linux/arch/sparc/lib/clear_page.S
David S. Miller b2d4383480 sparc64: Make PAGE_OFFSET variable.
Choose PAGE_OFFSET dynamically based upon cpu type.

Original UltraSPARC-I (spitfire) chips only supported a 44-bit
virtual address space.

Newer chips (T4 and later) support 52-bit virtual addresses
and up to 47-bits of physical memory space.

Therefore we have to adjust PAGE_SIZE dynamically based upon
the capabilities of the chip.

Note that this change alone does not allow us to support > 43-bit
physical memory, to do that we need to re-arrange our page table
support.  The current encodings of the pmd_t and pgd_t pointers
restricts us to "32 + 11" == 43 bits.

This change can waste quite a bit of memory for the various tables.
In particular, a future change should work to size and allocate
kern_linear_bitmap[] and sparc64_valid_addr_bitmap[] dynamically.
This isn't easy as we really cannot take a TLB miss when accessing
kern_linear_bitmap[].  We'd have to lock it into the TLB or similar.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Bob Picco <bob.picco@oracle.com>
2013-11-12 15:22:34 -08:00

104 lines
2.4 KiB
ArmAsm

/* clear_page.S: UltraSparc optimized clear page.
*
* Copyright (C) 1996, 1998, 1999, 2000, 2004 David S. Miller (davem@redhat.com)
* Copyright (C) 1997 Jakub Jelinek (jakub@redhat.com)
*/
#include <asm/visasm.h>
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/spitfire.h>
#include <asm/head.h>
/* What we used to do was lock a TLB entry into a specific
* TLB slot, clear the page with interrupts disabled, then
* restore the original TLB entry. This was great for
* disturbing the TLB as little as possible, but it meant
* we had to keep interrupts disabled for a long time.
*
* Now, we simply use the normal TLB loading mechanism,
* and this makes the cpu choose a slot all by itself.
* Then we do a normal TLB flush on exit. We need only
* disable preemption during the clear.
*/
.text
.globl _clear_page
_clear_page: /* %o0=dest */
ba,pt %xcc, clear_page_common
clr %o4
/* This thing is pretty important, it shows up
* on the profiles via do_anonymous_page().
*/
.align 32
.globl clear_user_page
clear_user_page: /* %o0=dest, %o1=vaddr */
lduw [%g6 + TI_PRE_COUNT], %o2
sethi %hi(PAGE_OFFSET), %g2
sethi %hi(PAGE_SIZE), %o4
ldx [%g2 + %lo(PAGE_OFFSET)], %g2
sethi %hi(PAGE_KERNEL_LOCKED), %g3
ldx [%g3 + %lo(PAGE_KERNEL_LOCKED)], %g3
sub %o0, %g2, %g1 ! paddr
and %o1, %o4, %o0 ! vaddr D-cache alias bit
or %g1, %g3, %g1 ! TTE data
sethi %hi(TLBTEMP_BASE), %o3
add %o2, 1, %o4
add %o0, %o3, %o0 ! TTE vaddr
/* Disable preemption. */
mov TLB_TAG_ACCESS, %g3
stw %o4, [%g6 + TI_PRE_COUNT]
/* Load TLB entry. */
rdpr %pstate, %o4
wrpr %o4, PSTATE_IE, %pstate
stxa %o0, [%g3] ASI_DMMU
stxa %g1, [%g0] ASI_DTLB_DATA_IN
sethi %hi(KERNBASE), %g1
flush %g1
wrpr %o4, 0x0, %pstate
mov 1, %o4
clear_page_common:
VISEntryHalf
membar #StoreLoad | #StoreStore | #LoadStore
fzero %f0
sethi %hi(PAGE_SIZE/64), %o1
mov %o0, %g1 ! remember vaddr for tlbflush
fzero %f2
or %o1, %lo(PAGE_SIZE/64), %o1
faddd %f0, %f2, %f4
fmuld %f0, %f2, %f6
faddd %f0, %f2, %f8
fmuld %f0, %f2, %f10
faddd %f0, %f2, %f12
fmuld %f0, %f2, %f14
1: stda %f0, [%o0 + %g0] ASI_BLK_P
subcc %o1, 1, %o1
bne,pt %icc, 1b
add %o0, 0x40, %o0
membar #Sync
VISExitHalf
brz,pn %o4, out
nop
stxa %g0, [%g1] ASI_DMMU_DEMAP
membar #Sync
stw %o2, [%g6 + TI_PRE_COUNT]
out: retl
nop