1 // SPDX-License-Identifier: GPL-2.0
3  * x86 single-step support code, common to 32-bit and 64-bit.
18 	addr = regs->ip;  in convert_ip_to_linear()
19 	seg = regs->cs;  in convert_ip_to_linear()
28 	 * are all zero-based. That is largely true: the  in convert_ip_to_linear()
38 		mutex_lock(&child->mm->context.lock);  in convert_ip_to_linear()
39 		if (unlikely(!child->mm->context.ldt ||  in convert_ip_to_linear()
40 			     seg >= child->mm->context.ldt->nr_entries))  in convert_ip_to_linear()
41 			addr = -1L; /* bogus selector, access would fault */  in convert_ip_to_linear()
43 			desc = &child->mm->context.ldt->entries[seg];  in convert_ip_to_linear()
46 			/* 16-bit code segment? */  in convert_ip_to_linear()
47 			if (!desc->d)  in convert_ip_to_linear()
51 		mutex_unlock(&child->mm->context.lock);  in convert_ip_to_linear()
87 				/* 32-bit mode: register increment */  in is_setting_trap_flag()
89 			/* 64-bit mode: REX prefix */  in is_setting_trap_flag()
97 		 * the user see the TF bit being set. But  in is_setting_trap_flag()
99 		 * it, and a debugger could emulate this  in is_setting_trap_flag()
111  * Enable single-stepping.  Return nonzero if user mode is not using TF itself.
119 	 * If we stepped into a sysenter/syscall insn, it trapped in  in enable_single_step()
120 	 * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP.  in enable_single_step()
121 	 * If user-mode had set TF itself, then it's still clear from  in enable_single_step()
125 	 * set TIF_SINGLESTEP, then both TF and TIF_FORCED_TF are  in enable_single_step()
129 		regs->flags |= X86_EFLAGS_TF;  in enable_single_step()
133 	 * cause us to set TF when returning to user mode.  in enable_single_step()
138 	 * Ensure that a trap is triggered once stepping out of a system  in enable_single_step()
143 	oflags = regs->flags;  in enable_single_step()
145 	/* Set TF on the kernel stack.. */  in enable_single_step()
146 	regs->flags |= X86_EFLAGS_TF;  in enable_single_step()
149 	 * ..but if TF is changed by the instruction we will trace,  in enable_single_step()
154 	 * of a signal arriving right now or suchlike, we will lose  in enable_single_step()
163 	 * If TF was already set, check whether it was us who set it.  in enable_single_step()
164 	 * If not, we should never attempt a block step.  in enable_single_step()
210 	 * So no one should try to use debugger block stepping in a program  in enable_step()
211 	 * that uses user-mode single stepping itself.  in enable_step()
241 	/* But touch TF only if it was set by us.. */  in user_disable_single_step()
243 		task_pt_regs(child)->flags &= ~X86_EFLAGS_TF;  in user_disable_single_step()