mirror of
https://github.com/torvalds/linux.git
synced 2024-11-01 01:31:44 +00:00
459 lines
12 KiB
C
459 lines
12 KiB
C
/*
|
|
* linux/arch/cris/mm/fault.c
|
|
*
|
|
* Copyright (C) 2000, 2001 Axis Communications AB
|
|
*
|
|
* Authors: Bjorn Wesen
|
|
*
|
|
* $Log: fault.c,v $
|
|
* Revision 1.20 2005/03/04 08:16:18 starvik
|
|
* Merge of Linux 2.6.11.
|
|
*
|
|
* Revision 1.19 2005/01/14 10:07:59 starvik
|
|
* Fixed warning.
|
|
*
|
|
* Revision 1.18 2005/01/12 08:10:14 starvik
|
|
* Readded the change of frametype when handling kernel page fault fixup
|
|
* for v10. This is necessary to avoid that the CPU remakes the faulting
|
|
* access.
|
|
*
|
|
* Revision 1.17 2005/01/11 13:53:05 starvik
|
|
* Use raw_printk.
|
|
*
|
|
* Revision 1.16 2004/12/17 11:39:41 starvik
|
|
* SMP support.
|
|
*
|
|
* Revision 1.15 2004/11/23 18:36:18 starvik
|
|
* Stack is now non-executable.
|
|
* Signal handler trampolines are placed in a reserved page mapped into all
|
|
* processes.
|
|
*
|
|
* Revision 1.14 2004/11/23 07:10:21 starvik
|
|
* Moved find_fixup_code to generic code.
|
|
*
|
|
* Revision 1.13 2004/11/23 07:00:54 starvik
|
|
* Actually use the execute permission bit in the MMU. This makes it possible
|
|
* to prevent e.g. attacks where executable code is put on the stack.
|
|
*
|
|
* Revision 1.12 2004/09/29 06:16:04 starvik
|
|
* Use instruction_pointer
|
|
*
|
|
* Revision 1.11 2004/05/14 07:58:05 starvik
|
|
* Merge of changes from 2.4
|
|
*
|
|
* Revision 1.10 2003/10/27 14:51:24 starvik
|
|
* Removed debugcode
|
|
*
|
|
* Revision 1.9 2003/10/27 14:50:42 starvik
|
|
* Changed do_page_fault signature
|
|
*
|
|
* Revision 1.8 2003/07/04 13:02:48 tobiasa
|
|
* Moved code snippet from arch/cris/mm/fault.c that searches for fixup code
|
|
* to seperate function in arch-specific files.
|
|
*
|
|
* Revision 1.7 2003/01/22 06:48:38 starvik
|
|
* Fixed warnings issued by GCC 3.2.1
|
|
*
|
|
* Revision 1.6 2003/01/09 14:42:52 starvik
|
|
* Merge of Linux 2.5.55
|
|
*
|
|
* Revision 1.5 2002/12/11 14:44:48 starvik
|
|
* Extracted v10 (ETRAX 100LX) specific stuff to arch/cris/arch-v10/mm
|
|
*
|
|
* Revision 1.4 2002/11/13 15:10:28 starvik
|
|
* pte_offset has been renamed to pte_offset_kernel
|
|
*
|
|
* Revision 1.3 2002/11/05 06:45:13 starvik
|
|
* Merge of Linux 2.5.45
|
|
*
|
|
* Revision 1.2 2001/12/18 13:35:22 bjornw
|
|
* Applied the 2.4.13->2.4.16 CRIS patch to 2.5.1 (is a copy of 2.4.15).
|
|
*
|
|
* Revision 1.20 2001/11/22 13:34:06 bjornw
|
|
* * Bug workaround (LX TR89): force a rerun of the whole of an interrupted
|
|
* unaligned write, because the second half of the write will be corrupted
|
|
* otherwise. Affected unaligned writes spanning not-yet mapped pages.
|
|
* * Optimization: use the wr_rd bit in R_MMU_CAUSE to know whether a miss
|
|
* was due to a read or a write (before we didn't know this until the next
|
|
* restart of the interrupted instruction, thus wasting one fault-irq)
|
|
*
|
|
* Revision 1.19 2001/11/12 19:02:10 pkj
|
|
* Fixed compiler warnings.
|
|
*
|
|
* Revision 1.18 2001/07/18 22:14:32 bjornw
|
|
* Enable interrupts in the bulk of do_page_fault
|
|
*
|
|
* Revision 1.17 2001/07/18 13:07:23 bjornw
|
|
* * Detect non-existant PTE's in vmalloc pmd synchronization
|
|
* * Remove comment about fast-paths for VMALLOC_START etc, because all that
|
|
* was totally bogus anyway it turned out :)
|
|
* * Fix detection of vmalloc-area synchronization
|
|
* * Add some comments
|
|
*
|
|
* Revision 1.16 2001/06/13 00:06:08 bjornw
|
|
* current_pgd should be volatile
|
|
*
|
|
* Revision 1.15 2001/06/13 00:02:23 bjornw
|
|
* Use a separate variable to store the current pgd to avoid races in schedule
|
|
*
|
|
* Revision 1.14 2001/05/16 17:41:07 hp
|
|
* Last comment tweak further tweaked.
|
|
*
|
|
* Revision 1.13 2001/05/15 00:58:44 hp
|
|
* Expand a bit on the comment why we compare address >= TASK_SIZE rather
|
|
* than >= VMALLOC_START.
|
|
*
|
|
* Revision 1.12 2001/04/04 10:51:14 bjornw
|
|
* mmap_sem is grabbed for reading
|
|
*
|
|
* Revision 1.11 2001/03/23 07:36:07 starvik
|
|
* Corrected according to review remarks
|
|
*
|
|
* Revision 1.10 2001/03/21 16:10:11 bjornw
|
|
* CRIS_FRAME_FIXUP not needed anymore, use FRAME_NORMAL
|
|
*
|
|
* Revision 1.9 2001/03/05 13:22:20 bjornw
|
|
* Spell-fix and fix in vmalloc_fault handling
|
|
*
|
|
* Revision 1.8 2000/11/22 14:45:31 bjornw
|
|
* * 2.4.0-test10 removed the set_pgdir instantaneous kernel global mapping
|
|
* into all processes. Instead we fill in the missing PTE entries on demand.
|
|
*
|
|
* Revision 1.7 2000/11/21 16:39:09 bjornw
|
|
* fixup switches frametype
|
|
*
|
|
* Revision 1.6 2000/11/17 16:54:08 bjornw
|
|
* More detailed siginfo reporting
|
|
*
|
|
*
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/module.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
extern int find_fixup_code(struct pt_regs *);
|
|
extern void die_if_kernel(const char *, struct pt_regs *, long);
|
|
extern int raw_printk(const char *fmt, ...);
|
|
|
|
/* debug of low-level TLB reload */
|
|
#undef DEBUG
|
|
|
|
#ifdef DEBUG
|
|
#define D(x) x
|
|
#else
|
|
#define D(x)
|
|
#endif
|
|
|
|
/* debug of higher-level faults */
|
|
#define DPG(x)
|
|
|
|
/* current active page directory */
|
|
|
|
volatile DEFINE_PER_CPU(pgd_t *,current_pgd);
|
|
unsigned long cris_signal_return_page;
|
|
|
|
/*
|
|
* This routine handles page faults. It determines the address,
|
|
* and the problem, and then passes it off to one of the appropriate
|
|
* routines.
|
|
*
|
|
* Notice that the address we're given is aligned to the page the fault
|
|
* occurred in, since we only get the PFN in R_MMU_CAUSE not the complete
|
|
* address.
|
|
*
|
|
* error_code:
|
|
* bit 0 == 0 means no page found, 1 means protection fault
|
|
* bit 1 == 0 means read, 1 means write
|
|
*
|
|
* If this routine detects a bad access, it returns 1, otherwise it
|
|
* returns 0.
|
|
*/
|
|
|
|
asmlinkage void
|
|
do_page_fault(unsigned long address, struct pt_regs *regs,
|
|
int protection, int writeaccess)
|
|
{
|
|
struct task_struct *tsk;
|
|
struct mm_struct *mm;
|
|
struct vm_area_struct * vma;
|
|
siginfo_t info;
|
|
|
|
D(printk("Page fault for %lX on %X at %lX, prot %d write %d\n",
|
|
address, smp_processor_id(), instruction_pointer(regs),
|
|
protection, writeaccess));
|
|
|
|
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 (error_code & 1).
|
|
*/
|
|
|
|
if (address >= VMALLOC_START &&
|
|
!protection &&
|
|
!user_mode(regs))
|
|
goto vmalloc_fault;
|
|
|
|
/* When stack execution is not allowed we store the signal
|
|
* trampolines in the reserved cris_signal_return_page.
|
|
* Handle this in the exact same way as vmalloc (we know
|
|
* that the mapping is there and is valid so no need to
|
|
* call handle_mm_fault).
|
|
*/
|
|
if (cris_signal_return_page &&
|
|
address == cris_signal_return_page &&
|
|
!protection && user_mode(regs))
|
|
goto vmalloc_fault;
|
|
|
|
/* we can and should enable interrupts at this point */
|
|
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;
|
|
|
|
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 < rdusp())
|
|
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 (writeaccess == 2){
|
|
if (!(vma->vm_flags & VM_EXEC))
|
|
goto bad_area;
|
|
} else if (writeaccess == 1) {
|
|
if (!(vma->vm_flags & VM_WRITE))
|
|
goto bad_area;
|
|
} else {
|
|
if (!(vma->vm_flags & (VM_READ | VM_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.
|
|
*/
|
|
|
|
switch (handle_mm_fault(mm, vma, address, writeaccess & 1)) {
|
|
case VM_FAULT_MINOR:
|
|
tsk->min_flt++;
|
|
break;
|
|
case VM_FAULT_MAJOR:
|
|
tsk->maj_flt++;
|
|
break;
|
|
case VM_FAULT_SIGBUS:
|
|
goto do_sigbus;
|
|
default:
|
|
goto out_of_memory;
|
|
}
|
|
|
|
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:
|
|
DPG(show_registers(regs));
|
|
|
|
/* 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)
|
|
*/
|
|
|
|
if (find_fixup_code(regs))
|
|
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)
|
|
raw_printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
|
|
else
|
|
raw_printk(KERN_ALERT "Unable to handle kernel access");
|
|
raw_printk(" at virtual address %08lx\n",address);
|
|
|
|
die_if_kernel("Oops", regs, (writeaccess << 1) | protection);
|
|
|
|
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);
|
|
printk("VM: killing process %s\n", tsk->comm);
|
|
if (user_mode(regs))
|
|
do_exit(SIGKILL);
|
|
goto no_context;
|
|
|
|
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;
|
|
|
|
pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + 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;
|
|
}
|
|
}
|
|
|
|
/* Find fixup code. */
|
|
int
|
|
find_fixup_code(struct pt_regs *regs)
|
|
{
|
|
const struct exception_table_entry *fixup;
|
|
|
|
if ((fixup = search_exception_tables(instruction_pointer(regs))) != 0) {
|
|
/* Adjust the instruction pointer in the stackframe. */
|
|
instruction_pointer(regs) = fixup->fixup;
|
|
arch_fixup(regs);
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|