uml: speed page fault path
Give the page fault code a specialized path. There is only one page to look
at, so there's no point in going into the general page table walking code.
There's only going to be one host operation, so there are no opportunities for
merging. So, we go straight to the pte we want, figure out what needs doing,
and do it.
While I was in here, I fixed the wart where the address passed to unmap was a
void *, but an unsigned long to map and protect.
This gives me just under 10% on a kernel build.
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>
diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index d663809..e11bdcd 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -302,7 +302,7 @@
extern int map(struct mm_id * mm_idp, unsigned long virt,
unsigned long len, int r, int w, int x, int phys_fd,
unsigned long long offset, int done, void **data);
-extern int unmap(struct mm_id * mm_idp, void *addr, unsigned long len,
+extern int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
int done, void **data);
extern int protect(struct mm_id * mm_idp, unsigned long addr,
unsigned long len, int r, int w, int x, int done,
diff --git a/arch/um/include/skas/mode_kern_skas.h b/arch/um/include/skas/mode_kern_skas.h
index 9cd9c6e..8ee6285 100644
--- a/arch/um/include/skas/mode_kern_skas.h
+++ b/arch/um/include/skas/mode_kern_skas.h
@@ -33,6 +33,8 @@
extern int start_uml_skas(void);
extern int external_pid_skas(struct task_struct *task);
extern int thread_pid_skas(struct task_struct *task);
+extern void flush_tlb_page_skas(struct vm_area_struct *vma,
+ unsigned long address);
#define kmem_end_skas (host_task_size - 1024 * 1024)
diff --git a/arch/um/kernel/skas/tlb.c b/arch/um/kernel/skas/tlb.c
index 304a5b0..c43901a 100644
--- a/arch/um/kernel/skas/tlb.c
+++ b/arch/um/kernel/skas/tlb.c
@@ -32,8 +32,7 @@
op->u.mmap.offset, finished, flush);
break;
case MUNMAP:
- ret = unmap(&mmu->skas.id,
- (void *) op->u.munmap.addr,
+ ret = unmap(&mmu->skas.id, op->u.munmap.addr,
op->u.munmap.len, finished, flush);
break;
case MPROTECT:
@@ -94,3 +93,66 @@
unsigned long end = proc_mm ? task_size : CONFIG_STUB_START;
fix_range(current->mm, 0, end, 1);
}
+
+void flush_tlb_page_skas(struct vm_area_struct *vma, unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ struct mm_struct *mm = vma->vm_mm;
+ void *flush = NULL;
+ int r, w, x, err = 0;
+ struct mm_id *mm_id;
+
+ pgd = pgd_offset(vma->vm_mm, address);
+ if(!pgd_present(*pgd))
+ goto kill;
+
+ pud = pud_offset(pgd, address);
+ if(!pud_present(*pud))
+ goto kill;
+
+ pmd = pmd_offset(pud, address);
+ if(!pmd_present(*pmd))
+ goto kill;
+
+ pte = pte_offset_kernel(pmd, address);
+
+ 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;
+ }
+
+ mm_id = &mm->context.skas.id;
+ if(pte_newpage(*pte)){
+ if(pte_present(*pte)){
+ unsigned long long offset;
+ int fd;
+
+ fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
+ err = map(mm_id, address, PAGE_SIZE, r, w, x, fd,
+ offset, 1, &flush);
+ }
+ else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
+ }
+ else if(pte_newprot(*pte))
+ err = protect(mm_id, address, PAGE_SIZE, r, w, x, 1, &flush);
+
+ if(err)
+ goto kill;
+
+ *pte = pte_mkuptodate(*pte);
+
+ return;
+
+kill:
+ printk("Failed to flush page for address 0x%lx\n", address);
+ force_sig(SIGKILL, current);
+}
+
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index e201ccf..00de86e 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -381,7 +381,9 @@
void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
{
address &= PAGE_MASK;
- flush_tlb_range(vma, address, address + PAGE_SIZE);
+
+ CHOOSE_MODE(flush_tlb_range(vma, address, address + PAGE_SIZE),
+ flush_tlb_page_skas(vma, address));
}
void flush_tlb_all(void)
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index 6cdfda8..af07907 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -219,8 +219,8 @@
return ret;
}
-int unmap(struct mm_id * mm_idp, void *addr, unsigned long len, int done,
- void **data)
+int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
+ int done, void **data)
{
int ret;
