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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 <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Dike
Linus Torvalds
parent
f30c2c983e
commit
7f0536f80c
@ -6,6 +6,7 @@
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#include "linux/mm.h"
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#include "asm/page.h"
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#include "asm/pgalloc.h"
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#include "asm/pgtable.h"
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#include "asm/tlbflush.h"
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#include "choose-mode.h"
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#include "mode_kern.h"
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@ -123,106 +124,143 @@ static int add_mprotect(unsigned long addr, unsigned long len, int r, int w,
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#define ADD_ROUND(n, inc) (((n) + (inc)) & ~((inc) - 1))
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static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
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unsigned long end, struct host_vm_op *ops,
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int last_op, int *op_index, int force,
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union mm_context *mmu, void **flush,
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int (*do_ops)(union mm_context *,
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struct host_vm_op *, int, int,
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void **))
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{
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pte_t *pte;
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int r, w, x, ret = 0;
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pte = pte_offset_kernel(pmd, addr);
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do {
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r = pte_read(*pte);
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w = pte_write(*pte);
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x = pte_exec(*pte);
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if (!pte_young(*pte)) {
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r = 0;
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w = 0;
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} else if (!pte_dirty(*pte)) {
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w = 0;
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}
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if(force || pte_newpage(*pte)){
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if(pte_present(*pte))
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ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
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PAGE_SIZE, r, w, x, ops,
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op_index, last_op, mmu, flush,
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do_ops);
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else ret = add_munmap(addr, PAGE_SIZE, ops, op_index,
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last_op, mmu, flush, do_ops);
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}
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else if(pte_newprot(*pte))
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ret = add_mprotect(addr, PAGE_SIZE, r, w, x, ops,
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op_index, last_op, mmu, flush,
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do_ops);
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*pte = pte_mkuptodate(*pte);
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} while (pte++, addr += PAGE_SIZE, ((addr != end) && !ret));
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return ret;
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}
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static inline int update_pmd_range(pud_t *pud, unsigned long addr,
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unsigned long end, struct host_vm_op *ops,
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int last_op, int *op_index, int force,
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union mm_context *mmu, void **flush,
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int (*do_ops)(union mm_context *,
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struct host_vm_op *, int, int,
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void **))
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{
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pmd_t *pmd;
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unsigned long next;
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int ret = 0;
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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if(!pmd_present(*pmd)){
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if(force || pmd_newpage(*pmd)){
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ret = add_munmap(addr, next - addr, ops,
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op_index, last_op, mmu,
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flush, do_ops);
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pmd_mkuptodate(*pmd);
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}
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}
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else ret = update_pte_range(pmd, addr, next, ops, last_op,
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op_index, force, mmu, flush,
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do_ops);
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} while (pmd++, addr = next, ((addr != end) && !ret));
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return ret;
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}
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static inline int update_pud_range(pgd_t *pgd, unsigned long addr,
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unsigned long end, struct host_vm_op *ops,
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int last_op, int *op_index, int force,
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union mm_context *mmu, void **flush,
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int (*do_ops)(union mm_context *,
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struct host_vm_op *, int, int,
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void **))
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{
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pud_t *pud;
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unsigned long next;
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int ret = 0;
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pud = pud_offset(pgd, addr);
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do {
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next = pud_addr_end(addr, end);
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if(!pud_present(*pud)){
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if(force || pud_newpage(*pud)){
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ret = add_munmap(addr, next - addr, ops,
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op_index, last_op, mmu,
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flush, do_ops);
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pud_mkuptodate(*pud);
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}
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}
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else ret = update_pmd_range(pud, addr, next, ops, last_op,
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op_index, force, mmu, flush,
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do_ops);
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} while (pud++, addr = next, ((addr != end) && !ret));
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return ret;
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}
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void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
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unsigned long end_addr, int force,
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int (*do_ops)(union mm_context *, struct host_vm_op *,
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int, int, void **))
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{
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pgd_t *npgd;
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pud_t *npud;
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pmd_t *npmd;
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pte_t *npte;
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pgd_t *pgd;
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union mm_context *mmu = &mm->context;
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unsigned long addr, end;
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int r, w, x;
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struct host_vm_op ops[1];
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unsigned long addr = start_addr, next;
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int ret = 0, last_op = ARRAY_SIZE(ops) - 1, op_index = -1;
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void *flush = NULL;
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int op_index = -1, last_op = ARRAY_SIZE(ops) - 1;
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int ret = 0;
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if(mm == NULL)
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return;
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unsigned long long start_time, end_time;
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start_time = os_nsecs();
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ops[0].type = NONE;
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for(addr = start_addr; addr < end_addr && !ret;){
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npgd = pgd_offset(mm, addr);
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if(!pgd_present(*npgd)){
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end = ADD_ROUND(addr, PGDIR_SIZE);
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if(end > end_addr)
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end = end_addr;
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if(force || pgd_newpage(*npgd)){
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ret = add_munmap(addr, end - addr, ops,
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pgd = pgd_offset(mm, addr);
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do {
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next = pgd_addr_end(addr, end_addr);
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if(!pgd_present(*pgd)){
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if (force || pgd_newpage(*pgd)){
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ret = add_munmap(addr, next - addr, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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pgd_mkuptodate(*npgd);
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pgd_mkuptodate(*pgd);
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}
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addr = end;
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continue;
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}
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else ret = update_pud_range(pgd, addr, next, ops, last_op,
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&op_index, force, mmu, &flush,
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do_ops);
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} while (pgd++, addr = next, ((addr != end_addr) && !ret));
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end_time = os_nsecs();
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log_info("total flush time - %Ld nsecs\n", end_time - start_time);
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npud = pud_offset(npgd, addr);
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if(!pud_present(*npud)){
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end = ADD_ROUND(addr, PUD_SIZE);
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if(end > end_addr)
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end = end_addr;
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if(force || pud_newpage(*npud)){
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ret = add_munmap(addr, end - addr, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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pud_mkuptodate(*npud);
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}
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addr = end;
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continue;
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}
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npmd = pmd_offset(npud, addr);
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if(!pmd_present(*npmd)){
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end = ADD_ROUND(addr, PMD_SIZE);
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if(end > end_addr)
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end = end_addr;
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if(force || pmd_newpage(*npmd)){
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ret = add_munmap(addr, end - addr, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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pmd_mkuptodate(*npmd);
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}
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addr = end;
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continue;
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}
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npte = pte_offset_kernel(npmd, addr);
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r = pte_read(*npte);
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w = pte_write(*npte);
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x = pte_exec(*npte);
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if (!pte_young(*npte)) {
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r = 0;
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w = 0;
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} else if (!pte_dirty(*npte)) {
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w = 0;
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}
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if(force || pte_newpage(*npte)){
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if(pte_present(*npte))
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ret = add_mmap(addr,
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pte_val(*npte) & PAGE_MASK,
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PAGE_SIZE, r, w, x, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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else ret = add_munmap(addr, PAGE_SIZE, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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}
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else if(pte_newprot(*npte))
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ret = add_mprotect(addr, PAGE_SIZE, r, w, x, ops,
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&op_index, last_op, mmu,
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&flush, do_ops);
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*npte = pte_mkuptodate(*npte);
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addr += PAGE_SIZE;
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}
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if(!ret)
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ret = (*do_ops)(mmu, ops, op_index, 1, &flush);
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/* This is not an else because ret is modified above */
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/* This is not an else because ret is modified above */
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if(ret) {
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printk("fix_range_common: failed, killing current process\n");
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force_sig(SIGKILL, current);
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