Commit 3d2a71a5 authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar
Browse files

x86, traps: converge do_debug handlers 



Make the x86_64-version and the i386-version of do_debug
more similar.

 - introduce preempt_conditional_sti/cli to i386. The preempt-count
	is now elevated during the trap handler, like on x86_64. It
	does not run on a separate stack, however.
 - replace an open-coded "send_sigtrap"
 - copy some comments

Signed-off-by: default avatarAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e407d620

arch/x86/kernel/traps_32.c

+21 −9
Original line number Diff line number Diff line
@@ -88,6 +88,20 @@ static inline void conditional_sti(struct pt_regs *regs) 
		local_irq_enable();

}



static inline void preempt_conditional_sti(struct pt_regs *regs)

{

	inc_preempt_count();

	if (regs->flags & X86_EFLAGS_IF)

		local_irq_enable();

}



static inline void preempt_conditional_cli(struct pt_regs *regs)

{

	if (regs->flags & X86_EFLAGS_IF)

		local_irq_disable();

	dec_preempt_count();

}



static inline void

die_if_kernel(const char *str, struct pt_regs *regs, long err)

{
@@ -498,7 +512,7 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code) 
dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)

{

	struct task_struct *tsk = current;

	unsigned int condition;

	unsigned long condition;

	int si_code;



	get_debugreg(condition, 6);
@@ -512,9 +526,9 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
	if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,

						SIGTRAP) == NOTIFY_STOP)

		return;



	/* It's safe to allow irq's after DR6 has been saved */

	if (regs->flags & X86_EFLAGS_IF)

		local_irq_enable();

	preempt_conditional_sti(regs);



	/* Mask out spurious debug traps due to lazy DR7 setting */

	if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
@@ -533,16 +547,11 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
	 * kernel space (but re-enable TF when returning to user mode).

	 */

	if (condition & DR_STEP) {

		/*

		 * We already checked v86 mode above, so we can

		 * check for kernel mode by just checking the CPL

		 * of CS.

		 */

		if (!user_mode(regs))

			goto clear_TF_reenable;

	}



	si_code = get_si_code((unsigned long)condition);

	si_code = get_si_code(condition);

	/* Ok, finally something we can handle */

	send_sigtrap(tsk, regs, error_code, si_code);
@@ -552,15 +561,18 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
	 */

clear_dr7:

	set_debugreg(0, 7);

	preempt_conditional_cli(regs);

	return;



debug_vm86:

	handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);

	preempt_conditional_cli(regs);

	return;



clear_TF_reenable:

	set_tsk_thread_flag(tsk, TIF_SINGLESTEP);

	regs->flags &= ~X86_EFLAGS_TF;

	preempt_conditional_cli(regs);

	return;

}

arch/x86/kernel/traps_64.c

+9 −8
Original line number Diff line number Diff line
@@ -380,7 +380,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
{

	struct task_struct *tsk = current;

	unsigned long condition;

	siginfo_t info;

	int si_code;



	get_debugreg(condition, 6);
@@ -394,6 +394,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
						SIGTRAP) == NOTIFY_STOP)

		return;



	/* It's safe to allow irq's after DR6 has been saved */

	preempt_conditional_sti(regs);



	/* Mask out spurious debug traps due to lazy DR7 setting */
@@ -402,6 +403,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
			goto clear_dr7;

	}



	/* Save debug status register where ptrace can see it */

	tsk->thread.debugreg6 = condition;



	/*
@@ -413,15 +415,14 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
			goto clear_TF_reenable;

	}



	si_code = get_si_code(condition);

	/* Ok, finally something we can handle */

	tsk->thread.trap_no = 1;

	tsk->thread.error_code = error_code;

	info.si_signo = SIGTRAP;

	info.si_errno = 0;

	info.si_code = get_si_code(condition);

	info.si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;

	force_sig_info(SIGTRAP, &info, tsk);

	send_sigtrap(tsk, regs, error_code, si_code);



	/*

	 * Disable additional traps. They'll be re-enabled when

	 * the signal is delivered.

	 */

clear_dr7:

	set_debugreg(0, 7);

	preempt_conditional_cli(regs);

include/asm-x86/ptrace.h

+0 −4
Original line number Diff line number Diff line
@@ -174,12 +174,8 @@ extern unsigned long profile_pc(struct pt_regs *regs); 


extern unsigned long

convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);



#ifdef CONFIG_X86_32

extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,

			 int error_code, int si_code);

#endif



void signal_fault(struct pt_regs *regs, void __user *frame, char *where);



extern long syscall_trace_enter(struct pt_regs *);

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