diff options
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 1333 |
1 files changed, 772 insertions, 561 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index c76ef1d701c..a03b7279efa 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1,73 +1,79 @@ /* * Copyright (C) 1995 Linus Torvalds - * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. + * Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs. + * Copyright (C) 2008-2009, Red Hat Inc., Ingo Molnar */ - -#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/mmiotrace.h> -#include <linux/mman.h> -#include <linux/mm.h> -#include <linux/smp.h> #include <linux/interrupt.h> -#include <linux/init.h> -#include <linux/tty.h> -#include <linux/vt_kern.h> /* For unblank_screen() */ +#include <linux/mmiotrace.h> +#include <linux/bootmem.h> #include <linux/compiler.h> #include <linux/highmem.h> -#include <linux/bootmem.h> /* for max_low_pfn */ -#include <linux/vmalloc.h> -#include <linux/module.h> #include <linux/kprobes.h> #include <linux/uaccess.h> +#include <linux/vmalloc.h> +#include <linux/vt_kern.h> +#include <linux/signal.h> +#include <linux/kernel.h> +#include <linux/ptrace.h> +#include <linux/string.h> +#include <linux/module.h> #include <linux/kdebug.h> +#include <linux/errno.h> +#include <linux/magic.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/init.h> +#include <linux/mman.h> +#include <linux/tty.h> +#include <linux/smp.h> +#include <linux/mm.h> + +#include <asm-generic/sections.h> -#include <asm/system.h> -#include <asm/desc.h> -#include <asm/segment.h> -#include <asm/pgalloc.h> -#include <asm/smp.h> #include <asm/tlbflush.h> +#include <asm/pgalloc.h> +#include <asm/segment.h> +#include <asm/system.h> #include <asm/proto.h> -#include <asm-generic/sections.h> #include <asm/traps.h> +#include <asm/desc.h> /* - * Page fault error code bits - * bit 0 == 0 means no page found, 1 means protection fault - * bit 1 == 0 means read, 1 means write - * bit 2 == 0 means kernel, 1 means user-mode - * bit 3 == 1 means use of reserved bit detected - * bit 4 == 1 means fault was an instruction fetch + * Page fault error code bits: + * + * bit 0 == 0: no page found 1: protection fault + * bit 1 == 0: read access 1: write access + * bit 2 == 0: kernel-mode access 1: user-mode access + * bit 3 == 1: use of reserved bit detected + * bit 4 == 1: fault was an instruction fetch */ -#define PF_PROT (1<<0) -#define PF_WRITE (1<<1) -#define PF_USER (1<<2) -#define PF_RSVD (1<<3) -#define PF_INSTR (1<<4) +enum x86_pf_error_code { + + PF_PROT = 1 << 0, + PF_WRITE = 1 << 1, + PF_USER = 1 << 2, + PF_RSVD = 1 << 3, + PF_INSTR = 1 << 4, +}; +/* + * Returns 0 if mmiotrace is disabled, or if the fault is not + * handled by mmiotrace: + */ static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr) { -#ifdef CONFIG_MMIOTRACE if (unlikely(is_kmmio_active())) if (kmmio_handler(regs, addr) == 1) return -1; -#endif return 0; } static inline int notify_page_fault(struct pt_regs *regs) { -#ifdef CONFIG_KPROBES int ret = 0; /* kprobe_running() needs smp_processor_id() */ - if (!user_mode_vm(regs)) { + if (kprobes_built_in() && !user_mode_vm(regs)) { preempt_disable(); if (kprobe_running() && kprobe_fault_handler(regs, 14)) ret = 1; @@ -75,29 +81,76 @@ static inline int notify_page_fault(struct pt_regs *regs) } return ret; -#else - return 0; -#endif } /* - * X86_32 - * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. - * Check that here and ignore it. + * Prefetch quirks: + * + * 32-bit mode: + * + * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. + * Check that here and ignore it. + * + * 64-bit mode: * - * X86_64 - * Sometimes the CPU reports invalid exceptions on prefetch. - * Check that here and ignore it. + * Sometimes the CPU reports invalid exceptions on prefetch. + * Check that here and ignore it. * - * Opcode checker based on code by Richard Brunner + * Opcode checker based on code by Richard Brunner. */ -static int is_prefetch(struct pt_regs *regs, unsigned long addr, - unsigned long error_code) +static inline int +check_prefetch_opcode(struct pt_regs *regs, unsigned char *instr, + unsigned char opcode, int *prefetch) { + unsigned char instr_hi = opcode & 0xf0; + unsigned char instr_lo = opcode & 0x0f; + + switch (instr_hi) { + case 0x20: + case 0x30: + /* + * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. + * In X86_64 long mode, the CPU will signal invalid + * opcode if some of these prefixes are present so + * X86_64 will never get here anyway + */ + return ((instr_lo & 7) == 0x6); +#ifdef CONFIG_X86_64 + case 0x40: + /* + * In AMD64 long mode 0x40..0x4F are valid REX prefixes + * Need to figure out under what instruction mode the + * instruction was issued. Could check the LDT for lm, + * but for now it's good enough to assume that long + * mode only uses well known segments or kernel. + */ + return (!user_mode(regs)) || (regs->cs == __USER_CS); +#endif + case 0x60: + /* 0x64 thru 0x67 are valid prefixes in all modes. */ + return (instr_lo & 0xC) == 0x4; + case 0xF0: + /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ + return !instr_lo || (instr_lo>>1) == 1; + case 0x00: + /* Prefetch instruction is 0x0F0D or 0x0F18 */ + if (probe_kernel_address(instr, opcode)) + return 0; + + *prefetch = (instr_lo == 0xF) && + (opcode == 0x0D || opcode == 0x18); + return 0; + default: + return 0; + } +} + +static int +is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr) +{ + unsigned char *max_instr; unsigned char *instr; - int scan_more = 1; int prefetch = 0; - unsigned char *max_instr; /* * If it was a exec (instruction fetch) fault on NX page, then @@ -106,106 +159,170 @@ static int is_prefetch(struct pt_regs *regs, unsigned long addr, if (error_code & PF_INSTR) return 0; - instr = (unsigned char *)convert_ip_to_linear(current, regs); + instr = (void *)convert_ip_to_linear(current, regs); max_instr = instr + 15; if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) return 0; - while (scan_more && instr < max_instr) { + while (instr < max_instr) { unsigned char opcode; - unsigned char instr_hi; - unsigned char instr_lo; if (probe_kernel_address(instr, opcode)) break; - instr_hi = opcode & 0xf0; - instr_lo = opcode & 0x0f; instr++; - switch (instr_hi) { - case 0x20: - case 0x30: - /* - * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. - * In X86_64 long mode, the CPU will signal invalid - * opcode if some of these prefixes are present so - * X86_64 will never get here anyway - */ - scan_more = ((instr_lo & 7) == 0x6); + if (!check_prefetch_opcode(regs, instr, opcode, &prefetch)) break; -#ifdef CONFIG_X86_64 - case 0x40: - /* - * In AMD64 long mode 0x40..0x4F are valid REX prefixes - * Need to figure out under what instruction mode the - * instruction was issued. Could check the LDT for lm, - * but for now it's good enough to assume that long - * mode only uses well known segments or kernel. - */ - scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS); - break; -#endif - case 0x60: - /* 0x64 thru 0x67 are valid prefixes in all modes. */ - scan_more = (instr_lo & 0xC) == 0x4; - break; - case 0xF0: - /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ - scan_more = !instr_lo || (instr_lo>>1) == 1; - break; - case 0x00: - /* Prefetch instruction is 0x0F0D or 0x0F18 */ - scan_more = 0; - - if (probe_kernel_address(instr, opcode)) - break; - prefetch = (instr_lo == 0xF) && - (opcode == 0x0D || opcode == 0x18); - break; - default: - scan_more = 0; - break; - } } return prefetch; } -static void force_sig_info_fault(int si_signo, int si_code, - unsigned long address, struct task_struct *tsk) +static void +force_sig_info_fault(int si_signo, int si_code, unsigned long address, + struct task_struct *tsk) { siginfo_t info; - info.si_signo = si_signo; - info.si_errno = 0; - info.si_code = si_code; - info.si_addr = (void __user *)address; + info.si_signo = si_signo; + info.si_errno = 0; + info.si_code = si_code; + info.si_addr = (void __user *)address; + force_sig_info(si_signo, &info, tsk); } -#ifdef CONFIG_X86_64 -static int bad_address(void *p) +DEFINE_SPINLOCK(pgd_lock); +LIST_HEAD(pgd_list); + +#ifdef CONFIG_X86_32 +static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) { - unsigned long dummy; - return probe_kernel_address((unsigned long *)p, dummy); + unsigned index = pgd_index(address); + pgd_t *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + + pgd += index; + pgd_k = init_mm.pgd + index; + + if (!pgd_present(*pgd_k)) + return NULL; + + /* + * set_pgd(pgd, *pgd_k); here would be useless on PAE + * and redundant with the set_pmd() on non-PAE. As would + * set_pud. + */ + pud = pud_offset(pgd, address); + pud_k = pud_offset(pgd_k, address); + if (!pud_present(*pud_k)) + return NULL; + + pmd = pmd_offset(pud, address); + pmd_k = pmd_offset(pud_k, address); + if (!pmd_present(*pmd_k)) + return NULL; + + if (!pmd_present(*pmd)) { + set_pmd(pmd, *pmd_k); + arch_flush_lazy_mmu_mode(); + } else { + BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); + } + + return pmd_k; +} + +void vmalloc_sync_all(void) +{ + unsigned long address; + + if (SHARED_KERNEL_PMD) + return; + + for (address = VMALLOC_START & PMD_MASK; + address >= TASK_SIZE && address < FIXADDR_TOP; + address += PMD_SIZE) { + + 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); + } +} + +/* + * 32-bit: + * + * Handle a fault on the vmalloc or module mapping area + */ +static noinline int vmalloc_fault(unsigned long address) +{ + unsigned long pgd_paddr; + pmd_t *pmd_k; + pte_t *pte_k; + + /* Make sure we are in vmalloc area: */ + if (!(address >= VMALLOC_START && address < VMALLOC_END)) + return -1; + + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + * + * Do _not_ use "current" here. We might be inside + * an interrupt in the middle of a task switch.. + */ + pgd_paddr = read_cr3(); + pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); + if (!pmd_k) + return -1; + + pte_k = pte_offset_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + return -1; + + return 0; +} + +/* + * Did it hit the DOS screen memory VA from vm86 mode? + */ +static inline void +check_v8086_mode(struct pt_regs *regs, unsigned long address, + struct task_struct *tsk) +{ + unsigned long bit; + + if (!v8086_mode(regs)) + return; + + bit = (address - 0xA0000) >> PAGE_SHIFT; + if (bit < 32) + tsk->thread.screen_bitmap |= 1 << bit; } -#endif static void dump_pagetable(unsigned long address) { -#ifdef CONFIG_X86_32 __typeof__(pte_val(__pte(0))) page; page = read_cr3(); page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT]; + #ifdef CONFIG_X86_PAE printk("*pdpt = %016Lx ", page); if ((page >> PAGE_SHIFT) < max_low_pfn && page & _PAGE_PRESENT) { page &= PAGE_MASK; page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT) - & (PTRS_PER_PMD - 1)]; + & (PTRS_PER_PMD - 1)]; printk(KERN_CONT "*pde = %016Lx ", page); page &= ~_PAGE_NX; } @@ -217,19 +334,145 @@ static void dump_pagetable(unsigned long address) * We must not directly access the pte in the highpte * case if the page table is located in highmem. * And let's rather not kmap-atomic the pte, just in case - * it's allocated already. + * it's allocated already: */ if ((page >> PAGE_SHIFT) < max_low_pfn && (page & _PAGE_PRESENT) && !(page & _PAGE_PSE)) { + page &= PAGE_MASK; page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT) - & (PTRS_PER_PTE - 1)]; + & (PTRS_PER_PTE - 1)]; printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page); } printk("\n"); -#else /* CONFIG_X86_64 */ +} + +#else /* CONFIG_X86_64: */ + +void vmalloc_sync_all(void) +{ + unsigned long address; + + for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END; + address += PGDIR_SIZE) { + + const pgd_t *pgd_ref = pgd_offset_k(address); + unsigned long flags; + struct page *page; + + if (pgd_none(*pgd_ref)) + continue; + + spin_lock_irqsave(&pgd_lock, flags); + 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_irqrestore(&pgd_lock, flags); + } +} + +/* + * 64-bit: + * + * Handle a fault on the vmalloc area + * + * This assumes no large pages in there. + */ +static noinline 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; + + /* 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->active_mm, address); + pgd_ref = pgd_offset_k(address); + if (pgd_none(*pgd_ref)) + return -1; + + if (pgd_none(*pgd)) + set_pgd(pgd, *pgd_ref); + else + BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + + /* + * Below here mismatches are bugs because these lower tables + * are shared: + */ + + pud = pud_offset(pgd, address); + pud_ref = pud_offset(pgd_ref, address); + if (pud_none(*pud_ref)) + return -1; + + if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) + BUG(); + + pmd = pmd_offset(pud, address); + pmd_ref = pmd_offset(pud_ref, address); + if (pmd_none(*pmd_ref)) + return -1; + + if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) + BUG(); + + pte_ref = pte_offset_kernel(pmd_ref, address); + if (!pte_present(*pte_ref)) + return -1; + + pte = pte_offset_kernel(pmd, address); + + /* + * Don't use pte_page here, because the mappings can point + * outside mem_map, and the NUMA hash lookup cannot handle + * that: + */ + if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) + BUG(); + + return 0; +} + +static 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"; + +/* + * No vm86 mode in 64-bit mode: + */ +static inline void +check_v8086_mode(struct pt_regs *regs, unsigned long address, + struct task_struct *tsk) +{ +} + +static int bad_address(void *p) +{ + unsigned long dummy; + + return probe_kernel_address((unsigned long *)p, dummy); +} + +static void dump_pagetable(unsigned long address) +{ pgd_t *pgd; pud_t *pud; pmd_t *pmd; @@ -238,102 +481,77 @@ static void dump_pagetable(unsigned long address) pgd = (pgd_t *)read_cr3(); pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); + pgd += pgd_index(address); - if (bad_address(pgd)) goto bad; + if (bad_address(pgd)) + goto bad; + printk("PGD %lx ", pgd_val(*pgd)); - if (!pgd_present(*pgd)) goto ret; + + if (!pgd_present(*pgd)) + goto out; pud = pud_offset(pgd, address); - if (bad_address(pud)) goto bad; + if (bad_address(pud)) + goto bad; + printk("PUD %lx ", pud_val(*pud)); if (!pud_present(*pud) || pud_large(*pud)) - goto ret; + goto out; pmd = pmd_offset(pud, address); - if (bad_address(pmd)) goto bad; + if (bad_address(pmd)) + goto bad; + printk("PMD %lx ", pmd_val(*pmd)); - if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret; + if (!pmd_present(*pmd) || pmd_large(*pmd)) + goto out; pte = pte_offset_kernel(pmd, address); - if (bad_address(pte)) goto bad; + if (bad_address(pte)) + goto bad; + printk("PTE %lx", pte_val(*pte)); -ret: +out: printk("\n"); return; bad: printk("BAD\n"); -#endif -} - -#ifdef CONFIG_X86_32 -static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) -{ - unsigned index = pgd_index(address); - pgd_t *pgd_k; - pud_t *pud, *pud_k; - pmd_t *pmd, *pmd_k; - - pgd += index; - pgd_k = init_mm.pgd + index; - - if (!pgd_present(*pgd_k)) - return NULL; - - /* - * set_pgd(pgd, *pgd_k); here would be useless on PAE - * and redundant with the set_pmd() on non-PAE. As would - * set_pud. - */ - - pud = pud_offset(pgd, address); - pud_k = pud_offset(pgd_k, address); - if (!pud_present(*pud_k)) - return NULL; - - pmd = pmd_offset(pud, address); - pmd_k = pmd_offset(pud_k, address); - if (!pmd_present(*pmd_k)) - return NULL; - if (!pmd_present(*pmd)) { - set_pmd(pmd, *pmd_k); - arch_flush_lazy_mmu_mode(); - } else - BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); - return pmd_k; } -#endif -#ifdef CONFIG_X86_64 -static const char errata93_warning[] = -KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" -KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n" -KERN_ERR "******* Please consider a BIOS update.\n" -KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; -#endif +#endif /* CONFIG_X86_64 */ -/* 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. - Does nothing for X86_32 +/* + * 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. + * Does nothing on 32-bit. */ static int is_errata93(struct pt_regs *regs, unsigned long address) { #ifdef CONFIG_X86_64 - static int warned; + static int once; + if (address != regs->ip) 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) { + if (!once) { printk(errata93_warning); - warned = 1; + once = 1; } regs->ip = address; return 1; @@ -343,16 +561,17 @@ static int is_errata93(struct pt_regs *regs, unsigned long address) } /* - * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal - * addresses >4GB. We catch this in the page fault handler because these - * addresses are not reachable. Just detect this case and return. Any code + * Work around K8 erratum #100 K8 in compat mode occasionally jumps + * to illegal addresses >4GB. + * + * We catch this 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. */ static int is_errata100(struct pt_regs *regs, unsigned long address) { #ifdef CONFIG_X86_64 - if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && - (address >> 32)) + if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32)) return 1; #endif return 0; @@ -362,8 +581,9 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address) { #ifdef CONFIG_X86_F00F_BUG unsigned long nr; + /* - * Pentium F0 0F C7 C8 bug workaround. + * Pentium F0 0F C7 C8 bug workaround: */ if (boot_cpu_data.f00f_bug) { nr = (address - idt_descr.address) >> 3; @@ -377,62 +597,277 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address) return 0; } -static void show_fault_oops(struct pt_regs *regs, unsigned long error_code, - unsigned long address) +static const char nx_warning[] = KERN_CRIT +"kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n"; + +static void +show_fault_oops(struct pt_regs *regs, unsigned long error_code, + unsigned long address) { -#ifdef CONFIG_X86_32 if (!oops_may_print()) return; -#endif -#ifdef CONFIG_X86_PAE if (error_code & PF_INSTR) { unsigned int level; + pte_t *pte = lookup_address(address, &level); if (pte && pte_present(*pte) && !pte_exec(*pte)) - printk(KERN_CRIT "kernel tried to execute " - "NX-protected page - exploit attempt? " - "(uid: %d)\n", current_uid()); + printk(nx_warning, current_uid()); } -#endif printk(KERN_ALERT "BUG: unable to handle kernel "); if (address < PAGE_SIZE) printk(KERN_CONT "NULL pointer dereference"); else printk(KERN_CONT "paging request"); + printk(KERN_CONT " at %p\n", (void *) address); printk(KERN_ALERT "IP:"); printk_address(regs->ip, 1); + dump_pagetable(address); } -#ifdef CONFIG_X86_64 -static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, - unsigned long error_code) +static noinline void +pgtable_bad(struct pt_regs *regs, unsigned long error_code, + unsigned long address) { - unsigned long flags = oops_begin(); - int sig = SIGKILL; struct task_struct *tsk; + unsigned long flags; + int sig; + + flags = oops_begin(); + tsk = current; + sig = SIGKILL; printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", - current->comm, address); + tsk->comm, address); dump_pagetable(address); - tsk = current; - tsk->thread.cr2 = address; - tsk->thread.trap_no = 14; - tsk->thread.error_code = error_code; + + tsk->thread.cr2 = address; + tsk->thread.trap_no = 14; + tsk->thread.error_code = error_code; + if (__die("Bad pagetable", regs, error_code)) sig = 0; + oops_end(flags, regs, sig); } -#endif + +static noinline void +no_context(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + struct task_struct *tsk = current; + unsigned long *stackend; + unsigned long flags; + int sig; + + /* Are we prepared to handle this kernel fault? */ + if (fixup_exception(regs)) + return; + + /* + * 32-bit: + * + * Valid to do another page fault here, because if this fault + * had been triggered by is_prefetch fixup_exception would have + * handled it. + * + * 64-bit: + * + * Hall of shame of CPU/BIOS bugs. + */ + if (is_prefetch(regs, error_code, address)) + return; + + if (is_errata93(regs, address)) + return; + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice: + */ + flags = oops_begin(); + + show_fault_oops(regs, error_code, address); + + stackend = end_of_stack(tsk); + if (*stackend != STACK_END_MAGIC) + printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); + + tsk->thread.cr2 = address; + tsk->thread.trap_no = 14; + tsk->thread.error_code = error_code; + + sig = SIGKILL; + if (__die("Oops", regs, error_code)) + sig = 0; + + /* Executive summary in case the body of the oops scrolled away */ + printk(KERN_EMERG "CR2: %016lx\n", address); + + oops_end(flags, regs, sig); +} + +/* + * Print out info about fatal segfaults, if the show_unhandled_signals + * sysctl is set: + */ +static inline void +show_signal_msg(struct pt_regs *regs, unsigned long error_code, + unsigned long address, struct task_struct *tsk) +{ + if (!unhandled_signal(tsk, SIGSEGV)) + return; + + if (!printk_ratelimit()) + return; + + printk(KERN_CONT "%s%s[%d]: segfault at %lx ip %p sp %p error %lx", + task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, + tsk->comm, task_pid_nr(tsk), address, + (void *)regs->ip, (void *)regs->sp, error_code); + + print_vma_addr(KERN_CONT " in ", regs->ip); + + printk(KERN_CONT "\n"); +} + +static void +__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, + unsigned long address, int si_code) +{ + struct task_struct *tsk = current; + + /* 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, error_code, address)) + return; + + if (is_errata100(regs, address)) + return; + + if (unlikely(show_unhandled_signals)) + show_signal_msg(regs, error_code, address, tsk); + + /* Kernel addresses are always protection faults: */ + tsk->thread.cr2 = address; + 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(regs, error_code, address); +} + +static noinline void +bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR); +} + +static void +__bad_area(struct pt_regs *regs, unsigned long error_code, + unsigned long address, int si_code) +{ + struct mm_struct *mm = current->mm; + + /* + * Something tried to access memory that isn't in our memory map.. + * Fix it, but check if it's kernel or user first.. + */ + up_read(&mm->mmap_sem); + + __bad_area_nosemaphore(regs, error_code, address, si_code); +} + +static noinline void +bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address) +{ + __bad_area(regs, error_code, address, SEGV_MAPERR); +} + +static noinline void +bad_area_access_error(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + __bad_area(regs, error_code, address, SEGV_ACCERR); +} + +/* TODO: fixup for "mm-invoke-oom-killer-from-page-fault.patch" */ +static void +out_of_memory(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + /* + * We ran out of memory, call the OOM killer, and return the userspace + * (which will retry the fault, or kill us if we got oom-killed): + */ + up_read(¤t->mm->mmap_sem); + + pagefault_out_of_memory(); +} + +static void +do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address) +{ + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + + up_read(&mm->mmap_sem); + + /* Kernel mode? Handle exceptions or die: */ + if (!(error_code & PF_USER)) + no_context(regs, error_code, address); + + /* User-space => ok to do another page fault: */ + if (is_prefetch(regs, error_code, address)) + return; + + tsk->thread.cr2 = address; + tsk->thread.error_code = error_code; + tsk->thread.trap_no = 14; + + force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk); +} + +static noinline void +mm_fault_error(struct pt_regs *regs, unsigned long error_code, + unsigned long address, unsigned int fault) +{ + if (fault & VM_FAULT_OOM) { + out_of_memory(regs, error_code, address); + } else { + if (fault & VM_FAULT_SIGBUS) + do_sigbus(regs, error_code, address); + else + BUG(); + } +} static int spurious_fault_check(unsigned long error_code, pte_t *pte) { if ((error_code & PF_WRITE) && !pte_write(*pte)) return 0; + if ((error_code & PF_INSTR) && !pte_exec(*pte)) return 0; @@ -440,21 +875,25 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte) } /* - * Handle a spurious fault caused by a stale TLB entry. This allows - * us to lazily refresh the TLB when increasing the permissions of a - * kernel page (RO -> RW or NX -> X). Doing it eagerly is very - * expensive since that implies doing a full cross-processor TLB - * flush, even if no stale TLB entries exist on other processors. + * Handle a spurious fault caused by a stale TLB entry. + * + * This allows us to lazily refresh the TLB when increasing the + * permissions of a kernel page (RO -> RW or NX -> X). Doing it + * eagerly is very expensive since that implies doing a full + * cross-processor TLB flush, even if no stale TLB entries exist + * on other processors. + * * There are no security implications to leaving a stale TLB when * increasing the permissions on a page. */ -static int spurious_fault(unsigned long address, - unsigned long error_code) +static noinline int +spurious_fault(unsigned long error_code, unsigned long address) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; + int ret; /* Reserved-bit violation or user access to kernel space? */ if (error_code & (PF_USER | PF_RSVD)) @@ -482,127 +921,71 @@ static int spurious_fault(unsigned long address, if (!pte_present(*pte)) return 0; - return spurious_fault_check(error_code, pte); -} - -/* - * X86_32 - * Handle a fault on the vmalloc or module mapping area - * - * X86_64 - * Handle a fault on the vmalloc area - * - * This assumes no large pages in there. - */ -static int vmalloc_fault(unsigned long address) -{ -#ifdef CONFIG_X86_32 - unsigned long pgd_paddr; - pmd_t *pmd_k; - pte_t *pte_k; - - /* Make sure we are in vmalloc area */ - if (!(address >= VMALLOC_START && address < VMALLOC_END)) - return -1; + ret = spurious_fault_check(error_code, pte); + if (!ret) + return 0; /* - * Synchronize this task's top level page-table - * with the 'reference' page table. - * - * Do _not_ use "current" here. We might be inside - * an interrupt in the middle of a task switch.. + * Make sure we have permissions in PMD. + * If not, then there's a bug in the page tables: */ - pgd_paddr = read_cr3(); - pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); - if (!pmd_k) - return -1; - pte_k = pte_offset_kernel(pmd_k, address); - if (!pte_present(*pte_k)) - return -1; - return 0; -#else - pgd_t *pgd, *pgd_ref; - pud_t *pud, *pud_ref; - pmd_t *pmd, *pmd_ref; - pte_t *pte, *pte_ref; + ret = spurious_fault_check(error_code, (pte_t *) pmd); + WARN_ONCE(!ret, "PMD has incorrect permission bits\n"); - /* Make sure we are in vmalloc area */ - if (!(address >= VMALLOC_START && address < VMALLOC_END)) - return -1; + return ret; +} - /* Copy kernel mappings over when needed. This can also - happen within a race in page table update. In the later - case just flush. */ +int show_unhandled_signals = 1; - pgd = pgd_offset(current->active_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)); +static inline int +access_error(unsigned long error_code, int write, struct vm_area_struct *vma) +{ + if (write) { + /* write, present and write, not present: */ + if (unlikely(!(vma->vm_flags & VM_WRITE))) + return 1; + return 0; + } - /* Below here mismatches are bugs because these lower tables - are shared */ + /* read, present: */ + if (unlikely(error_code & PF_PROT)) + return 1; + + /* read, not present: */ + if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))) + return 1; - 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; +static int fault_in_kernel_space(unsigned long address) +{ + return address >= TASK_SIZE_MAX; +} /* * 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) +dotraplinkage 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; + struct task_struct *tsk; unsigned long address; - int write, si_code; + struct mm_struct *mm; + int write; int fault; -#ifdef CONFIG_X86_64 - unsigned long flags; - int sig; -#endif tsk = current; mm = tsk->mm; + prefetchw(&mm->mmap_sem); - /* get the address */ + /* Get the faulting address: */ address = read_cr2(); - si_code = SEGV_MAPERR; - if (unlikely(kmmio_fault(regs, address))) return; @@ -619,319 +1002,147 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) * (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 (unlikely(fault_in_kernel_space(address))) { 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)) + /* Can handle a stale RO->RW TLB: */ + if (spurious_fault(error_code, address)) return; - /* kprobes don't want to hook the spurious faults. */ + /* kprobes don't want to hook the spurious faults: */ if (notify_page_fault(regs)) return; /* * Don't take the mm semaphore here. If we fixup a prefetch - * fault we could otherwise deadlock. + * fault we could otherwise deadlock: */ - goto bad_area_nosemaphore; - } + bad_area_nosemaphore(regs, error_code, address); - /* kprobes don't want to hook the spurious faults. */ - if (notify_page_fault(regs)) return; + } + /* kprobes don't want to hook the spurious faults: */ + if (unlikely(notify_page_fault(regs))) + return; /* * It's safe to allow irq's after cr2 has been saved and the * vmalloc fault has been handled. * * User-mode registers count as a user access even for any - * potential system fault or CPU buglet. + * potential system fault or CPU buglet: */ if (user_mode_vm(regs)) { local_irq_enable(); error_code |= PF_USER; - } else if (regs->flags & X86_EFLAGS_IF) - local_irq_enable(); + } else { + if (regs->flags & X86_EFLAGS_IF) + local_irq_enable(); + } -#ifdef CONFIG_X86_64 if (unlikely(error_code & PF_RSVD)) - pgtable_bad(address, regs, error_code); -#endif + pgtable_bad(regs, error_code, address); /* - * 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 we're in an interrupt, have no user context or are running + * in an atomic region then we must not take the fault: */ - if (unlikely(in_atomic() || !mm)) - goto bad_area_nosemaphore; + if (unlikely(in_atomic() || !mm)) { + bad_area_nosemaphore(regs, error_code, address); + return; + } /* * 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. + * 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. + * 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 (unlikely(!down_read_trylock(&mm->mmap_sem))) { if ((error_code & PF_USER) == 0 && - !search_exception_tables(regs->ip)) - goto bad_area_nosemaphore; + !search_exception_tables(regs->ip)) { + bad_area_nosemaphore(regs, error_code, address); + return; + } down_read(&mm->mmap_sem); + } else { + /* + * The above down_read_trylock() might have succeeded in + * which case we'll have missed the might_sleep() from + * down_read(): + */ + might_sleep(); } vma = find_vma(mm, address); - if (!vma) - goto bad_area; - if (vma->vm_start <= address) + if (unlikely(!vma)) { + bad_area(regs, error_code, address); + return; + } + if (likely(vma->vm_start <= address)) goto good_area; - if (!(vma->vm_flags & VM_GROWSDOWN)) - goto bad_area; + if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) { + bad_area(regs, error_code, address); + return; + } 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 + * 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 (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) { + bad_area(regs, error_code, address); + return; + } } - if (expand_stack(vma, address)) - goto bad_area; -/* - * Ok, we have a good vm_area for this memory access, so - * we can handle it.. - */ + if (unlikely(expand_stack(vma, address))) { + bad_area(regs, error_code, address); + return; + } + + /* + * 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; + write = error_code & PF_WRITE; + + if (unlikely(access_error(error_code, write, vma))) { + bad_area_access_error(regs, error_code, address); + return; } /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo - * the fault. + * 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(); + mm_fault_error(regs, error_code, address, fault); + return; } + 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; + check_v8086_mode(regs, address, tsk); -/* - * 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( - "%s%s[%d]: segfault at %lx ip %p sp %p error %lx", - task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, - tsk->comm, task_pid_nr(tsk), address, - (void *) regs->ip, (void *) 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 - sig = SIGKILL; - if (__die("Oops", regs, error_code)) - sig = 0; - /* Executive summary in case the body of the oops scrolled away */ - printk(KERN_EMERG "CR2: %016lx\n", address); - oops_end(flags, regs, sig); -#endif - -out_of_memory: - /* - * We ran out of memory, call the OOM killer, and return the userspace - * (which will retry the fault, or kill us if we got oom-killed). - */ - up_read(&mm->mmap_sem); - pagefault_out_of_memory(); - return; - -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) -{ - unsigned long address; - -#ifdef CONFIG_X86_32 - if (SHARED_KERNEL_PMD) - return; - - for (address = VMALLOC_START & PMD_MASK; - address >= TASK_SIZE && address < FIXADDR_TOP; - address += PMD_SIZE) { - 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); - } -#else /* CONFIG_X86_64 */ - for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END; - address += PGDIR_SIZE) { - const pgd_t *pgd_ref = pgd_offset_k(address); - unsigned long flags; - struct page *page; - - if (pgd_none(*pgd_ref)) - continue; - spin_lock_irqsave(&pgd_lock, flags); - 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_irqrestore(&pgd_lock, flags); - } -#endif } |