From 84fc57a369dfac882cb9e9333635aaa11978948f Mon Sep 17 00:00:00 2001
From: Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
Date: Sat, 11 Apr 2026 16:19:39 +0200
Subject: linuxkpi: Add more `struct folio`-related functions

The i915 DRM driver started to replace the use of `struct page` by
`struct folio` in its GEM shmem code in Linux 6.12.

linuxkpi were missing a few more functions: `kmap_local_folio()`,
`memcpy_to_folio()` and `offset_in_folio()`. They are equivalent of
their `struct page` counterparts.

One difference is that `kmap_local_folio()` takes an offset argument and
the returned address takes this offset into account.

Reviewed by:	bz
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D56438
---
 sys/compat/linuxkpi/common/include/linux/highmem.h | 22 ++++++++++++++++++++++
 sys/compat/linuxkpi/common/include/linux/mm.h      |  1 +
 2 files changed, 23 insertions(+)

(limited to 'sys/compat/linuxkpi/common/include/linux')

diff --git a/sys/compat/linuxkpi/common/include/linux/highmem.h b/sys/compat/linuxkpi/common/include/linux/highmem.h
index dc1c4fe2f299..294b2666031b 100644
--- a/sys/compat/linuxkpi/common/include/linux/highmem.h
+++ b/sys/compat/linuxkpi/common/include/linux/highmem.h
@@ -99,6 +99,19 @@ kmap_local_page(struct page *page)
 	return (kmap(page));
 }
 
+static inline void *
+kmap_local_folio(struct folio *folio, size_t offset)
+{
+	struct page *page;
+	char *vaddr;
+
+	page = &folio->page;
+	vaddr = kmap_local_page(page);
+	vaddr += offset;
+
+	return (vaddr);
+}
+
 static inline void *
 kmap_local_page_prot(struct page *page, pgprot_t prot)
 {
@@ -168,4 +181,13 @@ memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
 	kunmap_local(to);
 }
 
+static inline void
+memcpy_to_folio(struct folio *folio, size_t offset, const char *from, size_t len)
+{
+	struct page *page;
+
+	page = &folio->page;
+	memcpy_to_page(page, offset, from, len);
+}
+
 #endif	/* _LINUXKPI_LINUX_HIGHMEM_H_ */
diff --git a/sys/compat/linuxkpi/common/include/linux/mm.h b/sys/compat/linuxkpi/common/include/linux/mm.h
index 156b00a0c0f0..a639c0947031 100644
--- a/sys/compat/linuxkpi/common/include/linux/mm.h
+++ b/sys/compat/linuxkpi/common/include/linux/mm.h
@@ -264,6 +264,7 @@ vma_pages(struct vm_area_struct *vma)
 }
 
 #define	offset_in_page(off)	((unsigned long)(off) & (PAGE_SIZE - 1))
+#define	offset_in_folio(folio, p) ((unsigned long)(p) & (folio_size(folio) - 1))
 
 static inline void
 set_page_dirty(struct page *page)
-- 
cgit v1.3