return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
319}
320
321static int brk_handler(unsigned long addr, unsigned int esr,
322 struct pt_regs *regs)
323{
324 if (user_mode(regs)) {
325 send_user_sigtrap(TRAP_BRKPT);
326 } else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) {
327 pr_warning("Unexpected kernel BRK exception at EL1\n");
328 return -EFAULT;
329 }
330
331 return 0;
332}
333
334int aarch32_break_handler(struct pt_regs *regs)
335{
336 u32 arm_instr;
337 u16 thumb_instr;
338 bool bp = false;
339 void __user *pc = (void __user *)instruction_pointer(regs);
340
341 if (!compat_user_mode(regs))
342 return -EFAULT;
343
344 if (compat_thumb_mode(regs)) {
345 /* get 16-bit Thumb instruction */
346 get_user(thumb_instr, (u16 __user *)pc);
347 thumb_instr = le16_to_cpu(thumb_instr);
348 if (thumb_instr == AARCH32_BREAK_THUMB2_LO) {
349 /* get second half of 32-bit Thumb-2 instruction */
350 get_user(thumb_instr, (u16 __user *)(pc + 2));
351 thumb_instr = le16_to_cpu(thumb_instr);
352 bp = thumb_instr == AARCH32_BREAK_THUMB2_HI;
353 } else {
354 bp = thumb_instr == AARCH32_BREAK_THUMB;
355 }
356 } else {
357 /* 32-bit ARM instruction */
358 get_user(arm_instr, (u32 __user *)pc);
359 arm_instr = le32_to_cpu(arm_instr);
360 bp = (arm_instr & ~0xf0000000) == AARCH32_BREAK_ARM;
361 }
362
363 if (!bp)
364 return -EFAULT;
365
366 send_user_sigtrap(TRAP_BRKPT);
367 return 0;
368}
369
370static int __init debug_traps_init(void)
371{
372 hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP,
373 TRAP_HWBKPT, "single-step handler");
374 hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP,
375 TRAP_BRKPT, "ptrace BRK handler");
376 return 0;
377}
378arch_initcall(debug_traps_init);
379
380/* Re-enable single step for syscall restarting. */
381void user_rewind_single_step(struct task_struct *task)
382{
383 /*
384 * If single step is active for this thread, then set SPSR.SS
385 * to 1 to avoid returning to the active-pending state.
386 */
387 if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP))
388 set_regs_spsr_ss(task_pt_regs(task));
389}
390
391void user_fastforward_single_step(struct task_struct *task)
392{
393 if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP))
394 clear_regs_spsr_ss(task_pt_regs(task));
395}
396
397/* Kernel API */
398void kernel_enable_single_step(struct pt_regs *regs)
399{
400 WARN_ON(!irqs_disabled());
401 set_regs_spsr_ss(regs);
402 mdscr_write(mdscr_read() | DBG_MDSCR_SS);
403 enable_debug_monitors(DBG_ACTIVE_EL1);
404}
405
406void kernel_disable_single_step(void)
407{
408 WARN_ON(!irqs_disabled());
409 mdscr_write(mdscr_read() & ~DBG_MDSCR_SS);
410 disable_debug_monitors(DBG_ACTIVE_EL1);
411}
412
413int kernel_active_single_step(void)
414{
415 WARN_ON(!irqs_disabled());
416 return mdscr_read() & DBG_MDSCR_SS;
417}
418
419/* ptrace API */
420void user_enable_single_step(struct task_struct *task)
421{
422 set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
423 set_regs_spsr_ss(task_pt_regs(task));
424}
425
426void user_disable_single_step(struct task_struct *task)
427{
428 clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
429}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ARMv8 single-step debug support and mdscr context switching.
4 *
5 * Copyright (C) 2012 ARM Limited
6 *
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>
15#include <linux/kprobes.h>
16#include <linux/stat.h>
17#include <linux/uaccess.h>
18#include <linux/sched/task_stack.h>
19
20#include <asm/cpufeature.h>
21#include <asm/cputype.h>
22#include <asm/daifflags.h>
23#include <asm/debug-monitors.h>
24#include <asm/system_misc.h>
25#include <asm/traps.h>
26
27/* Determine debug architecture. */
28u8 debug_monitors_arch(void)
29{
30 return cpuid_feature_extract_unsigned_field(read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1),
31 ID_AA64DFR0_EL1_DebugVer_SHIFT);
32}
33
34/*
35 * MDSCR access routines.
36 */
37static void mdscr_write(u32 mdscr)
38{
39 unsigned long flags;
40 flags = local_daif_save();
41 write_sysreg(mdscr, mdscr_el1);
42 local_daif_restore(flags);
43}
44NOKPROBE_SYMBOL(mdscr_write);
45
46static u32 mdscr_read(void)
47{
48 return read_sysreg(mdscr_el1);
49}
50NOKPROBE_SYMBOL(mdscr_read);
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 */
56static bool debug_enabled = true;
57
58static int create_debug_debugfs_entry(void)
59{
60 debugfs_create_bool("debug_enabled", 0644, NULL, &debug_enabled);
61 return 0;
62}
63fs_initcall(create_debug_debugfs_entry);
64
65static int __init early_debug_disable(char *buf)
66{
67 debug_enabled = false;
68 return 0;
69}
70
71early_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 */
77static DEFINE_PER_CPU(int, mde_ref_count);
78static DEFINE_PER_CPU(int, kde_ref_count);
79
80void enable_debug_monitors(enum dbg_active_el el)
81{
82 u32 mdscr, enable = 0;
83
84 WARN_ON(preemptible());
85
86 if (this_cpu_inc_return(mde_ref_count) == 1)
87 enable = DBG_MDSCR_MDE;
88
89 if (el == DBG_ACTIVE_EL1 &&
90 this_cpu_inc_return(kde_ref_count) == 1)
91 enable |= DBG_MDSCR_KDE;
92
93 if (enable && debug_enabled) {
94 mdscr = mdscr_read();
95 mdscr |= enable;
96 mdscr_write(mdscr);
97 }
98}
99NOKPROBE_SYMBOL(enable_debug_monitors);
100
101void disable_debug_monitors(enum dbg_active_el el)
102{
103 u32 mdscr, disable = 0;
104
105 WARN_ON(preemptible());
106
107 if (this_cpu_dec_return(mde_ref_count) == 0)
108 disable = ~DBG_MDSCR_MDE;
109
110 if (el == DBG_ACTIVE_EL1 &&
111 this_cpu_dec_return(kde_ref_count) == 0)
112 disable &= ~DBG_MDSCR_KDE;
113
114 if (disable) {
115 mdscr = mdscr_read();
116 mdscr &= disable;
117 mdscr_write(mdscr);
118 }
119}
120NOKPROBE_SYMBOL(disable_debug_monitors);
121
122/*
123 * OS lock clearing.
124 */
125static int clear_os_lock(unsigned int cpu)
126{
127 write_sysreg(0, osdlr_el1);
128 write_sysreg(0, oslar_el1);
129 isb();
130 return 0;
131}
132
133static int __init debug_monitors_init(void)
134{
135 return cpuhp_setup_state(CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING,
136 "arm64/debug_monitors:starting",
137 clear_os_lock, NULL);
138}
139postcore_initcall(debug_monitors_init);
140
141/*
142 * Single step API and exception handling.
143 */
144static void set_user_regs_spsr_ss(struct user_pt_regs *regs)
145{
146 regs->pstate |= DBG_SPSR_SS;
147}
148NOKPROBE_SYMBOL(set_user_regs_spsr_ss);
149
150static void clear_user_regs_spsr_ss(struct user_pt_regs *regs)
151{
152 regs->pstate &= ~DBG_SPSR_SS;
153}
154NOKPROBE_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)
158
159static DEFINE_SPINLOCK(debug_hook_lock);
160static LIST_HEAD(user_step_hook);
161static LIST_HEAD(kernel_step_hook);
162
163static void register_debug_hook(struct list_head *node, struct list_head *list)
164{
165 spin_lock(&debug_hook_lock);
166 list_add_rcu(node, list);
167 spin_unlock(&debug_hook_lock);
168
169}
170
171static void unregister_debug_hook(struct list_head *node)
172{
173 spin_lock(&debug_hook_lock);
174 list_del_rcu(node);
175 spin_unlock(&debug_hook_lock);
176 synchronize_rcu();
177}
178
179void register_user_step_hook(struct step_hook *hook)
180{
181 register_debug_hook(&hook->node, &user_step_hook);
182}
183
184void unregister_user_step_hook(struct step_hook *hook)
185{
186 unregister_debug_hook(&hook->node);
187}
188
189void register_kernel_step_hook(struct step_hook *hook)
190{
191 register_debug_hook(&hook->node, &kernel_step_hook);
192}
193
194void unregister_kernel_step_hook(struct step_hook *hook)
195{
196 unregister_debug_hook(&hook->node);
197}
198
199/*
200 * Call registered single step handlers
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 */
205static int call_step_hook(struct pt_regs *regs, unsigned long esr)
206{
207 struct step_hook *hook;
208 struct list_head *list;
209 int retval = DBG_HOOK_ERROR;
210
211 list = user_mode(regs) ? &user_step_hook : &kernel_step_hook;
212
213 /*
214 * Since single-step exception disables interrupt, this function is
215 * entirely not preemptible, and we can use rcu list safely here.
216 */
217 list_for_each_entry_rcu(hook, list, node) {
218 retval = hook->fn(regs, esr);
219 if (retval == DBG_HOOK_HANDLED)
220 break;
221 }
222
223 return retval;
224}
225NOKPROBE_SYMBOL(call_step_hook);
226
227static void send_user_sigtrap(int si_code)
228{
229 struct pt_regs *regs = current_pt_regs();
230
231 if (WARN_ON(!user_mode(regs)))
232 return;
233
234 if (interrupts_enabled(regs))
235 local_irq_enable();
236
237 arm64_force_sig_fault(SIGTRAP, si_code, instruction_pointer(regs),
238 "User debug trap");
239}
240
241static int single_step_handler(unsigned long unused, unsigned long esr,
242 struct pt_regs *regs)
243{
244 bool handler_found = false;
245
246 /*
247 * If we are stepping a pending breakpoint, call the hw_breakpoint
248 * handler first.
249 */
250 if (!reinstall_suspended_bps(regs))
251 return 0;
252
253 if (!handler_found && call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
254 handler_found = true;
255
256 if (!handler_found && user_mode(regs)) {
257 send_user_sigtrap(TRAP_TRACE);
258
259 /*
260 * ptrace will disable single step unless explicitly
261 * asked to re-enable it. For other clients, it makes
262 * sense to leave it enabled (i.e. rewind the controls
263 * to the active-not-pending state).
264 */
265 user_rewind_single_step(current);
266 } else if (!handler_found) {
267 pr_warn("Unexpected kernel single-step exception at EL1\n");
268 /*
269 * Re-enable stepping since we know that we will be
270 * returning to regs.
271 */
272 set_regs_spsr_ss(regs);
273 }
274
275 return 0;
276}
277NOKPROBE_SYMBOL(single_step_handler);
278
279static LIST_HEAD(user_break_hook);
280static LIST_HEAD(kernel_break_hook);
281
282void register_user_break_hook(struct break_hook *hook)
283{
284 register_debug_hook(&hook->node, &user_break_hook);
285}
286
287void unregister_user_break_hook(struct break_hook *hook)
288{
289 unregister_debug_hook(&hook->node);
290}
291
292void register_kernel_break_hook(struct break_hook *hook)
293{
294 register_debug_hook(&hook->node, &kernel_break_hook);
295}
296
297void unregister_kernel_break_hook(struct break_hook *hook)
298{
299 unregister_debug_hook(&hook->node);
300}
301
302static int call_break_hook(struct pt_regs *regs, unsigned long esr)
303{
304 struct break_hook *hook;
305 struct list_head *list;
306
307 list = user_mode(regs) ? &user_break_hook : &kernel_break_hook;
308
309 /*
310 * Since brk exception disables interrupt, this function is
311 * entirely not preemptible, and we can use rcu list safely here.
312 */
313 list_for_each_entry_rcu(hook, list, node) {
314 if ((esr_brk_comment(esr) & ~hook->mask) == hook->imm)
315 return hook->fn(regs, esr);
316 }
317
318 return DBG_HOOK_ERROR;
319}
320NOKPROBE_SYMBOL(call_break_hook);
321
322static int brk_handler(unsigned long unused, unsigned long esr,
323 struct pt_regs *regs)
324{
325 if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED)
326 return 0;
327
328 if (user_mode(regs)) {
329 send_user_sigtrap(TRAP_BRKPT);
330 } else {
331 pr_warn("Unexpected kernel BRK exception at EL1\n");
332 return -EFAULT;
333 }
334
335 return 0;
336}
337NOKPROBE_SYMBOL(brk_handler);
338
339int aarch32_break_handler(struct pt_regs *regs)
340{
341 u32 arm_instr;
342 u16 thumb_instr;
343 bool bp = false;
344 void __user *pc = (void __user *)instruction_pointer(regs);
345
346 if (!compat_user_mode(regs))
347 return -EFAULT;
348
349 if (compat_thumb_mode(regs)) {
350 /* get 16-bit Thumb instruction */
351 __le16 instr;
352 get_user(instr, (__le16 __user *)pc);
353 thumb_instr = le16_to_cpu(instr);
354 if (thumb_instr == AARCH32_BREAK_THUMB2_LO) {
355 /* get second half of 32-bit Thumb-2 instruction */
356 get_user(instr, (__le16 __user *)(pc + 2));
357 thumb_instr = le16_to_cpu(instr);
358 bp = thumb_instr == AARCH32_BREAK_THUMB2_HI;
359 } else {
360 bp = thumb_instr == AARCH32_BREAK_THUMB;
361 }
362 } else {
363 /* 32-bit ARM instruction */
364 __le32 instr;
365 get_user(instr, (__le32 __user *)pc);
366 arm_instr = le32_to_cpu(instr);
367 bp = (arm_instr & ~0xf0000000) == AARCH32_BREAK_ARM;
368 }
369
370 if (!bp)
371 return -EFAULT;
372
373 send_user_sigtrap(TRAP_BRKPT);
374 return 0;
375}
376NOKPROBE_SYMBOL(aarch32_break_handler);
377
378void __init debug_traps_init(void)
379{
380 hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP,
381 TRAP_TRACE, "single-step handler");
382 hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP,
383 TRAP_BRKPT, "BRK handler");
384}
385
386/* Re-enable single step for syscall restarting. */
387void user_rewind_single_step(struct task_struct *task)
388{
389 /*
390 * If single step is active for this thread, then set SPSR.SS
391 * to 1 to avoid returning to the active-pending state.
392 */
393 if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
394 set_regs_spsr_ss(task_pt_regs(task));
395}
396NOKPROBE_SYMBOL(user_rewind_single_step);
397
398void user_fastforward_single_step(struct task_struct *task)
399{
400 if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
401 clear_regs_spsr_ss(task_pt_regs(task));
402}
403
404void user_regs_reset_single_step(struct user_pt_regs *regs,
405 struct task_struct *task)
406{
407 if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
408 set_user_regs_spsr_ss(regs);
409 else
410 clear_user_regs_spsr_ss(regs);
411}
412
413/* Kernel API */
414void kernel_enable_single_step(struct pt_regs *regs)
415{
416 WARN_ON(!irqs_disabled());
417 set_regs_spsr_ss(regs);
418 mdscr_write(mdscr_read() | DBG_MDSCR_SS);
419 enable_debug_monitors(DBG_ACTIVE_EL1);
420}
421NOKPROBE_SYMBOL(kernel_enable_single_step);
422
423void kernel_disable_single_step(void)
424{
425 WARN_ON(!irqs_disabled());
426 mdscr_write(mdscr_read() & ~DBG_MDSCR_SS);
427 disable_debug_monitors(DBG_ACTIVE_EL1);
428}
429NOKPROBE_SYMBOL(kernel_disable_single_step);
430
431int kernel_active_single_step(void)
432{
433 WARN_ON(!irqs_disabled());
434 return mdscr_read() & DBG_MDSCR_SS;
435}
436NOKPROBE_SYMBOL(kernel_active_single_step);
437
438void kernel_rewind_single_step(struct pt_regs *regs)
439{
440 set_regs_spsr_ss(regs);
441}
442
443void kernel_fastforward_single_step(struct pt_regs *regs)
444{
445 clear_regs_spsr_ss(regs);
446}
447
448/* ptrace API */
449void user_enable_single_step(struct task_struct *task)
450{
451 struct thread_info *ti = task_thread_info(task);
452
453 if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP))
454 set_regs_spsr_ss(task_pt_regs(task));
455}
456NOKPROBE_SYMBOL(user_enable_single_step);
457
458void user_disable_single_step(struct task_struct *task)
459{
460 clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
461}
462NOKPROBE_SYMBOL(user_disable_single_step);