target/arm: Replace MTEDESC ESIZE+TSIZE with SIZEM1

After recent changes, mte_checkN does not use ESIZE,
and mte_check1 never used TSIZE.  We can combine the
two into a single field: SIZEM1.

Choose to pass size - 1 because size == 0 is never used,
our immediate need in mte_probe_int is for the address
of the last byte (ptr + size - 1), and since almost all
operations are powers of 2, this makes the immediate
constant one bit smaller.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210416183106.1516563-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 8 insertions, 10 deletions

diff --git a/target/arm/mte_helper.c b/target/arm/mte_helper.c
index 0ee0397eb2..804057d3f6 100644
--- a/target/arm/mte_helper.c
+++ b/target/arm/mte_helper.c
@@ -692,13 +692,13 @@ static int checkN(uint8_t *mem, int odd, int cmp, int count)
  * 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)
+                         uintptr_t ra, 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 tag_count, tag_size, n, c;
+    uint32_t sizem1, tag_count, tag_size, n, c;
     uint8_t *mem1, *mem2;
     MMUAccessType type;
 
@@ -718,9 +718,10 @@ static int mte_probe_int(CPUARMState *env, uint32_t desc, uint64_t ptr,
 
     mmu_idx = FIELD_EX32(desc, MTEDESC, MIDX);
     type = FIELD_EX32(desc, MTEDESC, WRITE) ? MMU_DATA_STORE : MMU_DATA_LOAD;
+    sizem1 = FIELD_EX32(desc, MTEDESC, SIZEM1);
 
     /* Find the addr of the end of the access */
-    ptr_last = ptr + total - 1;
+    ptr_last = ptr + sizem1;
 
     /* Round the bounds to the tag granule, and compute the number of tags. */
     tag_first = QEMU_ALIGN_DOWN(ptr, TAG_GRANULE);
@@ -738,7 +739,7 @@ static int mte_probe_int(CPUARMState *env, uint32_t desc, uint64_t ptr,
     if (likely(tag_last - prev_page <= TARGET_PAGE_SIZE)) {
         /* Memory access stays on one page. */
         tag_size = ((tag_byte_last - tag_byte_first) / (2 * TAG_GRANULE)) + 1;
-        mem1 = allocation_tag_mem(env, mmu_idx, ptr, type, total,
+        mem1 = allocation_tag_mem(env, mmu_idx, ptr, type, sizem1 + 1,
                                   MMU_DATA_LOAD, tag_size, ra);
         if (!mem1) {
             return 1;
@@ -792,8 +793,7 @@ 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);
+    int ret = mte_probe_int(env, desc, ptr, ra, &fault);
 
     if (unlikely(ret == 0)) {
         mte_check_fail(env, desc, fault, ra);
@@ -812,8 +812,7 @@ uint64_t mte_check1(CPUARMState *env, uint32_t desc,
                     uint64_t ptr, uintptr_t ra)
 {
     uint64_t fault;
-    uint32_t total = FIELD_EX32(desc, MTEDESC, ESIZE);
-    int ret = mte_probe_int(env, desc, ptr, ra, total, &fault);
+    int ret = mte_probe_int(env, desc, ptr, ra, &fault);
 
     if (unlikely(ret == 0)) {
         mte_check_fail(env, desc, fault, ra);
@@ -837,8 +836,7 @@ uint64_t HELPER(mte_check1)(CPUARMState *env, uint32_t desc, uint64_t ptr)
 bool mte_probe1(CPUARMState *env, uint32_t desc, uint64_t ptr)
 {
     uint64_t fault;
-    uint32_t total = FIELD_EX32(desc, MTEDESC, ESIZE);
-    int ret = mte_probe_int(env, desc, ptr, 0, total, &fault);
+    int ret = mte_probe_int(env, desc, ptr, 0, &fault);
 
     return ret != 0;
 }