[PATCH] uml: avoid already done dirtying

[pandora-kernel.git] / arch / um / kernel / trap_kern.c

diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c
index c20aef1..87cc6fd 100644 (file)
--- a/arch/um/kernel/trap_kern.c
+++ b/arch/um/kernel/trap_kern.c
@@ -26,6 +26,7 @@
 #include "mem.h"
 #include "mem_kern.h"
 
+/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
 int handle_page_fault(unsigned long address, unsigned long ip, 
                      int is_write, int is_user, int *code_out)
 {
@@ -35,7 +36,6 @@ int handle_page_fault(unsigned long address, unsigned long ip,
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
-       unsigned long page;
        int err = -EFAULT;
 
        *code_out = SEGV_MAPERR;
@@ -52,17 +52,17 @@ int handle_page_fault(unsigned long address, unsigned long ip,
        else if(expand_stack(vma, address)) 
                goto out;
 
- good_area:
+good_area:
        *code_out = SEGV_ACCERR;
        if(is_write && !(vma->vm_flags & VM_WRITE)) 
                goto out;
 
-        if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
+       /* Don't require VM_READ|VM_EXEC for write faults! */
+        if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
                 goto out;
 
-       page = address & PAGE_MASK;
        do {
- survive:
+survive:
                switch (handle_mm_fault(mm, vma, address, is_write)){
                case VM_FAULT_MINOR:
                        current->min_flt++;
@@ -79,16 +79,15 @@ int handle_page_fault(unsigned long address, unsigned long ip,
                default:
                        BUG();
                }
-               pgd = pgd_offset(mm, page);
-               pud = pud_offset(pgd, page);
-               pmd = pmd_offset(pud, page);
-               pte = pte_offset_kernel(pmd, page);
+               pgd = pgd_offset(mm, address);
+               pud = pud_offset(pgd, address);
+               pmd = pmd_offset(pud, address);
+               pte = pte_offset_kernel(pmd, address);
        } while(!pte_present(*pte));
        err = 0;
-       *pte = pte_mkyoung(*pte);
-       if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
-       flush_tlb_page(vma, page);
- out:
+       WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
+       flush_tlb_page(vma, address);
+out:
        up_read(&mm->mmap_sem);
        return(err);
 
@@ -144,19 +143,18 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
                panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", 
                      address, ip);
 
-       if(err == -EACCES){
+       if (err == -EACCES) {
                si.si_signo = SIGBUS;
                si.si_errno = 0;
                si.si_code = BUS_ADRERR;
                si.si_addr = (void *)address;
                 current->thread.arch.faultinfo = fi;
                force_sig_info(SIGBUS, &si, current);
-       }
-       else if(err == -ENOMEM){
+       } else if (err == -ENOMEM) {
                printk("VM: killing process %s\n", current->comm);
                do_exit(SIGKILL);
-       }
-       else {
+       } else {
+               BUG_ON(err != -EFAULT);
                si.si_signo = SIGSEGV;
                si.si_addr = (void *) address;
                 current->thread.arch.faultinfo = fi;
@@ -200,30 +198,3 @@ void winch(int sig, union uml_pt_regs *regs)
 void trap_init(void)
 {
 }
-
-DEFINE_SPINLOCK(trap_lock);
-
-static int trap_index = 0;
-
-int next_trap_index(int limit)
-{
-       int ret;
-
-       spin_lock(&trap_lock);
-       ret = trap_index;
-       if(++trap_index == limit)
-               trap_index = 0;
-       spin_unlock(&trap_lock);
-       return(ret);
-}
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */