x86_64: prepare shared mm/fault.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 0 insertions, 636 deletions

diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
deleted file mode 100644
index 54816adb8e9..00000000000
--- a/arch/x86_64/mm/fault.c
+++ /dev/null
@@ -1,636 +0,0 @@
-/*
- *  linux/arch/x86-64/mm/fault.c
- *
- *  Copyright (C) 1995  Linus Torvalds
- *  Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
- */
-
-#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/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/compiler.h>
-#include <linux/vmalloc.h>
-#include <linux/module.h>
-#include <linux/kprobes.h>
-#include <linux/uaccess.h>
-#include <linux/kdebug.h>
-
-#include <asm/system.h>
-#include <asm/pgalloc.h>
-#include <asm/smp.h>
-#include <asm/tlbflush.h>
-#include <asm/proto.h>
-#include <asm-generic/sections.h>
-
-/* Page fault error code bits */
-#define PF_PROT	(1<<0)		/* or no page found */
-#define PF_WRITE	(1<<1)
-#define PF_USER	(1<<2)
-#define PF_RSVD	(1<<3)
-#define PF_INSTR	(1<<4)
-
-static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
-
-/* Hook to register for page fault notifications */
-int register_page_fault_notifier(struct notifier_block *nb)
-{
-	vmalloc_sync_all();
-	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
-}
-EXPORT_SYMBOL_GPL(register_page_fault_notifier);
-
-int unregister_page_fault_notifier(struct notifier_block *nb)
-{
-	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
-}
-EXPORT_SYMBOL_GPL(unregister_page_fault_notifier);
-
-static inline int notify_page_fault(struct pt_regs *regs, long err)
-{
-	struct die_args args = {
-		.regs = regs,
-		.str = "page fault",
-		.err = err,
-		.trapnr = 14,
-		.signr = SIGSEGV
-	};
-	return atomic_notifier_call_chain(&notify_page_fault_chain,
-	                                  DIE_PAGE_FAULT, &args);
-}
-
-/* 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; 
-	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) { 
-		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 long mode, the CPU will signal
-			   invalid opcode if some of these prefixes are
-			   present so we will never get here anyway */
-			scan_more = ((instr_lo & 7) == 0x6);
-			break;
-			
-		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. */
-			scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
-			break;
-			
-		case 0x60:
-			/* 0x64 thru 0x67 are valid prefixes in all modes. */
-			scan_more = (instr_lo & 0xC) == 0x4;
-			break;		
-		case 0xF0:
-			/* 0xF0, 0xF2, and 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 int bad_address(void *p) 
-{ 
-	unsigned long dummy;
-	return probe_kernel_address((unsigned long *)p, dummy);
-} 
-
-void dump_pagetable(unsigned long address)
-{
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-
-	pgd = (pgd_t *)read_cr3();
-
-	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; 
-
-	pud = pud_offset(pgd, address);
-	if (bad_address(pud)) goto bad;
-	printk("PUD %lx ", pud_val(*pud));
-	if (!pud_present(*pud))	goto ret;
-
-	pmd = pmd_offset(pud, address);
-	if (bad_address(pmd)) goto bad;
-	printk("PMD %lx ", pmd_val(*pmd));
-	if (!pmd_present(*pmd))	goto ret;	 
-
-	pte = pte_offset_kernel(pmd, address);
-	if (bad_address(pte)) goto bad;
-	printk("PTE %lx", pte_val(*pte)); 
-ret:
-	printk("\n");
-	return;
-bad:
-	printk("BAD\n");
-}
-
-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";
-
-/* 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. */
-
-static int is_errata93(struct pt_regs *regs, unsigned long address) 
-{
-	static int warned;
-	if (address != regs->rip)
-		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) {
-			printk(errata93_warning); 		
-			warned = 1;
-		}
-		regs->rip = address;
-		return 1;
-	}
-	return 0;
-} 
-
-static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
-				 unsigned long error_code)
-{
-	unsigned long flags = oops_begin();
-	struct task_struct *tsk;
-
-	printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
-	       current->comm, address);
-	dump_pagetable(address);
-	tsk = current;
-	tsk->thread.cr2 = address;
-	tsk->thread.trap_no = 14;
-	tsk->thread.error_code = error_code;
-	__die("Bad pagetable", regs, error_code);
-	oops_end(flags);
-	do_exit(SIGKILL);
-}
-
-/*
- * Handle a fault on the vmalloc area
- *
- * This assumes no large pages in there.
- */
-static 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;
-
-	/* 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;
-}
-
-static int page_fault_trace;
-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.
- */
-asmlinkage 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;
-	const struct exception_table_entry *fixup;
-	int write, fault;
-	unsigned long flags;
-	siginfo_t info;
-
-	tsk = current;
-	mm = tsk->mm;
-	prefetchw(&mm->mmap_sem);
-
-	/* get the address */
-	address = read_cr2();
-
-	info.si_code = SEGV_MAPERR;
-
-
-	/*
-	 * 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.
-	 */
-	if (unlikely(address >= TASK_SIZE64)) {
-		/*
-		 * Don't check for the module range here: its PML4
-		 * is always initialized because it's shared with the main
-		 * kernel text. Only vmalloc may need PML4 syncups.
-		 */
-		if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
-		      ((address >= VMALLOC_START && address < VMALLOC_END))) {
-			if (vmalloc_fault(address) >= 0)
-				return;
-		}
-		if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
-			return;
-		/*
-		 * Don't take the mm semaphore here. If we fixup a prefetch
-		 * fault we could otherwise deadlock.
-		 */
-		goto bad_area_nosemaphore;
-	}
-
-	if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
-		return;
-
-	if (likely(regs->eflags & X86_EFLAGS_IF))
-		local_irq_enable();
-
-	if (unlikely(page_fault_trace))
-		printk("pagefault rip:%lx rsp:%lx cs:%lu ss:%lu address %lx error %lx\n",
-		       regs->rip,regs->rsp,regs->cs,regs->ss,address,error_code); 
-
-	if (unlikely(error_code & PF_RSVD))
-		pgtable_bad(address, regs, error_code);
-
-	/*
-	 * If we're in an interrupt or have no user
-	 * context, 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:
-	/* 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.  Unfortunatly, 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 possibilty 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->rip))
-			goto bad_area_nosemaphore;
-		down_read(&mm->mmap_sem);
-	}
-
-	vma = find_vma(mm, address);
-	if (!vma)
-		goto bad_area;
-	if (likely(vma->vm_start <= address))
-		goto good_area;
-	if (!(vma->vm_flags & VM_GROWSDOWN))
-		goto bad_area;
-	if (error_code & 4) {
-		/* Allow userspace just enough access below the stack pointer
-		 * to let the 'enter' instruction work.
-		 */
-		if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
-			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:
-	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 */
-			goto bad_area;
-		case 0:			/* read, not present */
-			if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
-				goto bad_area;
-	}
-
-	/*
-	 * 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++;
-	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();
-
-		if (is_prefetch(regs, address, error_code))
-			return;
-
-		/* Work around K8 erratum #100 K8 in compat mode
-		   occasionally jumps to illegal addresses >4GB.  We
-		   catch this here 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. */
-		if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
-		    (address >> 32))
-			return;
-
-		if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
-		    printk_ratelimit()) {
-			printk(
-		       "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
-					tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
-					tsk->comm, tsk->pid, address, regs->rip,
-					regs->rsp, error_code);
-		}
-       
-		tsk->thread.cr2 = address;
-		/* Kernel addresses are always protection faults */
-		tsk->thread.error_code = error_code | (address >= TASK_SIZE);
-		tsk->thread.trap_no = 14;
-		info.si_signo = SIGSEGV;
-		info.si_errno = 0;
-		/* info.si_code has been set above */
-		info.si_addr = (void __user *)address;
-		force_sig_info(SIGSEGV, &info, tsk);
-		return;
-	}
-
-no_context:
-	
-	/* Are we prepared to handle this kernel fault?  */
-	fixup = search_exception_tables(regs->rip);
-	if (fixup) {
-		regs->rip = fixup->fixup;
-		return;
-	}
-
-	/* 
-	 * 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.
- */
-
-	flags = oops_begin();
-
-	if (address < PAGE_SIZE)
-		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
-	else
-		printk(KERN_ALERT "Unable to handle kernel paging request");
-	printk(" at %016lx RIP: \n" KERN_ALERT,address);
-	printk_address(regs->rip);
-	dump_pagetable(address);
-	tsk->thread.cr2 = address;
-	tsk->thread.trap_no = 14;
-	tsk->thread.error_code = error_code;
-	__die("Oops", regs, error_code);
-	/* Executive summary in case the body of the oops scrolled away */
-	printk(KERN_EMERG "CR2: %016lx\n", address);
-	oops_end(flags);
-	do_exit(SIGKILL);
-
-/*
- * We ran out of memory, or some other thing happened to us that made
- * us unable to handle the page fault gracefully.
- */
-out_of_memory:
-	up_read(&mm->mmap_sem);
-	if (is_init(current)) {
-		yield();
-		goto again;
-	}
-	printk("VM: killing process %s\n", tsk->comm);
-	if (error_code & 4)
-		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;
-
-	tsk->thread.cr2 = address;
-	tsk->thread.error_code = error_code;
-	tsk->thread.trap_no = 14;
-	info.si_signo = SIGBUS;
-	info.si_errno = 0;
-	info.si_code = BUS_ADRERR;
-	info.si_addr = (void __user *)address;
-	force_sig_info(SIGBUS, &info, tsk);
-	return;
-}
-
-DEFINE_SPINLOCK(pgd_lock);
-LIST_HEAD(pgd_list);
-
-void vmalloc_sync_all(void)
-{
-	/* 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)));
-}
-
-static int __init enable_pagefaulttrace(char *str)
-{
-	page_fault_trace = 1;
-	return 1;
-}
-__setup("pagefaulttrace", enable_pagefaulttrace);