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sh: TLB miss fast-path optimizations. 

Handle simple TLB miss faults which can be resolved completely
from the page table in assembler.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy 2006-11-24 11:42:24 +09:00 committed by Paul Mundt
parent 9daa0c257d
commit 9b3a53ab76
6 changed files with 204 additions and 117 deletions
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3
arch/sh/Kconfig
View File

@ -379,6 +379,9 @@ config CPU_HAS_SR_RB
See <file:Documentation/sh/register-banks.txt> for further
information on SR.RB and register banking in the kernel in general.
config CPU_HAS_PTEA
bool
endmenu
menu "Timer support"

206
arch/sh/kernel/cpu/sh3/entry.S
View File

@ -13,8 +13,10 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/cpu/mmu_context.h>
#include <asm/unistd.h>
#include <asm/cpu/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/page.h>
! NOTE:
! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
@ -136,29 +138,14 @@ ENTRY(tlb_protection_violation_store)
call_dpf:
mov.l 1f, r0
mov r5, r8
mov.l @r0, r6
mov r6, r9
mov.l 2f, r0
sts pr, r10
jsr @r0
mov r15, r4
!
tst r0, r0
bf/s 0f
lds r10, pr
rts
nop
0: sti
mov.l @r0, r6 ! address
mov.l 3f, r0
mov r9, r6
mov r8, r5
sti
jmp @r0
mov r15, r4
mov r15, r4 ! regs
.align 2
1: .long MMU_TEA
2: .long __do_page_fault
3: .long do_page_fault
.align 2
@ -344,9 +331,176 @@ general_exception:
2: .long ret_from_exception
!
!
/* This code makes some assumptions to improve performance.
* Make sure they are stil true. */
#if PTRS_PER_PGD != PTRS_PER_PTE
#error PDG and PTE sizes don't match
#endif
/* gas doesn't flag impossible values for mov #immediate as an error */
#if (_PAGE_PRESENT >> 2) > 0x7f
#error cannot load PAGE_PRESENT as an immediate
#endif
#if _PAGE_DIRTY > 0x7f
#error cannot load PAGE_DIRTY as an immediate
#endif
#if (_PAGE_PRESENT << 2) != _PAGE_ACCESSED
#error cannot derive PAGE_ACCESSED from PAGE_PRESENT
#endif
#if defined(CONFIG_CPU_SH4)
#define ldmmupteh(r) mov.l 8f, r
#else
#define ldmmupteh(r) mov #MMU_PTEH, r
#endif
.balign 1024,0,1024
tlb_miss:
mov.l 1f, k2
#ifdef COUNT_EXCEPTIONS
! Increment the counts
mov.l 9f, k1
mov.l @k1, k2
add #1, k2
mov.l k2, @k1
#endif
! k0 scratch
! k1 pgd and pte pointers
! k2 faulting address
! k3 pgd and pte index masks
! k4 shift
! Load up the pgd entry (k1)
ldmmupteh(k0) ! 9 LS (latency=2) MMU_PTEH
mov.w 4f, k3 ! 8 LS (latency=2) (PTRS_PER_PGD-1) << 2
mov #-(PGDIR_SHIFT-2), k4 ! 6 EX
mov.l @(MMU_TEA-MMU_PTEH,k0), k2 ! 18 LS (latency=2)
mov.l @(MMU_TTB-MMU_PTEH,k0), k1 ! 18 LS (latency=2)
mov k2, k0 ! 5 MT (latency=0)
shld k4, k0 ! 99 EX
and k3, k0 ! 78 EX
mov.l @(k0, k1), k1 ! 21 LS (latency=2)
mov #-(PAGE_SHIFT-2), k4 ! 6 EX
! Load up the pte entry (k2)
mov k2, k0 ! 5 MT (latency=0)
shld k4, k0 ! 99 EX
tst k1, k1 ! 86 MT
bt 20f ! 110 BR
and k3, k0 ! 78 EX
mov.w 5f, k4 ! 8 LS (latency=2) _PAGE_PRESENT
mov.l @(k0, k1), k2 ! 21 LS (latency=2)
add k0, k1 ! 49 EX
#ifdef CONFIG_CPU_HAS_PTEA
! Test the entry for present and _PAGE_ACCESSED
mov #-28, k3 ! 6 EX
mov k2, k0 ! 5 MT (latency=0)
tst k4, k2 ! 68 MT
shld k3, k0 ! 99 EX
bt 20f ! 110 BR
! Set PTEA register
! MMU_PTEA = ((pteval >> 28) & 0xe) | (pteval & 0x1)
!
! k0=pte>>28, k1=pte*, k2=pte, k3=<unused>, k4=_PAGE_PRESENT
and #0xe, k0 ! 79 EX
mov k0, k3 ! 5 MT (latency=0)
mov k2, k0 ! 5 MT (latency=0)
and #1, k0 ! 79 EX
or k0, k3 ! 82 EX
ldmmupteh(k0) ! 9 LS (latency=2)
shll2 k4 ! 101 EX _PAGE_ACCESSED
tst k4, k2 ! 68 MT
mov.l k3, @(MMU_PTEA-MMU_PTEH,k0) ! 27 LS
mov.l 7f, k3 ! 9 LS (latency=2) _PAGE_FLAGS_HARDWARE_MASK
! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
#else
! Test the entry for present and _PAGE_ACCESSED
mov.l 7f, k3 ! 9 LS (latency=2) _PAGE_FLAGS_HARDWARE_MASK
tst k4, k2 ! 68 MT
shll2 k4 ! 101 EX _PAGE_ACCESSED
ldmmupteh(k0) ! 9 LS (latency=2)
bt 20f ! 110 BR
tst k4, k2 ! 68 MT
! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
#endif
! Set up the entry
and k2, k3 ! 78 EX
bt/s 10f ! 108 BR
mov.l k3, @(MMU_PTEL-MMU_PTEH,k0) ! 27 LS
ldtlb ! 128 CO
! At least one instruction between ldtlb and rte
nop ! 119 NOP
rte ! 126 CO
nop ! 119 NOP
10: or k4, k2 ! 82 EX
ldtlb ! 128 CO
! At least one instruction between ldtlb and rte
mov.l k2, @k1 ! 27 LS
rte ! 126 CO
! Note we cannot execute mov here, because it is executed after
! restoring SSR, so would be executed in user space.
nop ! 119 NOP
.align 5
! Once cache line if possible...
1: .long swapper_pg_dir
4: .short (PTRS_PER_PGD-1) << 2
5: .short _PAGE_PRESENT
7: .long _PAGE_FLAGS_HARDWARE_MASK
8: .long MMU_PTEH
#ifdef COUNT_EXCEPTIONS
9: .long exception_count_miss
#endif
! Either pgd or pte not present
20: mov.l 1f, k2
mov.l 4f, k3
bra handle_exception
mov.l @k2, k2
@ -496,6 +650,15 @@ skip_save:
bf interrupt_exception
shlr2 r8
shlr r8
#ifdef COUNT_EXCEPTIONS
mov.l 5f, r9
add r8, r9
mov.l @r9, r10
add #1, r10
mov.l r10, @r9
#endif
mov.l 4f, r9
add r8, r9
mov.l @r9, r9
@ -509,6 +672,9 @@ skip_save:
2: .long 0x000080f0 ! FD=1, IMASK=15
3: .long 0xcfffffff ! RB=0, BL=0
4: .long exception_handling_table
#ifdef COUNT_EXCEPTIONS
5: .long exception_count_table
#endif
interrupt_exception:
mov.l 1f, r9

19
arch/sh/kernel/cpu/sh4/probe.c
View File

@ -79,16 +79,16 @@ int __init detect_cpu_and_cache_system(void)
case 0x205:
cpu_data->type = CPU_SH7750;
cpu_data->flags |= CPU_HAS_P2_FLUSH_BUG | CPU_HAS_FPU |
CPU_HAS_PERF_COUNTER | CPU_HAS_PTEA;
CPU_HAS_PERF_COUNTER;
break;
case 0x206:
cpu_data->type = CPU_SH7750S;
cpu_data->flags |= CPU_HAS_P2_FLUSH_BUG | CPU_HAS_FPU |
CPU_HAS_PERF_COUNTER | CPU_HAS_PTEA;
CPU_HAS_PERF_COUNTER;
break;
case 0x1100:
cpu_data->type = CPU_SH7751;
cpu_data->flags |= CPU_HAS_FPU | CPU_HAS_PTEA;
cpu_data->flags |= CPU_HAS_FPU;
break;
case 0x2000:
cpu_data->type = CPU_SH73180;
@ -126,23 +126,22 @@ int __init detect_cpu_and_cache_system(void)
break;
case 0x8000:
cpu_data->type = CPU_ST40RA;
cpu_data->flags |= CPU_HAS_FPU | CPU_HAS_PTEA;
cpu_data->flags |= CPU_HAS_FPU;
break;
case 0x8100:
cpu_data->type = CPU_ST40GX1;
cpu_data->flags |= CPU_HAS_FPU | CPU_HAS_PTEA;
cpu_data->flags |= CPU_HAS_FPU;
break;
case 0x700:
cpu_data->type = CPU_SH4_501;
cpu_data->icache.ways = 2;
cpu_data->dcache.ways = 2;
cpu_data->flags |= CPU_HAS_PTEA;
break;
case 0x600:
cpu_data->type = CPU_SH4_202;
cpu_data->icache.ways = 2;
cpu_data->dcache.ways = 2;
cpu_data->flags |= CPU_HAS_FPU | CPU_HAS_PTEA;
cpu_data->flags |= CPU_HAS_FPU;
break;
case 0x500 ... 0x501:
switch (prr) {
@ -160,7 +159,7 @@ int __init detect_cpu_and_cache_system(void)
cpu_data->icache.ways = 2;
cpu_data->dcache.ways = 2;
cpu_data->flags |= CPU_HAS_FPU | CPU_HAS_PTEA;
cpu_data->flags |= CPU_HAS_FPU;
break;
default:
@ -173,6 +172,10 @@ int __init detect_cpu_and_cache_system(void)
cpu_data->dcache.ways = 1;
#endif
#ifdef CONFIG_CPU_HAS_PTEA
cpu_data->flags |= CPU_HAS_PTEA;
#endif
/*
* On anything that's not a direct-mapped cache, look to the CVR
* for I/D-cache specifics.

1
arch/sh/mm/Kconfig
View File

@ -20,6 +20,7 @@ config CPU_SH4
bool
select CPU_HAS_INTEVT
select CPU_HAS_SR_RB
select CPU_HAS_PTEA if !CPU_SUBTYPE_ST40
config CPU_SH4A
bool

86
arch/sh/mm/fault.c
View File

@ -223,89 +223,3 @@ do_sigbus:
if (!user_mode(regs))
goto no_context;
}
#ifdef CONFIG_SH_STORE_QUEUES
/*
* This is a special case for the SH-4 store queues, as pages for this
* space still need to be faulted in before it's possible to flush the
* store queue cache for writeout to the remapped region.
*/
#define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000)
#else
#define P3_ADDR_MAX P4SEG
#endif
/*
* Called with interrupts disabled.
*/
asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pte_t entry;
struct mm_struct *mm = current->mm;
spinlock_t *ptl;
int ret = 1;
#ifdef CONFIG_SH_KGDB
if (kgdb_nofault && kgdb_bus_err_hook)
kgdb_bus_err_hook();
#endif
/*
* We don't take page faults for P1, P2, and parts of P4, these
* are always mapped, whether it be due to legacy behaviour in
* 29-bit mode, or due to PMB configuration in 32-bit mode.
*/
if (address >= P3SEG && address < P3_ADDR_MAX) {
pgd = pgd_offset_k(address);
mm = NULL;
} else {
if (unlikely(address >= TASK_SIZE || !mm))
return 1;
pgd = pgd_offset(mm, address);
}
pud = pud_offset(pgd, address);
if (pud_none_or_clear_bad(pud))
return 1;
pmd = pmd_offset(pud, address);
if (pmd_none_or_clear_bad(pmd))
return 1;
if (mm)
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
else
pte = pte_offset_kernel(pmd, address);
entry = *pte;
if (unlikely(pte_none(entry) || pte_not_present(entry)))
goto unlock;
if (unlikely(writeaccess && !pte_write(entry)))
goto unlock;
if (writeaccess)
entry = pte_mkdirty(entry);
entry = pte_mkyoung(entry);
#ifdef CONFIG_CPU_SH4
/*
* ITLB is not affected by "ldtlb" instruction.
* So, we need to flush the entry by ourselves.
*/
__flush_tlb_page(get_asid(), address & PAGE_MASK);
#endif
set_pte(pte, entry);
update_mmu_cache(NULL, address, entry);
ret = 0;
unlock:
if (mm)
pte_unmap_unlock(pte, ptl);
return ret;
}

6
include/asm-sh/pgtable.h
View File

@ -43,12 +43,12 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
/* PGD bits */
#define PGDIR_SHIFT (PTE_SHIFT + PTE_BITS)
#define PGDIR_BITS (32 - PGDIR_SHIFT)
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_SIZE (1 << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/* Entries per level */
#define PTRS_PER_PTE (1UL << PTE_BITS)
#define PTRS_PER_PGD (1UL << PGDIR_BITS)
#define PTRS_PER_PTE (1 << PTE_BITS)
#define PTRS_PER_PGD (1 << PGDIR_BITS)
#define USER_PTRS_PER_PGD (TASK_SIZE/PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0