1 // SPDX-License-Identifier: GPL-2.0
3  * x86 single-step support code, common to 32-bit and 64-bit.
16 	addr = regs->ip;  in convert_ip_to_linear()
17 	seg = regs->cs;  in convert_ip_to_linear()
26 	 * are all zero-based. That is largely true: the  in convert_ip_to_linear()
36 		mutex_lock(&child->mm->context.lock);  in convert_ip_to_linear()
37 		if (unlikely(!child->mm->context.ldt ||  in convert_ip_to_linear()
38 			     seg >= child->mm->context.ldt->nr_entries))  in convert_ip_to_linear()
39 			addr = -1L; /* bogus selector, access would fault */  in convert_ip_to_linear()
41 			desc = &child->mm->context.ldt->entries[seg];  in convert_ip_to_linear()
44 			/* 16-bit code segment? */  in convert_ip_to_linear()
45 			if (!desc->d)  in convert_ip_to_linear()
49 		mutex_unlock(&child->mm->context.lock);  in convert_ip_to_linear()
85 				/* 32-bit mode: register increment */  in is_setting_trap_flag()
87 			/* 64-bit mode: REX prefix */  in is_setting_trap_flag()
95 		 * the user see the TF bit being set. But  in is_setting_trap_flag()
97 		 * it, and a debugger could emulate this  in is_setting_trap_flag()
109  * Enable single-stepping.  Return nonzero if user mode is not using TF itself.
117 	 * If we stepped into a sysenter/syscall insn, it trapped in  in enable_single_step()
118 	 * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP.  in enable_single_step()
119 	 * If user-mode had set TF itself, then it's still clear from  in enable_single_step()
123 	 * set TIF_SINGLESTEP, then both TF and TIF_FORCED_TF are  in enable_single_step()
127 		regs->flags |= X86_EFLAGS_TF;  in enable_single_step()
130 	 * Always set TIF_SINGLESTEP - this guarantees that  in enable_single_step()
131 	 * we single-step system calls etc..  This will also  in enable_single_step()
132 	 * cause us to set TF when returning to user mode.  in enable_single_step()
136 	oflags = regs->flags;  in enable_single_step()
138 	/* Set TF on the kernel stack.. */  in enable_single_step()
139 	regs->flags |= X86_EFLAGS_TF;  in enable_single_step()
142 	 * ..but if TF is changed by the instruction we will trace,  in enable_single_step()
147 	 * of a signal arriving right now or suchlike, we will lose  in enable_single_step()
156 	 * If TF was already set, check whether it was us who set it.  in enable_single_step()
157 	 * If not, we should never attempt a block step.  in enable_single_step()
204 	 * So no one should try to use debugger block stepping in a program  in enable_step()
205 	 * that uses user-mode single stepping itself.  in enable_step()
234 	/* But touch TF only if it was set by us.. */  in user_disable_single_step()
236 		task_pt_regs(child)->flags &= ~X86_EFLAGS_TF;  in user_disable_single_step()