LinuxKPI: Factor out vmf_insert_pfn_prot() routine

from GEM and TTM page fault handlers and move it in to base system. This
code is tightly integrated with LKPI mmap support to belong to drm-kmod.

As this routine requires associated vm_object to be locked, it got
additional _locked suffix.

Reviewed by:	hselasky, markj
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D32068

2 files changed, 55 insertions, 0 deletions

diff --git a/sys/compat/linuxkpi/common/include/linux/mm.h b/sys/compat/linuxkpi/common/include/linux/mm.h
index 74709299ba1a..dc75ae4483c3 100644
--- a/sys/compat/linuxkpi/common/include/linux/mm.h
+++ b/sys/compat/linuxkpi/common/include/linux/mm.h
@@ -82,6 +82,9 @@ CTASSERT((VM_PROT_ALL & -(1 << 8)) == 0);
 #define	VM_FAULT_RETRY		(1 << 9)
 #define	VM_FAULT_FALLBACK	(1 << 10)
 
+#define	VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
+	VM_FAULT_HWPOISON |VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
+
 #define	FAULT_FLAG_WRITE	(1 << 0)
 #define	FAULT_FLAG_MKWRITE	(1 << 1)
 #define	FAULT_FLAG_ALLOW_RETRY	(1 << 2)
@@ -183,6 +186,26 @@ io_remap_pfn_range(struct vm_area_struct *vma,
 	return (0);
 }
 
+vm_fault_t
+lkpi_vmf_insert_pfn_prot_locked(struct vm_area_struct *vma, unsigned long addr,
+    unsigned long pfn, pgprot_t prot);
+
+static inline vm_fault_t
+vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
+    unsigned long pfn, pgprot_t prot)
+{
+	vm_fault_t ret;
+
+	VM_OBJECT_WLOCK(vma->vm_obj);
+	ret = lkpi_vmf_insert_pfn_prot_locked(vma, addr, pfn, prot);
+	VM_OBJECT_WUNLOCK(vma->vm_obj);
+
+	return (ret);
+}
+#define	vmf_insert_pfn_prot(...)	\
+	_Static_assert(false,		\
+"This function is always called in a loop. Consider using the locked version")
+
 static inline int
 apply_to_page_range(struct mm_struct *mm, unsigned long address,
     unsigned long size, pte_fn_t fn, void *data)
diff --git a/sys/compat/linuxkpi/common/src/linux_page.c b/sys/compat/linuxkpi/common/src/linux_page.c
index ee41366c53a6..cbe6d2530b91 100644
--- a/sys/compat/linuxkpi/common/src/linux_page.c
+++ b/sys/compat/linuxkpi/common/src/linux_page.c
@@ -275,3 +275,35 @@ is_vmalloc_addr(const void *addr)
 {
 	return (vtoslab((vm_offset_t)addr & ~UMA_SLAB_MASK) != NULL);
 }
+
+vm_fault_t
+lkpi_vmf_insert_pfn_prot_locked(struct vm_area_struct *vma, unsigned long addr,
+    unsigned long pfn, pgprot_t prot)
+{
+	vm_object_t vm_obj = vma->vm_obj;
+	vm_page_t page;
+	vm_pindex_t pindex;
+
+	VM_OBJECT_ASSERT_WLOCKED(vm_obj);
+	pindex = OFF_TO_IDX(addr - vma->vm_start);
+	if (vma->vm_pfn_count == 0)
+		vma->vm_pfn_first = pindex;
+	MPASS(pindex <= OFF_TO_IDX(vma->vm_end));
+
+retry:
+	page = vm_page_grab(vm_obj, pindex, VM_ALLOC_NOCREAT);
+	if (page == NULL) {
+		page = PHYS_TO_VM_PAGE(IDX_TO_OFF(pfn));
+		if (!vm_page_busy_acquire(page, VM_ALLOC_WAITFAIL))
+			goto retry;
+		if (vm_page_insert(page, vm_obj, pindex)) {
+			vm_page_xunbusy(page);
+			return (VM_FAULT_OOM);
+		}
+		vm_page_valid(page);
+	}
+	pmap_page_set_memattr(page, pgprot2cachemode(prot));
+	vma->vm_pfn_count++;
+
+	return (VM_FAULT_NOPAGE);
+}