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Commit 1b38f006 authored by Bodo Stroesser's avatar Bodo Stroesser Committed by Linus Torvalds
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[PATCH] Uml support: add PTRACE_SYSEMU_SINGLESTEP option to i386 



This patch implements the new ptrace option PTRACE_SYSEMU_SINGLESTEP, which
can be used by UML to singlestep a process: it will receive SINGLESTEP
interceptions for normal instructions and syscalls, but syscall execution will
be skipped just like with PTRACE_SYSEMU.

Signed-off-by: default avatarBodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c8c86cec

arch/i386/kernel/ptrace.c

+17 −4
Original line number Diff line number Diff line
@@ -547,11 +547,17 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data) 
		wake_up_process(child);

		break;



	case PTRACE_SYSEMU_SINGLESTEP: /* Same as SYSEMU, but singlestep if not syscall */

	case PTRACE_SINGLESTEP:	/* set the trap flag. */

		ret = -EIO;

		if (!valid_signal(data))

			break;



		if (request == PTRACE_SYSEMU_SINGLESTEP)

			set_tsk_thread_flag(child, TIF_SYSCALL_EMU);

		else

			clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);



		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

		set_singlestep(child);

		child->exit_code = data;
@@ -686,7 +692,10 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code) 
__attribute__((regparm(3)))

int do_syscall_trace(struct pt_regs *regs, int entryexit)

{

	int is_sysemu, is_singlestep, ret = 0;

	int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU), ret = 0;

	/* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP */

	int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);



	/* do the secure computing check first */

	secure_computing(regs->orig_eax);
@@ -696,8 +705,11 @@ int do_syscall_trace(struct pt_regs *regs, int entryexit) 
	if (!(current->ptrace & PT_PTRACED))

		goto out;



	is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);

	is_singlestep = test_thread_flag(TIF_SINGLESTEP);

	/* If a process stops on the 1st tracepoint with SYSCALL_TRACE

	 * and then is resumed with SYSEMU_SINGLESTEP, it will come in

	 * here. We have to check this and return */

	if (is_sysemu && entryexit)

		return 0;



	/* Fake a debug trap */

	if (is_singlestep)
@@ -728,6 +740,7 @@ int do_syscall_trace(struct pt_regs *regs, int entryexit) 
	if (ret == 0)

		return 0;



	regs->orig_eax = -1; /* force skip of syscall restarting */

	if (unlikely(current->audit_context))

		audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);

	return 1;

include/linux/ptrace.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 


#define PTRACE_SYSCALL		  24

#define PTRACE_SYSEMU		  31

#define PTRACE_SYSEMU_SINGLESTEP  32



/* 0x4200-0x4300 are reserved for architecture-independent additions.  */

#define PTRACE_SETOPTIONS	0x4200