403 lines
8.8 KiB
C
403 lines
8.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
// Copyright (C) 2005-2017 Andes Technology Corporation
|
|
|
|
#include <linux/extable.h>
|
|
#include <linux/module.h>
|
|
#include <linux/signal.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/init.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/perf_event.h>
|
|
|
|
#include <asm/tlbflush.h>
|
|
|
|
extern void die(const char *str, struct pt_regs *regs, long err);
|
|
|
|
/*
|
|
* This is useful to dump out the page tables associated with
|
|
* 'addr' in mm 'mm'.
|
|
*/
|
|
void show_pte(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
pgd_t *pgd;
|
|
if (!mm)
|
|
mm = &init_mm;
|
|
|
|
pr_alert("pgd = %p\n", mm->pgd);
|
|
pgd = pgd_offset(mm, addr);
|
|
pr_alert("[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
|
|
|
|
do {
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
|
|
if (pgd_none(*pgd))
|
|
break;
|
|
|
|
if (pgd_bad(*pgd)) {
|
|
pr_alert("(bad)");
|
|
break;
|
|
}
|
|
|
|
p4d = p4d_offset(pgd, addr);
|
|
pud = pud_offset(p4d, addr);
|
|
pmd = pmd_offset(pud, addr);
|
|
#if PTRS_PER_PMD != 1
|
|
pr_alert(", *pmd=%08lx", pmd_val(*pmd));
|
|
#endif
|
|
|
|
if (pmd_none(*pmd))
|
|
break;
|
|
|
|
if (pmd_bad(*pmd)) {
|
|
pr_alert("(bad)");
|
|
break;
|
|
}
|
|
|
|
if (IS_ENABLED(CONFIG_HIGHMEM))
|
|
{
|
|
pte_t *pte;
|
|
/* We must not map this if we have highmem enabled */
|
|
pte = pte_offset_map(pmd, addr);
|
|
pr_alert(", *pte=%08lx", pte_val(*pte));
|
|
pte_unmap(pte);
|
|
}
|
|
} while (0);
|
|
|
|
pr_alert("\n");
|
|
}
|
|
|
|
void do_page_fault(unsigned long entry, unsigned long addr,
|
|
unsigned int error_code, struct pt_regs *regs)
|
|
{
|
|
struct task_struct *tsk;
|
|
struct mm_struct *mm;
|
|
struct vm_area_struct *vma;
|
|
int si_code;
|
|
vm_fault_t fault;
|
|
unsigned int mask = VM_ACCESS_FLAGS;
|
|
unsigned int flags = FAULT_FLAG_DEFAULT;
|
|
|
|
error_code = error_code & (ITYPE_mskINST | ITYPE_mskETYPE);
|
|
tsk = current;
|
|
mm = tsk->mm;
|
|
si_code = SEGV_MAPERR;
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (addr >= TASK_SIZE) {
|
|
if (user_mode(regs))
|
|
goto bad_area_nosemaphore;
|
|
|
|
if (addr >= TASK_SIZE && addr < VMALLOC_END
|
|
&& (entry == ENTRY_PTE_NOT_PRESENT))
|
|
goto vmalloc_fault;
|
|
else
|
|
goto no_context;
|
|
}
|
|
|
|
/* Send a signal to the task for handling the unalignment access. */
|
|
if (entry == ENTRY_GENERAL_EXCPETION
|
|
&& error_code == ETYPE_ALIGNMENT_CHECK) {
|
|
if (user_mode(regs))
|
|
goto bad_area_nosemaphore;
|
|
else
|
|
goto no_context;
|
|
}
|
|
|
|
/*
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
if (unlikely(faulthandler_disabled() || !mm))
|
|
goto no_context;
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
|
|
|
|
/*
|
|
* As per x86, we may deadlock here. However, since the kernel only
|
|
* validly references user space from well defined areas of the code,
|
|
* we can bug out early if this is from code which shouldn't.
|
|
*/
|
|
if (unlikely(!mmap_read_trylock(mm))) {
|
|
if (!user_mode(regs) &&
|
|
!search_exception_tables(instruction_pointer(regs)))
|
|
goto no_context;
|
|
retry:
|
|
mmap_read_lock(mm);
|
|
} else {
|
|
/*
|
|
* The above down_read_trylock() might have succeeded in which
|
|
* case, we'll have missed the might_sleep() from down_read().
|
|
*/
|
|
might_sleep();
|
|
if (IS_ENABLED(CONFIG_DEBUG_VM)) {
|
|
if (!user_mode(regs) &&
|
|
!search_exception_tables(instruction_pointer(regs)))
|
|
goto no_context;
|
|
}
|
|
}
|
|
|
|
vma = find_vma(mm, addr);
|
|
|
|
if (unlikely(!vma))
|
|
goto bad_area;
|
|
|
|
if (vma->vm_start <= addr)
|
|
goto good_area;
|
|
|
|
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
|
|
goto bad_area;
|
|
|
|
if (unlikely(expand_stack(vma, addr)))
|
|
goto bad_area;
|
|
|
|
/*
|
|
* Ok, we have a good vm_area for this memory access, so
|
|
* we can handle it..
|
|
*/
|
|
|
|
good_area:
|
|
si_code = SEGV_ACCERR;
|
|
|
|
/* first do some preliminary protection checks */
|
|
if (entry == ENTRY_PTE_NOT_PRESENT) {
|
|
if (error_code & ITYPE_mskINST)
|
|
mask = VM_EXEC;
|
|
else {
|
|
mask = VM_READ | VM_WRITE;
|
|
}
|
|
} else if (entry == ENTRY_TLB_MISC) {
|
|
switch (error_code & ITYPE_mskETYPE) {
|
|
case RD_PROT:
|
|
mask = VM_READ;
|
|
break;
|
|
case WRT_PROT:
|
|
mask = VM_WRITE;
|
|
flags |= FAULT_FLAG_WRITE;
|
|
break;
|
|
case NOEXEC:
|
|
mask = VM_EXEC;
|
|
break;
|
|
case PAGE_MODIFY:
|
|
mask = VM_WRITE;
|
|
flags |= FAULT_FLAG_WRITE;
|
|
break;
|
|
case ACC_BIT:
|
|
BUG();
|
|
default:
|
|
break;
|
|
}
|
|
|
|
}
|
|
if (!(vma->vm_flags & mask))
|
|
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(vma, addr, flags, regs);
|
|
|
|
/*
|
|
* If we need to retry but a fatal signal is pending, handle the
|
|
* signal first. We do not need to release the mmap_lock because it
|
|
* would already be released in __lock_page_or_retry in mm/filemap.c.
|
|
*/
|
|
if (fault_signal_pending(fault, regs)) {
|
|
if (!user_mode(regs))
|
|
goto no_context;
|
|
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;
|
|
else
|
|
goto bad_area;
|
|
}
|
|
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
if (fault & VM_FAULT_RETRY) {
|
|
flags |= FAULT_FLAG_TRIED;
|
|
|
|
/* No need to mmap_read_unlock(mm) as we would
|
|
* have already released it in __lock_page_or_retry
|
|
* in mm/filemap.c.
|
|
*/
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
mmap_read_unlock(mm);
|
|
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:
|
|
mmap_read_unlock(mm);
|
|
|
|
bad_area_nosemaphore:
|
|
|
|
/* User mode accesses just cause a SIGSEGV */
|
|
|
|
if (user_mode(regs)) {
|
|
tsk->thread.address = addr;
|
|
tsk->thread.error_code = error_code;
|
|
tsk->thread.trap_no = entry;
|
|
force_sig_fault(SIGSEGV, si_code, (void __user *)addr);
|
|
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;
|
|
|
|
if ((entry =
|
|
search_exception_tables(instruction_pointer(regs))) !=
|
|
NULL) {
|
|
/* Adjust the instruction pointer in the stackframe */
|
|
instruction_pointer(regs) = entry->fixup;
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Oops. The kernel tried to access some bad page. We'll have to
|
|
* terminate things with extreme prejudice.
|
|
*/
|
|
|
|
bust_spinlocks(1);
|
|
pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
|
|
(addr < PAGE_SIZE) ? "NULL pointer dereference" :
|
|
"paging request", addr);
|
|
|
|
show_pte(mm, addr);
|
|
die("Oops", regs, error_code);
|
|
bust_spinlocks(0);
|
|
do_exit(SIGKILL);
|
|
|
|
return;
|
|
|
|
/*
|
|
* 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:
|
|
mmap_read_unlock(mm);
|
|
if (!user_mode(regs))
|
|
goto no_context;
|
|
pagefault_out_of_memory();
|
|
return;
|
|
|
|
do_sigbus:
|
|
mmap_read_unlock(mm);
|
|
|
|
/* Kernel mode? Handle exceptions or die */
|
|
if (!user_mode(regs))
|
|
goto no_context;
|
|
|
|
/*
|
|
* Send a sigbus
|
|
*/
|
|
tsk->thread.address = addr;
|
|
tsk->thread.error_code = error_code;
|
|
tsk->thread.trap_no = entry;
|
|
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)addr);
|
|
|
|
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...).
|
|
*/
|
|
|
|
unsigned int index = pgd_index(addr);
|
|
pgd_t *pgd, *pgd_k;
|
|
p4d_t *p4d, *p4d_k;
|
|
pud_t *pud, *pud_k;
|
|
pmd_t *pmd, *pmd_k;
|
|
pte_t *pte_k;
|
|
|
|
pgd = (pgd_t *) __va(__nds32__mfsr(NDS32_SR_L1_PPTB)) + index;
|
|
pgd_k = init_mm.pgd + index;
|
|
|
|
if (!pgd_present(*pgd_k))
|
|
goto no_context;
|
|
|
|
p4d = p4d_offset(pgd, addr);
|
|
p4d_k = p4d_offset(pgd_k, addr);
|
|
if (!p4d_present(*p4d_k))
|
|
goto no_context;
|
|
|
|
pud = pud_offset(p4d, addr);
|
|
pud_k = pud_offset(p4d_k, addr);
|
|
if (!pud_present(*pud_k))
|
|
goto no_context;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
pmd_k = pmd_offset(pud_k, addr);
|
|
if (!pmd_present(*pmd_k))
|
|
goto no_context;
|
|
|
|
if (!pmd_present(*pmd))
|
|
set_pmd(pmd, *pmd_k);
|
|
else
|
|
BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
/* Make sure the actual PTE exists as well to
|
|
* catch kernel vmalloc-area accesses to non-mapped
|
|
* addres. If we don't do this, this will just
|
|
* silently loop forever.
|
|
*/
|
|
|
|
pte_k = pte_offset_kernel(pmd_k, addr);
|
|
if (!pte_present(*pte_k))
|
|
goto no_context;
|
|
|
|
return;
|
|
}
|
|
}
|