[PATCH v6 06/30] arm64: set_memory: Implement set_memory_pkey()

Kevin Brodsky
2026-02-27T17:56:15Z

Implement set_memory_pkey() using POE.

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
arch/arm64/include/asm/set_memory.h | 4 ++++
arch/arm64/mm/pageattr.c | 26 ++++++++++++++++++++++++++
2 files changed, 30 insertions(+)

diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h
index 90f61b17275e..b6cd6de34abf 100644
--- a/arch/arm64/include/asm/set_memory.h
+++ b/arch/arm64/include/asm/set_memory.h
@@ -19,4 +19,8 @@ bool kernel_page_present(struct page *page);
int set_memory_encrypted(unsigned long addr, int numpages);
int set_memory_decrypted(unsigned long addr, int numpages);

+#ifdef CONFIG_ARCH_HAS_KPKEYS
+int set_memory_pkey(unsigned long addr, int numpages, int pkey);
+#endif
+
#endif /* _ASM_ARM64_SET_MEMORY_H */
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 358d1dc9a576..d2a7e104a5c2 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -9,6 +9,8 @@
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <linux/pagewalk.h>
+#include <linux/pkeys.h>
+#include <linux/kpkeys.h>

#include <asm/cacheflush.h>
#include <asm/pgtable-prot.h>
@@ -359,6 +361,30 @@ int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
return set_memory_valid(addr, nr, valid);
}

+#ifdef CONFIG_ARCH_HAS_KPKEYS
+int set_memory_pkey(unsigned long addr, int numpages, int pkey)
+{
+ unsigned long set_prot = 0;
+
+ if (!arch_kpkeys_enabled())
+ return 0;
+
+ if (!__is_lm_address(addr))
+ return -EINVAL;
+
+ if (pkey >= arch_max_pkey())
+ return -EINVAL;
+
+ set_prot |= pkey & BIT(0) ? PTE_PO_IDX_0 : 0;
+ set_prot |= pkey & BIT(1) ? PTE_PO_IDX_1 : 0;
+ set_prot |= pkey & BIT(2) ? PTE_PO_IDX_2 : 0;
+
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(set_prot),
+ __pgprot(PTE_PO_IDX_MASK));
+}
+#endif
+
#ifdef CONFIG_DEBUG_PAGEALLOC
/*
* This is - apart from the return value - doing the same
--
2.51.2