Commit 53357f14 authored by Ryan Roberts's avatar Ryan Roberts Committed by Will Deacon
Browse files

arm64: mm: Tidy up force_pte_mapping() 



Tidy up the implementation of force_pte_mapping() to make it easier to
read and introduce the split_leaf_mapping_possible() helper to reduce
code duplication in split_kernel_leaf_mapping() and
arch_kfence_init_pool().

Suggested-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Signed-off-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Reviewed-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: default avatarYang Shi <yang@os.amperecomputing.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 40a292f7

arch/arm64/mm/mmu.c

+23 −20
Original line number Diff line number Diff line
@@ -710,12 +710,26 @@ static int split_kernel_leaf_mapping_locked(unsigned long addr) 


static inline bool force_pte_mapping(void)

{

	bool bbml2 = system_capabilities_finalized() ?

	const bool bbml2 = system_capabilities_finalized() ?

		system_supports_bbml2_noabort() : cpu_supports_bbml2_noabort();



	return (!bbml2 && (rodata_full || arm64_kfence_can_set_direct_map() ||

			   is_realm_world())) ||

		debug_pagealloc_enabled();

	if (debug_pagealloc_enabled())

		return true;

	if (bbml2)

		return false;

	return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world();

}



static inline bool split_leaf_mapping_possible(void)

{

	/*

	 * !BBML2_NOABORT systems should never run into scenarios where we would

	 * have to split. So exit early and let calling code detect it and raise

	 * a warning.

	 */

	if (!system_supports_bbml2_noabort())

		return false;

	return !force_pte_mapping();

}



static DEFINE_MUTEX(pgtable_split_lock);
@@ -725,22 +739,11 @@ int split_kernel_leaf_mapping(unsigned long start, unsigned long end) 
	int ret;



	/*

	 * !BBML2_NOABORT systems should not be trying to change permissions on

	 * anything that is not pte-mapped in the first place. Just return early

	 * and let the permission change code raise a warning if not already

	 * pte-mapped.

	 */

	if (!system_supports_bbml2_noabort())

		return 0;



	/*

	 * If the region is within a pte-mapped area, there is no need to try to

	 * split. Additionally, CONFIG_DEBUG_PAGEALLOC and CONFIG_KFENCE may

	 * change permissions from atomic context so for those cases (which are

	 * always pte-mapped), we must not go any further because taking the

	 * mutex below may sleep.

	 * Exit early if the region is within a pte-mapped area or if we can't

	 * split. For the latter case, the permission change code will raise a

	 * warning if not already pte-mapped.

	 */

	if (force_pte_mapping() || is_kfence_address((void *)start))

	if (!split_leaf_mapping_possible() || is_kfence_address((void *)start))

		return 0;



	/*
@@ -1039,7 +1042,7 @@ bool arch_kfence_init_pool(void) 
	int ret;



	/* Exit early if we know the linear map is already pte-mapped. */

	if (!system_supports_bbml2_noabort() || force_pte_mapping())

	if (!split_leaf_mapping_possible())

		return true;



	/* Kfence pool is already pte-mapped for the early init case. */