1 // SPDX-License-Identifier: GPL-2.0-or-later
14  * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
42 /* Per cpu debug address registers values */
46  * Stores the breakpoints currently in use on each breakpoint address
90  * We seek a free debug address register and use it for this
93  * Atomic: we hold the counter->ctx->lock and we only handle variables
94  * and registers local to this cpu.
114 		return -EBUSY;  in arch_install_hw_breakpoint()
116 	set_debugreg(info->address, i);  in arch_install_hw_breakpoint()
117 	__this_cpu_write(cpu_debugreg[i], info->address);  in arch_install_hw_breakpoint()
120 	*dr7 |= encode_dr7(i, info->len, info->type);  in arch_install_hw_breakpoint()
129 	if (info->mask)  in arch_install_hw_breakpoint()
130 		amd_set_dr_addr_mask(info->mask, i);  in arch_install_hw_breakpoint()
138  * First we search the debug address register it uses and then we disable
141  * Atomic: we hold the counter->ctx->lock and we only handle variables
142  * and registers local to this cpu.
165 	dr7 &= ~__encode_dr7(i, info->len, info->type);  in arch_uninstall_hw_breakpoint()
168 	if (info->mask)  in arch_uninstall_hw_breakpoint()
194 		return -EINVAL;  in arch_bp_generic_len()
207 			return -EINVAL;  in arch_bp_generic_fields()
219 		return -EINVAL;  in arch_bp_generic_fields()
225 		return -EINVAL;  in arch_bp_generic_fields()
232  * Check for virtual address in kernel space.
239 	va = hw->address;  in arch_check_bp_in_kernelspace()
240 	len = arch_bp_generic_len(hw->len);  in arch_check_bp_in_kernelspace()
244 	 * We don't need to worry about va + len - 1 overflowing:  in arch_check_bp_in_kernelspace()
247 	return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX);  in arch_check_bp_in_kernelspace()
273 	 * When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU  in within_cpu_entry()
313 		 * will read per-cpu cpu_dr7 before clear dr7 register.  in within_cpu_entry()
329 	bp_end = attr->bp_addr + attr->bp_len - 1;  in arch_build_bp_info()
330 	if (bp_end < attr->bp_addr)  in arch_build_bp_info()
331 		return -EINVAL;  in arch_build_bp_info()
339 	if (within_cpu_entry(attr->bp_addr, bp_end))  in arch_build_bp_info()
340 		return -EINVAL;  in arch_build_bp_info()
342 	hw->address = attr->bp_addr;  in arch_build_bp_info()
343 	hw->mask = 0;  in arch_build_bp_info()
346 	switch (attr->bp_type) {  in arch_build_bp_info()
348 		hw->type = X86_BREAKPOINT_WRITE;  in arch_build_bp_info()
351 		hw->type = X86_BREAKPOINT_RW;  in arch_build_bp_info()
356 		 * acceptable for kprobes.  On non-kprobes kernels, we don't  in arch_build_bp_info()
359 		if (attr->bp_addr >= TASK_SIZE_MAX) {  in arch_build_bp_info()
360 			if (within_kprobe_blacklist(attr->bp_addr))  in arch_build_bp_info()
361 				return -EINVAL;  in arch_build_bp_info()
364 		hw->type = X86_BREAKPOINT_EXECUTE;  in arch_build_bp_info()
370 		if (attr->bp_len == sizeof(long)) {  in arch_build_bp_info()
371 			hw->len = X86_BREAKPOINT_LEN_X;  in arch_build_bp_info()
376 		return -EINVAL;  in arch_build_bp_info()
380 	switch (attr->bp_len) {  in arch_build_bp_info()
382 		hw->len = X86_BREAKPOINT_LEN_1;  in arch_build_bp_info()
385 		hw->len = X86_BREAKPOINT_LEN_2;  in arch_build_bp_info()
388 		hw->len = X86_BREAKPOINT_LEN_4;  in arch_build_bp_info()
392 		hw->len = X86_BREAKPOINT_LEN_8;  in arch_build_bp_info()
397 		if (!is_power_of_2(attr->bp_len))  in arch_build_bp_info()
398 			return -EINVAL;  in arch_build_bp_info()
399 		if (attr->bp_addr & (attr->bp_len - 1))  in arch_build_bp_info()
400 			return -EINVAL;  in arch_build_bp_info()
403 			return -EOPNOTSUPP;  in arch_build_bp_info()
407 		 * user vs kernel detection because bp_len - 1 can't  in arch_build_bp_info()
409 		 * breakpoints, then we'll have to check for kprobe-blacklisted  in arch_build_bp_info()
412 		hw->mask = attr->bp_len - 1;  in arch_build_bp_info()
413 		hw->len = X86_BREAKPOINT_LEN_1;  in arch_build_bp_info()
420  * Validate the arch-specific HW Breakpoint register settings
434 	switch (hw->len) {  in hw_breakpoint_arch_parse()
437 		if (hw->mask)  in hw_breakpoint_arch_parse()
438 			align = hw->mask;  in hw_breakpoint_arch_parse()
453 		return -EINVAL;  in hw_breakpoint_arch_parse()
457 	 * Check that the low-order bits of the address are appropriate  in hw_breakpoint_arch_parse()
460 	if (hw->address & align)  in hw_breakpoint_arch_parse()
461 		return -EINVAL;  in hw_breakpoint_arch_parse()
472 	struct thread_struct *t = &tsk->thread;  in flush_ptrace_hw_breakpoint()
475 		unregister_hw_breakpoint(t->ptrace_bps[i]);  in flush_ptrace_hw_breakpoint()
476 		t->ptrace_bps[i] = NULL;  in flush_ptrace_hw_breakpoint()
479 	t->virtual_dr6 = 0;  in flush_ptrace_hw_breakpoint()
480 	t->ptrace_dr7 = 0;  in flush_ptrace_hw_breakpoint()
500  * i) When the causative address is from user-space and the exception
504  * as BD, BS or BT) indicating that more than one debug condition is
518 	/* The DR6 value is pointed by args->err */  in hw_breakpoint_handler()
519 	dr6_p = (unsigned long *)ERR_PTR(args->err);  in hw_breakpoint_handler()
535 		bpx = bp->hw.info.type == X86_BREAKPOINT_EXECUTE;  in hw_breakpoint_handler()
555 		perf_bp_event(bp, args->regs);  in hw_breakpoint_handler()
562 			args->regs->flags |= X86_EFLAGS_RF;  in hw_breakpoint_handler()
566 	 * Further processing in do_debug() is needed for a) user-space  in hw_breakpoint_handler()
570 	if ((current->thread.virtual_dr6 & DR_TRAP_BITS) ||  in hw_breakpoint_handler()