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[SPARC64]: Make use of Niagara 256MB PTEs for kernel mappings.
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We use a bitmap, one bit for every 256MB of memory.  If the
bit is set we can use a 256MB PTE for linear mappings, else
we have to use a 4MB PTE.

SUN4V support is there, and we can very easily add support
for Panther cpu 256MB PTEs in the future.

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller authored and David S. Miller committed Mar 20, 2006
1 parent 30c91d5 commit 9cc3a1a
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Showing 2 changed files with 96 additions and 15 deletions.
29 changes: 27 additions & 2 deletions arch/sparc64/kernel/ktlb.S
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Original file line number Diff line number Diff line change
Expand Up @@ -133,8 +133,33 @@ kvmap_dtlb_4v:
brgez,pn %g4, kvmap_dtlb_nonlinear
nop

sethi %hi(kern_linear_pte_xor), %g2
ldx [%g2 + %lo(kern_linear_pte_xor)], %g2
sethi %hi(kpte_linear_bitmap), %g2
or %g2, %lo(kpte_linear_bitmap), %g2

/* Clear the PAGE_OFFSET top virtual bits, then shift
* down to get a 256MB physical address index.
*/
sllx %g4, 21, %g5
mov 1, %g7
srlx %g5, 21 + 28, %g5

/* Don't try this at home kids... this depends upon srlx
* only taking the low 6 bits of the shift count in %g5.
*/
sllx %g7, %g5, %g7

/* Divide by 64 to get the offset into the bitmask. */
srlx %g5, 6, %g5

/* kern_linear_pte_xor[((mask & bit) ? 1 : 0)] */
ldx [%g2 + %g5], %g2
andcc %g2, %g7, %g0
sethi %hi(kern_linear_pte_xor), %g5
or %g5, %lo(kern_linear_pte_xor), %g5
bne,a,pt %xcc, 1f
add %g5, 8, %g5

1: ldx [%g5], %g2

.globl kvmap_linear_patch
kvmap_linear_patch:
Expand Down
82 changes: 69 additions & 13 deletions arch/sparc64/mm/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,19 @@

extern void device_scan(void);

#define MAX_PHYS_ADDRESS (1UL << 42UL)
#define KPTE_BITMAP_CHUNK_SZ (256UL * 1024UL * 1024UL)
#define KPTE_BITMAP_BYTES \
((MAX_PHYS_ADDRESS / KPTE_BITMAP_CHUNK_SZ) / 8)

unsigned long kern_linear_pte_xor[2] __read_mostly;

/* A bitmap, one bit for every 256MB of physical memory. If the bit
* is clear, we should use a 4MB page (via kern_linear_pte_xor[0]) else
* if set we should use a 256MB page (via kern_linear_pte_xor[1]).
*/
unsigned long kpte_linear_bitmap[KPTE_BITMAP_BYTES / sizeof(unsigned long)];

#define MAX_BANKS 32

static struct linux_prom64_registers pavail[MAX_BANKS] __initdata;
Expand Down Expand Up @@ -119,7 +132,6 @@ unsigned long phys_base __read_mostly;
unsigned long kern_base __read_mostly;
unsigned long kern_size __read_mostly;
unsigned long pfn_base __read_mostly;
unsigned long kern_linear_pte_xor __read_mostly;

/* get_new_mmu_context() uses "cache + 1". */
DEFINE_SPINLOCK(ctx_alloc_lock);
Expand Down Expand Up @@ -878,6 +890,9 @@ unsigned long __init bootmem_init(unsigned long *pages_avail)
return end_pfn;
}

static struct linux_prom64_registers pall[MAX_BANKS] __initdata;
static int pall_ents __initdata;

#ifdef CONFIG_DEBUG_PAGEALLOC
static unsigned long kernel_map_range(unsigned long pstart, unsigned long pend, pgprot_t prot)
{
Expand Down Expand Up @@ -933,14 +948,41 @@ static unsigned long kernel_map_range(unsigned long pstart, unsigned long pend,
return alloc_bytes;
}

static struct linux_prom64_registers pall[MAX_BANKS] __initdata;
static int pall_ents __initdata;

extern unsigned int kvmap_linear_patch[1];
#endif /* CONFIG_DEBUG_PAGEALLOC */

static void __init mark_kpte_bitmap(unsigned long start, unsigned long end)
{
const unsigned long shift_256MB = 28;
const unsigned long mask_256MB = ((1UL << shift_256MB) - 1UL);
const unsigned long size_256MB = (1UL << shift_256MB);

while (start < end) {
long remains;

if (start & mask_256MB) {
start = (start + size_256MB) & ~mask_256MB;
continue;
}

remains = end - start;
while (remains >= size_256MB) {
unsigned long index = start >> shift_256MB;

__set_bit(index, kpte_linear_bitmap);

start += size_256MB;
remains -= size_256MB;
}
}
}

static void __init kernel_physical_mapping_init(void)
{
unsigned long i, mem_alloced = 0UL;
unsigned long i;
#ifdef CONFIG_DEBUG_PAGEALLOC
unsigned long mem_alloced = 0UL;
#endif

read_obp_memory("reg", &pall[0], &pall_ents);

Expand All @@ -949,19 +991,27 @@ static void __init kernel_physical_mapping_init(void)

phys_start = pall[i].phys_addr;
phys_end = phys_start + pall[i].reg_size;

mark_kpte_bitmap(phys_start, phys_end);

#ifdef CONFIG_DEBUG_PAGEALLOC
mem_alloced += kernel_map_range(phys_start, phys_end,
PAGE_KERNEL);
#endif
}

#ifdef CONFIG_DEBUG_PAGEALLOC
printk("Allocated %ld bytes for kernel page tables.\n",
mem_alloced);

kvmap_linear_patch[0] = 0x01000000; /* nop */
flushi(&kvmap_linear_patch[0]);

__flush_tlb_all();
#endif
}

#ifdef CONFIG_DEBUG_PAGEALLOC
void kernel_map_pages(struct page *page, int numpages, int enable)
{
unsigned long phys_start = page_to_pfn(page) << PAGE_SHIFT;
Expand Down Expand Up @@ -1172,9 +1222,7 @@ void __init paging_init(void)
pages_avail = 0;
last_valid_pfn = end_pfn = bootmem_init(&pages_avail);

#ifdef CONFIG_DEBUG_PAGEALLOC
kernel_physical_mapping_init();
#endif

{
unsigned long zones_size[MAX_NR_ZONES];
Expand Down Expand Up @@ -1413,10 +1461,13 @@ static void __init sun4u_pgprot_init(void)
pg_iobits = (_PAGE_VALID | _PAGE_PRESENT_4U | __DIRTY_BITS_4U |
__ACCESS_BITS_4U | _PAGE_E_4U);

kern_linear_pte_xor = (_PAGE_VALID | _PAGE_SZ4MB_4U) ^
kern_linear_pte_xor[0] = (_PAGE_VALID | _PAGE_SZ4MB_4U) ^
0xfffff80000000000;
kern_linear_pte_xor |= (_PAGE_CP_4U | _PAGE_CV_4U |
_PAGE_P_4U | _PAGE_W_4U);
kern_linear_pte_xor[0] |= (_PAGE_CP_4U | _PAGE_CV_4U |
_PAGE_P_4U | _PAGE_W_4U);

/* XXX Should use 256MB on Panther. XXX */
kern_linear_pte_xor[1] = kern_linear_pte_xor[0];

_PAGE_SZBITS = _PAGE_SZBITS_4U;
_PAGE_ALL_SZ_BITS = (_PAGE_SZ4MB_4U | _PAGE_SZ512K_4U |
Expand Down Expand Up @@ -1454,10 +1505,15 @@ static void __init sun4v_pgprot_init(void)
_PAGE_E = _PAGE_E_4V;
_PAGE_CACHE = _PAGE_CACHE_4V;

kern_linear_pte_xor = (_PAGE_VALID | _PAGE_SZ4MB_4V) ^
kern_linear_pte_xor[0] = (_PAGE_VALID | _PAGE_SZ4MB_4V) ^
0xfffff80000000000;
kern_linear_pte_xor[0] |= (_PAGE_CP_4V | _PAGE_CV_4V |
_PAGE_P_4V | _PAGE_W_4V);

kern_linear_pte_xor[1] = (_PAGE_VALID | _PAGE_SZ256MB_4V) ^
0xfffff80000000000;
kern_linear_pte_xor |= (_PAGE_CP_4V | _PAGE_CV_4V |
_PAGE_P_4V | _PAGE_W_4V);
kern_linear_pte_xor[1] |= (_PAGE_CP_4V | _PAGE_CV_4V |
_PAGE_P_4V | _PAGE_W_4V);

pg_iobits = (_PAGE_VALID | _PAGE_PRESENT_4V | __DIRTY_BITS_4V |
__ACCESS_BITS_4V | _PAGE_E_4V);
Expand Down

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