arch/arc/mm/fault.c - kernel/skids - Git at Google

 /*
  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/interrupt.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/version.h>
 #include <linux/console.h>
 #include <linux/notifier.h>
 #include <linux/kprobes.h>

 #include <asm/hardirq.h>
 #include <asm/pgalloc.h>
 #include <asm/mmu_context.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <asm/traps.h>

 extern void die(const char *,struct pt_regs *,long,long);
 extern int fixup_exception(struct pt_regs *regs);

 static inline int notify_page_fault(struct pt_regs *regs, unsigned long cause)
 {
     int ret = 0;

 #ifdef CONFIG_KPROBES
     if (!user_mode(regs)) {
         preempt_disable();
         if (kprobe_running() && kprobe_fault_handler(regs, cause))
             ret = 1;
         preempt_enable();
     }
 #endif

     return ret;
 }

 asmlinkage int do_page_fault(struct pt_regs *regs, int write,
                   unsigned long address, unsigned long cause)
 {
     struct vm_area_struct *vma = NULL;
     struct task_struct *tsk = current;
     struct mm_struct *mm = tsk->mm;
     siginfo_t info;
     int fault;

     /*
      * 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.
      *
      * Quantenna customization:VMALLOC_END->PAGE_OFFSET,
      * we have VMALLOC, PCI_REMAP and DMA_NOCACHE kernel virtual memory regions,
      * not only VMALLOC.
      */
     if (address >= VMALLOC_START && address < PAGE_OFFSET)
         goto vmalloc_fault;

     info.si_code = SEGV_MAPERR;
     /*
      * If we're in an interrupt or have no user
      * context, we must not take the fault..
      */
 #ifndef CONFIG_ARC_FAULTS_DBG
     if (in_interrupt() || !mm)
         goto no_context;
 #else
     if (in_interrupt()) {
         printk("Page fault in interrupt\n");
         goto no_context;
     }

     if (!mm) {
         printk("Page fault for task without a mm\n");
         goto no_context;
     }
 #endif
     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 (expand_stack(vma, address))
         goto bad_area;

 	// vineetg-TODO:
 	//shady_area:
 	// Check if we ever land HERE, when address doesn't belong to vma,
 	// but it's not BAD either
 	// when we just fall thru into good_area

     /*
      * Ok, we have a good vm_area for this memory access, so
      * we can handle it..
      */
 good_area:
     info.si_code = SEGV_ACCERR;

 // Handle protection violation, execute on heap or stack

     if (cause == ((PROTECTION_VIOL <<16) | INST_FETCH_PROT_VIOL)) {
         goto bad_area;
     }

     if (write) {
         if (!(vma->vm_flags & VM_WRITE))
             goto bad_area;
     } else {
         if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
             goto bad_area;
     }

 survive:
     /*
      * 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++;


     /* Diagnostic Code to force a signal such as Ctrl C to task */
 #if 0
     if ( induce_problem && write && address == 0x14a00c) {
         info.si_signo = SIGINT;
         info.si_errno = 0;
         info.si_addr = (void *)address;
         force_sig_info(SIGINT, &info, tsk);
     }
 #endif

 	/* Fault Handled Gracefully, back to what user was trying to do */
     up_read(&mm->mmap_sem);
     return 0;

     /*
      * 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 (user_mode(regs)) {
         tsk->thread.fault_address = address;
         tsk->thread.cause_code = cause;
         info.si_signo = SIGSEGV;
         info.si_errno = 0;
         /* info.si_code has been set above */
         info.si_addr = (void *)address;
         force_sig_info(SIGSEGV, &info, tsk);
         return 1;
     }

 no_context:
     /* Are we prepared to handle this kernel fault?
      *
      * (The kernel has valid exception-points in the source
      *  when it acesses user-memory. When it fails in one
      *  of those points, we find it in a table and do a jump
      *  to some fixup code that loads an appropriate error
      *  code)
      */
     if (fixup_exception(regs))
         return 0;

     /*
      * Oops. The kernel tried to access some bad page. We'll have to
      * terminate things with extreme prejudice.
      */

     die("Unable to handle kernel paging request", regs, address, cause);
     /* Game over.  */

     /*
      * 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:
     if (tsk->pid == 1) {
         yield();
         goto survive;
     }
     up_read(&mm->mmap_sem);

     if (user_mode(regs))
         do_exit(SIGKILL);	/* This will never return */

     goto no_context;

 do_sigbus:
     up_read(&mm->mmap_sem);

     /*
      * Send a sigbus, regardless of whether we were in kernel
      * or user mode.
      */
     tsk->thread.fault_address = address;
     tsk->thread.cause_code = cause;
     info.si_signo = SIGBUS;
     info.si_errno = 0;
     info.si_code = BUS_ADRERR;
     info.si_addr = (void *)address;
     force_sig_info(SIGBUS, &info, tsk);

     /* Kernel mode? Handle exceptions or die */
     if (!user_mode(regs))
         goto no_context;

     return 1;

 vmalloc_fault:
     {
         /*
          * Synchronize this task's top level page-table
          * with the 'reference' page table.
          */
         pgd_t *pgd, *pgd_k;
         pud_t *pud, *pud_k;
         pmd_t *pmd, *pmd_k;

         pgd = pgd_offset_fast(mm,address);
         pgd_k = pgd_offset_k(address);

         if (!pgd_present(*pgd_k))
             goto bad_area_nosemaphore;

         pud = pud_offset(pgd, address);
         pud_k = pud_offset(pgd_k, address);
         if (!pud_present(*pud_k))
             goto bad_area_nosemaphore;

         pmd = pmd_offset(pud, address);
         pmd_k = pmd_offset(pud_k, address);
         if (!pmd_present(*pmd_k))
             goto bad_area_nosemaphore;

         set_pmd(pmd, *pmd_k);
     }

     return 0;
 }
	/*
	* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/signal.h>
	#include <linux/sched.h>
	#include <linux/interrupt.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/version.h>
	#include <linux/console.h>
	#include <linux/notifier.h>
	#include <linux/kprobes.h>

	#include <asm/hardirq.h>
	#include <asm/pgalloc.h>
	#include <asm/mmu_context.h>
	#include <asm/system.h>
	#include <asm/uaccess.h>
	#include <asm/traps.h>

	extern void die(const char ,struct pt_regs ,long,long);
	extern int fixup_exception(struct pt_regs *regs);

	static inline int notify_page_fault(struct pt_regs *regs, unsigned long cause)
	{
	int ret = 0;

	#ifdef CONFIG_KPROBES
	if (!user_mode(regs)) {
	preempt_disable();
	if (kprobe_running() && kprobe_fault_handler(regs, cause))
	ret = 1;
	preempt_enable();
	}
	#endif

	return ret;
	}

	asmlinkage int do_page_fault(struct pt_regs *regs, int write,
	unsigned long address, unsigned long cause)
	{
	struct vm_area_struct *vma = NULL;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	siginfo_t info;
	int fault;

	/*
	* 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.
	*
	* Quantenna customization:VMALLOC_END->PAGE_OFFSET,
	* we have VMALLOC, PCI_REMAP and DMA_NOCACHE kernel virtual memory regions,
	* not only VMALLOC.
	*/
	if (address >= VMALLOC_START && address < PAGE_OFFSET)
	goto vmalloc_fault;

	info.si_code = SEGV_MAPERR;
	/*
	* If we're in an interrupt or have no user
	* context, we must not take the fault..
	*/
	#ifndef CONFIG_ARC_FAULTS_DBG
	if (in_interrupt() \|\| !mm)
	goto no_context;
	#else
	if (in_interrupt()) {
	printk("Page fault in interrupt\n");
	goto no_context;
	}

	if (!mm) {
	printk("Page fault for task without a mm\n");
	goto no_context;
	}
	#endif
	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 (expand_stack(vma, address))
	goto bad_area;

	// vineetg-TODO:
	//shady_area:
	// Check if we ever land HERE, when address doesn't belong to vma,
	// but it's not BAD either
	// when we just fall thru into good_area

	/*
	* Ok, we have a good vm_area for this memory access, so
	* we can handle it..
	*/
	good_area:
	info.si_code = SEGV_ACCERR;

	// Handle protection violation, execute on heap or stack

	if (cause == ((PROTECTION_VIOL <<16) \| INST_FETCH_PROT_VIOL)) {
	goto bad_area;
	}

	if (write) {
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	} else {
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}

	survive:
	/*
	* 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++;


	/* Diagnostic Code to force a signal such as Ctrl C to task */
	#if 0
	if ( induce_problem && write && address == 0x14a00c) {
	info.si_signo = SIGINT;
	info.si_errno = 0;
	info.si_addr = (void *)address;
	force_sig_info(SIGINT, &info, tsk);
	}
	#endif

	/* Fault Handled Gracefully, back to what user was trying to do */
	up_read(&mm->mmap_sem);
	return 0;

	/*
	* 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 (user_mode(regs)) {
	tsk->thread.fault_address = address;
	tsk->thread.cause_code = cause;
	info.si_signo = SIGSEGV;
	info.si_errno = 0;
	/* info.si_code has been set above */
	info.si_addr = (void *)address;
	force_sig_info(SIGSEGV, &info, tsk);
	return 1;
	}

	no_context:
	/* Are we prepared to handle this kernel fault?
	*
	* (The kernel has valid exception-points in the source
	* when it acesses user-memory. When it fails in one
	* of those points, we find it in a table and do a jump
	* to some fixup code that loads an appropriate error
	* code)
	*/
	if (fixup_exception(regs))
	return 0;

	/*
	* Oops. The kernel tried to access some bad page. We'll have to
	* terminate things with extreme prejudice.
	*/

	die("Unable to handle kernel paging request", regs, address, cause);
	/* Game over. */

	/*
	* 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:
	if (tsk->pid == 1) {
	yield();
	goto survive;
	}
	up_read(&mm->mmap_sem);

	if (user_mode(regs))
	do_exit(SIGKILL); /* This will never return */

	goto no_context;

	do_sigbus:
	up_read(&mm->mmap_sem);

	/*
	* Send a sigbus, regardless of whether we were in kernel
	* or user mode.
	*/
	tsk->thread.fault_address = address;
	tsk->thread.cause_code = cause;
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *)address;
	force_sig_info(SIGBUS, &info, tsk);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
	goto no_context;

	return 1;

	vmalloc_fault:
	{
	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*/
	pgd_t pgd, pgd_k;
	pud_t pud, pud_k;
	pmd_t pmd, pmd_k;

	pgd = pgd_offset_fast(mm,address);
	pgd_k = pgd_offset_k(address);

	if (!pgd_present(*pgd_k))
	goto bad_area_nosemaphore;

	pud = pud_offset(pgd, address);
	pud_k = pud_offset(pgd_k, address);
	if (!pud_present(*pud_k))
	goto bad_area_nosemaphore;

	pmd = pmd_offset(pud, address);
	pmd_k = pmd_offset(pud_k, address);
	if (!pmd_present(*pmd_k))
	goto bad_area_nosemaphore;

	set_pmd(pmd, *pmd_k);
	}

	return 0;
	}