566 строки
15 KiB
C
566 строки
15 KiB
C
/*
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* linux/arch/x86-64/mm/fault.c
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*
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* Copyright (C) 1995 Linus Torvalds
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* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
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*/
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#include <linux/config.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/tty.h>
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#include <linux/vt_kern.h> /* For unblank_screen() */
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#include <linux/compiler.h>
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/pgalloc.h>
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#include <asm/smp.h>
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#include <asm/tlbflush.h>
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#include <asm/proto.h>
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#include <asm/kdebug.h>
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#include <asm-generic/sections.h>
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#include <asm/kdebug.h>
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void bust_spinlocks(int yes)
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{
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int loglevel_save = console_loglevel;
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if (yes) {
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oops_in_progress = 1;
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} else {
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#ifdef CONFIG_VT
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unblank_screen();
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#endif
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oops_in_progress = 0;
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/*
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* OK, the message is on the console. Now we call printk()
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* without oops_in_progress set so that printk will give klogd
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* a poke. Hold onto your hats...
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*/
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console_loglevel = 15; /* NMI oopser may have shut the console up */
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printk(" ");
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console_loglevel = loglevel_save;
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}
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}
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/* Sometimes the CPU reports invalid exceptions on prefetch.
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Check that here and ignore.
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Opcode checker based on code by Richard Brunner */
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static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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unsigned long error_code)
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{
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unsigned char *instr;
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int scan_more = 1;
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int prefetch = 0;
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unsigned char *max_instr;
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/* If it was a exec fault ignore */
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if (error_code & (1<<4))
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return 0;
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instr = (unsigned char *)convert_rip_to_linear(current, regs);
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max_instr = instr + 15;
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if ((regs->cs & 3) != 0 && instr >= (unsigned char *)TASK_SIZE)
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return 0;
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while (scan_more && instr < max_instr) {
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unsigned char opcode;
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unsigned char instr_hi;
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unsigned char instr_lo;
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if (__get_user(opcode, instr))
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break;
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instr_hi = opcode & 0xf0;
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instr_lo = opcode & 0x0f;
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instr++;
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switch (instr_hi) {
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case 0x20:
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case 0x30:
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/* Values 0x26,0x2E,0x36,0x3E are valid x86
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prefixes. In long mode, the CPU will signal
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invalid opcode if some of these prefixes are
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present so we will never get here anyway */
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scan_more = ((instr_lo & 7) == 0x6);
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break;
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case 0x40:
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/* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes
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Need to figure out under what instruction mode the
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instruction was issued ... */
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/* Could check the LDT for lm, but for now it's good
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enough to assume that long mode only uses well known
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segments or kernel. */
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scan_more = ((regs->cs & 3) == 0) || (regs->cs == __USER_CS);
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break;
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case 0x60:
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/* 0x64 thru 0x67 are valid prefixes in all modes. */
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scan_more = (instr_lo & 0xC) == 0x4;
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break;
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case 0xF0:
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/* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
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scan_more = !instr_lo || (instr_lo>>1) == 1;
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break;
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case 0x00:
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/* Prefetch instruction is 0x0F0D or 0x0F18 */
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scan_more = 0;
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if (__get_user(opcode, instr))
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break;
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prefetch = (instr_lo == 0xF) &&
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(opcode == 0x0D || opcode == 0x18);
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break;
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default:
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scan_more = 0;
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break;
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}
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}
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return prefetch;
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}
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static int bad_address(void *p)
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{
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unsigned long dummy;
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return __get_user(dummy, (unsigned long *)p);
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}
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void dump_pagetable(unsigned long address)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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asm("movq %%cr3,%0" : "=r" (pgd));
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pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
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pgd += pgd_index(address);
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printk("PGD %lx ", pgd_val(*pgd));
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if (bad_address(pgd)) goto bad;
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if (!pgd_present(*pgd)) goto ret;
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pud = __pud_offset_k((pud_t *)pgd_page(*pgd), address);
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if (bad_address(pud)) goto bad;
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printk("PUD %lx ", pud_val(*pud));
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if (!pud_present(*pud)) goto ret;
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pmd = pmd_offset(pud, address);
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if (bad_address(pmd)) goto bad;
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printk("PMD %lx ", pmd_val(*pmd));
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if (!pmd_present(*pmd)) goto ret;
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pte = pte_offset_kernel(pmd, address);
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if (bad_address(pte)) goto bad;
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printk("PTE %lx", pte_val(*pte));
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ret:
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printk("\n");
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return;
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bad:
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printk("BAD\n");
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}
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static const char errata93_warning[] =
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KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
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KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
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KERN_ERR "******* Please consider a BIOS update.\n"
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KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
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/* Workaround for K8 erratum #93 & buggy BIOS.
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BIOS SMM functions are required to use a specific workaround
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to avoid corruption of the 64bit RIP register on C stepping K8.
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A lot of BIOS that didn't get tested properly miss this.
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The OS sees this as a page fault with the upper 32bits of RIP cleared.
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Try to work around it here.
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Note we only handle faults in kernel here. */
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static int is_errata93(struct pt_regs *regs, unsigned long address)
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{
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static int warned;
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if (address != regs->rip)
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return 0;
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if ((address >> 32) != 0)
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return 0;
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address |= 0xffffffffUL << 32;
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if ((address >= (u64)_stext && address <= (u64)_etext) ||
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(address >= MODULES_VADDR && address <= MODULES_END)) {
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if (!warned) {
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printk(errata93_warning);
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warned = 1;
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}
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regs->rip = address;
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return 1;
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}
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return 0;
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}
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int unhandled_signal(struct task_struct *tsk, int sig)
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{
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if (tsk->pid == 1)
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return 1;
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/* Warn for strace, but not for gdb */
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if (!test_ti_thread_flag(tsk->thread_info, TIF_SYSCALL_TRACE) &&
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(tsk->ptrace & PT_PTRACED))
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return 0;
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return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
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(tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
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}
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static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
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unsigned long error_code)
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{
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oops_begin();
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printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
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current->comm, address);
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dump_pagetable(address);
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__die("Bad pagetable", regs, error_code);
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oops_end();
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do_exit(SIGKILL);
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}
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/*
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* Handle a fault on the vmalloc or module mapping area
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*/
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static int vmalloc_fault(unsigned long address)
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{
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pgd_t *pgd, *pgd_ref;
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pud_t *pud, *pud_ref;
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pmd_t *pmd, *pmd_ref;
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pte_t *pte, *pte_ref;
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/* Copy kernel mappings over when needed. This can also
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happen within a race in page table update. In the later
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case just flush. */
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pgd = pgd_offset(current->mm ?: &init_mm, address);
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pgd_ref = pgd_offset_k(address);
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if (pgd_none(*pgd_ref))
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return -1;
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if (pgd_none(*pgd))
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set_pgd(pgd, *pgd_ref);
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/* Below here mismatches are bugs because these lower tables
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are shared */
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pud = pud_offset(pgd, address);
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pud_ref = pud_offset(pgd_ref, address);
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if (pud_none(*pud_ref))
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return -1;
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if (pud_none(*pud) || pud_page(*pud) != pud_page(*pud_ref))
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BUG();
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pmd = pmd_offset(pud, address);
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pmd_ref = pmd_offset(pud_ref, address);
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if (pmd_none(*pmd_ref))
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return -1;
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if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
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BUG();
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pte_ref = pte_offset_kernel(pmd_ref, address);
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if (!pte_present(*pte_ref))
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return -1;
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pte = pte_offset_kernel(pmd, address);
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if (!pte_present(*pte) || pte_page(*pte) != pte_page(*pte_ref))
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BUG();
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__flush_tlb_all();
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return 0;
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}
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int page_fault_trace = 0;
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int exception_trace = 1;
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* error_code:
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* bit 0 == 0 means no page found, 1 means protection fault
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* bit 1 == 0 means read, 1 means write
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* bit 2 == 0 means kernel, 1 means user-mode
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* bit 3 == 1 means fault was an instruction fetch
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*/
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asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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unsigned long address;
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const struct exception_table_entry *fixup;
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int write;
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siginfo_t info;
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#ifdef CONFIG_CHECKING
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{
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unsigned long gs;
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struct x8664_pda *pda = cpu_pda + stack_smp_processor_id();
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rdmsrl(MSR_GS_BASE, gs);
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if (gs != (unsigned long)pda) {
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wrmsrl(MSR_GS_BASE, pda);
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printk("page_fault: wrong gs %lx expected %p\n", gs, pda);
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}
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}
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#endif
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/* get the address */
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__asm__("movq %%cr2,%0":"=r" (address));
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if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
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SIGSEGV) == NOTIFY_STOP)
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return;
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if (likely(regs->eflags & X86_EFLAGS_IF))
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local_irq_enable();
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if (unlikely(page_fault_trace))
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printk("pagefault rip:%lx rsp:%lx cs:%lu ss:%lu address %lx error %lx\n",
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regs->rip,regs->rsp,regs->cs,regs->ss,address,error_code);
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tsk = current;
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mm = tsk->mm;
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info.si_code = SEGV_MAPERR;
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*
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* This verifies that the fault happens in kernel space
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* (error_code & 4) == 0, and that the fault was not a
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* protection error (error_code & 1) == 0.
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*/
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if (unlikely(address >= TASK_SIZE)) {
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if (!(error_code & 5)) {
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if (vmalloc_fault(address) < 0)
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goto bad_area_nosemaphore;
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return;
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}
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/*
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* Don't take the mm semaphore here. If we fixup a prefetch
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* fault we could otherwise deadlock.
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*/
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goto bad_area_nosemaphore;
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}
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if (unlikely(error_code & (1 << 3)))
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pgtable_bad(address, regs, error_code);
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (unlikely(in_atomic() || !mm))
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goto bad_area_nosemaphore;
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again:
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/* When running in the kernel we expect faults to occur only to
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* addresses in user space. All other faults represent errors in the
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* kernel and should generate an OOPS. Unfortunatly, in the case of an
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* erroneous fault occuring in a code path which already holds mmap_sem
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* we will deadlock attempting to validate the fault against the
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* address space. Luckily the kernel only validly references user
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* space from well defined areas of code, which are listed in the
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* exceptions table.
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*
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* As the vast majority of faults will be valid we will only perform
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* the source reference check when there is a possibilty of a deadlock.
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* Attempt to lock the address space, if we cannot we then validate the
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* source. If this is invalid we can skip the address space check,
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* thus avoiding the deadlock.
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*/
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if (!down_read_trylock(&mm->mmap_sem)) {
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if ((error_code & 4) == 0 &&
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!search_exception_tables(regs->rip))
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goto bad_area_nosemaphore;
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down_read(&mm->mmap_sem);
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}
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (likely(vma->vm_start <= address))
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (error_code & 4) {
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// XXX: align red zone size with ABI
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if (address + 128 < regs->rsp)
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goto bad_area;
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}
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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info.si_code = SEGV_ACCERR;
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write = 0;
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switch (error_code & 3) {
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default: /* 3: write, present */
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/* fall through */
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case 2: /* write, not present */
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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write++;
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break;
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case 1: /* read, present */
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goto bad_area;
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case 0: /* read, not present */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
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goto bad_area;
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}
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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switch (handle_mm_fault(mm, vma, address, write)) {
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case 1:
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tsk->min_flt++;
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break;
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case 2:
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tsk->maj_flt++;
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break;
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case 0:
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goto do_sigbus;
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default:
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goto out_of_memory;
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}
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up_read(&mm->mmap_sem);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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bad_area_nosemaphore:
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/* User mode accesses just cause a SIGSEGV */
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if (error_code & 4) {
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if (is_prefetch(regs, address, error_code))
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return;
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/* Work around K8 erratum #100 K8 in compat mode
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occasionally jumps to illegal addresses >4GB. We
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catch this here in the page fault handler because
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these addresses are not reachable. Just detect this
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case and return. Any code segment in LDT is
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compatibility mode. */
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if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
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(address >> 32))
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return;
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if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
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printk(
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"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
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tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
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tsk->comm, tsk->pid, address, regs->rip,
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regs->rsp, error_code);
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}
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tsk->thread.cr2 = address;
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/* Kernel addresses are always protection faults */
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tsk->thread.error_code = error_code | (address >= TASK_SIZE);
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tsk->thread.trap_no = 14;
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info.si_signo = SIGSEGV;
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info.si_errno = 0;
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/* info.si_code has been set above */
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info.si_addr = (void __user *)address;
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force_sig_info(SIGSEGV, &info, tsk);
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return;
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}
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no_context:
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/* Are we prepared to handle this kernel fault? */
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fixup = search_exception_tables(regs->rip);
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if (fixup) {
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regs->rip = fixup->fixup;
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return;
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}
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/*
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* Hall of shame of CPU/BIOS bugs.
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*/
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if (is_prefetch(regs, address, error_code))
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return;
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if (is_errata93(regs, address))
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|
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);
|
|
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;
|
|
}
|