Commit dbdb4e9f authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: Tidy up and generalize page fault error paths. 



This follows the x86 changes for tidying up the page fault error paths.
We'll build on top of this for _32/_64 unification.

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent c4f10e5c

arch/sh/include/asm/kdebug.h

+2 −0
Original line number Diff line number Diff line
@@ -10,4 +10,6 @@ enum die_val { 
	DIE_SSTEP,

};



extern void printk_address(unsigned long address, int reliable);



#endif /* __ASM_SH_KDEBUG_H */

arch/sh/mm/fault_32.c

+220 −105
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
 * Page fault handler for SH with an MMU.

 *

 *  Copyright (C) 1999  Niibe Yutaka

 *  Copyright (C) 2003 - 2009  Paul Mundt

 *  Copyright (C) 2003 - 2012  Paul Mundt

 *

 *  Based on linux/arch/i386/mm/fault.c:

 *   Copyright (C) 1995  Linus Torvalds
@@ -16,6 +16,7 @@ 
#include <linux/hardirq.h>

#include <linux/kprobes.h>

#include <linux/perf_event.h>

#include <linux/kdebug.h>

#include <asm/io_trapped.h>

#include <asm/mmu_context.h>

#include <asm/tlbflush.h>
@@ -35,6 +36,20 @@ static inline int notify_page_fault(struct pt_regs *regs, int trap) 
	return ret;

}



static void

force_sig_info_fault(int si_signo, int si_code, unsigned long address,

		     struct task_struct *tsk)

{

	siginfo_t info;



	info.si_signo	= si_signo;

	info.si_errno	= 0;

	info.si_code	= si_code;

	info.si_addr	= (void __user *)address;



	force_sig_info(si_signo, &info, tsk);

}



/*

 * This is useful to dump out the page tables associated with

 * 'addr' in mm 'mm'.
@@ -176,6 +191,185 @@ static noinline int vmalloc_fault(unsigned long address) 
	return 0;

}



static void

show_fault_oops(struct pt_regs *regs, unsigned long address)

{

	if (!oops_may_print())

		return;



	printk(KERN_ALERT "BUG: unable to handle kernel ");

	if (address < PAGE_SIZE)

		printk(KERN_CONT "NULL pointer dereference");

	else

		printk(KERN_CONT "paging request");



	printk(KERN_CONT " at %08lx\n", address);

	printk(KERN_ALERT "PC:");

	printk_address(regs->pc, 1);



	show_pte(NULL, address);

}



static noinline void

no_context(struct pt_regs *regs, unsigned long writeaccess,

	   unsigned long address)

{

	/* Are we prepared to handle this kernel fault?  */

	if (fixup_exception(regs))

		return;



	if (handle_trapped_io(regs, address))

		return;



	/*

	 * Oops. The kernel tried to access some bad page. We'll have to

	 * terminate things with extreme prejudice.

	 */

	bust_spinlocks(1);



	show_fault_oops(regs, address);



	die("Oops", regs, writeaccess);

	bust_spinlocks(0);

	do_exit(SIGKILL);

}



static void

__bad_area_nosemaphore(struct pt_regs *regs, unsigned long writeaccess,

		       unsigned long address, int si_code)

{

	struct task_struct *tsk = current;



	/* User mode accesses just cause a SIGSEGV */

	if (user_mode(regs)) {

		/*

		 * It's possible to have interrupts off here:

		 */

		local_irq_enable();



		force_sig_info_fault(SIGSEGV, si_code, address, tsk);



		return;

	}



	no_context(regs, writeaccess, address);

}



static noinline void

bad_area_nosemaphore(struct pt_regs *regs, unsigned long writeaccess,

		     unsigned long address)

{

	__bad_area_nosemaphore(regs, writeaccess, address, SEGV_MAPERR);

}



static void

__bad_area(struct pt_regs *regs, unsigned long writeaccess,

	   unsigned long address, int si_code)

{

	struct mm_struct *mm = current->mm;



	/*

	 * Something tried to access memory that isn't in our memory map..

	 * Fix it, but check if it's kernel or user first..

	 */

	up_read(&mm->mmap_sem);



	__bad_area_nosemaphore(regs, writeaccess, address, si_code);

}



static noinline void

bad_area(struct pt_regs *regs, unsigned long writeaccess, unsigned long address)

{

	__bad_area(regs, writeaccess, address, SEGV_MAPERR);

}



static noinline void

bad_area_access_error(struct pt_regs *regs, unsigned long writeaccess,

		      unsigned long address)

{

	__bad_area(regs, writeaccess, address, SEGV_ACCERR);

}



static void out_of_memory(void)

{

	/*

	 * We ran out of memory, call the OOM killer, and return the userspace

	 * (which will retry the fault, or kill us if we got oom-killed):

	 */

	up_read(&current->mm->mmap_sem);



	pagefault_out_of_memory();

}



static void

do_sigbus(struct pt_regs *regs, unsigned long writeaccess, unsigned long address)

{

	struct task_struct *tsk = current;

	struct mm_struct *mm = tsk->mm;



	up_read(&mm->mmap_sem);



	/* Kernel mode? Handle exceptions or die: */

	if (!user_mode(regs))

		no_context(regs, writeaccess, address);



	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);

}



static noinline int

mm_fault_error(struct pt_regs *regs, unsigned long writeaccess,

	       unsigned long address, unsigned int fault)

{

	/*

	 * Pagefault was interrupted by SIGKILL. We have no reason to

	 * continue pagefault.

	 */

	if (fatal_signal_pending(current)) {

		if (!(fault & VM_FAULT_RETRY))

			up_read(&current->mm->mmap_sem);

		if (!user_mode(regs))

			no_context(regs, writeaccess, address);

		return 1;

	}



	if (!(fault & VM_FAULT_ERROR))

		return 0;



	if (fault & VM_FAULT_OOM) {

		/* Kernel mode? Handle exceptions or die: */

		if (!user_mode(regs)) {

			up_read(&current->mm->mmap_sem);

			no_context(regs, writeaccess, address);

			return 1;

		}



		out_of_memory();

	} else {

		if (fault & VM_FAULT_SIGBUS)

			do_sigbus(regs, writeaccess, address);

		else

			BUG();

	}



	return 1;

}



static inline int access_error(int write, struct vm_area_struct *vma)

{

	if (write) {

		/* write, present and write, not present: */

		if (unlikely(!(vma->vm_flags & VM_WRITE)))

			return 1;

		return 0;

	}



	/* read, not present: */

	if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))

		return 1;



	return 0;

}



static int fault_in_kernel_space(unsigned long address)

{

	return address >= TASK_SIZE;
@@ -194,15 +388,12 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	struct task_struct *tsk;

	struct mm_struct *mm;

	struct vm_area_struct * vma;

	int si_code;

	int fault;

	siginfo_t info;

	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |

			      (writeaccess ? FAULT_FLAG_WRITE : 0));



	tsk = current;

	mm = tsk->mm;

	si_code = SEGV_MAPERR;

	vec = lookup_exception_vector();



	/*
@@ -220,7 +411,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
		if (notify_page_fault(regs, vec))

			return;



		goto bad_area_nosemaphore;

		bad_area_nosemaphore(regs, writeaccess, address);

		return;

	}



	if (unlikely(notify_page_fault(regs, vec)))
@@ -236,34 +428,38 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	 * 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 (in_atomic() || !mm)

		goto no_context;

	if (unlikely(in_atomic() || !mm)) {

		bad_area_nosemaphore(regs, writeaccess, address);

		return;

	}



retry:

	down_read(&mm->mmap_sem);



	vma = find_vma(mm, address);

	if (!vma)

		goto bad_area;

	if (vma->vm_start <= address)

	if (unlikely(!vma)) {

		bad_area(regs, writeaccess, address);

		return;

	}

	if (likely(vma->vm_start <= address))

		goto good_area;

	if (!(vma->vm_flags & VM_GROWSDOWN))

		goto bad_area;

	if (expand_stack(vma, address))

		goto bad_area;

	if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {

		bad_area(regs, writeaccess, address);

		return;

	}

	if (unlikely(expand_stack(vma, address))) {

		bad_area(regs, writeaccess, address);

		return;

	}



	/*

	 * Ok, we have a good vm_area for this memory access, so

	 * we can handle it..

	 */

good_area:

	si_code = SEGV_ACCERR;

	if (writeaccess) {

		if (!(vma->vm_flags & VM_WRITE))

			goto bad_area;

	} else {

		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))

			goto bad_area;

	if (unlikely(access_error(writeaccess, vma))) {

		bad_area_access_error(regs, writeaccess, address);

		return;

	}



	/*
@@ -273,17 +469,10 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	 */

	fault = handle_mm_fault(mm, vma, address, flags);



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

	if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))

		if (mm_fault_error(regs, writeaccess, address, fault))

			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) {

		if (fault & VM_FAULT_MAJOR) {

			tsk->maj_flt++;
@@ -307,80 +496,6 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	}



	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:

	if (user_mode(regs)) {

		info.si_signo = SIGSEGV;

		info.si_errno = 0;

		info.si_code = si_code;

		info.si_addr = (void *) address;

		force_sig_info(SIGSEGV, &info, tsk);

		return;

	}



no_context:

	/* Are we prepared to handle this kernel fault?  */

	if (fixup_exception(regs))

		return;



	if (handle_trapped_io(regs, address))

		return;

/*

 * Oops. The kernel tried to access some bad page. We'll have to

 * terminate things with extreme prejudice.

 *

 */



	bust_spinlocks(1);



	if (oops_may_print()) {

		printk(KERN_ALERT

		       "Unable to handle kernel %s at virtual address %08lx\n",

		       (address < PAGE_SIZE) ? "NULL pointer dereference" :

		       "paging request", address);



		show_pte(mm, address);

	}



	die("Oops", regs, writeaccess);

	bust_spinlocks(0);

	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 (!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;

}



/*