Commit ef22d8ab authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Geert Uytterhoeven
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m68k: mm: Restructure Motorola MMU page-table layout 



The Motorola 68xxx MMUs, 040 (and later) have a fixed 7,7,{5,6}
page-table setup, where the last depends on the page-size selected (8k
vs 4k resp.), and head.S selects 4K pages. For 030 (and earlier) we
explicitly program 7,7,6 and 4K pages in %tc.

However, the current code implements this mightily weird. What it does
is group 16 of those (6 bit) pte tables into one 4k page to not waste
space. The down-side is that that forces pmd_t to be a 16-tuple
pointing to consecutive pte tables.

This breaks the generic code which assumes READ_ONCE(*pmd) will be
word sized.

Therefore implement a straight forward 7,7,6 3 level page-table setup,
with the addition (for 020/030) of (partial) large-page support. For
now this increases the memory footprint for pte-tables 15 fold.

Tested with ARAnyM/68040 emulation.

Suggested-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will@kernel.org>
Acked-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
Tested-by: default avatarMichael Schmitz <schmitzmic@gmail.com>
Tested-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
Link: https://lore.kernel.org/r/20200131125403.711478295@infradead.org


Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 5ad272ab

arch/m68k/include/asm/motorola_pgtable.h

+2 −13
Original line number Diff line number Diff line
@@ -108,13 +108,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) 


static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)

{

	unsigned long ptbl = virt_to_phys(ptep) | _PAGE_TABLE | _PAGE_ACCESSED;

	unsigned long *ptr = pmdp->pmd;

	short i = 16;

	while (--i >= 0) {

		*ptr++ = ptbl;

		ptbl += (sizeof(pte_t)*PTRS_PER_PTE/16);

	}

	pmd_val(*pmdp) = virt_to_phys(ptep) | _PAGE_TABLE | _PAGE_ACCESSED;

}



static inline void pud_set(pud_t *pudp, pmd_t *pmdp)
@@ -138,12 +132,7 @@ static inline void pud_set(pud_t *pudp, pmd_t *pmdp) 
#define pmd_none(pmd)		(!pmd_val(pmd))

#define pmd_bad(pmd)		((pmd_val(pmd) & _DESCTYPE_MASK) != _PAGE_TABLE)

#define pmd_present(pmd)	(pmd_val(pmd) & _PAGE_TABLE)

#define pmd_clear(pmdp) ({			\

	unsigned long *__ptr = pmdp->pmd;	\

	short __i = 16;				\

	while (--__i >= 0)			\

		*__ptr++ = 0;			\

})

#define pmd_clear(pmdp)		({ pmd_val(*pmdp) = 0; })

#define pmd_page(pmd)		virt_to_page(__va(pmd_val(pmd)))

arch/m68k/include/asm/page.h

+3 −3
Original line number Diff line number Diff line
@@ -22,9 +22,9 @@ 
 * These are used to make use of C type-checking..

 */

#if !defined(CONFIG_MMU) || CONFIG_PGTABLE_LEVELS == 3

typedef struct { unsigned long pmd[16]; } pmd_t;

#define pmd_val(x)	((&x)->pmd[0])

#define __pmd(x)	((pmd_t) { { (x) }, })

typedef struct { unsigned long pmd; } pmd_t;

#define pmd_val(x)	((&x)->pmd)

#define __pmd(x)	((pmd_t) { (x) } )

#endif



typedef struct { unsigned long pte; } pte_t;

arch/m68k/include/asm/pgtable_mm.h

+5 −5
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 


/* PMD_SHIFT determines the size of the area a second-level page table can map */

#if CONFIG_PGTABLE_LEVELS == 3

#define PMD_SHIFT	22

#define PMD_SHIFT	18

#endif

#define PMD_SIZE	(1UL << PMD_SHIFT)

#define PMD_MASK	(~(PMD_SIZE-1))
@@ -67,8 +67,8 @@ 
#define PTRS_PER_PMD	1

#define PTRS_PER_PGD	1024

#else

#define PTRS_PER_PTE	1024

#define PTRS_PER_PMD	8

#define PTRS_PER_PTE	64

#define PTRS_PER_PMD	128

#define PTRS_PER_PGD	128

#endif

#define USER_PTRS_PER_PGD	(TASK_SIZE/PGDIR_SIZE)
@@ -76,8 +76,8 @@ 


/* Virtual address region for use by kernel_map() */

#ifdef CONFIG_SUN3

#define KMAP_START     0x0DC00000

#define KMAP_END       0x0E000000

#define KMAP_START	0x0dc00000

#define KMAP_END	0x0e000000

#elif defined(CONFIG_COLDFIRE)

#define KMAP_START	0xe0000000

#define KMAP_END	0xf0000000

arch/m68k/mm/kmap.c

+16 −20
Original line number Diff line number Diff line
@@ -24,8 +24,6 @@ 


#undef DEBUG



#define PTRTREESIZE	(256*1024)



/*

 * For 040/060 we can use the virtual memory area like other architectures,

 * but for 020/030 we want to use early termination page descriptors and we
@@ -50,7 +48,7 @@ static inline void free_io_area(void *addr) 


#else



#define IO_SIZE		(256*1024)

#define IO_SIZE		PMD_SIZE



static struct vm_struct *iolist;
@@ -81,14 +79,13 @@ static void __free_io_area(void *addr, unsigned long size) 


#if CONFIG_PGTABLE_LEVELS == 3

		if (CPU_IS_020_OR_030) {

			int pmd_off = (virtaddr/PTRTREESIZE) & 15;

			int pmd_type = pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK;

			int pmd_type = pmd_val(*pmd_dir) & _DESCTYPE_MASK;



			if (pmd_type == _PAGE_PRESENT) {

				pmd_dir->pmd[pmd_off] = 0;

				virtaddr += PTRTREESIZE;

				size -= PTRTREESIZE;

				continue;

				pmd_clear(pmd_dir);

				virtaddr += PMD_SIZE;

				size -= PMD_SIZE;



			} else if (pmd_type == 0)

				continue;

		}
@@ -249,7 +246,7 @@ void __iomem *__ioremap(unsigned long physaddr, unsigned long size, int cachefla 


	while ((long)size > 0) {

#ifdef DEBUG

		if (!(virtaddr & (PTRTREESIZE-1)))

		if (!(virtaddr & (PMD_SIZE-1)))

			printk ("\npa=%#lx va=%#lx ", physaddr, virtaddr);

#endif

		pgd_dir = pgd_offset_k(virtaddr);
@@ -263,10 +260,10 @@ void __iomem *__ioremap(unsigned long physaddr, unsigned long size, int cachefla 


#if CONFIG_PGTABLE_LEVELS == 3

		if (CPU_IS_020_OR_030) {

			pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;

			physaddr += PTRTREESIZE;

			virtaddr += PTRTREESIZE;

			size -= PTRTREESIZE;

			pmd_val(*pmd_dir) = physaddr;

			physaddr += PMD_SIZE;

			virtaddr += PMD_SIZE;

			size -= PMD_SIZE;

		} else

#endif

		{
@@ -367,13 +364,12 @@ void kernel_set_cachemode(void *addr, unsigned long size, int cmode) 


#if CONFIG_PGTABLE_LEVELS == 3

		if (CPU_IS_020_OR_030) {

			int pmd_off = (virtaddr/PTRTREESIZE) & 15;

			unsigned long pmd = pmd_val(*pmd_dir);



			if ((pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK) == _PAGE_PRESENT) {

				pmd_dir->pmd[pmd_off] = (pmd_dir->pmd[pmd_off] &

							 _CACHEMASK040) | cmode;

				virtaddr += PTRTREESIZE;

				size -= PTRTREESIZE;

			if ((pmd & _DESCTYPE_MASK) == _PAGE_PRESENT) {

				*pmd_dir = __pmd((pmd & _CACHEMASK040) | cmode);

				virtaddr += PMD_SIZE;

				size -= PMD_SIZE;

				continue;

			}

		}

arch/m68k/mm/motorola.c

+13 −15
Original line number Diff line number Diff line
@@ -236,8 +236,6 @@ static pmd_t * __init kernel_ptr_table(void) 


static void __init map_node(int node)

{

#define PTRTREESIZE (256*1024)

#define ROOTTREESIZE (32*1024*1024)

	unsigned long physaddr, virtaddr, size;

	pgd_t *pgd_dir;

	p4d_t *p4d_dir;
@@ -255,21 +253,21 @@ static void __init map_node(int node) 


	while (size > 0) {

#ifdef DEBUG

		if (!(virtaddr & (PTRTREESIZE-1)))

		if (!(virtaddr & (PMD_SIZE-1)))

			printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,

				virtaddr);

#endif

		pgd_dir = pgd_offset_k(virtaddr);

		if (virtaddr && CPU_IS_020_OR_030) {

			if (!(virtaddr & (ROOTTREESIZE-1)) &&

			    size >= ROOTTREESIZE) {

			if (!(virtaddr & (PGDIR_SIZE-1)) &&

			    size >= PGDIR_SIZE) {

#ifdef DEBUG

				printk ("[very early term]");

#endif

				pgd_val(*pgd_dir) = physaddr;

				size -= ROOTTREESIZE;

				virtaddr += ROOTTREESIZE;

				physaddr += ROOTTREESIZE;

				size -= PGDIR_SIZE;

				virtaddr += PGDIR_SIZE;

				physaddr += PGDIR_SIZE;

				continue;

			}

		}
@@ -289,8 +287,8 @@ static void __init map_node(int node) 
#ifdef DEBUG

				printk ("[early term]");

#endif

				pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;

				physaddr += PTRTREESIZE;

				pmd_val(*pmd_dir) = physaddr;

				physaddr += PMD_SIZE;

			} else {

				int i;

#ifdef DEBUG
@@ -298,15 +296,15 @@ static void __init map_node(int node) 
#endif

				zero_pgtable = kernel_ptr_table();

				pte_dir = (pte_t *)zero_pgtable;

				pmd_dir->pmd[0] = virt_to_phys(pte_dir) |

					_PAGE_TABLE | _PAGE_ACCESSED;

				pmd_set(pmd_dir, pte_dir);



				pte_val(*pte_dir++) = 0;

				physaddr += PAGE_SIZE;

				for (i = 1; i < 64; physaddr += PAGE_SIZE, i++)

				for (i = 1; i < PTRS_PER_PTE; physaddr += PAGE_SIZE, i++)

					pte_val(*pte_dir++) = physaddr;

			}

			size -= PTRTREESIZE;

			virtaddr += PTRTREESIZE;

			size -= PMD_SIZE;

			virtaddr += PMD_SIZE;

		} else {

			if (!pmd_present(*pmd_dir)) {

#ifdef DEBUG

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