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arm64: mm: Tidy up force_pte_mapping()

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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: David Hildenbrand (Red Hat) <david@kernel.org>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ryan Roberts
2025-11-06 16:09:43 +00:00
committed by Will Deacon
parent 40a292f701
commit 53357f14f9
1 changed files with 23 additions and 20 deletions
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43
arch/arm64/mm/mmu.c
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@@ -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.
* 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 (!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.
*/
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. */