Commit 9a32584b authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/ptrace: Split gpr32_set_common 



objtool reports the following warning:

  arch/powerpc/kernel/ptrace/ptrace-view.o: warning: objtool:
    gpr32_set_common+0x23c (.text+0x860): redundant UACCESS disable

gpr32_set_common() conditionally opens and closes UACCESS based on
whether kbuf pointer is NULL or not. This is wackelig.

Split gpr32_set_common() in two fonctions, one for user one for
kernel.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix oops in gpr32_set_common_user() due to NULL kbuf]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/b8d6ae4483fcfd17524e79d803c969694a85cc02.1687428075.git.christophe.leroy@csgroup.eu
parent 0e216fa5

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

+67 −38
Original line number Diff line number Diff line
@@ -716,69 +716,86 @@ int gpr32_get_common(struct task_struct *target, 
	return membuf_zero(&to, (ELF_NGREG - PT_REGS_COUNT) * sizeof(u32));

}



int gpr32_set_common(struct task_struct *target,

static int gpr32_set_common_kernel(struct task_struct *target,

				   const struct user_regset *regset,

				   unsigned int pos, unsigned int count,

		     const void *kbuf, const void __user *ubuf,

		     unsigned long *regs)

				   const void *kbuf, unsigned long *regs)

{

	const compat_ulong_t *k = kbuf;



	pos /= sizeof(compat_ulong_t);

	count /= sizeof(compat_ulong_t);



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

		regs[pos++] = *k++;



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

		set_user_msr(target, *k++);

		++pos;

		--count;

	}



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

		regs[pos++] = *k++;

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

		++k;



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

		set_user_trap(target, *k++);

		++pos;

		--count;

	}



	kbuf = k;

	pos *= sizeof(compat_ulong_t);

	count *= sizeof(compat_ulong_t);

	user_regset_copyin_ignore(&pos, &count, &kbuf, NULL,

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

	return 0;

}



static int gpr32_set_common_user(struct task_struct *target,

				 const struct user_regset *regset,

				 unsigned int pos, unsigned int count,

				 const void __user *ubuf, unsigned long *regs)

{

	const compat_ulong_t __user *u = ubuf;

	const void *kbuf = NULL;

	compat_ulong_t reg;



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

	if (!user_read_access_begin(u, count))

		return -EFAULT;



	pos /= sizeof(reg);

	count /= sizeof(reg);



	if (kbuf)

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

			regs[pos++] = *k++;

	else

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

		unsafe_get_user(reg, u++, Efault);

		regs[pos++] = reg;

	}





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

		if (kbuf)

			reg = *k++;

		else

		unsafe_get_user(reg, u++, Efault);

		set_user_msr(target, reg);

		++pos;

		--count;

	}



	if (kbuf) {

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

			regs[pos++] = *k++;

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

			++k;

	} else {

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

		unsafe_get_user(reg, u++, Efault);

		regs[pos++] = reg;

	}

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

		unsafe_get_user(reg, u++, Efault);

	}



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

		if (kbuf)

			reg = *k++;

		else

		unsafe_get_user(reg, u++, Efault);

		set_user_trap(target, reg);

		++pos;

		--count;

	}

	if (!kbuf)

	user_read_access_end();



	kbuf = k;

	ubuf = u;

	pos *= sizeof(reg);

	count *= sizeof(reg);
@@ -791,6 +808,18 @@ int gpr32_set_common(struct task_struct *target, 
	return -EFAULT;

}



int gpr32_set_common(struct task_struct *target,

		     const struct user_regset *regset,

		     unsigned int pos, unsigned int count,

		     const void *kbuf, const void __user *ubuf,

		     unsigned long *regs)

{

	if (kbuf)

		return gpr32_set_common_kernel(target, regset, pos, count, kbuf, regs);

	else

		return gpr32_set_common_user(target, regset, pos, count, ubuf, regs);

}



static int gpr32_get(struct task_struct *target,

		     const struct user_regset *regset,

		     struct membuf to)