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authorSuren Baghdasaryan <surenb@google.com>2023-02-27 09:36:29 -0800
committerAndrew Morton <akpm@linux-foundation.org>2023-04-05 20:03:01 -0700
commitcd7f176aea5f5929a09a91c661a26912cc995d1b (patch)
treef25888e8b320649ba0d81438501515a8592fdd5e /arch/arm64/mm
parent0bff0aaea03e2a3ed6bfa302155cca8a432a1829 (diff)
arm64/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. Link: https://lkml.kernel.org/r/20230227173632.3292573-31-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/arm64/mm')
-rw-r--r--arch/arm64/mm/fault.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index f4cb0f85ccf4..9e0db5c387e3 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -535,6 +535,9 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
unsigned long vm_flags;
unsigned int mm_flags = FAULT_FLAG_DEFAULT;
unsigned long addr = untagged_addr(far);
+#ifdef CONFIG_PER_VMA_LOCK
+ struct vm_area_struct *vma;
+#endif
if (kprobe_page_fault(regs, esr))
return 0;
@@ -585,6 +588,36 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+#ifdef CONFIG_PER_VMA_LOCK
+ if (!(mm_flags & FAULT_FLAG_USER))
+ goto lock_mmap;
+
+ vma = lock_vma_under_rcu(mm, addr);
+ if (!vma)
+ goto lock_mmap;
+
+ if (!(vma->vm_flags & vm_flags)) {
+ vma_end_read(vma);
+ goto lock_mmap;
+ }
+ fault = handle_mm_fault(vma, addr & PAGE_MASK,
+ mm_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);
+
+ /* Quick path to respond to signals */
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ goto no_context;
+ return 0;
+ }
+lock_mmap:
+#endif /* CONFIG_PER_VMA_LOCK */
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
@@ -628,6 +661,9 @@ retry:
}
mmap_read_unlock(mm);
+#ifdef CONFIG_PER_VMA_LOCK
+done:
+#endif
/*
* Handle the "normal" (no error) case first.
*/