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Commit efdc1e20 authored by David S. Miller's avatar David S. Miller
Browse files

[SPARC64]: Simplify user fault fixup handling. 



Instead of doing byte-at-a-time user accesses to figure
out where the fault occurred, read the saved fault_address
from the current thread structure.

For the sake of defensive programming, if the fault_address
does not fall into the user buffer range, simply assume the
whole area faulted.  This will cause the fixup for
copy_from_user() to clear the entire kernel side buffer.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5fd29752

arch/sparc64/lib/user_fixup.c

+29 −34
Original line number Diff line number Diff line
@@ -11,61 +11,56 @@ 


/* Calculating the exact fault address when using

 * block loads and stores can be very complicated.

 *

 * Instead of trying to be clever and handling all

 * of the cases, just fix things up simply here.

 */



unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)

static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)

{

	char *dst = to;

	const char __user *src = from;

	unsigned long fault_addr = current_thread_info()->fault_address;

	unsigned long end = start + size;



	while (size) {

		if (__get_user(*dst, src))

			break;

		dst++;

		src++;

		size--;

	if (fault_addr < start || fault_addr >= end) {

		*offset = 0;

	} else {

		*offset = start - fault_addr;

		size = end - fault_addr;

	}

	return size;

}



	if (size)

		memset(dst, 0, size);

unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)

{

	unsigned long offset;



	size = compute_size((unsigned long) from, size, &offset);

	if (likely(size))

		memset(to + offset, 0, size);



	return size;

}



unsigned long copy_to_user_fixup(void __user *to, const void *from, unsigned long size)

{

	char __user *dst = to;

	const char *src = from;

	unsigned long offset;



	while (size) {

		if (__put_user(*src, dst))

			break;

		dst++;

		src++;

		size--;

	}



	return size;

	return compute_size((unsigned long) to, size, &offset);

}



unsigned long copy_in_user_fixup(void __user *to, void __user *from, unsigned long size)

{

	char __user *dst = to;

	char __user *src = from;

	unsigned long fault_addr = current_thread_info()->fault_address;

	unsigned long start = (unsigned long) to;

	unsigned long end = start + size;



	while (size) {

		char tmp;

	if (fault_addr >= start && fault_addr < end)

		return end - fault_addr;



		if (__get_user(tmp, src))

			break;

		if (__put_user(tmp, dst))

			break;

		dst++;

		src++;

		size--;

	}

	start = (unsigned long) from;

	end = start + size;

	if (fault_addr >= start && fault_addr < end)

		return end - fault_addr;



	return size;

}

arch/sparc64/mm/fault.c

+2 −8
Original line number Diff line number Diff line
@@ -457,7 +457,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 
	}



	up_read(&mm->mmap_sem);

	goto fault_done;

	return;



	/*

	 * Something tried to access memory that isn't in our memory map..
@@ -469,8 +469,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 


handle_kernel_fault:

	do_kernel_fault(regs, si_code, fault_code, insn, address);



	goto fault_done;

	return;



/*

 * We ran out of memory, or some other thing happened to us that made
@@ -501,9 +500,4 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 
	/* Kernel mode? Handle exceptions or die */

	if (regs->tstate & TSTATE_PRIV)

		goto handle_kernel_fault;



fault_done:

	/* These values are no longer needed, clear them. */

	set_thread_fault_code(0);

	current_thread_info()->fault_address = 0;

}

include/asm-sparc64/uaccess.h

+3 −3
Original line number Diff line number Diff line
@@ -251,7 +251,7 @@ copy_from_user(void *to, const void __user *from, unsigned long size) 
{

	unsigned long ret = ___copy_from_user(to, from, size);



	if (ret)

	if (unlikely(ret))

		ret = copy_from_user_fixup(to, from, size);

	return ret;

}
@@ -267,7 +267,7 @@ copy_to_user(void __user *to, const void *from, unsigned long size) 
{

	unsigned long ret = ___copy_to_user(to, from, size);



	if (ret)

	if (unlikely(ret))

		ret = copy_to_user_fixup(to, from, size);

	return ret;

}
@@ -283,7 +283,7 @@ copy_in_user(void __user *to, void __user *from, unsigned long size) 
{

	unsigned long ret = ___copy_in_user(to, from, size);



	if (ret)

	if (unlikely(ret))

		ret = copy_in_user_fixup(to, from, size);

	return ret;

}