351 lines
8.5 KiB
C
351 lines
8.5 KiB
C
|
// SPDX-License-Identifier: GPL-2.0-or-later
|
||
|
|
/*
|
||
|
|
* OpenRISC fault.c
|
||
|
|
*
|
||
|
|
* Linux architectural port borrowing liberally from similar works of
|
||
|
|
* others. All original copyrights apply as per the original source
|
||
|
|
* declaration.
|
||
|
|
*
|
||
|
|
* Modifications for the OpenRISC architecture:
|
||
|
|
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
|
||
|
|
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/mm.h>
|
||
|
|
#include <linux/interrupt.h>
|
||
|
|
#include <linux/extable.h>
|
||
|
|
#include <linux/sched/signal.h>
|
||
|
|
#include <linux/perf_event.h>
|
||
|
|
|
||
|
|
#include <linux/uaccess.h>
|
||
|
|
#include <asm/siginfo.h>
|
||
|
|
#include <asm/signal.h>
|
||
|
|
|
||
|
|
#define NUM_TLB_ENTRIES 64
|
||
|
|
#define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))
|
||
|
|
|
||
|
|
unsigned long pte_misses; /* updated by do_page_fault() */
|
||
|
|
unsigned long pte_errors; /* updated by do_page_fault() */
|
||
|
|
|
||
|
|
/* __PHX__ :: - check the vmalloc_fault in do_page_fault()
|
||
|
|
* - also look into include/asm/mmu_context.h
|
||
|
|
*/
|
||
|
|
volatile pgd_t *current_pgd[NR_CPUS];
|
||
|
|
|
||
|
|
extern void __noreturn die(char *, struct pt_regs *, long);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This routine handles page faults. It determines the address,
|
||
|
|
* and the problem, and then passes it off to one of the appropriate
|
||
|
|
* routines.
|
||
|
|
*
|
||
|
|
* If this routine detects a bad access, it returns 1, otherwise it
|
||
|
|
* returns 0.
|
||
|
|
*/
|
||
|
|
|
||
|
|
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
|
||
|
|
unsigned long vector, int write_acc)
|
||
|
|
{
|
||
|
|
struct task_struct *tsk;
|
||
|
|
struct mm_struct *mm;
|
||
|
|
struct vm_area_struct *vma;
|
||
|
|
int si_code;
|
||
|
|
vm_fault_t fault;
|
||
|
|
unsigned int flags = FAULT_FLAG_DEFAULT;
|
||
|
|
|
||
|
|
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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
if (address >= VMALLOC_START &&
|
||
|
|
(vector != 0x300 && vector != 0x400) &&
|
||
|
|
!user_mode(regs))
|
||
|
|
goto vmalloc_fault;
|
||
|
|
|
||
|
|
/* If exceptions were enabled, we can reenable them here */
|
||
|
|
if (user_mode(regs)) {
|
||
|
|
/* Exception was in userspace: reenable interrupts */
|
||
|
|
local_irq_enable();
|
||
|
|
flags |= FAULT_FLAG_USER;
|
||
|
|
} else {
|
||
|
|
/* If exception was in a syscall, then IRQ's may have
|
||
|
|
* been enabled or disabled. If they were enabled,
|
||
|
|
* reenable them.
|
||
|
|
*/
|
||
|
|
if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE))
|
||
|
|
local_irq_enable();
|
||
|
|
}
|
||
|
|
|
||
|
|
mm = tsk->mm;
|
||
|
|
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;
|
||
|
|
|
||
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
||
|
|
|
||
|
|
retry:
|
||
|
|
mmap_read_lock(mm);
|
||
|
|
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 < regs->sp)
|
||
|
|
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:
|
||
|
|
si_code = SEGV_ACCERR;
|
||
|
|
|
||
|
|
/* first do some preliminary protection checks */
|
||
|
|
|
||
|
|
if (write_acc) {
|
||
|
|
if (!(vma->vm_flags & VM_WRITE))
|
||
|
|
goto bad_area;
|
||
|
|
flags |= FAULT_FLAG_WRITE;
|
||
|
|
} else {
|
||
|
|
/* not present */
|
||
|
|
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
|
||
|
|
goto bad_area;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* are we trying to execute nonexecutable area */
|
||
|
|
if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
fault = handle_mm_fault(vma, address, flags, regs);
|
||
|
|
|
||
|
|
if (fault_signal_pending(fault, regs))
|
||
|
|
return;
|
||
|
|
|
||
|
|
if (unlikely(fault & VM_FAULT_ERROR)) {
|
||
|
|
if (fault & VM_FAULT_OOM)
|
||
|
|
goto out_of_memory;
|
||
|
|
else if (fault & VM_FAULT_SIGSEGV)
|
||
|
|
goto bad_area;
|
||
|
|
else if (fault & VM_FAULT_SIGBUS)
|
||
|
|
goto do_sigbus;
|
||
|
|
BUG();
|
||
|
|
}
|
||
|
|
|
||
|
|
/*RGD modeled on Cris */
|
||
|
|
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)) {
|
||
|
|
force_sig_fault(SIGSEGV, si_code, (void __user *)address);
|
||
|
|
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;
|
||
|
|
|
||
|
|
__asm__ __volatile__("l.nop 42");
|
||
|
|
|
||
|
|
if ((entry = search_exception_tables(regs->pc)) != NULL) {
|
||
|
|
/* Adjust the instruction pointer in the stackframe */
|
||
|
|
regs->pc = entry->fixup;
|
||
|
|
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)
|
||
|
|
printk(KERN_ALERT
|
||
|
|
"Unable to handle kernel NULL pointer dereference");
|
||
|
|
else
|
||
|
|
printk(KERN_ALERT "Unable to handle kernel access");
|
||
|
|
printk(" at virtual address 0x%08lx\n", address);
|
||
|
|
|
||
|
|
die("Oops", regs, write_acc);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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:
|
||
|
|
__asm__ __volatile__("l.nop 42");
|
||
|
|
__asm__ __volatile__("l.nop 1");
|
||
|
|
|
||
|
|
mmap_read_unlock(mm);
|
||
|
|
if (!user_mode(regs))
|
||
|
|
goto no_context;
|
||
|
|
pagefault_out_of_memory();
|
||
|
|
return;
|
||
|
|
|
||
|
|
do_sigbus:
|
||
|
|
mmap_read_unlock(mm);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Send a sigbus, regardless of whether we were in kernel
|
||
|
|
* or user mode.
|
||
|
|
*/
|
||
|
|
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
|
||
|
|
|
||
|
|
/* 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;
|
||
|
|
p4d_t *p4d, *p4d_k;
|
||
|
|
pud_t *pud, *pud_k;
|
||
|
|
pmd_t *pmd, *pmd_k;
|
||
|
|
pte_t *pte_k;
|
||
|
|
|
||
|
|
/*
|
||
|
|
phx_warn("do_page_fault(): vmalloc_fault will not work, "
|
||
|
|
"since current_pgd assign a proper value somewhere\n"
|
||
|
|
"anyhow we don't need this at the moment\n");
|
||
|
|
|
||
|
|
phx_mmu("vmalloc_fault");
|
||
|
|
*/
|
||
|
|
pgd = (pgd_t *)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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
p4d = p4d_offset(pgd, address);
|
||
|
|
p4d_k = p4d_offset(pgd_k, address);
|
||
|
|
if (!p4d_present(*p4d_k))
|
||
|
|
goto no_context;
|
||
|
|
|
||
|
|
pud = pud_offset(p4d, address);
|
||
|
|
pud_k = pud_offset(p4d_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;
|
||
|
|
}
|
||
|
|
}
|