#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/compiler.h>
#include <linux/module.h>
+#include <linux/kprobes.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
-#include <asm/hardirq.h>
#include <asm/smp.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm/kdebug.h>
#include <asm-generic/sections.h>
+#include <asm/kdebug.h>
void bust_spinlocks(int yes)
{
/* Sometimes the CPU reports invalid exceptions on prefetch.
Check that here and ignore.
Opcode checker based on code by Richard Brunner */
-static int is_prefetch(struct pt_regs *regs, unsigned long addr)
+static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
+ unsigned long error_code)
{
unsigned char *instr = (unsigned char *)(regs->rip);
int scan_more = 1;
int prefetch = 0;
unsigned char *max_instr = instr + 15;
- /* Avoid recursive faults for this common case */
- if (regs->rip == addr)
- return 0;
+ /* If it was a exec fault ignore */
+ if (error_code & (1<<4))
+ return 0;
/* Code segments in LDT could have a non zero base. Don't check
when that's possible */
void dump_pagetable(unsigned long address)
{
- pml4_t *pml4;
pgd_t *pgd;
+ pud_t *pud;
pmd_t *pmd;
pte_t *pte;
- asm("movq %%cr3,%0" : "=r" (pml4));
-
- pml4 = __va((unsigned long)pml4 & PHYSICAL_PAGE_MASK);
- pml4 += pml4_index(address);
- printk("PML4 %lx ", pml4_val(*pml4));
- if (bad_address(pml4)) goto bad;
- if (!pml4_present(*pml4)) goto ret;
+ asm("movq %%cr3,%0" : "=r" (pgd));
- pgd = __pgd_offset_k((pgd_t *)pml4_page(*pml4), address);
+ pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
+ pgd += pgd_index(address);
+ printk("PGD %lx ", pgd_val(*pgd));
if (bad_address(pgd)) goto bad;
- printk("PGD %lx ", pgd_val(*pgd));
- if (!pgd_present(*pgd)) goto ret;
+ if (!pgd_present(*pgd)) goto ret;
- pmd = pmd_offset(pgd, address);
+ pud = __pud_offset_k((pud_t *)pgd_page(*pgd), address);
+ if (bad_address(pud)) goto bad;
+ printk("PUD %lx ", pud_val(*pud));
+ if (!pud_present(*pud)) goto ret;
+
+ pmd = pmd_offset(pud, address);
if (bad_address(pmd)) goto bad;
printk("PMD %lx ", pmd_val(*pmd));
if (!pmd_present(*pmd)) goto ret;
int unhandled_signal(struct task_struct *tsk, int sig)
{
+ if (tsk->pid == 1)
+ return 1;
/* Warn for strace, but not for gdb */
if (!test_ti_thread_flag(tsk->thread_info, TIF_SYSCALL_TRACE) &&
(tsk->ptrace & PT_PTRACED))
(tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
}
-int page_fault_trace;
+static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
+ unsigned long error_code)
+{
+ oops_begin();
+ printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
+ current->comm, address);
+ dump_pagetable(address);
+ __die("Bad pagetable", regs, error_code);
+ oops_end();
+ do_exit(SIGKILL);
+}
+
+/*
+ * Handle a fault on the vmalloc or module mapping area
+ *
+ * This assumes no large pages in there.
+ */
+static int vmalloc_fault(unsigned long address)
+{
+ pgd_t *pgd, *pgd_ref;
+ pud_t *pud, *pud_ref;
+ pmd_t *pmd, *pmd_ref;
+ pte_t *pte, *pte_ref;
+
+ /* Copy kernel mappings over when needed. This can also
+ happen within a race in page table update. In the later
+ case just flush. */
+
+ pgd = pgd_offset(current->mm ?: &init_mm, address);
+ pgd_ref = pgd_offset_k(address);
+ if (pgd_none(*pgd_ref))
+ return -1;
+ if (pgd_none(*pgd))
+ set_pgd(pgd, *pgd_ref);
+
+ /* Below here mismatches are bugs because these lower tables
+ are shared */
+
+ pud = pud_offset(pgd, address);
+ pud_ref = pud_offset(pgd_ref, address);
+ if (pud_none(*pud_ref))
+ return -1;
+ if (pud_none(*pud) || pud_page(*pud) != pud_page(*pud_ref))
+ BUG();
+ pmd = pmd_offset(pud, address);
+ pmd_ref = pmd_offset(pud_ref, address);
+ if (pmd_none(*pmd_ref))
+ return -1;
+ if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
+ BUG();
+ pte_ref = pte_offset_kernel(pmd_ref, address);
+ if (!pte_present(*pte_ref))
+ return -1;
+ pte = pte_offset_kernel(pmd, address);
+ /* Don't use pte_page here, because the mappings can point
+ outside mem_map, and the NUMA hash lookup cannot handle
+ that. */
+ if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
+ BUG();
+ __flush_tlb_all();
+ return 0;
+}
+
+int page_fault_trace = 0;
int exception_trace = 1;
/*
/* get the address */
__asm__("movq %%cr2,%0":"=r" (address));
+ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+ SIGSEGV) == NOTIFY_STOP)
+ return;
if (likely(regs->eflags & X86_EFLAGS_IF))
local_irq_enable();
mm = tsk->mm;
info.si_code = SEGV_MAPERR;
- /* 5 => page not present and from supervisor mode */
- if (unlikely(!(error_code & 5) &&
- ((address >= VMALLOC_START && address <= VMALLOC_END) ||
- (address >= MODULES_VADDR && address <= MODULES_END))))
- goto vmalloc_fault;
+
+ /*
+ * We fault-in kernel-space virtual memory on-demand. The
+ * 'reference' page table is init_mm.pgd.
+ *
+ * NOTE! We MUST NOT take any locks for this case. We may
+ * be in an interrupt or a critical region, and should
+ * only copy the information from the master page table,
+ * nothing more.
+ *
+ * This verifies that the fault happens in kernel space
+ * (error_code & 4) == 0, and that the fault was not a
+ * protection error (error_code & 1) == 0.
+ */
+ if (unlikely(address >= TASK_SIZE)) {
+ if (!(error_code & 5) &&
+ ((address >= VMALLOC_START && address < VMALLOC_END) ||
+ (address >= MODULES_VADDR && address < MODULES_END))) {
+ if (vmalloc_fault(address) < 0)
+ goto bad_area_nosemaphore;
+ return;
+ }
+ /*
+ * Don't take the mm semaphore here. If we fixup a prefetch
+ * fault we could otherwise deadlock.
+ */
+ goto bad_area_nosemaphore;
+ }
+
+ if (unlikely(error_code & (1 << 3)))
+ pgtable_bad(address, regs, error_code);
/*
* If we're in an interrupt or have no user
goto bad_area_nosemaphore;
again:
- 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->rip))
+ goto bad_area_nosemaphore;
+ down_read(&mm->mmap_sem);
+ }
vma = find_vma(mm, address);
if (!vma)
bad_area_nosemaphore:
#ifdef CONFIG_IA32_EMULATION
- /* 32bit vsyscall. map on demand. */
- if (test_thread_flag(TIF_IA32) &&
- address >= 0xffffe000 && address < 0xffffe000 + PAGE_SIZE) {
- if (map_syscall32(mm, address) < 0)
- goto out_of_memory2;
- return;
- }
+ /* 32bit vsyscall. map on demand. */
+ if (test_thread_flag(TIF_IA32) &&
+ address >= VSYSCALL32_BASE && address < VSYSCALL32_END) {
+ if (map_syscall32(mm, address) < 0)
+ goto out_of_memory2;
+ return;
+ }
#endif
/* User mode accesses just cause a SIGSEGV */
if (error_code & 4) {
- if (is_prefetch(regs, address))
+ if (is_prefetch(regs, address, error_code))
return;
/* Work around K8 erratum #100 K8 in compat mode
return;
if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
- printk(KERN_INFO
- "%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
+ printk(
+ "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
+ tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, tsk->pid, address, regs->rip,
regs->rsp, error_code);
}
* Hall of shame of CPU/BIOS bugs.
*/
- if (is_prefetch(regs, address))
+ if (is_prefetch(regs, address, error_code))
return;
if (is_errata93(regs, address))
info.si_addr = (void __user *)address;
force_sig_info(SIGBUS, &info, tsk);
return;
-
-vmalloc_fault:
- {
- pgd_t *pgd;
- pmd_t *pmd;
- pte_t *pte;
-
- /*
- * x86-64 has the same kernel 3rd level pages for all CPUs.
- * But for vmalloc/modules the TLB synchronization works lazily,
- * so it can happen that we get a page fault for something
- * that is really already in the page table. Just check if it
- * is really there and when yes flush the local TLB.
- */
- pgd = pgd_offset_k(address);
- if (pgd != current_pgd_offset_k(address))
- BUG();
- if (!pgd_present(*pgd))
- goto bad_area_nosemaphore;
- pmd = pmd_offset(pgd, address);
- if (!pmd_present(*pmd))
- goto bad_area_nosemaphore;
- pte = pte_offset_kernel(pmd, address);
- if (!pte_present(*pte))
- goto bad_area_nosemaphore;
-
- __flush_tlb_all();
- return;
- }
}
git://git.onelab.eu / linux-2.6.git / blobdiff