[PATCH V3 03/30] mm/mmap: Add new config ARCH_HAS_VM_GET_PAGE_PROT

Anshuman Khandual
2022-02-28T10:59:26Z

Add a new config ARCH_HAS_VM_GET_PAGE_PROT, which when subscribed enables a
given platform to define its own vm_get_page_prot(). This framework will
help remove protection_map[] dependency going forward.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
mm/Kconfig | 3 +++
mm/mmap.c | 2 ++
2 files changed, 5 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 257ed9c86de3..fa436478a94c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -747,6 +747,9 @@ config ARCH_HAS_CACHE_LINE_SIZE
config ARCH_HAS_FILTER_PGPROT
bool

+config ARCH_HAS_VM_GET_PAGE_PROT
+ bool
+
config ARCH_HAS_PTE_DEVMAP
bool

diff --git a/mm/mmap.c b/mm/mmap.c
index 34000a7d7efa..f2310f6e7466 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -81,6 +81,7 @@ static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma, struct vm_area_struct *prev,
unsigned long start, unsigned long end);

+#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
/* description of effects of mapping type and prot in current implementation.
* this is due to the limited x86 page protection hardware. The expected
* behavior is in parens:
@@ -136,6 +137,7 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags)
return arch_filter_pgprot(ret);
}
EXPORT_SYMBOL(vm_get_page_prot);
+#endif /* CONFIG_ARCH_HAS_VM_GET_PAGE_PROT */

static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
{
--
2.25.1