From: Laurent Dufour <lduf...@linux.ibm.com>
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 <lduf...@linux.ibm.com>
Signed-off-by: Suren Baghdasaryan <sur...@google.com>
---
arch/powerpc/mm/fault.c | 41 ++++++++++++++++++++++++++
arch/powerpc/platforms/powernv/Kconfig | 1 +
arch/powerpc/platforms/pseries/Kconfig | 1 +
3 files changed, 43 insertions(+)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2bef19cc1b98..f92f8956d5f2 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -469,6 +469,44 @@ 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 = lock_vma_under_rcu(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
@@ -545,6 +583,9 @@ 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);
diff --git a/arch/powerpc/platforms/powernv/Kconfig
b/arch/powerpc/platforms/powernv/Kconfig
index ae248a161b43..70a46acc70d6 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -16,6 +16,7 @@ config PPC_POWERNV
select PPC_DOORBELL
select MMU_NOTIFIER
select FORCE_SMP
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config OPAL_PRD
diff --git a/arch/powerpc/platforms/pseries/Kconfig
b/arch/powerpc/platforms/pseries/Kconfig
index a3b4d99567cb..e036a04ff1ca 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -21,6 +21,7 @@ config PPC_PSERIES
select HOTPLUG_CPU
select FORCE_SMP
select SWIOTLB
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config PARAVIRT
--
2.39.0
