Commit 70d4cbc8 authored by Laurent Dufour's avatar Laurent Dufour Committed by Andrew Morton
Browse files

powerc/mm: try VMA lock-based page fault handling first 

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"

[ldufour@linux.ibm.com: powerpc/mm: fix mmap_lock bad unlock]
  Link: https://lkml.kernel.org/r/20230306154244.17560-1-ldufour@linux.ibm.com
  Link: https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@linux.ibm.com
Link: https://lkml.kernel.org/r/20230227173632.3292573-32-surenb@google.com


Signed-off-by: default avatarLaurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Cc: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent cd7f176a

arch/powerpc/mm/fault.c

+37 −0
Original line number Diff line number Diff line
@@ -474,6 +474,40 @@ 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))

		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))) {

		vma_end_read(vma);

		goto lock_mmap;

	}



	if (unlikely(access_error(is_write, is_exec, vma))) {

		vma_end_read(vma);

		goto lock_mmap;

	}



	fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);

	vma_end_read(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
@@ -550,6 +584,9 @@ 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);

arch/powerpc/platforms/powernv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/platforms/pseries/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ config PPC_PSERIES 
	select HOTPLUG_CPU

	select FORCE_SMP

	select SWIOTLB

	select ARCH_SUPPORTS_PER_VMA_LOCK

	default y



config PARAVIRT