diff options
Diffstat (limited to 'arch/x86/mm/fault_64.c')
| -rw-r--r-- | arch/x86/mm/fault_64.c | 151 |
1 files changed, 77 insertions, 74 deletions
diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c index 3a94941..7e98a769 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))); } |
