2 files changed, 56 insertions, 0 deletions
diff --git a/gdb/arch/aarch64-mte-linux.c b/gdb/arch/aarch64-mte-linux.c
index 3d72b8d..959c024 100644
--- a/gdb/arch/aarch64-mte-linux.c
+++ b/gdb/arch/aarch64-mte-linux.c
@@ -36,3 +36,41 @@ aarch64_mte_get_tag_granules (CORE_ADDR addr, size_t len, size_t granule_size)
   /* We always have at least 1 granule.  */
   return 1 + (e_addr - s_addr) / granule_size;
 }
+
+/* See arch/aarch64-mte-linux.h */
+
+CORE_ADDR
+aarch64_mte_make_ltag_bits (CORE_ADDR value)
+{
+  return value & AARCH64_MTE_LOGICAL_MAX_VALUE;
+}
+
+/* See arch/aarch64-mte-linux.h */
+
+CORE_ADDR
+aarch64_mte_make_ltag (CORE_ADDR value)
+{
+  return (aarch64_mte_make_ltag_bits (value)
+	  << AARCH64_MTE_LOGICAL_TAG_START_BIT);
+}
+
+/* See arch/aarch64-mte-linux.h */
+
+CORE_ADDR
+aarch64_mte_set_ltag (CORE_ADDR address, CORE_ADDR tag)
+{
+  /* Remove the existing tag.  */
+  address &= ~aarch64_mte_make_ltag (AARCH64_MTE_LOGICAL_MAX_VALUE);
+
+  /* Return the new tagged address.  */
+  return address | aarch64_mte_make_ltag (tag);
+}
+
+/* See arch/aarch64-mte-linux.h */
+
+CORE_ADDR
+aarch64_mte_get_ltag (CORE_ADDR address)
+{
+  CORE_ADDR ltag_addr = address >> AARCH64_MTE_LOGICAL_TAG_START_BIT;
+  return aarch64_mte_make_ltag_bits (ltag_addr);
+}
diff --git a/gdb/arch/aarch64-mte-linux.h b/gdb/arch/aarch64-mte-linux.h
index 88bd8d0..f517638 100644
--- a/gdb/arch/aarch64-mte-linux.h
+++ b/gdb/arch/aarch64-mte-linux.h
@@ -32,6 +32,8 @@
 
 /* We have one tag per 16 bytes of memory.  */
 #define AARCH64_MTE_GRANULE_SIZE 16
+#define AARCH64_MTE_LOGICAL_TAG_START_BIT 56
+#define AARCH64_MTE_LOGICAL_MAX_VALUE 0xf
 
 /* Memory tag types for AArch64.  */
 enum class aarch64_memtag_type
@@ -47,4 +49,20 @@ enum class aarch64_memtag_type
 extern size_t aarch64_mte_get_tag_granules (CORE_ADDR addr, size_t len,
 					    size_t granule_size);
 
+/* Return the 4-bit tag made from VALUE.  */
+extern CORE_ADDR aarch64_mte_make_ltag_bits (CORE_ADDR value);
+
+/* Return the 4-bit tag that can be OR-ed to an address.  */
+extern CORE_ADDR aarch64_mte_make_ltag (CORE_ADDR value);
+
+/* Helper to set the logical TAG for a 64-bit ADDRESS.
+
+   It is always possible to set the logical tag.  */
+extern CORE_ADDR aarch64_mte_set_ltag (CORE_ADDR address, CORE_ADDR tag);
+
+/* Helper to get the logical tag from a 64-bit ADDRESS.
+
+   It is always possible to get the logical tag.  */
+extern CORE_ADDR aarch64_mte_get_ltag (CORE_ADDR address);
+
 #endif /* ARCH_AARCH64_LINUX_H */