From: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails.
Copied from "x86/mm: try VMA lock-based page fault handling first"
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
---
arch/powerpc/mm/fault.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 014005428687..c92bdfcd1796 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -450,6 +450,44 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
if (is_exec)
flags |= FAULT_FLAG_INSTRUCTION;
+#ifdef CONFIG_PER_VMA_LOCK
+ if (!(flags & FAULT_FLAG_USER) || atomic_read(&mm->mm_users) == 1)
+ goto lock_mmap;
+
+ vma = find_and_lock_anon_vma(mm, address);
+ if (!vma)
+ goto lock_mmap;
+
+ if (unlikely(access_pkey_error(is_write, is_exec,
+ (error_code & DSISR_KEYFAULT), vma))) {
+ int rc = bad_access_pkey(regs, address, vma);
+
+ vma_read_unlock(vma);
+ return rc;
+ }
+
+ if (unlikely(access_error(is_write, is_exec, vma))) {
+ int rc = bad_access(regs, address);
+
+ vma_read_unlock(vma);
+ return rc;
+ }
+
+ fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
+ vma_read_unlock(vma);
+
+ if (!(fault & VM_FAULT_RETRY)) {
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+ goto done;
+ }
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+
+ if (fault_signal_pending(fault, regs))
+ return user_mode(regs) ? 0 : SIGBUS;
+
+lock_mmap:
+#endif /* CONFIG_PER_VMA_LOCK */
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -526,6 +564,9 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
mmap_read_unlock(current->mm);
+#ifdef CONFIG_PER_VMA_LOCK
+done:
+#endif
if (unlikely(fault & VM_FAULT_ERROR))
return mm_fault_error(regs, address, fault);
--
2.37.2.672.g94769d06f0-goog
