Merge "arm64/mm: add speculative page fault" (d971e9f4) · Commits · e / devices / android_kernel_oneplus_sm8150

arch/arm64/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -140,6 +140,7 @@ config ARM64
		select SPARSE_IRQ
		select SYSCTL_EXCEPTION_TRACE
		select THREAD_INFO_IN_TASK
		select ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
		help
		ARM 64-bit (AArch64) Linux support.

arch/arm64/mm/fault.c

+23 −4

Original line number	Diff line number	Diff line
		@@ -358,14 +358,12 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
		#define VM_FAULT_BADMAP 0x010000
		#define VM_FAULT_BADACCESS 0x020000

		static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
		static int __do_page_fault(struct vm_area_struct *vma, unsigned long addr,
		unsigned int mm_flags, unsigned long vm_flags,
		struct task_struct *tsk)
		{
		struct vm_area_struct *vma;
		int fault;

		vma = find_vma(mm, addr);
		fault = VM_FAULT_BADMAP;
		if (unlikely(!vma))
		goto out;
		@@ -408,6 +406,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
		int fault, sig, code, major = 0;
		unsigned long vm_flags = VM_READ \| VM_WRITE;
		unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
		struct vm_area_struct *vma = NULL;

		if (notify_page_fault(regs, esr))
		return 0;
		@@ -446,6 +445,14 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,

		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);

		/*
		* let's try a speculative page fault without grabbing the
		* mmap_sem.
		*/
		fault = handle_speculative_fault(mm, addr, mm_flags, &vma);
		if (fault != VM_FAULT_RETRY)
		goto done;

		/*
		* As per x86, we may deadlock here. However, since the kernel only
		* validly references user space from well defined areas of the code,
		@@ -468,7 +475,10 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
		#endif
		}

		fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
		if (!vma \|\| !can_reuse_spf_vma(vma, addr))
		vma = find_vma(mm, addr);

		fault = __do_page_fault(vma, addr, mm_flags, vm_flags, tsk);
		major \|= fault & VM_FAULT_MAJOR;

		if (fault & VM_FAULT_RETRY) {
		@@ -491,11 +501,20 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
		if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
		mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
		mm_flags \|= FAULT_FLAG_TRIED;

		/*
		* Do not try to reuse this vma and fetch it
		* again since we will release the mmap_sem.
		*/
		vma = NULL;

		goto retry;
		}
		}
		up_read(&mm->mmap_sem);

		done:

		/*
		* Handle the "normal" (no error) case first.
		*/