arm64/vdso: Handle faults on timens page (ee3cda8e) · Commits · 戴 / test

arch/arm64/kernel/vdso.c

+52 −4

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@
		#include <linux/sched.h>
		#include <linux/signal.h>
		#include <linux/slab.h>
		#include <linux/time_namespace.h>
		#include <linux/timekeeper_internal.h>
		#include <linux/vmalloc.h>
		#include <vdso/datapage.h>
		@@ -164,17 +165,64 @@ int vdso_join_timens(struct task_struct task, struct time_namespace ns)
		mmap_read_unlock(mm);
		return 0;
		}

		static struct page find_timens_vvar_page(struct vm_area_struct vma)
		{
		if (likely(vma->vm_mm == current->mm))
		return current->nsproxy->time_ns->vvar_page;

		/*
		* VM_PFNMAP \| VM_IO protect .fault() handler from being called
		* through interfaces like /proc/$pid/mem or
		* process_vm_{readv,writev}() as long as there's no .access()
		* in special_mapping_vmops.
		* For more details check_vma_flags() and __access_remote_vm()
		*/
		WARN(1, "vvar_page accessed remotely");

		return NULL;
		}
		#else
		static struct page find_timens_vvar_page(struct vm_area_struct vma)
		{
		return NULL;
		}
		#endif

		static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
		struct vm_area_struct vma, struct vm_fault vmf)
		{
		if (vmf->pgoff == 0)
		return vmf_insert_pfn(vma, vmf->address,
		sym_to_pfn(vdso_data));
		struct page *timens_page = find_timens_vvar_page(vma);
		unsigned long pfn;

		switch (vmf->pgoff) {
		case VVAR_DATA_PAGE_OFFSET:
		if (timens_page)
		pfn = page_to_pfn(timens_page);
		else
		pfn = sym_to_pfn(vdso_data);
		break;
		#ifdef CONFIG_TIME_NS
		case VVAR_TIMENS_PAGE_OFFSET:
		/*
		* If a task belongs to a time namespace then a namespace
		* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
		* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
		* offset.
		* See also the comment near timens_setup_vdso_data().
		*/
		if (!timens_page)
		return VM_FAULT_SIGBUS;
		pfn = sym_to_pfn(vdso_data);
		break;
		#endif /* CONFIG_TIME_NS */
		default:
		return VM_FAULT_SIGBUS;
		}

		return vmf_insert_pfn(vma, vmf->address, pfn);
		}

		static int __setup_additional_pages(enum vdso_abi abi,
		struct mm_struct *mm,
		struct linux_binprm *bprm,

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