[PATCH 10/16] powerpc/mm: Add speculative page fault
From: Laurent Dufour <hidden>
Date: 2017-08-08 14:36:27
Also in:
linux-mm, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
This patch enable the speculative page fault on the PowerPC architecture. This will try a speculative page fault without holding the mmap_sem, if it returns with WM_FAULT_RETRY, the mmap_sem is acquired and the traditional page fault processing is done. Signed-off-by: Laurent Dufour <redacted> --- arch/powerpc/mm/fault.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 4c422632047b..c6cd40901dd0 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c@@ -291,9 +291,31 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, if (is_write && is_user) store_update_sp = store_updates_sp(regs); - if (is_user) + if (is_user) { flags |= FAULT_FLAG_USER; + /* let's try a speculative page fault without grabbing the + * mmap_sem. + */ + + /* + * flags is set later based on the VMA's flags, for the common + * speculative service, we need some flags to be set. + */ + if (is_write) + flags |= FAULT_FLAG_WRITE; + + fault = handle_speculative_fault(mm, address, flags); + if (!(fault & VM_FAULT_RETRY || fault & VM_FAULT_ERROR)) + goto done; + + /* + * Resetting flags since the following code assumes + * FAULT_FLAG_WRITE is not set. + */ + flags &= ~FAULT_FLAG_WRITE; + } + /* 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
@@ -479,6 +501,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, rc = 0; } +done: /* * Major/minor page fault accounting. */
--
2.7.4