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Commit 06ee1b68 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
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x86: x86 ptrace getreg/putreg cleanup 



This cleans up the getreg/putreg functions to move the special cases
(segment registers and eflags) out into their own subroutines.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e39c2891

arch/x86/kernel/ptrace.c

+96 −66
Original line number Diff line number Diff line
@@ -45,90 +45,120 @@ 
static long *pt_regs_access(struct pt_regs *regs, unsigned long regno)

{

	BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0);

	regno >>= 2;

	if (regno > FS)

		--regno;

	return &regs->bx + regno;

}



static int putreg(struct task_struct *child,

	unsigned long regno, unsigned long value)

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)

{

	struct pt_regs *regs = task_pt_regs(child);

	regno >>= 2;

	switch (regno) {

	case GS:

	/*

	 * Returning the value truncates it to 16 bits.

	 */

	unsigned int retval;

	if (offset != offsetof(struct user_regs_struct, gs))

		retval = *pt_regs_access(task_pt_regs(task), offset);

	else {

		retval = task->thread.gs;

		if (task == current)

			savesegment(gs, retval);

	}

	return retval;

}



static int set_segment_reg(struct task_struct *task,

			   unsigned long offset, u16 value)

{

	/*

	 * The value argument was already truncated to 16 bits.

	 */

	if (value && (value & 3) != 3)

		return -EIO;

		child->thread.gs = value;

		if (child == current)



	if (offset != offsetof(struct user_regs_struct, gs))

		*pt_regs_access(task_pt_regs(task), offset) = value;

	else {

		task->thread.gs = value;

		if (task == current)

			/*

			 * The user-mode %gs is not affected by

			 * kernel entry, so we must update the CPU.

			 */

			loadsegment(gs, value);

	}



	return 0;

	case DS:

	case ES:

	case FS:

		if (value && (value & 3) != 3)

			return -EIO;

		value &= 0xffff;

		break;

	case SS:

	case CS:

		if ((value & 3) != 3)

			return -EIO;

		value &= 0xffff;

		break;

	case EFL:

		value &= FLAG_MASK;

}



static unsigned long get_flags(struct task_struct *task)

{

	unsigned long retval = task_pt_regs(task)->flags;



	/*

	 * If the debugger set TF, hide it from the readout.

	 */

	if (test_tsk_thread_flag(task, TIF_FORCED_TF))

		retval &= ~X86_EFLAGS_TF;



	return retval;

}



static int set_flags(struct task_struct *task, unsigned long value)

{

	struct pt_regs *regs = task_pt_regs(task);



	/*

	 * If the user value contains TF, mark that

	 * it was not "us" (the debugger) that set it.

	 * If not, make sure it stays set if we had.

	 */

	if (value & X86_EFLAGS_TF)

			clear_tsk_thread_flag(child, TIF_FORCED_TF);

		else if (test_tsk_thread_flag(child, TIF_FORCED_TF))

		clear_tsk_thread_flag(task, TIF_FORCED_TF);

	else if (test_tsk_thread_flag(task, TIF_FORCED_TF))

		value |= X86_EFLAGS_TF;

		value |= regs->flags & ~FLAG_MASK;

		break;



	regs->flags = (regs->flags & ~FLAG_MASK) | (value & FLAG_MASK);



	return 0;

}



static int putreg(struct task_struct *child,

		  unsigned long offset, unsigned long value)

{

	switch (offset) {

	case offsetof(struct user_regs_struct, cs):

	case offsetof(struct user_regs_struct, ds):

	case offsetof(struct user_regs_struct, es):

	case offsetof(struct user_regs_struct, fs):

	case offsetof(struct user_regs_struct, gs):

	case offsetof(struct user_regs_struct, ss):

		return set_segment_reg(child, offset, value);



	case offsetof(struct user_regs_struct, flags):

		return set_flags(child, value);

	}

	*pt_regs_access(regs, regno) = value;



	*pt_regs_access(task_pt_regs(child), offset) = value;

	return 0;

}



static unsigned long getreg(struct task_struct *child, unsigned long regno)

static unsigned long getreg(struct task_struct *task, unsigned long offset)

{

	struct pt_regs *regs = task_pt_regs(child);

	unsigned long retval = ~0UL;

	switch (offset) {

	case offsetof(struct user_regs_struct, cs):

	case offsetof(struct user_regs_struct, ds):

	case offsetof(struct user_regs_struct, es):

	case offsetof(struct user_regs_struct, fs):

	case offsetof(struct user_regs_struct, gs):

	case offsetof(struct user_regs_struct, ss):

		return get_segment_reg(task, offset);



	regno >>= 2;

	switch (regno) {

	case EFL:

		/*

		 * If the debugger set TF, hide it from the readout.

		 */

		retval = regs->flags;

		if (test_tsk_thread_flag(child, TIF_FORCED_TF))

			retval &= ~X86_EFLAGS_TF;

		break;

	case GS:

		retval = child->thread.gs;

		if (child == current)

			savesegment(gs, retval);

		break;

	case DS:

	case ES:

	case FS:

	case SS:

	case CS:

		retval = 0xffff;

		/* fall through */

	default:

		retval &= *pt_regs_access(regs, regno);

	case offsetof(struct user_regs_struct, flags):

		return get_flags(task);

	}

	return retval;



	return *pt_regs_access(task_pt_regs(task), offset);

}



/*