#include <asm/system.h>
#include <asm/uaccess.h>
-#include <asm/pgalloc.h>
-#include <asm/hardirq.h>
#include <asm/desc.h>
+#include <asm/kdebug.h>
extern void die(const char *,struct pt_regs *,long);
desc = (void *)desc + (seg & ~7);
} else {
/* Must disable preemption while reading the GDT. */
- desc = (u32 *)&cpu_gdt_table[get_cpu()];
+ desc = (u32 *)&per_cpu(cpu_gdt_table, get_cpu());
desc = (void *)desc + (seg & ~7);
}
/* Decode the code segment base from the descriptor */
- base = (desc[0] >> 16) |
- ((desc[1] & 0xff) << 16) |
- (desc[1] & 0xff000000);
+ base = get_desc_base((unsigned long *)desc);
if (seg & (1<<2)) {
up(¤t->mm->context.sem);
return prefetch;
}
-static inline int is_prefetch(struct pt_regs *regs, unsigned long addr)
+static inline int is_prefetch(struct pt_regs *regs, unsigned long addr,
+ unsigned long error_code)
{
if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
- boot_cpu_data.x86 >= 6))
+ boot_cpu_data.x86 >= 6)) {
+ /* Catch an obscure case of prefetch inside an NX page. */
+ if (nx_enabled && (error_code & 16))
+ return 0;
return __is_prefetch(regs, addr);
+ }
return 0;
}
-asmlinkage void do_invalid_op(struct pt_regs *, unsigned long);
+fastcall void do_invalid_op(struct pt_regs *, unsigned long);
/*
* This routine handles page faults. It determines the address,
* bit 1 == 0 means read, 1 means write
* bit 2 == 0 means kernel, 1 means user-mode
*/
-asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
+fastcall void do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
/* get the address */
__asm__("movl %%cr2,%0":"=r" (address));
+ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+ SIGSEGV) == NOTIFY_STOP)
+ return;
/* It's safe to allow irq's after cr2 has been saved */
if (regs->eflags & (X86_EFLAGS_IF|VM_MASK))
local_irq_enable();
if (in_atomic() || !mm)
goto bad_area_nosemaphore;
- down_read(&mm->mmap_sem);
+ /* When running in the kernel we expect faults to occur only to
+ * addresses in user space. All other faults represent errors in the
+ * kernel and should generate an OOPS. Unfortunatly, in the case of an
+ * erroneous fault occuring in a code path which already holds mmap_sem
+ * we will deadlock attempting to validate the fault against the
+ * address space. Luckily the kernel only validly references user
+ * space from well defined areas of code, which are listed in the
+ * exceptions table.
+ *
+ * As the vast majority of faults will be valid we will only perform
+ * the source reference check when there is a possibilty of a deadlock.
+ * Attempt to lock the address space, if we cannot we then validate the
+ * source. If this is invalid we can skip the address space check,
+ * thus avoiding the deadlock.
+ */
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if ((error_code & 4) == 0 &&
+ !search_exception_tables(regs->eip))
+ goto bad_area_nosemaphore;
+ down_read(&mm->mmap_sem);
+ }
vma = find_vma(mm, address);
if (!vma)
* Valid to do another page fault here because this one came
* from user space.
*/
- if (is_prefetch(regs, address))
+ if (is_prefetch(regs, address, error_code))
return;
tsk->thread.cr2 = address;
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
- info.si_addr = (void *)address;
+ info.si_addr = (void __user *)address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
* had been triggered by is_prefetch fixup_exception would have
* handled it.
*/
- if (is_prefetch(regs, address))
+ if (is_prefetch(regs, address, error_code))
return;
/*
bust_spinlocks(1);
+#ifdef CONFIG_X86_PAE
+ if (error_code & 16) {
+ pte_t *pte = lookup_address(address);
+
+ if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
+ printk(KERN_CRIT "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n", current->uid);
+ }
+#endif
if (address < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
else
goto no_context;
/* User space => ok to do another page fault */
- if (is_prefetch(regs, address))
+ if (is_prefetch(regs, address, error_code))
return;
tsk->thread.cr2 = address;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
- info.si_addr = (void *)address;
+ info.si_addr = (void __user *)address;
force_sig_info(SIGBUS, &info, tsk);
return;
* an interrupt in the middle of a task switch..
*/
int index = pgd_index(address);
+ unsigned long pgd_paddr;
pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
- asm("movl %%cr3,%0":"=r" (pgd));
- pgd = index + (pgd_t *)__va(pgd);
+ asm("movl %%cr3,%0":"=r" (pgd_paddr));
+ pgd = index + (pgd_t *)__va(pgd_paddr);
pgd_k = init_mm.pgd + index;
if (!pgd_present(*pgd_k))
/*
* set_pgd(pgd, *pgd_k); here would be useless on PAE
- * and redundant with the set_pmd() on non-PAE.
+ * and redundant with the set_pmd() on non-PAE. As would
+ * set_pud.
*/
- pmd = pmd_offset(pgd, address);
- pmd_k = pmd_offset(pgd_k, address);
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ goto no_context;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto no_context;
set_pmd(pmd, *pmd_k);
git://git.onelab.eu / linux-2.6.git / blobdiff