linux/arch/hexagon/mm/vm_fault.c
Johannes Weiner 759496ba64 arch: mm: pass userspace fault flag to generic fault handler
Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 15:38:01 -07:00

203 lines
4.6 KiB
C

/*
* Memory fault handling for Hexagon
*
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/*
* Page fault handling for the Hexagon Virtual Machine.
* Can also be called by a native port emulating the HVM
* execptions.
*/
#include <asm/pgtable.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <linux/mm.h>
#include <linux/signal.h>
#include <linux/module.h>
#include <linux/hardirq.h>
/*
* Decode of hardware exception sends us to one of several
* entry points. At each, we generate canonical arguments
* for handling by the abstract memory management code.
*/
#define FLT_IFETCH -1
#define FLT_LOAD 0
#define FLT_STORE 1
/*
* Canonical page fault handler
*/
void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
siginfo_t info;
int si_code = SEGV_MAPERR;
int fault;
const struct exception_table_entry *fixup;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
/*
* If we're in an interrupt or have no user context,
* then must not take the fault.
*/
if (unlikely(in_interrupt() || !mm))
goto no_context;
local_irq_enable();
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
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 (expand_stack(vma, address))
goto bad_area;
good_area:
/* Address space is OK. Now check access rights. */
si_code = SEGV_ACCERR;
switch (cause) {
case FLT_IFETCH:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case FLT_LOAD:
if (!(vma->vm_flags & VM_READ))
goto bad_area;
break;
case FLT_STORE:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
break;
}
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
/* The most common case -- we are done. */
if (likely(!(fault & VM_FAULT_ERROR))) {
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
up_read(&mm->mmap_sem);
return;
}
up_read(&mm->mmap_sem);
/* Handle copyin/out exception cases */
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return;
}
/* User-mode address is in the memory map, but we are
* unable to fix up the page fault.
*/
if (fault & VM_FAULT_SIGBUS) {
info.si_signo = SIGBUS;
info.si_code = BUS_ADRERR;
}
/* Address is not in the memory map */
else {
info.si_signo = SIGSEGV;
info.si_code = SEGV_ACCERR;
}
info.si_errno = 0;
info.si_addr = (void __user *)address;
force_sig_info(info.si_signo, &info, current);
return;
bad_area:
up_read(&mm->mmap_sem);
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(info.si_signo, &info, current);
return;
}
/* Kernel-mode fault falls through */
no_context:
fixup = search_exception_tables(pt_elr(regs));
if (fixup) {
pt_set_elr(regs, fixup->fixup);
return;
}
/* Things are looking very, very bad now */
bust_spinlocks(1);
printk(KERN_EMERG "Unable to handle kernel paging request at "
"virtual address 0x%08lx, regs %p\n", address, regs);
die("Bad Kernel VA", regs, SIGKILL);
}
void read_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_LOAD, regs);
}
void write_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_STORE, regs);
}
void execute_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_IFETCH, regs);
}