On Mon, Jul 31, 2023 at 02:43:20PM +0100, Mark Brown wrote:
Map pages flagged as being part of a GCS as such rather than using the full set of generic VM flags.
This is done using a conditional rather than extending the size of protection_map since that would make for a very sparse array.
Signed-off-by: Mark Brown broonie@kernel.org
arch/arm64/mm/mmap.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 8f5b7ce857ed..e2ca770920ed 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -79,8 +79,23 @@ arch_initcall(adjust_protection_map); pgprot_t vm_get_page_prot(unsigned long vm_flags) {
- pteval_t prot = pgprot_val(protection_map[vm_flags &
- pteval_t prot;
- /*
* If this is a GCS then only interpret VM_WRITE.** TODO: Just make protection_map[] bigger? Nothing seems* ideal here.*/
I think extending protection_map and updating adjust_protection_map() is cleaner and probably faster.
- if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) {
if (vm_flags & VM_WRITE)prot = _PAGE_GCS;elseprot = _PAGE_GCS_RO;- } else {
prot = pgprot_val(protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);- }
if (vm_flags & VM_ARM64_BTI) prot |= PTE_GP;
-- 2.30.2