/*
- * linux/arch/x86-64/mm/fault.c
- *
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
*/
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
-#include <linux/kprobes.h>
#include <asm/system.h>
#include <asm/pgalloc.h>
#include <asm/proto.h>
#include <asm-generic/sections.h>
-/* Page fault error code bits */
-#define PF_PROT (1<<0) /* or no page found */
+/*
+ * Page fault error code bits
+ * bit 0 == 0 means no page found, 1 means protection fault
+ * bit 1 == 0 means read, 1 means write
+ * bit 2 == 0 means kernel, 1 means user-mode
+ * bit 3 == 1 means use of reserved bit detected
+ * bit 4 == 1 means fault was an instruction fetch
+ */
+#define PF_PROT (1<<0)
#define PF_WRITE (1<<1)
-#define PF_USER (1<<2)
-#define PF_RSVD (1<<3)
+#define PF_USER (1<<2)
+#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
-#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs)
{
+#ifdef CONFIG_KPROBES
int ret = 0;
/* kprobe_running() needs smp_processor_id() */
}
return ret;
-}
#else
-static inline int notify_page_fault(struct pt_regs *regs)
-{
return 0;
-}
#endif
+}
-/* Sometimes the CPU reports invalid exceptions on prefetch.
- Check that here and ignore.
- Opcode checker based on code by Richard Brunner */
-static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
- unsigned long error_code)
-{
+/*
+ * X86_32
+ * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
+ * Check that here and ignore it.
+ *
+ * X86_64
+ * Sometimes the CPU reports invalid exceptions on prefetch.
+ * Check that here and ignore it.
+ *
+ * Opcode checker based on code by Richard Brunner
+ */
+static int is_prefetch(struct pt_regs *regs, unsigned long addr,
+ unsigned long error_code)
+{
unsigned char *instr;
int scan_more = 1;
- int prefetch = 0;
+ int prefetch = 0;
unsigned char *max_instr;
+#ifdef CONFIG_X86_32
+ if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+ boot_cpu_data.x86 >= 6)) {
+ /* Catch an obscure case of prefetch inside an NX page. */
+ if (nx_enabled && (error_code & PF_INSTR))
+ return 0;
+ } else {
+ return 0;
+ }
+#else
/* If it was a exec fault ignore */
if (error_code & PF_INSTR)
return 0;
-
- instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
+#endif
+
+ instr = (unsigned char *)convert_ip_to_linear(current, regs);
max_instr = instr + 15;
if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
return 0;
- while (scan_more && instr < max_instr) {
+ while (scan_more && instr < max_instr) {
unsigned char opcode;
unsigned char instr_hi;
unsigned char instr_lo;
if (probe_kernel_address(instr, opcode))
- break;
+ break;
- instr_hi = opcode & 0xf0;
- instr_lo = opcode & 0x0f;
+ instr_hi = opcode & 0xf0;
+ instr_lo = opcode & 0x0f;
instr++;
- switch (instr_hi) {
+ switch (instr_hi) {
case 0x20:
case 0x30:
- /* Values 0x26,0x2E,0x36,0x3E are valid x86
- prefixes. In long mode, the CPU will signal
- invalid opcode if some of these prefixes are
- present so we will never get here anyway */
+ /*
+ * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
+ * In X86_64 long mode, the CPU will signal invalid
+ * opcode if some of these prefixes are present so
+ * X86_64 will never get here anyway
+ */
scan_more = ((instr_lo & 7) == 0x6);
break;
-
+#ifdef CONFIG_X86_64
case 0x40:
- /* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes
- Need to figure out under what instruction mode the
- instruction was issued ... */
- /* Could check the LDT for lm, but for now it's good
- enough to assume that long mode only uses well known
- segments or kernel. */
+ /*
+ * In AMD64 long mode 0x40..0x4F are valid REX prefixes
+ * Need to figure out under what instruction mode the
+ * instruction was issued. Could check the LDT for lm,
+ * but for now it's good enough to assume that long
+ * mode only uses well known segments or kernel.
+ */
scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
break;
-
+#endif
case 0x60:
/* 0x64 thru 0x67 are valid prefixes in all modes. */
scan_more = (instr_lo & 0xC) == 0x4;
- break;
+ break;
case 0xF0:
- /* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
+ /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
scan_more = !instr_lo || (instr_lo>>1) == 1;
- break;
+ break;
case 0x00:
/* Prefetch instruction is 0x0F0D or 0x0F18 */
scan_more = 0;
+
if (probe_kernel_address(instr, opcode))
break;
prefetch = (instr_lo == 0xF) &&
(opcode == 0x0D || opcode == 0x18);
- break;
+ break;
default:
scan_more = 0;
break;
- }
+ }
}
return prefetch;
}
-static int bad_address(void *p)
-{
+static void force_sig_info_fault(int si_signo, int si_code,
+ unsigned long address, struct task_struct *tsk)
+{
+ siginfo_t info;
+
+ info.si_signo = si_signo;
+ info.si_errno = 0;
+ info.si_code = si_code;
+ info.si_addr = (void __user *)address;
+ force_sig_info(si_signo, &info, tsk);
+}
+
+static int bad_address(void *p)
+{
unsigned long dummy;
return probe_kernel_address((unsigned long *)p, dummy);
-}
+}
void dump_pagetable(unsigned long address)
{
pgd = (pgd_t *)read_cr3();
- pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
+ pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
pgd += pgd_index(address);
if (bad_address(pgd)) goto bad;
printk("PGD %lx ", pgd_val(*pgd));
- if (!pgd_present(*pgd)) goto ret;
+ if (!pgd_present(*pgd)) goto ret;
pud = pud_offset(pgd, address);
if (bad_address(pud)) goto bad;
pte = pte_offset_kernel(pmd, address);
if (bad_address(pte)) goto bad;
- printk("PTE %lx", pte_val(*pte));
+ printk("PTE %lx", pte_val(*pte));
ret:
printk("\n");
return;
printk("BAD\n");
}
-static const char errata93_warning[] =
+#ifdef CONFIG_X86_64
+static const char errata93_warning[] =
KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
KERN_ERR "******* Please consider a BIOS update.\n"
KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
+#endif
/* Workaround for K8 erratum #93 & buggy BIOS.
BIOS SMM functions are required to use a specific workaround
- to avoid corruption of the 64bit RIP register on C stepping K8.
- A lot of BIOS that didn't get tested properly miss this.
+ to avoid corruption of the 64bit RIP register on C stepping K8.
+ A lot of BIOS that didn't get tested properly miss this.
The OS sees this as a page fault with the upper 32bits of RIP cleared.
Try to work around it here.
- Note we only handle faults in kernel here. */
-
-static int is_errata93(struct pt_regs *regs, unsigned long address)
+ Note we only handle faults in kernel here.
+ Does nothing for X86_32
+ */
+static int is_errata93(struct pt_regs *regs, unsigned long address)
{
+#ifdef CONFIG_X86_64
static int warned;
- if (address != regs->rip)
+ if (address != regs->ip)
return 0;
- if ((address >> 32) != 0)
+ if ((address >> 32) != 0)
return 0;
address |= 0xffffffffUL << 32;
- if ((address >= (u64)_stext && address <= (u64)_etext) ||
- (address >= MODULES_VADDR && address <= MODULES_END)) {
+ if ((address >= (u64)_stext && address <= (u64)_etext) ||
+ (address >= MODULES_VADDR && address <= MODULES_END)) {
if (!warned) {
- printk(errata93_warning);
+ printk(errata93_warning);
warned = 1;
}
- regs->rip = address;
+ regs->ip = address;
return 1;
}
+#endif
return 0;
-}
+}
static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
unsigned long error_code)
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
- __die("Bad pagetable", regs, error_code);
- oops_end(flags);
- do_exit(SIGKILL);
+ if (__die("Bad pagetable", regs, error_code))
+ regs = NULL;
+ oops_end(flags, regs, SIGKILL);
}
/*
*/
static int vmalloc_fault(unsigned long address)
{
+#ifdef CONFIG_X86_32
+ unsigned long pgd_paddr;
+ pmd_t *pmd_k;
+ pte_t *pte_k;
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Do _not_ use "current" here. We might be inside
+ * an interrupt in the middle of a task switch..
+ */
+ pgd_paddr = read_cr3();
+ pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
+ if (!pmd_k)
+ return -1;
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ return -1;
+ return 0;
+#else
pgd_t *pgd, *pgd_ref;
pud_t *pud, *pud_ref;
pmd_t *pmd, *pmd_ref;
if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
BUG();
return 0;
+#endif
}
int show_unhandled_signals = 1;
{
struct task_struct *tsk;
struct mm_struct *mm;
- struct vm_area_struct * vma;
+ struct vm_area_struct *vma;
unsigned long address;
- const struct exception_table_entry *fixup;
int write, fault;
unsigned long flags;
- siginfo_t info;
+ int si_code;
/*
* We can fault from pretty much anywhere, with unknown IRQ state.
/* get the address */
address = read_cr2();
- info.si_code = SEGV_MAPERR;
+ si_code = SEGV_MAPERR;
+ if (notify_page_fault(regs))
+ return;
/*
* We fault-in kernel-space virtual memory on-demand. The
if (vmalloc_fault(address) >= 0)
return;
}
- if (notify_page_fault(regs))
- return;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
* fault we could otherwise deadlock.
goto bad_area_nosemaphore;
}
- if (notify_page_fault(regs))
- return;
-
- if (likely(regs->eflags & X86_EFLAGS_IF))
+ if (likely(regs->flags & X86_EFLAGS_IF))
local_irq_enable();
if (unlikely(error_code & PF_RSVD))
pgtable_bad(address, regs, error_code);
/*
- * If we're in an interrupt or have no user
- * context, we must not take the fault..
+ * If we're in an interrupt, have no user context or are running in an
+ * atomic region then we must not take the fault.
*/
if (unlikely(in_atomic() || !mm))
goto bad_area_nosemaphore;
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if ((error_code & PF_USER) == 0 &&
- !search_exception_tables(regs->rip))
+ !search_exception_tables(regs->ip))
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
}
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
- if (error_code & 4) {
- /* Allow userspace just enough access below the stack pointer
- * to let the 'enter' instruction work.
+ if (error_code & PF_USER) {
+ /*
+ * Accessing the stack below %sp is always a bug.
+ * The large cushion allows instructions like enter
+ * and pusha to work. ("enter $65535,$31" pushes
+ * 32 pointers and then decrements %sp by 65535.)
*/
- if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
+ if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp)
goto bad_area;
}
if (expand_stack(vma, address))
* we can handle it..
*/
good_area:
- info.si_code = SEGV_ACCERR;
+ si_code = SEGV_ACCERR;
write = 0;
switch (error_code & (PF_PROT|PF_WRITE)) {
- default: /* 3: write, present */
- /* fall through */
- case PF_WRITE: /* write, not present */
- if (!(vma->vm_flags & VM_WRITE))
- goto bad_area;
- write++;
- break;
- case PF_PROT: /* read, present */
+ default: /* 3: write, present */
+ /* fall through */
+ case PF_WRITE: /* write, not present */
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ write++;
+ break;
+ case PF_PROT: /* read, present */
+ goto bad_area;
+ case 0: /* read, not present */
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
- case 0: /* read, not present */
- if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
- goto bad_area;
}
/*
tsk->maj_flt++;
else
tsk->min_flt++;
+
+#ifdef CONFIG_X86_32
+ /*
+ * Did it hit the DOS screen memory VA from vm86 mode?
+ */
+ if (v8086_mode(regs)) {
+ unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
+ if (bit < 32)
+ tsk->thread.screen_bitmap |= 1 << bit;
+ }
+#endif
up_read(&mm->mmap_sem);
return;
if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
printk_ratelimit()) {
printk(
- "%s%s[%d]: segfault at %lx rip %lx rsp %lx error %lx\n",
- tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
- tsk->comm, tsk->pid, address, regs->rip,
- regs->rsp, error_code);
+#ifdef CONFIG_X86_32
+ "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
+#else
+ "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
+#endif
+ task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
+ tsk->comm, task_pid_nr(tsk), address, regs->ip,
+ regs->sp, error_code);
+ print_vma_addr(" in ", regs->ip);
+ printk("\n");
}
-
+
tsk->thread.cr2 = address;
/* Kernel addresses are always protection faults */
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
tsk->thread.trap_no = 14;
- info.si_signo = SIGSEGV;
- info.si_errno = 0;
- /* info.si_code has been set above */
- info.si_addr = (void __user *)address;
- force_sig_info(SIGSEGV, &info, tsk);
+
+ force_sig_info_fault(SIGSEGV, si_code, address, tsk);
return;
}
no_context:
-
/* Are we prepared to handle this kernel fault? */
- fixup = search_exception_tables(regs->rip);
- if (fixup) {
- regs->rip = fixup->fixup;
+ if (fixup_exception(regs))
return;
- }
- /*
+ /*
* Hall of shame of CPU/BIOS bugs.
*/
- if (is_prefetch(regs, address, error_code))
- return;
+ if (is_prefetch(regs, address, error_code))
+ return;
if (is_errata93(regs, address))
- return;
+ return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel paging request");
- printk(" at %016lx RIP: \n" KERN_ALERT,address);
- printk_address(regs->rip);
+ printk(" at %016lx RIP: \n" KERN_ALERT, address);
+ printk_address(regs->ip, 1);
dump_pagetable(address);
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
- __die("Oops", regs, error_code);
+ if (__die("Oops", regs, error_code))
+ regs = NULL;
/* Executive summary in case the body of the oops scrolled away */
printk(KERN_EMERG "CR2: %016lx\n", address);
- oops_end(flags);
- do_exit(SIGKILL);
+ oops_end(flags, regs, SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
goto again;
}
printk("VM: killing process %s\n", tsk->comm);
- if (error_code & 4)
+ if (error_code & PF_USER)
do_group_exit(SIGKILL);
goto no_context;
tsk->thread.cr2 = address;
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 14;
- info.si_signo = SIGBUS;
- info.si_errno = 0;
- info.si_code = BUS_ADRERR;
- info.si_addr = (void __user *)address;
- force_sig_info(SIGBUS, &info, tsk);
+ force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
return;
}
void vmalloc_sync_all(void)
{
- /* Note that races in the updates of insync and start aren't
- problematic:
- insync can only get set bits added, and updates to start are only
- improving performance (without affecting correctness if undone). */
+ /*
+ * Note that races in the updates of insync and start aren't
+ * problematic: insync can only get set bits added, and updates to
+ * start are only improving performance (without affecting correctness
+ * if undone).
+ */
static DECLARE_BITMAP(insync, PTRS_PER_PGD);
static unsigned long start = VMALLOC_START & PGDIR_MASK;
unsigned long address;
}
/* Check that there is no need to do the same for the modules area. */
BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
- BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
+ BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
(__START_KERNEL & PGDIR_MASK)));
}
projects / linux-2.6 / blobdiff