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authorPaul Mundt <lethal@linux-sh.org>2009-07-05 03:18:47 +0900
committerPaul Mundt <lethal@linux-sh.org>2009-07-05 03:18:47 +0900
commit0f60bb25b4036d30fd795709be09626c58c52464 (patch)
treeb15cd9771c5cff9349d510670cc51bcc64c318a7 /arch/sh
parentc63c3105e4991b2991ba73a742b8b59bfdbe4acd (diff)
sh: Tidy up vmalloc fault handling.
This rewrites the vmalloc fault handling as per x86, which subsequently allows for easy future tie-in for vmalloc_sync_all(). Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/mm/fault_32.c153
1 files changed, 97 insertions, 56 deletions
diff --git a/arch/sh/mm/fault_32.c b/arch/sh/mm/fault_32.c
index ce75b8882ef..08d0117d90f 100644
--- a/arch/sh/mm/fault_32.c
+++ b/arch/sh/mm/fault_32.c
@@ -2,7 +2,7 @@
* Page fault handler for SH with an MMU.
*
* Copyright (C) 1999 Niibe Yutaka
- * Copyright (C) 2003 - 2008 Paul Mundt
+ * Copyright (C) 2003 - 2009 Paul Mundt
*
* Based on linux/arch/i386/mm/fault.c:
* Copyright (C) 1995 Linus Torvalds
@@ -35,6 +35,74 @@ static inline int notify_page_fault(struct pt_regs *regs, int trap)
return ret;
}
+static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
+{
+ unsigned index = pgd_index(address);
+ pgd_t *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+
+ pgd += index;
+ pgd_k = init_mm.pgd + index;
+
+ if (!pgd_present(*pgd_k))
+ return NULL;
+
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ return NULL;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ return NULL;
+
+ if (!pmd_present(*pmd))
+ set_pmd(pmd, *pmd_k);
+ else
+ BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
+
+ return pmd_k;
+}
+
+/*
+ * Handle a fault on the vmalloc or module mapping area
+ */
+static noinline int vmalloc_fault(unsigned long address)
+{
+ pgd_t *pgd_k;
+ pmd_t *pmd_k;
+ pte_t *pte_k;
+
+ /* Make sure we are in vmalloc area: */
+ if (!(address >= VMALLOC_START && address < VMALLOC_END))
+ return -1;
+
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Do _not_ use "current" here. We might be inside
+ * an interrupt in the middle of a task switch..
+ */
+ pgd_k = get_TTB();
+ pmd_k = vmalloc_sync_one(__va((unsigned long)pgd_k), address);
+ if (!pmd_k)
+ return -1;
+
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ return -1;
+
+ return 0;
+}
+
+static int fault_in_kernel_space(unsigned long address)
+{
+ return address >= TASK_SIZE;
+}
+
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
@@ -44,6 +112,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long address)
{
+ unsigned long vec;
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
@@ -51,59 +120,30 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
int fault;
siginfo_t info;
- /*
- * We don't bother with any notifier callbacks here, as they are
- * all handled through the __do_page_fault() fast-path.
- */
-
tsk = current;
+ mm = tsk->mm;
si_code = SEGV_MAPERR;
+ vec = lookup_exception_vector();
- if (unlikely(address >= TASK_SIZE)) {
- /*
- * Synchronize this task's top level page-table
- * with the 'reference' page table.
- *
- * Do _not_ use "tsk" here. We might be inside
- * an interrupt in the middle of a task switch..
- */
- int offset = pgd_index(address);
- pgd_t *pgd, *pgd_k;
- pud_t *pud, *pud_k;
- pmd_t *pmd, *pmd_k;
-
- pgd = get_TTB() + offset;
- pgd_k = swapper_pg_dir + offset;
-
- if (!pgd_present(*pgd)) {
- if (!pgd_present(*pgd_k))
- goto bad_area_nosemaphore;
- set_pgd(pgd, *pgd_k);
+ /*
+ * 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 (unlikely(fault_in_kernel_space(address))) {
+ if (vmalloc_fault(address) >= 0)
return;
- }
-
- pud = pud_offset(pgd, address);
- pud_k = pud_offset(pgd_k, address);
-
- if (!pud_present(*pud)) {
- if (!pud_present(*pud_k))
- goto bad_area_nosemaphore;
- set_pud(pud, *pud_k);
+ if (notify_page_fault(regs, vec))
return;
- }
-
- pmd = pmd_offset(pud, address);
- pmd_k = pmd_offset(pud_k, address);
- if (pmd_present(*pmd) || !pmd_present(*pmd_k))
- goto bad_area_nosemaphore;
- set_pmd(pmd, *pmd_k);
- return;
+ goto bad_area_nosemaphore;
}
- mm = tsk->mm;
-
- if (unlikely(notify_page_fault(regs, lookup_exception_vector())))
+ if (unlikely(notify_page_fault(regs, vec)))
return;
/* Only enable interrupts if they were on before the fault */
@@ -113,8 +153,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
/*
- * If we're in an interrupt or have no user
- * context, we must not take the fault..
+ * If we're in an interrupt, have no user context or are running
+ * in an atomic region then we must not take the fault:
*/
if (in_atomic() || !mm)
goto no_context;
@@ -130,10 +170,11 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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..
- */
+
+ /*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
good_area:
si_code = SEGV_ACCERR;
if (writeaccess) {
@@ -171,10 +212,10 @@ survive:
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..
- */
+ /*
+ * 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);