[PULL 04/43] target/arm: Split out mte_probe_int

[Peter Maydell <peter.maydell@linaro.org>]

From: Richard Henderson <richard.henderson@linaro.org>

Split out a helper function from mte_checkN to perform
all of the checking and address manpulation.  So far,
just use this in mte_checkN itself.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210416183106.1516563-3-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/mte_helper.c | 52 +++++++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 12 deletions(-)

diff --git a/target/arm/mte_helper.c b/target/arm/mte_helper.c
index 010d1c2e993..2b5331f8dbc 100644
--- a/target/arm/mte_helper.c
+++ b/target/arm/mte_helper.c
@@ -753,33 +753,45 @@ static int checkN(uint8_t *mem, int odd, int cmp, int count)
     return n;
 }
 
-uint64_t mte_checkN(CPUARMState *env, uint32_t desc,
-                    uint64_t ptr, uintptr_t ra)
+/**
+ * mte_probe_int() - helper for mte_probe and mte_check
+ * @env: CPU environment
+ * @desc: MTEDESC descriptor
+ * @ptr: virtual address of the base of the access
+ * @fault: return virtual address of the first check failure
+ *
+ * Internal routine for both mte_probe and mte_check.
+ * Return zero on failure, filling in *fault.
+ * Return negative on trivial success for tbi disabled.
+ * Return positive on success with tbi enabled.
+ */
+static int mte_probe_int(CPUARMState *env, uint32_t desc, uint64_t ptr,
+                         uintptr_t ra, uint32_t total, uint64_t *fault)
 {
     int mmu_idx, ptr_tag, bit55;
     uint64_t ptr_last, prev_page, next_page;
     uint64_t tag_first, tag_last;
     uint64_t tag_byte_first, tag_byte_last;
-    uint32_t total, tag_count, tag_size, n, c;
+    uint32_t tag_count, tag_size, n, c;
     uint8_t *mem1, *mem2;
     MMUAccessType type;
 
     bit55 = extract64(ptr, 55, 1);
+    *fault = ptr;
 
     /* If TBI is disabled, the access is unchecked, and ptr is not dirty. */
     if (unlikely(!tbi_check(desc, bit55))) {
-        return ptr;
+        return -1;
     }
 
     ptr_tag = allocation_tag_from_addr(ptr);
 
     if (tcma_check(desc, bit55, ptr_tag)) {
-        goto done;
+        return 1;
     }
 
     mmu_idx = FIELD_EX32(desc, MTEDESC, MIDX);
     type = FIELD_EX32(desc, MTEDESC, WRITE) ? MMU_DATA_STORE : MMU_DATA_LOAD;
-    total = FIELD_EX32(desc, MTEDESC, TSIZE);
 
     /* Find the addr of the end of the access */
     ptr_last = ptr + total - 1;
@@ -803,7 +815,7 @@ uint64_t mte_checkN(CPUARMState *env, uint32_t desc,
         mem1 = allocation_tag_mem(env, mmu_idx, ptr, type, total,
                                   MMU_DATA_LOAD, tag_size, ra);
         if (!mem1) {
-            goto done;
+            return 1;
         }
         /* Perform all of the comparisons. */
         n = checkN(mem1, ptr & TAG_GRANULE, ptr_tag, tag_count);
@@ -829,23 +841,39 @@ uint64_t mte_checkN(CPUARMState *env, uint32_t desc,
         }
         if (n == c) {
             if (!mem2) {
-                goto done;
+                return 1;
             }
             n += checkN(mem2, 0, ptr_tag, tag_count - c);
         }
     }
 
+    if (likely(n == tag_count)) {
+        return 1;
+    }
+
     /*
      * If we failed, we know which granule.  For the first granule, the
      * failure address is @ptr, the first byte accessed.  Otherwise the
      * failure address is the first byte of the nth granule.
      */
-    if (unlikely(n < tag_count)) {
-        uint64_t fault = (n == 0 ? ptr : tag_first + n * TAG_GRANULE);
-        mte_check_fail(env, desc, fault, ra);
+    if (n > 0) {
+        *fault = tag_first + n * TAG_GRANULE;
     }
+    return 0;
+}
 
- done:
+uint64_t mte_checkN(CPUARMState *env, uint32_t desc,
+                    uint64_t ptr, uintptr_t ra)
+{
+    uint64_t fault;
+    uint32_t total = FIELD_EX32(desc, MTEDESC, TSIZE);
+    int ret = mte_probe_int(env, desc, ptr, ra, total, &fault);
+
+    if (unlikely(ret == 0)) {
+        mte_check_fail(env, desc, fault, ra);
+    } else if (ret < 0) {
+        return ptr;
+    }
     return useronly_clean_ptr(ptr);
 }
 
-- 
2.20.1