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UPSTREAM: arm64/mm: try VMA lock-based page fault handling first

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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>

(cherry picked from commit cd7f176aea)

Bug: 161210518
Change-Id: I0630cfa72467bb5f0ec162c3c276aa7745e49780
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan
2023-02-27 09:36:29 -08:00
committed by Carlos Llamas
parent 51b88c16a3
commit e6bf4cded6
2 changed files with 37 additions and 0 deletions
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1
arch/arm64/Kconfig
View File

@@ -96,6 +96,7 @@ config ARM64
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_SUPPORTS_PAGE_TABLE_CHECK
select ARCH_SUPPORTS_PER_VMA_LOCK
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
select ARCH_WANT_DEFAULT_BPF_JIT
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT

36
arch/arm64/mm/fault.c
View File

@@ -554,6 +554,9 @@ 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;
@@ -611,6 +614,36 @@ 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,
@@ -654,6 +687,9 @@ retry:
}
mmap_read_unlock(mm);
#ifdef CONFIG_PER_VMA_LOCK
done:
#endif
/*
* Handle the "normal" (no error) case first.
*/