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Diffstat (limited to 'arch/x86/mm/fault_64.c')
-rw-r--r--arch/x86/mm/fault_64.c636
1 files changed, 636 insertions, 0 deletions
diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c
new file mode 100644
index 000000000000..54816adb8e93
--- /dev/null
+++ b/arch/x86/mm/fault_64.c
@@ -0,0 +1,636 @@
+/*
+ * linux/arch/x86-64/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/vt_kern.h> /* For unblank_screen() */
+#include <linux/compiler.h>
+#include <linux/vmalloc.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/kdebug.h>
+
+#include <asm/system.h>
+#include <asm/pgalloc.h>
+#include <asm/smp.h>
+#include <asm/tlbflush.h>
+#include <asm/proto.h>
+#include <asm-generic/sections.h>
+
+/* Page fault error code bits */
+#define PF_PROT (1<<0) /* or no page found */
+#define PF_WRITE (1<<1)
+#define PF_USER (1<<2)
+#define PF_RSVD (1<<3)
+#define PF_INSTR (1<<4)
+
+static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
+
+/* Hook to register for page fault notifications */
+int register_page_fault_notifier(struct notifier_block *nb)
+{
+ vmalloc_sync_all();
+ return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
+}
+EXPORT_SYMBOL_GPL(register_page_fault_notifier);
+
+int unregister_page_fault_notifier(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_page_fault_notifier);
+
+static inline int notify_page_fault(struct pt_regs *regs, long err)
+{
+ struct die_args args = {
+ .regs = regs,
+ .str = "page fault",
+ .err = err,
+ .trapnr = 14,
+ .signr = SIGSEGV
+ };
+ return atomic_notifier_call_chain(&notify_page_fault_chain,
+ DIE_PAGE_FAULT, &args);
+}
+
+/* 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)
+{
+ unsigned char *instr;
+ int scan_more = 1;
+ int prefetch = 0;
+ unsigned char *max_instr;
+
+ /* If it was a exec fault ignore */
+ if (error_code & PF_INSTR)
+ return 0;
+
+ instr = (unsigned char __user *)convert_rip_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) {
+ unsigned char opcode;
+ unsigned char instr_hi;
+ unsigned char instr_lo;
+
+ if (probe_kernel_address(instr, opcode))
+ break;
+
+ instr_hi = opcode & 0xf0;
+ instr_lo = opcode & 0x0f;
+ instr++;
+
+ 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 */
+ scan_more = ((instr_lo & 7) == 0x6);
+ break;
+
+ 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. */
+ scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
+ break;
+
+ case 0x60:
+ /* 0x64 thru 0x67 are valid prefixes in all modes. */
+ scan_more = (instr_lo & 0xC) == 0x4;
+ break;
+ case 0xF0:
+ /* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
+ scan_more = !instr_lo || (instr_lo>>1) == 1;
+ 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;
+ default:
+ scan_more = 0;
+ break;
+ }
+ }
+ return prefetch;
+}
+
+static int bad_address(void *p)
+{
+ unsigned long dummy;
+ return probe_kernel_address((unsigned long *)p, dummy);
+}
+
+void dump_pagetable(unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = (pgd_t *)read_cr3();
+
+ 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;
+
+ pud = pud_offset(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;
+
+ pte = pte_offset_kernel(pmd, address);
+ if (bad_address(pte)) goto bad;
+ printk("PTE %lx", pte_val(*pte));
+ret:
+ printk("\n");
+ return;
+bad:
+ printk("BAD\n");
+}
+
+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";
+
+/* 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.
+ 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)
+{
+ static int warned;
+ if (address != regs->rip)
+ return 0;
+ if ((address >> 32) != 0)
+ return 0;
+ address |= 0xffffffffUL << 32;
+ if ((address >= (u64)_stext && address <= (u64)_etext) ||
+ (address >= MODULES_VADDR && address <= MODULES_END)) {
+ if (!warned) {
+ printk(errata93_warning);
+ warned = 1;
+ }
+ regs->rip = address;
+ return 1;
+ }
+ return 0;
+}
+
+static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
+ unsigned long error_code)
+{
+ unsigned long flags = oops_begin();
+ struct task_struct *tsk;
+
+ printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
+ current->comm, address);
+ dump_pagetable(address);
+ tsk = current;
+ 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);
+}
+
+/*
+ * Handle a fault on the vmalloc 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);
+ else
+ BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*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_vaddr(*pud) != pud_page_vaddr(*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();
+ return 0;
+}
+
+static int page_fault_trace;
+int show_unhandled_signals = 1;
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+ unsigned long error_code)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ struct vm_area_struct * vma;
+ unsigned long address;
+ const struct exception_table_entry *fixup;
+ int write, fault;
+ unsigned long flags;
+ siginfo_t info;
+
+ tsk = current;
+ mm = tsk->mm;
+ prefetchw(&mm->mmap_sem);
+
+ /* get the address */
+ address = read_cr2();
+
+ info.si_code = SEGV_MAPERR;
+
+
+ /*
+ * 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 & 9) == 0.
+ */
+ if (unlikely(address >= TASK_SIZE64)) {
+ /*
+ * Don't check for the module range here: its PML4
+ * is always initialized because it's shared with the main
+ * kernel text. Only vmalloc may need PML4 syncups.
+ */
+ if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
+ ((address >= VMALLOC_START && address < VMALLOC_END))) {
+ if (vmalloc_fault(address) >= 0)
+ return;
+ }
+ if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
+ 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, error_code) == NOTIFY_STOP)
+ return;
+
+ if (likely(regs->eflags & X86_EFLAGS_IF))
+ local_irq_enable();
+
+ if (unlikely(page_fault_trace))
+ printk("pagefault rip:%lx rsp:%lx cs:%lu ss:%lu address %lx error %lx\n",
+ regs->rip,regs->rsp,regs->cs,regs->ss,address,error_code);
+
+ 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 (unlikely(in_atomic() || !mm))
+ goto bad_area_nosemaphore;
+
+ /*
+ * User-mode registers count as a user access even for any
+ * potential system fault or CPU buglet.
+ */
+ if (user_mode_vm(regs))
+ error_code |= PF_USER;
+
+ again:
+ /* 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 occurring 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 & PF_USER) == 0 &&
+ !search_exception_tables(regs->rip))
+ goto bad_area_nosemaphore;
+ down_read(&mm->mmap_sem);
+ }
+
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto bad_area;
+ if (likely(vma->vm_start <= address))
+ 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 (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
+ goto bad_area;
+ }
+ if (expand_stack(vma, address))
+ goto bad_area;
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+ info.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 */
+ goto bad_area;
+ case 0: /* read, not present */
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+ goto bad_area;
+ }
+
+ /*
+ * If for any reason at all we couldn't handle the fault,
+ * make sure we exit gracefully rather than endlessly redo
+ * the fault.
+ */
+ fault = handle_mm_fault(mm, vma, address, write);
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ if (fault & VM_FAULT_OOM)
+ goto out_of_memory;
+ else if (fault & VM_FAULT_SIGBUS)
+ goto do_sigbus;
+ BUG();
+ }
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+ up_read(&mm->mmap_sem);
+ return;
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+ up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+ /* User mode accesses just cause a SIGSEGV */
+ if (error_code & PF_USER) {
+
+ /*
+ * It's possible to have interrupts off here.
+ */
+ local_irq_enable();
+
+ if (is_prefetch(regs, address, error_code))
+ return;
+
+ /* Work around K8 erratum #100 K8 in compat mode
+ occasionally jumps to illegal addresses >4GB. We
+ catch this here in the page fault handler because
+ these addresses are not reachable. Just detect this
+ case and return. Any code segment in LDT is
+ compatibility mode. */
+ if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
+ (address >> 32))
+ return;
+
+ if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
+ 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);
+ }
+
+ 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);
+ return;
+ }
+
+no_context:
+
+ /* Are we prepared to handle this kernel fault? */
+ fixup = search_exception_tables(regs->rip);
+ if (fixup) {
+ regs->rip = fixup->fixup;
+ return;
+ }
+
+ /*
+ * Hall of shame of CPU/BIOS bugs.
+ */
+
+ if (is_prefetch(regs, address, error_code))
+ return;
+
+ if (is_errata93(regs, address))
+ return;
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+
+ flags = oops_begin();
+
+ if (address < PAGE_SIZE)
+ 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);
+ dump_pagetable(address);
+ tsk->thread.cr2 = address;
+ tsk->thread.trap_no = 14;
+ tsk->thread.error_code = error_code;
+ __die("Oops", regs, error_code);
+ /* Executive summary in case the body of the oops scrolled away */
+ printk(KERN_EMERG "CR2: %016lx\n", address);
+ oops_end(flags);
+ do_exit(SIGKILL);
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+out_of_memory:
+ up_read(&mm->mmap_sem);
+ if (is_init(current)) {
+ yield();
+ goto again;
+ }
+ printk("VM: killing process %s\n", tsk->comm);
+ if (error_code & 4)
+ do_group_exit(SIGKILL);
+ goto no_context;
+
+do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!(error_code & PF_USER))
+ 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);
+ return;
+}
+
+DEFINE_SPINLOCK(pgd_lock);
+LIST_HEAD(pgd_list);
+
+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). */
+ static DECLARE_BITMAP(insync, PTRS_PER_PGD);
+ static unsigned long start = VMALLOC_START & PGDIR_MASK;
+ unsigned long address;
+
+ for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
+ if (!test_bit(pgd_index(address), insync)) {
+ const pgd_t *pgd_ref = pgd_offset_k(address);
+ struct page *page;
+
+ if (pgd_none(*pgd_ref))
+ continue;
+ spin_lock(&pgd_lock);
+ list_for_each_entry(page, &pgd_list, lru) {
+ pgd_t *pgd;
+ pgd = (pgd_t *)page_address(page) + pgd_index(address);
+ if (pgd_none(*pgd))
+ set_pgd(pgd, *pgd_ref);
+ else
+ BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
+ }
+ spin_unlock(&pgd_lock);
+ set_bit(pgd_index(address), insync);
+ }
+ if (address == start)
+ start = address + PGDIR_SIZE;
+ }
+ /* 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) ==
+ (__START_KERNEL & PGDIR_MASK)));
+}
+
+static int __init enable_pagefaulttrace(char *str)
+{
+ page_fault_trace = 1;
+ return 1;
+}
+__setup("pagefaulttrace", enable_pagefaulttrace);
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-16 10:09:55 +0300