Patch "arm64/mm: fold check for KFENCE into can_set_direct_map()" has been added to the 6.0-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    arm64/mm: fold check for KFENCE into can_set_direct_map()

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-mm-fold-check-for-kfence-into-can_set_direct_m.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 829c8c4d6a38d2e384016170c505d8ecef5815a0
Author: Mike Rapoport <rppt@xxxxxxxxxx>
Date:   Wed Sep 21 10:48:41 2022 +0300

    arm64/mm: fold check for KFENCE into can_set_direct_map()
    
    [ Upstream commit b9dd04a20f81333e4b99662f1bbaf7c9e3a1e137 ]
    
    KFENCE requires linear map to be mapped at page granularity, so that it
    is possible to protect/unprotect single pages, just like with
    rodata_full and DEBUG_PAGEALLOC.
    
    Instead of repating
    
            can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)
    
    make can_set_direct_map() handle the KFENCE case.
    
    This also prevents potential false positives in kernel_page_present()
    that may return true for non-present page if CONFIG_KFENCE is enabled.
    
    Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
    Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
    Link: https://lore.kernel.org/r/20220921074841.382615-1-rppt@xxxxxxxxxx
    Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
    Stable-dep-of: 2081b3bd0c11 ("arm64: fix rodata=full again")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index eb489302c28a..e8de94dd5a60 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -539,7 +539,7 @@ static void __init map_mem(pgd_t *pgdp)
 	 */
 	BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end));
 
-	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
+	if (can_set_direct_map())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	/*
@@ -1551,11 +1551,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
 
 	VM_BUG_ON(!mhp_range_allowed(start, size, true));
 
-	/*
-	 * KFENCE requires linear map to be mapped at page granularity, so that
-	 * it is possible to protect/unprotect single pages in the KFENCE pool.
-	 */
-	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
+	if (can_set_direct_map())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 64e985eaa52d..d107c3d434e2 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -21,7 +21,13 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED
 
 bool can_set_direct_map(void)
 {
-	return rodata_full || debug_pagealloc_enabled();
+	/*
+	 * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be
+	 * mapped at page granularity, so that it is possible to
+	 * protect/unprotect single pages.
+	 */
+	return rodata_full || debug_pagealloc_enabled() ||
+		IS_ENABLED(CONFIG_KFENCE);
 }
 
 static int change_page_range(pte_t *ptep, unsigned long addr, void *data)