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authorHaavard Skinnemoen <haavard.skinnemoen@atmel.com>2008-01-14 22:15:05 +0100
committerHaavard Skinnemoen <haavard.skinnemoen@atmel.com>2008-07-02 11:01:28 +0200
commitcfd23e93a0289cf6711fd3877c5226658d87240a (patch)
tree1030f0ee5ccd59d1d80b2b5fdc892987f90fac8e /arch
parentebe74597a55fef00edc80a414ef5c6477d035e0a (diff)
downloadlinux-cfd23e93a0289cf6711fd3877c5226658d87240a.tar.gz
linux-cfd23e93a0289cf6711fd3877c5226658d87240a.tar.xz
avr32: Store virtual addresses in the PGD
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/avr32/kernel/entry-avr32b.S45
-rw-r--r--arch/avr32/kernel/vmlinux.lds.S4
-rw-r--r--arch/avr32/mm/init.c4
3 files changed, 27 insertions, 26 deletions
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 050c006a7f0c..3cdd7071f35e 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -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
diff --git a/arch/avr32/kernel/vmlinux.lds.S b/arch/avr32/kernel/vmlinux.lds.S
index 033dd46bfa62..5d25d8eeb750 100644
--- a/arch/avr32/kernel/vmlinux.lds.S
+++ b/arch/avr32/kernel/vmlinux.lds.S
@@ -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)
diff --git a/arch/avr32/mm/init.c b/arch/avr32/mm/init.c
index 0e77578c358d..3f90a87527bb 100644
--- a/arch/avr32/mm/init.c
+++ b/arch/avr32/mm/init.c
@@ -24,9 +24,11 @@
#include <asm/setup.h>
#include <asm/sections.h>
+#define __page_aligned __attribute__((section(".data.page_aligned")))
+
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-pgd_t swapper_pg_dir[PTRS_PER_PGD];
+pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned;
struct page *empty_zero_page;
EXPORT_SYMBOL(empty_zero_page);