[PATCH RFC v10 05/22] arm64: set_memory: Implement set_direct_map_pkey()

[Kevin Brodsky]

Implement set_direct_map_pkey() using POE.

Reviewed-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
Signed-off-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>
---
 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 0091ba12200e..8322615b8ffb 100644
--- a/arch/arm64/include/asm/set_memory.h
+++ b/arch/arm64/include/asm/set_memory.h
@@ -18,4 +18,8 @@ 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_direct_map_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 de7bf95003ea..7143bb2dfecd 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>
@@ -319,6 +321,30 @@ int __set_memory_enc_dec(unsigned long addr, int numpages, bool encrypt)
 				      __pgprot(PTE_PRESENT_INVALID));
 }
 
+#ifdef CONFIG_ARCH_HAS_KPKEYS
+int set_direct_map_pkey(unsigned long addr, int numpages, int pkey)
+{
+	unsigned long set_prot = 0;
+
+	if (!kpkeys_supported() || !can_set_direct_map())
+		return 0;
+
+	if (!__is_lm_address(kasan_reset_tag((void *)addr)))
+		return -EINVAL;
+
+	if (pkey < 0 || 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
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {

-- 
2.56.0