aboutsummaryrefslogtreecommitdiff
path: root/arch/x86_64/mm/fault.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86_64/mm/fault.c')
-rw-r--r--arch/x86_64/mm/fault.c579
1 files changed, 579 insertions, 0 deletions
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
new file mode 100644
index 000000000000..5724370475cc
--- /dev/null
+++ b/arch/x86_64/mm/fault.c
@@ -0,0 +1,579 @@
+/*
+ * linux/arch/x86-64/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
+ */
+
+#include <linux/config.h>
+#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/smp_lock.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/module.h>
+#include <linux/kprobes.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/pgalloc.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)
+{
+ int loglevel_save = console_loglevel;
+ if (yes) {
+ oops_in_progress = 1;
+ } else {
+#ifdef CONFIG_VT
+ unblank_screen();
+#endif
+ oops_in_progress = 0;
+ /*
+ * OK, the message is on the console. Now we call printk()
+ * without oops_in_progress set so that printk will give klogd
+ * a poke. Hold onto your hats...
+ */
+ console_loglevel = 15; /* NMI oopser may have shut the console up */
+ printk(" ");
+ console_loglevel = loglevel_save;
+ }
+}
+
+/* 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 = (unsigned char *)(regs->rip);
+ int scan_more = 1;
+ int prefetch = 0;
+ unsigned char *max_instr = instr + 15;
+
+ /* 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 */
+ if (regs->cs & (1<<2))
+ return 0;
+
+ if ((regs->cs & 3) != 0 && regs->rip >= TASK_SIZE)
+ return 0;
+
+ while (scan_more && instr < max_instr) {
+ unsigned char opcode;
+ unsigned char instr_hi;
+ unsigned char instr_lo;
+
+ if (__get_user(opcode, instr))
+ 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 = ((regs->cs & 3) == 0) || (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 (__get_user(opcode, instr))
+ 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 __get_user(dummy, (unsigned long *)p);
+}
+
+void dump_pagetable(unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ asm("movq %%cr3,%0" : "=r" (pgd));
+
+ pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
+ pgd += pgd_index(address);
+ printk("PGD %lx ", pgd_val(*pgd));
+ if (bad_address(pgd)) goto bad;
+ if (!pgd_present(*pgd)) goto ret;
+
+ 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;
+
+ 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;
+}
+
+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))
+ return 0;
+ return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
+ (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
+}
+
+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
+ */
+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);
+ if (!pte_present(*pte) || pte_page(*pte) != pte_page(*pte_ref))
+ BUG();
+ __flush_tlb_all();
+ return 0;
+}
+
+int page_fault_trace = 0;
+int exception_trace = 1;
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * error_code:
+ * 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 fault was an instruction fetch
+ */
+asmlinkage void 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;
+ siginfo_t info;
+
+#ifdef CONFIG_CHECKING
+ {
+ unsigned long gs;
+ struct x8664_pda *pda = cpu_pda + stack_smp_processor_id();
+ rdmsrl(MSR_GS_BASE, gs);
+ if (gs != (unsigned long)pda) {
+ wrmsrl(MSR_GS_BASE, pda);
+ printk("page_fault: wrong gs %lx expected %p\n", gs, pda);
+ }
+ }
+#endif
+
+ /* 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();
+
+ 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);
+
+ tsk = current;
+ mm = tsk->mm;
+ 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 & 1) == 0.
+ */
+ if (unlikely(address >= TASK_SIZE)) {
+ if (!(error_code & 5)) {
+ 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
+ * context, we must not take the fault..
+ */
+ if (unlikely(in_atomic() || !mm))
+ goto bad_area_nosemaphore;
+
+ 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 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)
+ 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) {
+ // XXX: align red zone size with ABI
+ if (address + 128 < 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 & 3) {
+ default: /* 3: write, present */
+ /* fall through */
+ case 2: /* write, not present */
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ write++;
+ break;
+ case 1: /* read, present */
+ goto bad_area;
+ case 0: /* read, not present */
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+ 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.
+ */
+ switch (handle_mm_fault(mm, vma, address, write)) {
+ case 1:
+ tsk->min_flt++;
+ break;
+ case 2:
+ tsk->maj_flt++;
+ break;
+ case 0:
+ goto do_sigbus;
+ default:
+ goto out_of_memory;
+ }
+
+ 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:
+
+#ifdef CONFIG_IA32_EMULATION
+ /* 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, 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 (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ 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.
+ */
+
+ 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);
+ printk("\n");
+ dump_pagetable(address);
+ __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();
+ 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);
+out_of_memory2:
+ if (current->pid == 1) {
+ yield();
+ goto again;
+ }
+ printk("VM: killing process %s\n", tsk->comm);
+ if (error_code & 4)
+ do_exit(SIGKILL);
+ goto no_context;
+
+do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!(error_code & 4))
+ 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 04:10:28 +0000