From 7f0536f80cfbefd753eb123ed20940978f223900 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sun, 6 May 2007 14:51:30 -0700 Subject: uml: speed up page table walking The previous page table walking code was horribly inefficient. This patch replaces it with code taken from elsewhere in the kernel. Forking from bash is now ~5% faster and page faults are handled ~10% faster. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/tlb.c | 202 ++++++++++++++++++++++++++++++--------------------- 1 file changed, 120 insertions(+), 82 deletions(-) (limited to 'arch/um') diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c index e40f3352bd2..153dec13cf9 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -6,6 +6,7 @@ #include "linux/mm.h" #include "asm/page.h" #include "asm/pgalloc.h" +#include "asm/pgtable.h" #include "asm/tlbflush.h" #include "choose-mode.h" #include "mode_kern.h" @@ -123,106 +124,143 @@ static int add_mprotect(unsigned long addr, unsigned long len, int r, int w, #define ADD_ROUND(n, inc) (((n) + (inc)) & ~((inc) - 1)) +static inline int update_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end, struct host_vm_op *ops, + int last_op, int *op_index, int force, + union mm_context *mmu, void **flush, + int (*do_ops)(union mm_context *, + struct host_vm_op *, int, int, + void **)) +{ + pte_t *pte; + int r, w, x, ret = 0; + + pte = pte_offset_kernel(pmd, addr); + do { + r = pte_read(*pte); + w = pte_write(*pte); + x = pte_exec(*pte); + if (!pte_young(*pte)) { + r = 0; + w = 0; + } else if (!pte_dirty(*pte)) { + w = 0; + } + if(force || pte_newpage(*pte)){ + if(pte_present(*pte)) + ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK, + PAGE_SIZE, r, w, x, ops, + op_index, last_op, mmu, flush, + do_ops); + else ret = add_munmap(addr, PAGE_SIZE, ops, op_index, + last_op, mmu, flush, do_ops); + } + else if(pte_newprot(*pte)) + ret = add_mprotect(addr, PAGE_SIZE, r, w, x, ops, + op_index, last_op, mmu, flush, + do_ops); + *pte = pte_mkuptodate(*pte); + } while (pte++, addr += PAGE_SIZE, ((addr != end) && !ret)); + return ret; +} + +static inline int update_pmd_range(pud_t *pud, unsigned long addr, + unsigned long end, struct host_vm_op *ops, + int last_op, int *op_index, int force, + union mm_context *mmu, void **flush, + int (*do_ops)(union mm_context *, + struct host_vm_op *, int, int, + void **)) +{ + pmd_t *pmd; + unsigned long next; + int ret = 0; + + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if(!pmd_present(*pmd)){ + if(force || pmd_newpage(*pmd)){ + ret = add_munmap(addr, next - addr, ops, + op_index, last_op, mmu, + flush, do_ops); + pmd_mkuptodate(*pmd); + } + } + else ret = update_pte_range(pmd, addr, next, ops, last_op, + op_index, force, mmu, flush, + do_ops); + } while (pmd++, addr = next, ((addr != end) && !ret)); + return ret; +} + +static inline int update_pud_range(pgd_t *pgd, unsigned long addr, + unsigned long end, struct host_vm_op *ops, + int last_op, int *op_index, int force, + union mm_context *mmu, void **flush, + int (*do_ops)(union mm_context *, + struct host_vm_op *, int, int, + void **)) +{ + pud_t *pud; + unsigned long next; + int ret = 0; + + pud = pud_offset(pgd, addr); + do { + next = pud_addr_end(addr, end); + if(!pud_present(*pud)){ + if(force || pud_newpage(*pud)){ + ret = add_munmap(addr, next - addr, ops, + op_index, last_op, mmu, + flush, do_ops); + pud_mkuptodate(*pud); + } + } + else ret = update_pmd_range(pud, addr, next, ops, last_op, + op_index, force, mmu, flush, + do_ops); + } while (pud++, addr = next, ((addr != end) && !ret)); + return ret; +} + void fix_range_common(struct mm_struct *mm, unsigned long start_addr, unsigned long end_addr, int force, int (*do_ops)(union mm_context *, struct host_vm_op *, int, int, void **)) { - pgd_t *npgd; - pud_t *npud; - pmd_t *npmd; - pte_t *npte; + pgd_t *pgd; union mm_context *mmu = &mm->context; - unsigned long addr, end; - int r, w, x; struct host_vm_op ops[1]; + unsigned long addr = start_addr, next; + int ret = 0, last_op = ARRAY_SIZE(ops) - 1, op_index = -1; void *flush = NULL; - int op_index = -1, last_op = ARRAY_SIZE(ops) - 1; - int ret = 0; - - if(mm == NULL) - return; + unsigned long long start_time, end_time; + start_time = os_nsecs(); ops[0].type = NONE; - for(addr = start_addr; addr < end_addr && !ret;){ - npgd = pgd_offset(mm, addr); - if(!pgd_present(*npgd)){ - end = ADD_ROUND(addr, PGDIR_SIZE); - if(end > end_addr) - end = end_addr; - if(force || pgd_newpage(*npgd)){ - ret = add_munmap(addr, end - addr, ops, - &op_index, last_op, mmu, - &flush, do_ops); - pgd_mkuptodate(*npgd); - } - addr = end; - continue; - } - - npud = pud_offset(npgd, addr); - if(!pud_present(*npud)){ - end = ADD_ROUND(addr, PUD_SIZE); - if(end > end_addr) - end = end_addr; - if(force || pud_newpage(*npud)){ - ret = add_munmap(addr, end - addr, ops, - &op_index, last_op, mmu, - &flush, do_ops); - pud_mkuptodate(*npud); - } - addr = end; - continue; - } - - npmd = pmd_offset(npud, addr); - if(!pmd_present(*npmd)){ - end = ADD_ROUND(addr, PMD_SIZE); - if(end > end_addr) - end = end_addr; - if(force || pmd_newpage(*npmd)){ - ret = add_munmap(addr, end - addr, ops, + pgd = pgd_offset(mm, addr); + do { + next = pgd_addr_end(addr, end_addr); + if(!pgd_present(*pgd)){ + if (force || pgd_newpage(*pgd)){ + ret = add_munmap(addr, next - addr, ops, &op_index, last_op, mmu, &flush, do_ops); - pmd_mkuptodate(*npmd); + pgd_mkuptodate(*pgd); } - addr = end; - continue; } + else ret = update_pud_range(pgd, addr, next, ops, last_op, + &op_index, force, mmu, &flush, + do_ops); + } while (pgd++, addr = next, ((addr != end_addr) && !ret)); + end_time = os_nsecs(); + log_info("total flush time - %Ld nsecs\n", end_time - start_time); - npte = pte_offset_kernel(npmd, addr); - r = pte_read(*npte); - w = pte_write(*npte); - x = pte_exec(*npte); - if (!pte_young(*npte)) { - r = 0; - w = 0; - } else if (!pte_dirty(*npte)) { - w = 0; - } - if(force || pte_newpage(*npte)){ - if(pte_present(*npte)) - ret = add_mmap(addr, - pte_val(*npte) & PAGE_MASK, - PAGE_SIZE, r, w, x, ops, - &op_index, last_op, mmu, - &flush, do_ops); - else ret = add_munmap(addr, PAGE_SIZE, ops, - &op_index, last_op, mmu, - &flush, do_ops); - } - else if(pte_newprot(*npte)) - ret = add_mprotect(addr, PAGE_SIZE, r, w, x, ops, - &op_index, last_op, mmu, - &flush, do_ops); - - *npte = pte_mkuptodate(*npte); - addr += PAGE_SIZE; - } if(!ret) ret = (*do_ops)(mmu, ops, op_index, 1, &flush); -/* This is not an else because ret is modified above */ + /* This is not an else because ret is modified above */ if(ret) { printk("fix_range_common: failed, killing current process\n"); force_sig(SIGKILL, current); -- cgit v1.2.3