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Commit 378b1e7a authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/mm: fix pmd_huge() usage for kernel mapping 



pmd_huge() will always return 0 on !HUGETLBFS, however we use that helper
function when walking the kernel page tables to decide if we have a
1MB page frame or not.
Since we create 1MB frames for the kernel 1:1 mapping independently of
HUGETLBFS this can lead to incorrect storage accesses since the code
can assume that we have a pointer to a page table instead of a pointer
to a 1MB frame.

Fix this by adding a pmd_large() primitive like other architectures have
it already and remove all references to HUGETLBFS/HUGETLBPAGE from the
code that walks kernel page tables.

Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 521b3d79

arch/s390/include/asm/pgtable.h

+9 −0
Original line number Diff line number Diff line
@@ -507,6 +507,15 @@ static inline int pmd_none(pmd_t pmd) 
	return (pmd_val(pmd) & _SEGMENT_ENTRY_INV) != 0UL;

}



static inline int pmd_large(pmd_t pmd)

{

#ifdef CONFIG_64BIT

	return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);

#else

	return 0;

#endif

}



static inline int pmd_bad(pmd_t pmd)

{

	unsigned long mask = ~_SEGMENT_ENTRY_ORIGIN & ~_SEGMENT_ENTRY_INV;

arch/s390/mm/pageattr.c

+1 −1
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ static void change_page_attr(unsigned long addr, int numpages, 
		pgdp = pgd_offset(&init_mm, addr);

		pudp = pud_offset(pgdp, addr);

		pmdp = pmd_offset(pudp, addr);

		if (pmd_huge(*pmdp)) {

		if (pmd_large(*pmdp)) {

			WARN_ON_ONCE(1);

			continue;

		}

arch/s390/mm/vmem.c

+15 −14
Original line number Diff line number Diff line
@@ -79,7 +79,8 @@ static pte_t __ref *vmem_pte_alloc(unsigned long address) 
 */

static int vmem_add_mem(unsigned long start, unsigned long size, int ro)

{

	unsigned long address;

	unsigned long end = start + size;

	unsigned long address = start;

	pgd_t *pg_dir;

	pud_t *pu_dir;

	pmd_t *pm_dir;
@@ -87,7 +88,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) 
	pte_t  pte;

	int ret = -ENOMEM;



	for (address = start; address < start + size; address += PAGE_SIZE) {

	while (address < end) {

		pg_dir = pgd_offset_k(address);

		if (pgd_none(*pg_dir)) {

			pu_dir = vmem_pud_alloc();
@@ -108,12 +109,11 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) 
		pm_dir = pmd_offset(pu_dir, address);



#if defined(CONFIG_64BIT) && !defined(CONFIG_DEBUG_PAGEALLOC)

		if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&

		    (address + HPAGE_SIZE <= start + size) &&

		    (address >= HPAGE_SIZE)) {

		if (MACHINE_HAS_EDAT1 && address && !(address & ~PMD_MASK) &&

		    (address + PMD_SIZE <= end)) {

			pte_val(pte) |= _SEGMENT_ENTRY_LARGE;

			pmd_val(*pm_dir) = pte_val(pte);

			address += HPAGE_SIZE - PAGE_SIZE;

			address += PMD_SIZE;

			continue;

		}

#endif
@@ -126,10 +126,11 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) 


		pt_dir = pte_offset_kernel(pm_dir, address);

		*pt_dir = pte;

		address += PAGE_SIZE;

	}

	ret = 0;

out:

	flush_tlb_kernel_range(start, start + size);

	flush_tlb_kernel_range(start, end);

	return ret;

}
@@ -139,7 +140,8 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) 
 */

static void vmem_remove_range(unsigned long start, unsigned long size)

{

	unsigned long address;

	unsigned long end = start + size;

	unsigned long address = start;

	pgd_t *pg_dir;

	pud_t *pu_dir;

	pmd_t *pm_dir;
@@ -147,7 +149,7 @@ static void vmem_remove_range(unsigned long start, unsigned long size) 
	pte_t  pte;



	pte_val(pte) = _PAGE_TYPE_EMPTY;

	for (address = start; address < start + size; address += PAGE_SIZE) {

	while (address < end) {

		pg_dir = pgd_offset_k(address);

		pu_dir = pud_offset(pg_dir, address);

		if (pud_none(*pu_dir))
@@ -155,17 +157,16 @@ static void vmem_remove_range(unsigned long start, unsigned long size) 
		pm_dir = pmd_offset(pu_dir, address);

		if (pmd_none(*pm_dir))

			continue;



		if (pmd_huge(*pm_dir)) {

		if (pmd_large(*pm_dir)) {

			pmd_clear(pm_dir);

			address += HPAGE_SIZE - PAGE_SIZE;

			address += PMD_SIZE;

			continue;

		}



		pt_dir = pte_offset_kernel(pm_dir, address);

		*pt_dir = pte;

		address += PAGE_SIZE;

	}

	flush_tlb_kernel_range(start, start + size);

	flush_tlb_kernel_range(start, end);

}



/*