lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

avr32: Store virtual addresses in the PGD

Browse Source 
Instead of storing physical addresses along with page flags in the
PGD, store virtual addresses and use NULL to indicate a not present
second-level page table. A non-page-aligned page table indicates a bad
PMD.

This simplifies the TLB miss handler since it no longer has to check
the Present bit and no longer has to convert the PGD entry from
physical to virtual address. Instead, it has to check for a NULL
entry, which is slightly cheaper than either.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
This commit is contained in:
Haavard Skinnemoen
2008-01-14 22:15:05 +01:00
parent ebe74597a5
commit cfd23e93a0
5 changed files with 51 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
arch/avr32/kernel/entry-avr32b.S
View File

@@ -74,12 +74,6 @@ exception_vectors:
.align 2
bral do_dtlb_modified
/*
* r0 : PGD/PT/PTE
* r1 : Offending address
* r2 : Scratch register
* r3 : Cause (5, 12 or 13)
*/
#define tlbmiss_save pushm r0-r3
#define tlbmiss_restore popm r0-r3
@@ -108,17 +102,17 @@ tlb_miss_common:
bld r0, 31
brcs handle_vmalloc_miss
/* First level lookup */
/*
* First level lookup: The PGD contains virtual pointers to
* the second-level page tables, but they may be NULL if not
* present.
*/
pgtbl_lookup:
lsr r2, r0, PGDIR_SHIFT
ld.w r3, r1[r2 << 2]
bfextu r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
bld r3, _PAGE_BIT_PRESENT
brcc page_table_not_present
/* Translate to virtual address in P1. */
andl r3, 0xf000
sbr r3, 31
cp.w r3, 0
breq page_table_not_present
/* Second level lookup */
ld.w r2, r3[r1 << 2]
@@ -155,6 +149,19 @@ handle_vmalloc_miss:
orh r1, hi(swapper_pg_dir)
rjmp pgtbl_lookup
/* The slow path of the TLB miss handler */
.align 2
page_table_not_present:
page_not_present:
tlbmiss_restore
sub sp, 4
stmts --sp, r0-lr
rcall save_full_context_ex
mfsr r12, SYSREG_ECR
mov r11, sp
rcall do_page_fault
rjmp ret_from_exception
/* --- System Call --- */
@@ -267,18 +274,6 @@ syscall_exit_work:
brcc syscall_exit_cont
rjmp enter_monitor_mode
/* The slow path of the TLB miss handler */
page_table_not_present:
page_not_present:
tlbmiss_restore
sub sp, 4
stmts --sp, r0-lr
rcall save_full_context_ex
mfsr r12, SYSREG_ECR
mov r11, sp
rcall do_page_fault
rjmp ret_from_exception
/* This function expects to find offending PC in SYSREG_RAR_EX */
.type save_full_context_ex, @function
.align 2

4
arch/avr32/kernel/vmlinux.lds.S
View File

@@ -99,6 +99,10 @@ SECTIONS
*/
*(.data.init_task)
/* Then, the page-aligned data */
. = ALIGN(PAGE_SIZE);
*(.data.page_aligned)
/* Then, the cacheline aligned data */
. = ALIGN(L1_CACHE_BYTES);
*(.data.cacheline_aligned)