arch/openrisc/mm/fault.c - kernel/msm-4.9 - Gitiles

 /*
  * OpenRISC fault.c
  *
  * Linux architectural port borrowing liberally from similar works of
  * others.  All original copyrights apply as per the original source
  * declaration.
  *
  * Modifications for the OpenRISC architecture:
  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  *
  *      This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License
  *      as published by the Free Software Foundation; either version
  *      2 of the License, or (at your option) any later version.
  */

 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/sched.h>

 #include <asm/uaccess.h>
 #include <asm/siginfo.h>
 #include <asm/signal.h>

 #define NUM_TLB_ENTRIES 64
 #define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))

 unsigned long pte_misses;	/* updated by do_page_fault() */
 unsigned long pte_errors;	/* updated by do_page_fault() */

 /* __PHX__ :: - check the vmalloc_fault in do_page_fault()
  *            - also look into include/asm-or32/mmu_context.h
  */
 volatile pgd_t *current_pgd;

 extern void die(char *, struct pt_regs *, long);

 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  *
  * If this routine detects a bad access, it returns 1, otherwise it
  * returns 0.
  */

 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
 			      unsigned long vector, int write_acc)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	siginfo_t info;
 	int fault;
 	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

 	tsk = current;

 	/*
 	 * 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.
 	 *
 	 * NOTE2: This is done so that, when updating the vmalloc
 	 * mappings we don't have to walk all processes pgdirs and
 	 * add the high mappings all at once. Instead we do it as they
 	 * are used. However vmalloc'ed page entries have the PAGE_GLOBAL
 	 * bit set so sometimes the TLB can use a lingering entry.
 	 *
 	 * This verifies that the fault happens in kernel space
 	 * and that the fault was not a protection error.
 	 */

 	if (address >= VMALLOC_START &&
 	    (vector != 0x300 && vector != 0x400) &&
 	    !user_mode(regs))
 		goto vmalloc_fault;

 	/* If exceptions were enabled, we can reenable them here */
 	if (user_mode(regs)) {
 		/* Exception was in userspace: reenable interrupts */
 		local_irq_enable();
 		flags |= FAULT_FLAG_USER;
 	} else {
 		/* If exception was in a syscall, then IRQ's may have
 		 * been enabled or disabled.  If they were enabled,
 		 * reenable them.
 		 */
 		if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE))
 			local_irq_enable();
 	}

 	mm = tsk->mm;
 	info.si_code = SEGV_MAPERR;

 	/*
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
 	 */

 	if (in_interrupt() || !mm)
 		goto no_context;

 retry:
 	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 (user_mode(regs)) {
 		/*
 		 * accessing the stack below usp is always a bug.
 		 * we get page-aligned addresses so we can only check
 		 * if we're within a page from usp, but that might be
 		 * enough to catch brutal errors at least.
 		 */
 		if (address + PAGE_SIZE < regs->sp)
 			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;

 	/* first do some preliminary protection checks */

 	if (write_acc) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 		flags |= FAULT_FLAG_WRITE;
 	} else {
 		/* not present */
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}

 	/* are we trying to execute nonexecutable area */
 	if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC))
 		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, flags);

 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;

 	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 (flags & FAULT_FLAG_ALLOW_RETRY) {
 		/*RGD modeled on Cris */
 		if (fault & VM_FAULT_MAJOR)
 			tsk->maj_flt++;
 		else
 			tsk->min_flt++;
 		if (fault & VM_FAULT_RETRY) {
 			flags &= ~FAULT_FLAG_ALLOW_RETRY;
 			flags |= FAULT_FLAG_TRIED;

 			 /* No need to up_read(&mm->mmap_sem) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

 			goto retry;
 		}
 	}

 	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 (user_mode(regs)) {
 		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;
 	}

 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)
 	 */

 	{
 		const struct exception_table_entry *entry;

 		__asm__ __volatile__("l.nop 42");

 		if ((entry = search_exception_tables(regs->pc)) != NULL) {
 			/* Adjust the instruction pointer in the stackframe */
 			regs->pc = entry->fixup;
 			return;
 		}
 	}

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

 	if ((unsigned long)(address) < PAGE_SIZE)
 		printk(KERN_ALERT
 		       "Unable to handle kernel NULL pointer dereference");
 	else
 		printk(KERN_ALERT "Unable to handle kernel access");
 	printk(" at virtual address 0x%08lx\n", address);

 	die("Oops", regs, write_acc);

 	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:
 	__asm__ __volatile__("l.nop 42");
 	__asm__ __volatile__("l.nop 1");

 	up_read(&mm->mmap_sem);
 	if (!user_mode(regs))
 		goto no_context;
 	pagefault_out_of_memory();
 	return;

 do_sigbus:
 	up_read(&mm->mmap_sem);

 	/*
 	 * Send a sigbus, regardless of whether we were in kernel
 	 * or user mode.
 	 */
 	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;

 vmalloc_fault:
 	{
 		/*
 		 * Synchronize this task's top level page-table
 		 * with the 'reference' page table.
 		 *
 		 * Use current_pgd instead of tsk->active_mm->pgd
 		 * since the latter might be unavailable if this
 		 * code is executed in a misfortunately run irq
 		 * (like inside schedule() between switch_mm and
 		 *  switch_to...).
 		 */

 		int offset = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
 		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;

 /*
 		phx_warn("do_page_fault(): vmalloc_fault will not work, "
 			 "since current_pgd assign a proper value somewhere\n"
 			 "anyhow we don't need this at the moment\n");

 		phx_mmu("vmalloc_fault");
 */
 		pgd = (pgd_t *)current_pgd + offset;
 		pgd_k = init_mm.pgd + offset;

 		/* Since we're two-level, we don't need to do both
 		 * set_pgd and set_pmd (they do the same thing). If
 		 * we go three-level at some point, do the right thing
 		 * with pgd_present and set_pgd here.
 		 *
 		 * Also, since the vmalloc area is global, we don't
 		 * need to copy individual PTE's, it is enough to
 		 * copy the pgd pointer into the pte page of the
 		 * root task. If that is there, we'll find our pte if
 		 * it exists.
 		 */

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

 		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);

 		/* Make sure the actual PTE exists as well to
 		 * catch kernel vmalloc-area accesses to non-mapped
 		 * addresses. If we don't do this, this will just
 		 * silently loop forever.
 		 */

 		pte_k = pte_offset_kernel(pmd_k, address);
 		if (!pte_present(*pte_k))
 			goto no_context;

 		return;
 	}
 }
	/*
	* OpenRISC fault.c
	*
	* Linux architectural port borrowing liberally from similar works of
	* others. All original copyrights apply as per the original source
	* declaration.
	*
	* Modifications for the OpenRISC architecture:
	* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
	* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/mm.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/sched.h>

	#include <asm/uaccess.h>
	#include <asm/siginfo.h>
	#include <asm/signal.h>

	#define NUM_TLB_ENTRIES 64
	#define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))

	unsigned long pte_misses; /* updated by do_page_fault() */
	unsigned long pte_errors; /* updated by do_page_fault() */

	/* __PHX__ :: - check the vmalloc_fault in do_page_fault()
	* - also look into include/asm-or32/mmu_context.h
	*/
	volatile pgd_t *current_pgd;

	extern void die(char , struct pt_regs , long);

	/*
	* This routine handles page faults. It determines the address,
	* and the problem, and then passes it off to one of the appropriate
	* routines.
	*
	* If this routine detects a bad access, it returns 1, otherwise it
	* returns 0.
	*/

	asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
	unsigned long vector, int write_acc)
	{
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	siginfo_t info;
	int fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;

	tsk = current;

	/*
	* 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.
	*
	* NOTE2: This is done so that, when updating the vmalloc
	* mappings we don't have to walk all processes pgdirs and
	* add the high mappings all at once. Instead we do it as they
	* are used. However vmalloc'ed page entries have the PAGE_GLOBAL
	* bit set so sometimes the TLB can use a lingering entry.
	*
	* This verifies that the fault happens in kernel space
	* and that the fault was not a protection error.
	*/

	if (address >= VMALLOC_START &&
	(vector != 0x300 && vector != 0x400) &&
	!user_mode(regs))
	goto vmalloc_fault;

	/* If exceptions were enabled, we can reenable them here */
	if (user_mode(regs)) {
	/* Exception was in userspace: reenable interrupts */
	local_irq_enable();
	flags \|= FAULT_FLAG_USER;
	} else {
	/* If exception was in a syscall, then IRQ's may have
	* been enabled or disabled. If they were enabled,
	* reenable them.
	*/
	if (regs->sr && (SPR_SR_IEE \| SPR_SR_TEE))
	local_irq_enable();
	}

	mm = tsk->mm;
	info.si_code = SEGV_MAPERR;

	/*
	* If we're in an interrupt or have no user
	* context, we must not take the fault..
	*/

	if (in_interrupt() \|\| !mm)
	goto no_context;

	retry:
	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 (user_mode(regs)) {
	/*
	* accessing the stack below usp is always a bug.
	* we get page-aligned addresses so we can only check
	* if we're within a page from usp, but that might be
	* enough to catch brutal errors at least.
	*/
	if (address + PAGE_SIZE < regs->sp)
	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;

	/* first do some preliminary protection checks */

	if (write_acc) {
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	flags \|= FAULT_FLAG_WRITE;
	} else {
	/* not present */
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}

	/* are we trying to execute nonexecutable area */
	if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC))
	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, flags);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	return;

	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 (flags & FAULT_FLAG_ALLOW_RETRY) {
	/RGD modeled on Cris /
	if (fault & VM_FAULT_MAJOR)
	tsk->maj_flt++;
	else
	tsk->min_flt++;
	if (fault & VM_FAULT_RETRY) {
	flags &= ~FAULT_FLAG_ALLOW_RETRY;
	flags \|= FAULT_FLAG_TRIED;

	/* No need to up_read(&mm->mmap_sem) as we would
	* have already released it in __lock_page_or_retry
	* in mm/filemap.c.
	*/

	goto retry;
	}
	}

	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 (user_mode(regs)) {
	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;
	}

	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)
	*/

	{
	const struct exception_table_entry *entry;

	__asm__ __volatile__("l.nop 42");

	if ((entry = search_exception_tables(regs->pc)) != NULL) {
	/* Adjust the instruction pointer in the stackframe */
	regs->pc = entry->fixup;
	return;
	}
	}

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

	if ((unsigned long)(address) < PAGE_SIZE)
	printk(KERN_ALERT
	"Unable to handle kernel NULL pointer dereference");
	else
	printk(KERN_ALERT "Unable to handle kernel access");
	printk(" at virtual address 0x%08lx\n", address);

	die("Oops", regs, write_acc);

	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:
	__asm__ __volatile__("l.nop 42");
	__asm__ __volatile__("l.nop 1");

	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
	goto no_context;
	pagefault_out_of_memory();
	return;

	do_sigbus:
	up_read(&mm->mmap_sem);

	/*
	* Send a sigbus, regardless of whether we were in kernel
	* or user mode.
	*/
	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;

	vmalloc_fault:
	{
	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*
	* Use current_pgd instead of tsk->active_mm->pgd
	* since the latter might be unavailable if this
	* code is executed in a misfortunately run irq
	* (like inside schedule() between switch_mm and
	* switch_to...).
	*/

	int offset = pgd_index(address);
	pgd_t pgd, pgd_k;
	pud_t pud, pud_k;
	pmd_t pmd, pmd_k;
	pte_t *pte_k;

	/*
	phx_warn("do_page_fault(): vmalloc_fault will not work, "
	"since current_pgd assign a proper value somewhere\n"
	"anyhow we don't need this at the moment\n");

	phx_mmu("vmalloc_fault");
	*/
	pgd = (pgd_t *)current_pgd + offset;
	pgd_k = init_mm.pgd + offset;

	/* Since we're two-level, we don't need to do both
	* set_pgd and set_pmd (they do the same thing). If
	* we go three-level at some point, do the right thing
	* with pgd_present and set_pgd here.
	*
	* Also, since the vmalloc area is global, we don't
	* need to copy individual PTE's, it is enough to
	* copy the pgd pointer into the pte page of the
	* root task. If that is there, we'll find our pte if
	* it exists.
	*/

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

	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);

	/* Make sure the actual PTE exists as well to
	* catch kernel vmalloc-area accesses to non-mapped
	* addresses. If we don't do this, this will just
	* silently loop forever.
	*/

	pte_k = pte_offset_kernel(pmd_k, address);
	if (!pte_present(*pte_k))
	goto no_context;

	return;
	}
	}