d8b57bb700
In very rare cases, on certain CPUs, we could end up in the spurious fault handler and ignore a large pud/pmd mapping. The resulting pte pointer points into the mapped physical space and dereferencing it will fault recursively. Make the code aware of large mappings and do the permission check on the pmd/pud entry, when a large pud/pmd mapping is detected. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
985 lines
24 KiB
C
985 lines
24 KiB
C
/*
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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/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/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/highmem.h>
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#include <linux/bootmem.h> /* for max_low_pfn */
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#include <linux/vmalloc.h>
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <linux/kdebug.h>
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#include <asm/system.h>
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#include <asm/desc.h>
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#include <asm/segment.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-generic/sections.h>
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/*
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* Page fault error code bits
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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 use of reserved bit detected
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* bit 4 == 1 means fault was an instruction fetch
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*/
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#define PF_PROT (1<<0)
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#define PF_WRITE (1<<1)
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#define PF_USER (1<<2)
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#define PF_RSVD (1<<3)
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#define PF_INSTR (1<<4)
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static inline int notify_page_fault(struct pt_regs *regs)
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{
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#ifdef CONFIG_KPROBES
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int ret = 0;
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/* kprobe_running() needs smp_processor_id() */
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#ifdef CONFIG_X86_32
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if (!user_mode_vm(regs)) {
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#else
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if (!user_mode(regs)) {
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#endif
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, 14))
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ret = 1;
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preempt_enable();
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}
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return ret;
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#else
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return 0;
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#endif
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}
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/*
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* X86_32
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* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* X86_64
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* Sometimes the CPU reports invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* Opcode checker based on code by Richard Brunner
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*/
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static 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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#ifdef CONFIG_X86_32
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if (!(__supported_pte_mask & _PAGE_NX))
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return 0;
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#endif
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/* If it was a exec fault on NX page, ignore */
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if (error_code & PF_INSTR)
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return 0;
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instr = (unsigned char *)convert_ip_to_linear(current, regs);
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max_instr = instr + 15;
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if (user_mode(regs) && 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 (probe_kernel_address(instr, opcode))
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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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/*
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* Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
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* In X86_64 long mode, the CPU will signal invalid
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* opcode if some of these prefixes are present so
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* X86_64 will never get here anyway
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*/
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scan_more = ((instr_lo & 7) == 0x6);
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break;
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#ifdef CONFIG_X86_64
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case 0x40:
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/*
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* In AMD64 long mode 0x40..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. Could check the LDT for lm,
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* but for now it's good enough to assume that long
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* mode only uses well known segments or kernel.
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*/
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scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
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break;
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#endif
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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, 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 (probe_kernel_address(instr, opcode))
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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 void force_sig_info_fault(int si_signo, int si_code,
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unsigned long address, struct task_struct *tsk)
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{
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siginfo_t info;
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info.si_signo = si_signo;
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void __user *)address;
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force_sig_info(si_signo, &info, tsk);
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}
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#ifdef CONFIG_X86_64
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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 probe_kernel_address((unsigned long *)p, dummy);
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}
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#endif
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void dump_pagetable(unsigned long address)
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{
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#ifdef CONFIG_X86_32
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__typeof__(pte_val(__pte(0))) page;
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page = read_cr3();
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page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
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#ifdef CONFIG_X86_PAE
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printk("*pdpt = %016Lx ", page);
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if ((page >> PAGE_SHIFT) < max_low_pfn
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&& page & _PAGE_PRESENT) {
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page &= PAGE_MASK;
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page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
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& (PTRS_PER_PMD - 1)];
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printk(KERN_CONT "*pde = %016Lx ", page);
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page &= ~_PAGE_NX;
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}
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#else
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printk("*pde = %08lx ", page);
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#endif
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/*
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* We must not directly access the pte in the highpte
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* case if the page table is located in highmem.
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* And let's rather not kmap-atomic the pte, just in case
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* it's allocated already.
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*/
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if ((page >> PAGE_SHIFT) < max_low_pfn
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&& (page & _PAGE_PRESENT)
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&& !(page & _PAGE_PSE)) {
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page &= PAGE_MASK;
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page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
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& (PTRS_PER_PTE - 1)];
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printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
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}
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printk("\n");
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#else /* CONFIG_X86_64 */
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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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pgd = (pgd_t *)read_cr3();
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pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
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pgd += pgd_index(address);
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if (bad_address(pgd)) goto bad;
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printk("PGD %lx ", pgd_val(*pgd));
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if (!pgd_present(*pgd)) goto ret;
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pud = pud_offset(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) || pud_large(*pud))
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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) || pmd_large(*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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#endif
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}
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#ifdef CONFIG_X86_32
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static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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{
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unsigned index = pgd_index(address);
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pgd_t *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pgd += index;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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return NULL;
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/*
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* set_pgd(pgd, *pgd_k); here would be useless on PAE
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* and redundant with the set_pmd() on non-PAE. As would
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* set_pud.
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*/
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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_k, address);
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if (!pud_present(*pud_k))
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return NULL;
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pmd = pmd_offset(pud, address);
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pmd_k = pmd_offset(pud_k, address);
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if (!pmd_present(*pmd_k))
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return NULL;
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if (!pmd_present(*pmd)) {
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set_pmd(pmd, *pmd_k);
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arch_flush_lazy_mmu_mode();
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} else
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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return pmd_k;
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}
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#endif
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#ifdef CONFIG_X86_64
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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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#endif
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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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Does nothing for X86_32
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*/
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static int is_errata93(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_64
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static int warned;
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if (address != regs->ip)
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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->ip = address;
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return 1;
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}
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#endif
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return 0;
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}
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/*
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* Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
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* addresses >4GB. We catch this in the page fault handler because these
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* addresses are not reachable. Just detect this case and return. Any code
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* segment in LDT is compatibility mode.
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*/
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static int is_errata100(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_64
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if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
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(address >> 32))
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return 1;
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#endif
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return 0;
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}
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void do_invalid_op(struct pt_regs *, unsigned long);
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static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
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{
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#ifdef CONFIG_X86_F00F_BUG
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unsigned long nr;
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/*
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* Pentium F0 0F C7 C8 bug workaround.
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*/
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if (boot_cpu_data.f00f_bug) {
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nr = (address - idt_descr.address) >> 3;
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if (nr == 6) {
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do_invalid_op(regs, 0);
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return 1;
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}
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}
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#endif
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return 0;
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}
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static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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#ifdef CONFIG_X86_32
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if (!oops_may_print())
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return;
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#endif
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#ifdef CONFIG_X86_PAE
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if (error_code & PF_INSTR) {
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unsigned int level;
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pte_t *pte = lookup_address(address, &level);
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if (pte && pte_present(*pte) && !pte_exec(*pte))
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printk(KERN_CRIT "kernel tried to execute "
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"NX-protected page - exploit attempt? "
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"(uid: %d)\n", current->uid);
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}
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#endif
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printk(KERN_ALERT "BUG: unable to handle kernel ");
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if (address < PAGE_SIZE)
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printk(KERN_CONT "NULL pointer dereference");
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else
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printk(KERN_CONT "paging request");
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#ifdef CONFIG_X86_32
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printk(KERN_CONT " at %08lx\n", address);
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#else
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printk(KERN_CONT " at %016lx\n", address);
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#endif
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printk(KERN_ALERT "IP:");
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printk_address(regs->ip, 1);
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dump_pagetable(address);
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}
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#ifdef CONFIG_X86_64
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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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unsigned long flags = oops_begin();
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struct task_struct *tsk;
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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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tsk = current;
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tsk->thread.cr2 = address;
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tsk->thread.trap_no = 14;
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tsk->thread.error_code = error_code;
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if (__die("Bad pagetable", regs, error_code))
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regs = NULL;
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oops_end(flags, regs, SIGKILL);
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}
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#endif
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static int spurious_fault_check(unsigned long error_code, pte_t *pte)
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{
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if ((error_code & PF_WRITE) && !pte_write(*pte))
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return 0;
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if ((error_code & PF_INSTR) && !pte_exec(*pte))
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return 0;
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return 1;
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}
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|
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/*
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* Handle a spurious fault caused by a stale TLB entry. This allows
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* us to lazily refresh the TLB when increasing the permissions of a
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* kernel page (RO -> RW or NX -> X). Doing it eagerly is very
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* expensive since that implies doing a full cross-processor TLB
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* flush, even if no stale TLB entries exist on other processors.
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* There are no security implications to leaving a stale TLB when
|
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* increasing the permissions on a page.
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*/
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static int spurious_fault(unsigned long address,
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unsigned long error_code)
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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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|
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/* Reserved-bit violation or user access to kernel space? */
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if (error_code & (PF_USER | PF_RSVD))
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return 0;
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|
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pgd = init_mm.pgd + pgd_index(address);
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if (!pgd_present(*pgd))
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return 0;
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|
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pud = pud_offset(pgd, address);
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if (!pud_present(*pud))
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return 0;
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|
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if (pud_large(*pud))
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return spurious_fault_check(error_code, (pte_t *) pud);
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|
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pmd = pmd_offset(pud, address);
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if (!pmd_present(*pmd))
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return 0;
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|
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if (pmd_large(*pmd))
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return spurious_fault_check(error_code, (pte_t *) pmd);
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|
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pte = pte_offset_kernel(pmd, address);
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if (!pte_present(*pte))
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return 0;
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return spurious_fault_check(error_code, pte);
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}
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|
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/*
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* X86_32
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* Handle a fault on the vmalloc or module mapping area
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*
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* X86_64
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* Handle a fault on the vmalloc area
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*
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* This assumes no large pages in there.
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*/
|
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static int vmalloc_fault(unsigned long address)
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{
|
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#ifdef CONFIG_X86_32
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unsigned long pgd_paddr;
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pmd_t *pmd_k;
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pte_t *pte_k;
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/*
|
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* Synchronize this task's top level page-table
|
|
* with the 'reference' page table.
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|
*
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|
* Do _not_ use "current" here. We might be inside
|
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* an interrupt in the middle of a task switch..
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|
*/
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pgd_paddr = read_cr3();
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pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
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if (!pmd_k)
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return -1;
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pte_k = pte_offset_kernel(pmd_k, address);
|
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if (!pte_present(*pte_k))
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|
return -1;
|
|
return 0;
|
|
#else
|
|
pgd_t *pgd, *pgd_ref;
|
|
pud_t *pud, *pud_ref;
|
|
pmd_t *pmd, *pmd_ref;
|
|
pte_t *pte, *pte_ref;
|
|
|
|
/* Make sure we are in vmalloc area */
|
|
if (!(address >= VMALLOC_START && address < VMALLOC_END))
|
|
return -1;
|
|
|
|
/* 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;
|
|
#endif
|
|
}
|
|
|
|
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.
|
|
*/
|
|
#ifdef CONFIG_X86_64
|
|
asmlinkage
|
|
#endif
|
|
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;
|
|
int write, si_code;
|
|
int fault;
|
|
#ifdef CONFIG_X86_64
|
|
unsigned long flags;
|
|
#endif
|
|
|
|
/*
|
|
* We can fault from pretty much anywhere, with unknown IRQ state.
|
|
*/
|
|
trace_hardirqs_fixup();
|
|
|
|
tsk = current;
|
|
mm = tsk->mm;
|
|
prefetchw(&mm->mmap_sem);
|
|
|
|
/* get the address */
|
|
address = read_cr2();
|
|
|
|
si_code = SEGV_MAPERR;
|
|
|
|
if (notify_page_fault(regs))
|
|
return;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
#ifdef CONFIG_X86_32
|
|
if (unlikely(address >= TASK_SIZE)) {
|
|
#else
|
|
if (unlikely(address >= TASK_SIZE64)) {
|
|
#endif
|
|
if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
|
|
vmalloc_fault(address) >= 0)
|
|
return;
|
|
|
|
/* Can handle a stale RO->RW TLB */
|
|
if (spurious_fault(address, error_code))
|
|
return;
|
|
|
|
/*
|
|
* Don't take the mm semaphore here. If we fixup a prefetch
|
|
* fault we could otherwise deadlock.
|
|
*/
|
|
goto bad_area_nosemaphore;
|
|
}
|
|
|
|
|
|
#ifdef CONFIG_X86_32
|
|
/* It's safe to allow irq's after cr2 has been saved and the vmalloc
|
|
fault has been handled. */
|
|
if (regs->flags & (X86_EFLAGS_IF|VM_MASK))
|
|
local_irq_enable();
|
|
|
|
/*
|
|
* 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 (in_atomic() || !mm)
|
|
goto bad_area_nosemaphore;
|
|
#else /* CONFIG_X86_64 */
|
|
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, 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;
|
|
|
|
/*
|
|
* 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:
|
|
#endif
|
|
/* 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. Unfortunately, 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 possibility 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->ip))
|
|
goto bad_area_nosemaphore;
|
|
down_read(&mm->mmap_sem);
|
|
}
|
|
|
|
vma = find_vma(mm, address);
|
|
if (!vma)
|
|
goto bad_area;
|
|
if (vma->vm_start <= address)
|
|
goto good_area;
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
goto bad_area;
|
|
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->sp)
|
|
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:
|
|
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;
|
|
}
|
|
|
|
#ifdef CONFIG_X86_32
|
|
survive:
|
|
#endif
|
|
/*
|
|
* 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++;
|
|
|
|
#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;
|
|
|
|
/*
|
|
* 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();
|
|
|
|
/*
|
|
* Valid to do another page fault here because this one came
|
|
* from user space.
|
|
*/
|
|
if (is_prefetch(regs, address, error_code))
|
|
return;
|
|
|
|
if (is_errata100(regs, address))
|
|
return;
|
|
|
|
if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
|
|
printk_ratelimit()) {
|
|
printk(
|
|
#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;
|
|
force_sig_info_fault(SIGSEGV, si_code, address, tsk);
|
|
return;
|
|
}
|
|
|
|
if (is_f00f_bug(regs, address))
|
|
return;
|
|
|
|
no_context:
|
|
/* Are we prepared to handle this kernel fault? */
|
|
if (fixup_exception(regs))
|
|
return;
|
|
|
|
/*
|
|
* X86_32
|
|
* Valid to do another page fault here, because if this fault
|
|
* had been triggered by is_prefetch fixup_exception would have
|
|
* handled it.
|
|
*
|
|
* X86_64
|
|
* 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.
|
|
*/
|
|
#ifdef CONFIG_X86_32
|
|
bust_spinlocks(1);
|
|
#else
|
|
flags = oops_begin();
|
|
#endif
|
|
|
|
show_fault_oops(regs, error_code, address);
|
|
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.trap_no = 14;
|
|
tsk->thread.error_code = error_code;
|
|
|
|
#ifdef CONFIG_X86_32
|
|
die("Oops", regs, error_code);
|
|
bust_spinlocks(0);
|
|
do_exit(SIGKILL);
|
|
#else
|
|
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, regs, SIGKILL);
|
|
#endif
|
|
|
|
/*
|
|
* 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_global_init(tsk)) {
|
|
yield();
|
|
#ifdef CONFIG_X86_32
|
|
down_read(&mm->mmap_sem);
|
|
goto survive;
|
|
#else
|
|
goto again;
|
|
#endif
|
|
}
|
|
|
|
printk("VM: killing process %s\n", tsk->comm);
|
|
if (error_code & PF_USER)
|
|
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;
|
|
#ifdef CONFIG_X86_32
|
|
/* User space => ok to do another page fault */
|
|
if (is_prefetch(regs, address, error_code))
|
|
return;
|
|
#endif
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.error_code = error_code;
|
|
tsk->thread.trap_no = 14;
|
|
force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
|
|
}
|
|
|
|
DEFINE_SPINLOCK(pgd_lock);
|
|
LIST_HEAD(pgd_list);
|
|
|
|
void vmalloc_sync_all(void)
|
|
{
|
|
#ifdef CONFIG_X86_32
|
|
/*
|
|
* 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 = TASK_SIZE;
|
|
unsigned long address;
|
|
|
|
if (SHARED_KERNEL_PMD)
|
|
return;
|
|
|
|
BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
|
|
for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
|
|
if (!test_bit(pgd_index(address), insync)) {
|
|
unsigned long flags;
|
|
struct page *page;
|
|
|
|
spin_lock_irqsave(&pgd_lock, flags);
|
|
list_for_each_entry(page, &pgd_list, lru) {
|
|
if (!vmalloc_sync_one(page_address(page),
|
|
address))
|
|
break;
|
|
}
|
|
spin_unlock_irqrestore(&pgd_lock, flags);
|
|
if (!page)
|
|
set_bit(pgd_index(address), insync);
|
|
}
|
|
if (address == start && test_bit(pgd_index(address), insync))
|
|
start = address + PGDIR_SIZE;
|
|
}
|
|
#else /* CONFIG_X86_64 */
|
|
/*
|
|
* 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)));
|
|
#endif
|
|
}
|