Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

Implements helper functions to read and write the key related
registers; AMR, IAMR, UAMOR.

AMR register tracks the read,write permission of a key
IAMR register tracks the execute permission of a key
UAMOR register enables and disables a key

Signed-off-by: Ram Pai <redacted>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
 1 files changed, 60 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 85bc987..435d6a7 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
 }
 
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+
+#include <asm/reg.h>
+static inline u64 read_amr(void)
+{
+	return mfspr(SPRN_AMR);
+}
+static inline void write_amr(u64 value)
+{
+	mtspr(SPRN_AMR, value);
+}
+static inline u64 read_iamr(void)
+{
+	return mfspr(SPRN_IAMR);
+}
+static inline void write_iamr(u64 value)
+{
+	mtspr(SPRN_IAMR, value);
+}
+static inline u64 read_uamor(void)
+{
+	return mfspr(SPRN_UAMOR);
+}
+static inline void write_uamor(u64 value)
+{
+	mtspr(SPRN_UAMOR, value);
+}
+
+#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
+static inline u64 read_amr(void)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+	return -1;
+}