diff options
| -rw-r--r-- | arch/x86/mm/fault_32.c | 148 | ||||
| -rw-r--r-- | arch/x86/mm/fault_64.c | 151 |
2 files changed, 160 insertions, 139 deletions
diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c index db8d748814e..bfb0917d699 100644 --- a/arch/x86/mm/fault_32.c +++ b/arch/x86/mm/fault_32.c @@ -1,6 +1,4 @@ /* - * linux/arch/i386/mm/fault.c - * * Copyright (C) 1995 Linus Torvalds */ @@ -30,11 +28,25 @@ #include <asm/desc.h> #include <asm/segment.h> -extern void die(const char *,struct pt_regs *,long); +/* + * 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 + */ +#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) + +extern void die(const char *, struct pt_regs *, long); -#ifdef CONFIG_KPROBES static inline int notify_page_fault(struct pt_regs *regs) { +#ifdef CONFIG_KPROBES int ret = 0; /* kprobe_running() needs smp_processor_id() */ @@ -46,13 +58,10 @@ static inline int notify_page_fault(struct pt_regs *regs) } return ret; -} #else -static inline int notify_page_fault(struct pt_regs *regs) -{ return 0; -} #endif +} /* * Return EIP plus the CS segment base. The segment limit is also @@ -65,7 +74,7 @@ static inline int notify_page_fault(struct pt_regs *regs) * If CS is no longer a valid code segment, or if EIP is beyond the * limit, or if it is a kernel address when CS is not a kernel segment, * then the returned value will be greater than *eip_limit. - * + * * This is slow, but is very rarely executed. */ static inline unsigned long get_segment_eip(struct pt_regs *regs, @@ -84,7 +93,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, /* The standard kernel/user address space limit. */ *eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg; - + /* By far the most common cases. */ if (likely(SEGMENT_IS_FLAT_CODE(seg))) return ip; @@ -99,7 +108,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, return 1; /* So that returned ip > *eip_limit. */ } - /* Get the GDT/LDT descriptor base. + /* Get the GDT/LDT descriptor base. When you look for races in this code remember that LDT and other horrors are only used in user space. */ if (seg & (1<<2)) { @@ -109,16 +118,16 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, desc = (void *)desc + (seg & ~7); } else { /* Must disable preemption while reading the GDT. */ - desc = (u32 *)get_cpu_gdt_table(get_cpu()); + desc = (u32 *)get_cpu_gdt_table(get_cpu()); desc = (void *)desc + (seg & ~7); } /* Decode the code segment base from the descriptor */ base = get_desc_base((struct desc_struct *)desc); - if (seg & (1<<2)) { + if (seg & (1<<2)) mutex_unlock(¤t->mm->context.lock); - } else + else put_cpu(); /* Adjust EIP and segment limit, and clamp at the kernel limit. @@ -129,19 +138,19 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, return ip + base; } -/* +/* * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. * Check that here and ignore it. */ static int __is_prefetch(struct pt_regs *regs, unsigned long addr) -{ +{ unsigned long limit; - unsigned char *instr = (unsigned char *)get_segment_eip (regs, &limit); + unsigned char *instr = (unsigned char *)get_segment_eip(regs, &limit); int scan_more = 1; - int prefetch = 0; + int prefetch = 0; int i; - for (i = 0; scan_more && i < 15; i++) { + for (i = 0; scan_more && i < 15; i++) { unsigned char opcode; unsigned char instr_hi; unsigned char instr_lo; @@ -149,27 +158,43 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr) if (instr > (unsigned char *)limit) break; if (probe_kernel_address(instr, opcode)) - break; + break; - instr_hi = opcode & 0xf0; - instr_lo = opcode & 0x0f; + instr_hi = opcode & 0xf0; + instr_lo = opcode & 0x0f; instr++; - switch (instr_hi) { + switch (instr_hi) { case 0x20: case 0x30: - /* Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. */ + /* + * 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); 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; + break; case 0xF0: - /* 0xF0, 0xF2, and 0xF3 are valid prefixes */ + /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ scan_more = !instr_lo || (instr_lo>>1) == 1; - break; + break; case 0x00: /* Prefetch instruction is 0x0F0D or 0x0F18 */ scan_more = 0; @@ -179,11 +204,11 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr) break; prefetch = (instr_lo == 0xF) && (opcode == 0x0D || opcode == 0x18); - break; + break; default: scan_more = 0; break; - } + } } return prefetch; } @@ -199,7 +224,7 @@ static inline int is_prefetch(struct pt_regs *regs, unsigned long addr, return __is_prefetch(regs, addr); } return 0; -} +} static noinline void force_sig_info_fault(int si_signo, int si_code, unsigned long address, struct task_struct *tsk) @@ -284,19 +309,12 @@ 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. - * - * error_code: - * bit 0 == 0 means no page found, 1 means protection fault - * bit 1 == 0 means read, 1 means write - * bit 2 == 0 means kernel, 1 means user-mode - * bit 3 == 1 means use of reserved bit detected - * bit 4 == 1 means fault was an instruction fetch */ 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 vm_area_struct *vma; unsigned long address; int write, si_code; int fault; @@ -307,7 +325,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) trace_hardirqs_fixup(); /* get the address */ - address = read_cr2(); + address = read_cr2(); tsk = current; @@ -350,7 +368,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long 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.. + * atomic region then we must not take the fault. */ if (in_atomic() || !mm) goto bad_area_nosemaphore; @@ -371,7 +389,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) * thus avoiding the deadlock. */ if (!down_read_trylock(&mm->mmap_sem)) { - if ((error_code & 4) == 0 && + if ((error_code & PF_USER) == 0 && !search_exception_tables(regs->ip)) goto bad_area_nosemaphore; down_read(&mm->mmap_sem); @@ -384,7 +402,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; - if (error_code & 4) { + if (error_code & PF_USER) { /* * Accessing the stack below %sp is always a bug. * The large cushion allows instructions like enter @@ -403,19 +421,19 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) good_area: si_code = SEGV_ACCERR; write = 0; - switch (error_code & 3) { - default: /* 3: write, present */ - /* fall through */ - case 2: /* write, not present */ - if (!(vma->vm_flags & VM_WRITE)) - goto bad_area; - write++; - break; - case 1: /* read, present */ + 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; - case 0: /* read, not present */ - if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) - goto bad_area; } survive: @@ -457,14 +475,14 @@ bad_area: bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ - if (error_code & 4) { + 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 + /* + * Valid to do another page fault here because this one came * from user space. */ if (is_prefetch(regs, address, error_code)) @@ -492,7 +510,7 @@ bad_area_nosemaphore: */ if (boot_cpu_data.f00f_bug) { unsigned long nr; - + nr = (address - idt_descr.address) >> 3; if (nr == 6) { @@ -507,13 +525,13 @@ no_context: if (fixup_exception(regs)) return; - /* + /* * Valid to do another page fault here, because if this fault - * had been triggered by is_prefetch fixup_exception would have + * had been triggered by is_prefetch fixup_exception would have * handled it. */ - if (is_prefetch(regs, address, error_code)) - return; + if (is_prefetch(regs, address, error_code)) + return; /* * Oops. The kernel tried to access some bad page. We'll have to @@ -541,7 +559,7 @@ no_context: else printk(KERN_ALERT "BUG: unable to handle kernel paging" " request"); - printk(" at virtual address %08lx\n",address); + printk(" at virtual address %08lx\n", address); printk(KERN_ALERT "printing ip: %08lx ", regs->ip); page = read_cr3(); @@ -605,7 +623,7 @@ do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ - if (!(error_code & 4)) + if (!(error_code & PF_USER)) goto no_context; /* User space => ok to do another page fault */ diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c index 3a94941578f..7e98a769128 100644 --- a/arch/x86/mm/fault_64.c +++ b/arch/x86/mm/fault_64.c @@ -1,6 +1,4 @@ /* - * linux/arch/x86-64/mm/fault.c - * * Copyright (C) 1995 Linus Torvalds * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. */ @@ -33,16 +31,23 @@ #include <asm/proto.h> #include <asm-generic/sections.h> -/* Page fault error code bits */ -#define PF_PROT (1<<0) /* or no page found */ +/* + * 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 + */ +#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) -#ifdef CONFIG_KPROBES static inline int notify_page_fault(struct pt_regs *regs) { +#ifdef CONFIG_KPROBES int ret = 0; /* kprobe_running() needs smp_processor_id() */ @@ -54,75 +59,75 @@ static inline int notify_page_fault(struct pt_regs *regs) } return ret; -} #else -static inline int notify_page_fault(struct pt_regs *regs) -{ return 0; -} #endif +} /* Sometimes the CPU reports invalid exceptions on prefetch. Check that here and ignore. Opcode checker based on code by Richard Brunner */ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr, unsigned long error_code) -{ +{ unsigned char *instr; int scan_more = 1; - int prefetch = 0; + int prefetch = 0; unsigned char *max_instr; /* If it was a exec fault ignore */ if (error_code & PF_INSTR) return 0; - + instr = (unsigned char __user *)convert_rip_to_linear(current, regs); max_instr = instr + 15; if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) return 0; - while (scan_more && instr < max_instr) { + while (scan_more && instr < max_instr) { unsigned char opcode; unsigned char instr_hi; unsigned char instr_lo; if (probe_kernel_address(instr, opcode)) - break; + break; - instr_hi = opcode & 0xf0; - instr_lo = opcode & 0x0f; + instr_hi = opcode & 0xf0; + instr_lo = opcode & 0x0f; instr++; - switch (instr_hi) { + switch (instr_hi) { case 0x20: case 0x30: - /* Values 0x26,0x2E,0x36,0x3E are valid x86 - prefixes. In long mode, the CPU will signal - invalid opcode if some of these prefixes are - present so we will never get here anyway */ + /* + * 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); break; - +#ifdef CONFIG_X86_64 case 0x40: - /* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes - Need to figure out under what instruction mode the - instruction was issued ... */ - /* Could check the LDT for lm, but for now it's good - enough to assume that long mode only uses well known - segments or kernel. */ + /* + * 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; + break; case 0xF0: /* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */ scan_more = !instr_lo || (instr_lo>>1) == 1; - break; + break; case 0x00: /* Prefetch instruction is 0x0F0D or 0x0F18 */ scan_more = 0; @@ -130,20 +135,20 @@ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr, break; prefetch = (instr_lo == 0xF) && (opcode == 0x0D || opcode == 0x18); - break; + break; default: scan_more = 0; break; - } + } } return prefetch; } -static int bad_address(void *p) -{ +static int bad_address(void *p) +{ unsigned long dummy; return probe_kernel_address((unsigned long *)p, dummy); -} +} void dump_pagetable(unsigned long address) { @@ -154,11 +159,11 @@ void dump_pagetable(unsigned long address) pgd = (pgd_t *)read_cr3(); - pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); + pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); pgd += pgd_index(address); if (bad_address(pgd)) goto bad; printk("PGD %lx ", pgd_val(*pgd)); - if (!pgd_present(*pgd)) goto ret; + if (!pgd_present(*pgd)) goto ret; pud = pud_offset(pgd, address); if (bad_address(pud)) goto bad; @@ -172,7 +177,7 @@ void dump_pagetable(unsigned long address) pte = pte_offset_kernel(pmd, address); if (bad_address(pte)) goto bad; - printk("PTE %lx", pte_val(*pte)); + printk("PTE %lx", pte_val(*pte)); ret: printk("\n"); return; @@ -180,7 +185,7 @@ bad: printk("BAD\n"); } -static const char errata93_warning[] = +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" @@ -188,31 +193,31 @@ KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; /* Workaround for K8 erratum #93 & buggy BIOS. BIOS SMM functions are required to use a specific workaround - to avoid corruption of the 64bit RIP register on C stepping K8. - A lot of BIOS that didn't get tested properly miss this. + to avoid corruption of the 64bit RIP register on C stepping K8. + A lot of BIOS that didn't get tested properly miss this. The OS sees this as a page fault with the upper 32bits of RIP cleared. Try to work around it here. Note we only handle faults in kernel here. */ -static int is_errata93(struct pt_regs *regs, unsigned long address) +static int is_errata93(struct pt_regs *regs, unsigned long address) { static int warned; if (address != regs->ip) return 0; - if ((address >> 32) != 0) + if ((address >> 32) != 0) return 0; address |= 0xffffffffUL << 32; - if ((address >= (u64)_stext && address <= (u64)_etext) || - (address >= MODULES_VADDR && address <= MODULES_END)) { + if ((address >= (u64)_stext && address <= (u64)_etext) || + (address >= MODULES_VADDR && address <= MODULES_END)) { if (!warned) { - printk(errata93_warning); + printk(errata93_warning); warned = 1; } regs->ip = address; return 1; } return 0; -} +} static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, unsigned long error_code) @@ -296,7 +301,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, { struct task_struct *tsk; struct mm_struct *mm; - struct vm_area_struct * vma; + struct vm_area_struct *vma; unsigned long address; int write, fault; unsigned long flags; @@ -360,8 +365,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, pgtable_bad(address, regs, error_code); /* - * If we're in an interrupt or have no user - * context, 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; @@ -403,7 +408,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; - if (error_code & 4) { + if (error_code & PF_USER) { /* Allow userspace just enough access below the stack pointer * to let the 'enter' instruction work. */ @@ -420,18 +425,18 @@ good_area: info.si_code = SEGV_ACCERR; write = 0; switch (error_code & (PF_PROT|PF_WRITE)) { - default: /* 3: write, present */ - /* fall through */ - case PF_WRITE: /* write, not present */ - if (!(vma->vm_flags & VM_WRITE)) - goto bad_area; - write++; - break; - case PF_PROT: /* read, present */ + 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; - case 0: /* read, not present */ - if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) - goto bad_area; } /* @@ -491,7 +496,7 @@ bad_area_nosemaphore: tsk->comm, tsk->pid, address, regs->ip, regs->sp, error_code); } - + tsk->thread.cr2 = address; /* Kernel addresses are always protection faults */ tsk->thread.error_code = error_code | (address >= TASK_SIZE); @@ -505,21 +510,19 @@ bad_area_nosemaphore: } no_context: - /* Are we prepared to handle this kernel fault? */ - if (fixup_exception(regs)) { + if (fixup_exception(regs)) return; - } - /* + /* * Hall of shame of CPU/BIOS bugs. */ - if (is_prefetch(regs, address, error_code)) - return; + if (is_prefetch(regs, address, error_code)) + return; if (is_errata93(regs, address)) - return; + return; /* * Oops. The kernel tried to access some bad page. We'll have to @@ -532,7 +535,7 @@ no_context: printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); else printk(KERN_ALERT "Unable to handle kernel paging request"); - printk(" at %016lx RIP: \n" KERN_ALERT,address); + printk(" at %016lx RIP: \n" KERN_ALERT, address); printk_address(regs->ip); dump_pagetable(address); tsk->thread.cr2 = address; @@ -582,7 +585,7 @@ LIST_HEAD(pgd_list); void vmalloc_sync_all(void) { - /* Note that races in the updates of insync and start aren't + /* 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). */ @@ -614,6 +617,6 @@ void vmalloc_sync_all(void) } /* 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) == + BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == (__START_KERNEL & PGDIR_MASK))); } |