Commit 93c043e3 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/ptrace: Convert gpr32_set_common() to user access block 



Use user access block in gpr32_set_common() instead of
repetitive __get_user() which imply repetitive KUAP open/close.

To get it clean, force inlining of the small set of tiny functions
called inside the block.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bdcb8652c3bb4ab5b8b3bfd08147434be8fc04c9.1615398498.git.christophe.leroy@csgroup.eu
parent 870779f4

arch/powerpc/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -222,7 +222,7 @@ do { \ 
} while (0)

#endif /* __powerpc64__ */



static inline void set_trap(struct pt_regs *regs, unsigned long val)

static __always_inline void set_trap(struct pt_regs *regs, unsigned long val)

{

	regs->trap = (regs->trap & TRAP_FLAGS_MASK) | (val & ~TRAP_FLAGS_MASK);

}

arch/powerpc/kernel/ptrace/ptrace-view.c

+18 −12
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ static unsigned long get_user_msr(struct task_struct *task) 
	return task->thread.regs->msr | task->thread.fpexc_mode;

}



static int set_user_msr(struct task_struct *task, unsigned long msr)

static __always_inline int set_user_msr(struct task_struct *task, unsigned long msr)

{

	task->thread.regs->msr &= ~MSR_DEBUGCHANGE;

	task->thread.regs->msr |= msr & MSR_DEBUGCHANGE;
@@ -147,7 +147,7 @@ static int set_user_dscr(struct task_struct *task, unsigned long dscr) 
 * We prevent mucking around with the reserved area of trap

 * which are used internally by the kernel.

 */

static int set_user_trap(struct task_struct *task, unsigned long trap)

static __always_inline int set_user_trap(struct task_struct *task, unsigned long trap)

{

	set_trap(task->thread.regs, trap);

	return 0;
@@ -661,6 +661,9 @@ int gpr32_set_common(struct task_struct *target, 
	const compat_ulong_t __user *u = ubuf;

	compat_ulong_t reg;



	if (!kbuf && !user_read_access_begin(u, count))

		return -EFAULT;



	pos /= sizeof(reg);

	count /= sizeof(reg);
@@ -669,8 +672,7 @@ int gpr32_set_common(struct task_struct *target, 
			regs[pos++] = *k++;

	else

		for (; count > 0 && pos < PT_MSR; --count) {

			if (__get_user(reg, u++))

				return -EFAULT;

			unsafe_get_user(reg, u++, Efault);

			regs[pos++] = reg;

		}
@@ -678,8 +680,8 @@ int gpr32_set_common(struct task_struct *target, 
	if (count > 0 && pos == PT_MSR) {

		if (kbuf)

			reg = *k++;

		else if (__get_user(reg, u++))

			return -EFAULT;

		else

			unsafe_get_user(reg, u++, Efault);

		set_user_msr(target, reg);

		++pos;

		--count;
@@ -692,24 +694,24 @@ int gpr32_set_common(struct task_struct *target, 
			++k;

	} else {

		for (; count > 0 && pos <= PT_MAX_PUT_REG; --count) {

			if (__get_user(reg, u++))

				return -EFAULT;

			unsafe_get_user(reg, u++, Efault);

			regs[pos++] = reg;

		}

		for (; count > 0 && pos < PT_TRAP; --count, ++pos)

			if (__get_user(reg, u++))

				return -EFAULT;

			unsafe_get_user(reg, u++, Efault);

	}



	if (count > 0 && pos == PT_TRAP) {

		if (kbuf)

			reg = *k++;

		else if (__get_user(reg, u++))

			return -EFAULT;

		else

			unsafe_get_user(reg, u++, Efault);

		set_user_trap(target, reg);

		++pos;

		--count;

	}

	if (!kbuf)

		user_read_access_end();



	kbuf = k;

	ubuf = u;
@@ -717,6 +719,10 @@ int gpr32_set_common(struct task_struct *target, 
	count *= sizeof(reg);

	return user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,

					 (PT_TRAP + 1) * sizeof(reg), -1);



Efault:

	user_read_access_end();

	return -EFAULT;

}



static int gpr32_get(struct task_struct *target,