target/arm: Implement helper_mte_check1

Fill out the stub that was added earlier.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-26-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/target/arm/internals.h b/target/arm/internals.h
index fb92ef6b84..807830cc40 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1318,6 +1318,10 @@ FIELD(MTEDESC, WRITE, 8, 1)
 FIELD(MTEDESC, ESIZE, 9, 5)
 FIELD(MTEDESC, TSIZE, 14, 10)  /* mte_checkN only */
 
+bool mte_probe1(CPUARMState *env, uint32_t desc, uint64_t ptr);
+uint64_t mte_check1(CPUARMState *env, uint32_t desc,
+                    uint64_t ptr, uintptr_t ra);
+
 static inline int allocation_tag_from_addr(uint64_t ptr)
 {
     return extract64(ptr, 56, 4);
@@ -1328,4 +1332,48 @@ static inline uint64_t address_with_allocation_tag(uint64_t ptr, int rtag)
     return deposit64(ptr, 56, 4, rtag);
 }
 
+/* Return true if tbi bits mean that the access is checked.  */
+static inline bool tbi_check(uint32_t desc, int bit55)
+{
+    return (desc >> (R_MTEDESC_TBI_SHIFT + bit55)) & 1;
+}
+
+/* Return true if tcma bits mean that the access is unchecked.  */
+static inline bool tcma_check(uint32_t desc, int bit55, int ptr_tag)
+{
+    /*
+     * We had extracted bit55 and ptr_tag for other reasons, so fold
+     * (ptr<59:55> == 00000 || ptr<59:55> == 11111) into a single test.
+     */
+    bool match = ((ptr_tag + bit55) & 0xf) == 0;
+    bool tcma = (desc >> (R_MTEDESC_TCMA_SHIFT + bit55)) & 1;
+    return tcma && match;
+}
+
+/*
+ * For TBI, ideally, we would do nothing.  Proper behaviour on fault is
+ * for the tag to be present in the FAR_ELx register.  But for user-only
+ * mode, we do not have a TLB with which to implement this, so we must
+ * remove the top byte.
+ */
+static inline uint64_t useronly_clean_ptr(uint64_t ptr)
+{
+    /* TBI is known to be enabled. */
+#ifdef CONFIG_USER_ONLY
+    ptr = sextract64(ptr, 0, 56);
+#endif
+    return ptr;
+}
+
+static inline uint64_t useronly_maybe_clean_ptr(uint32_t desc, uint64_t ptr)
+{
+#ifdef CONFIG_USER_ONLY
+    int64_t clean_ptr = sextract64(ptr, 0, 56);
+    if (tbi_check(desc, clean_ptr < 0)) {
+        ptr = clean_ptr;
+    }
+#endif
+    return ptr;
+}
+
 #endif