android_kernel_xiaomi_sm8350/arch/ia64/mm/fault.c
Andrew Burgess e8c59c0cf9 [IA64] Failure to grow RBS
There is a bug in the ia64_do_page_fault code that can cause a failure
to grow the register backing store, or any mapping that is marked as
VM_GROWSUP if the mapping is the highest mapped area of memory.

When the address accessed is below the first mapping the previous mapping
is returned as NULL, and this case is handled.  However, when the address
accessed is above the highest mapping the vma returned is NULL, this
case is not handled correctly, and it fails to spot that this access
might require an existing mapping to grow upwards.

Signed-off-by: Andrew Burgess <andrew@transitive.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2007-08-16 10:30:46 -07:00

287 lines
7.2 KiB
C

/*
* MMU fault handling support.
*
* Copyright (C) 1998-2002 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
extern void die (char *, struct pt_regs *, long);
#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, int trap)
{
int ret = 0;
if (!user_mode(regs)) {
/* kprobe_running() needs smp_processor_id() */
preempt_disable();
if (kprobe_running() && kprobes_fault_handler(regs, trap))
ret = 1;
preempt_enable();
}
return ret;
}
#else
static inline int notify_page_fault(struct pt_regs *regs, int trap)
{
return 0;
}
#endif
/*
* Return TRUE if ADDRESS points at a page in the kernel's mapped segment
* (inside region 5, on ia64) and that page is present.
*/
static int
mapped_kernel_page_is_present (unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep, pte;
pgd = pgd_offset_k(address);
if (pgd_none(*pgd) || pgd_bad(*pgd))
return 0;
pud = pud_offset(pgd, address);
if (pud_none(*pud) || pud_bad(*pud))
return 0;
pmd = pmd_offset(pud, address);
if (pmd_none(*pmd) || pmd_bad(*pmd))
return 0;
ptep = pte_offset_kernel(pmd, address);
if (!ptep)
return 0;
pte = *ptep;
return pte_present(pte);
}
void __kprobes
ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
{
int signal = SIGSEGV, code = SEGV_MAPERR;
struct vm_area_struct *vma, *prev_vma;
struct mm_struct *mm = current->mm;
struct siginfo si;
unsigned long mask;
int fault;
/* mmap_sem is performance critical.... */
prefetchw(&mm->mmap_sem);
/*
* If we're in an interrupt or have no user context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto no_context;
#ifdef CONFIG_VIRTUAL_MEM_MAP
/*
* If fault is in region 5 and we are in the kernel, we may already
* have the mmap_sem (pfn_valid macro is called during mmap). There
* is no vma for region 5 addr's anyway, so skip getting the semaphore
* and go directly to the exception handling code.
*/
if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
goto bad_area_no_up;
#endif
/*
* This is to handle the kprobes on user space access instructions
*/
if (notify_page_fault(regs, TRAP_BRKPT))
return;
down_read(&mm->mmap_sem);
vma = find_vma_prev(mm, address, &prev_vma);
if (!vma && !prev_vma )
goto bad_area;
/*
* find_vma_prev() returns vma such that address < vma->vm_end or NULL
*
* May find no vma, but could be that the last vm area is the
* register backing store that needs to expand upwards, in
* this case vma will be null, but prev_vma will ne non-null
*/
if (( !vma && prev_vma ) || (address < vma->vm_start) )
goto check_expansion;
good_area:
code = SEGV_ACCERR;
/* OK, we've got a good vm_area for this memory area. Check the access permissions: */
# define VM_READ_BIT 0
# define VM_WRITE_BIT 1
# define VM_EXEC_BIT 2
# if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
|| (1 << VM_EXEC_BIT) != VM_EXEC)
# error File is out of sync with <linux/mm.h>. Please update.
# endif
if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
goto bad_area;
mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
if ((vma->vm_flags & mask) != mask)
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, (mask & VM_WRITE) != 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
/*
* We ran out of memory, or some other thing happened
* to us that made us unable to handle the page fault
* gracefully.
*/
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
} else if (fault & VM_FAULT_SIGBUS) {
signal = SIGBUS;
goto bad_area;
}
BUG();
}
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
up_read(&mm->mmap_sem);
return;
check_expansion:
if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
if (!vma)
goto bad_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
|| REGION_OFFSET(address) >= RGN_MAP_LIMIT)
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
} else {
vma = prev_vma;
if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
|| REGION_OFFSET(address) >= RGN_MAP_LIMIT)
goto bad_area;
/*
* Since the register backing store is accessed sequentially,
* we disallow growing it by more than a page at a time.
*/
if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
goto bad_area;
if (expand_upwards(vma, address))
goto bad_area;
}
goto good_area;
bad_area:
up_read(&mm->mmap_sem);
#ifdef CONFIG_VIRTUAL_MEM_MAP
bad_area_no_up:
#endif
if ((isr & IA64_ISR_SP)
|| ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
{
/*
* This fault was due to a speculative load or lfetch.fault, set the "ed"
* bit in the psr to ensure forward progress. (Target register will get a
* NaT for ld.s, lfetch will be canceled.)
*/
ia64_psr(regs)->ed = 1;
return;
}
if (user_mode(regs)) {
si.si_signo = signal;
si.si_errno = 0;
si.si_code = code;
si.si_addr = (void __user *) address;
si.si_isr = isr;
si.si_flags = __ISR_VALID;
force_sig_info(signal, &si, current);
return;
}
no_context:
if ((isr & IA64_ISR_SP)
|| ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
{
/*
* This fault was due to a speculative load or lfetch.fault, set the "ed"
* bit in the psr to ensure forward progress. (Target register will get a
* NaT for ld.s, lfetch will be canceled.)
*/
ia64_psr(regs)->ed = 1;
return;
}
/*
* Since we have no vma's for region 5, we might get here even if the address is
* valid, due to the VHPT walker inserting a non present translation that becomes
* stale. If that happens, the non present fault handler already purged the stale
* translation, which fixed the problem. So, we check to see if the translation is
* valid, and return if it is.
*/
if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
return;
if (ia64_done_with_exception(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to terminate things
* with extreme prejudice.
*/
bust_spinlocks(1);
if (address < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
else
printk(KERN_ALERT "Unable to handle kernel paging request at "
"virtual address %016lx\n", address);
die("Oops", regs, isr);
bust_spinlocks(0);
do_exit(SIGKILL);
return;
out_of_memory:
up_read(&mm->mmap_sem);
if (is_init(current)) {
yield();
down_read(&mm->mmap_sem);
goto survive;
}
printk(KERN_CRIT "VM: killing process %s\n", current->comm);
if (user_mode(regs))
do_exit(SIGKILL);
goto no_context;
}