On Tue, Jun 30, 2020 at 04:45:14PM -0400, Peter Xu wrote:
> Use the general page fault accounting by passing regs into handle_mm_fault().
> It naturally solve the issue of multiple page fault accounting when page fault
> retry happened. To do this, we pass pt_regs pointer into __do_page_fault().
>
> CC: Catalin Marinas <catalin.marinas@xxxxxxx>
> CC: Will Deacon <will@xxxxxxxxxx>
> CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> ---
> arch/arm64/mm/fault.c | 29 ++++++-----------------------
> 1 file changed, 6 insertions(+), 23 deletions(-)
>
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index be29f4076fe3..f07333e86c2f 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -404,7 +404,8 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
> #define VM_FAULT_BADACCESS 0x020000
>
> static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
> - unsigned int mm_flags, unsigned long vm_flags)
> + unsigned int mm_flags, unsigned long vm_flags,
> + struct pt_regs *regs)
> {
> struct vm_area_struct *vma = find_vma(mm, addr);
>
> @@ -428,7 +429,7 @@ static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
> */
> if (!(vma->vm_flags & vm_flags))
> return VM_FAULT_BADACCESS;
> - return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags, NULL);
> + return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags, regs);
> }
>
> static bool is_el0_instruction_abort(unsigned int esr)
> @@ -450,7 +451,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
> {
> const struct fault_info *inf;
> struct mm_struct *mm = current->mm;
> - vm_fault_t fault, major = 0;
> + vm_fault_t fault;
> unsigned long vm_flags = VM_ACCESS_FLAGS;
> unsigned int mm_flags = FAULT_FLAG_DEFAULT;
>
> @@ -516,8 +517,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
> #endif
> }
>
> - fault = __do_page_fault(mm, addr, mm_flags, vm_flags);
> - major |= fault & VM_FAULT_MAJOR;
> + fault = __do_page_fault(mm, addr, mm_flags, vm_flags, regs);
>
> /* Quick path to respond to signals */
> if (fault_signal_pending(fault, regs)) {
> @@ -538,25 +538,8 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
> * Handle the "normal" (no error) case first.
> */
> if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
> - VM_FAULT_BADACCESS)))) {
> - /*
> - * Major/minor page fault accounting is only done
> - * once. If we go through a retry, it is extremely
> - * likely that the page will be found in page cache at
> - * that point.
> - */
> - if (major) {
> - current->maj_flt++;
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
> - addr);
> - } else {
> - current->min_flt++;
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
> - addr);
> - }
> -
> + VM_FAULT_BADACCESS))))
> return 0;
> - }
Thanks, looks good to me:
Acked-by: Will Deacon <will@xxxxxxxxxx>
Will
