Commit f67c2da9 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/mm,fault: use get_kernel_nofault() to dereference in dump_pagetable() 



The page table dumper uses get_kernel_nofault() to test if dereferencing
page table entries is possible. Use the result, which is the required page
table entry, instead of throwing it away and dereferencing a second time
without any safe guard.

Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 5be05c35

arch/s390/mm/fault.c

+19 −26
Original line number Diff line number Diff line
@@ -112,59 +112,52 @@ static __always_inline bool fault_is_write(struct pt_regs *regs) 
	return false;

}



static int bad_address(void *p)

{

	unsigned long dummy;



	return get_kernel_nofault(dummy, (unsigned long *)p);

}



static void dump_pagetable(unsigned long asce, unsigned long address)

{

	unsigned long *table = __va(asce & _ASCE_ORIGIN);

	unsigned long entry, *table = __va(asce & _ASCE_ORIGIN);



	pr_alert("AS:%016lx ", asce);

	switch (asce & _ASCE_TYPE_MASK) {

	case _ASCE_TYPE_REGION1:

		table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;

		if (bad_address(table))

		if (get_kernel_nofault(entry, table))

			goto bad;

		pr_cont("R1:%016lx ", *table);

		if (*table & _REGION_ENTRY_INVALID)

		pr_cont("R1:%016lx ", entry);

		if (entry & _REGION_ENTRY_INVALID)

			goto out;

		table = __va(*table & _REGION_ENTRY_ORIGIN);

		table = __va(entry & _REGION_ENTRY_ORIGIN);

		fallthrough;

	case _ASCE_TYPE_REGION2:

		table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;

		if (bad_address(table))

		if (get_kernel_nofault(entry, table))

			goto bad;

		pr_cont("R2:%016lx ", *table);

		if (*table & _REGION_ENTRY_INVALID)

		pr_cont("R2:%016lx ", entry);

		if (entry & _REGION_ENTRY_INVALID)

			goto out;

		table = __va(*table & _REGION_ENTRY_ORIGIN);

		table = __va(entry & _REGION_ENTRY_ORIGIN);

		fallthrough;

	case _ASCE_TYPE_REGION3:

		table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;

		if (bad_address(table))

		if (get_kernel_nofault(entry, table))

			goto bad;

		pr_cont("R3:%016lx ", *table);

		if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))

		pr_cont("R3:%016lx ", entry);

		if (entry & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))

			goto out;

		table = __va(*table & _REGION_ENTRY_ORIGIN);

		table = __va(entry & _REGION_ENTRY_ORIGIN);

		fallthrough;

	case _ASCE_TYPE_SEGMENT:

		table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;

		if (bad_address(table))

		if (get_kernel_nofault(entry, table))

			goto bad;

		pr_cont("S:%016lx ", *table);

		if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))

		pr_cont("S:%016lx ", entry);

		if (entry & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))

			goto out;

		table = __va(*table & _SEGMENT_ENTRY_ORIGIN);

		table = __va(entry & _SEGMENT_ENTRY_ORIGIN);

	}

	table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;

	if (bad_address(table))

	if (get_kernel_nofault(entry, table))

		goto bad;

	pr_cont("P:%016lx ", *table);

	pr_cont("P:%016lx ", entry);

out:

	pr_cont("\n");

	return;