[Qemu-devel] [PATCH v1 2/4] tests/tcg: better detect truncated reads

["Alex Bennée" <alex.bennee@linaro.org>]

If we've truncated a wider read we can detect the condition earlier by
looking at the number of zeros we've read. So we don't trip up on
cases where we have written zeros to the start of the buffer we also
ensure we only start each offset read from the right address.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 tests/tcg/multiarch/system/memory.c | 36 +++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/tests/tcg/multiarch/system/memory.c b/tests/tcg/multiarch/system/memory.c
index dc1d8a98ff..d124502d73 100644
--- a/tests/tcg/multiarch/system/memory.c
+++ b/tests/tcg/multiarch/system/memory.c
@@ -208,6 +208,7 @@ static bool read_test_data_u32(int offset)
 
     for (i = 0; i < max; i++) {
         uint8_t b1, b2, b3, b4;
+        int zeros = 0;
         word = *ptr++;
 
         b1 = word >> 24 & 0xff;
@@ -215,6 +216,16 @@ static bool read_test_data_u32(int offset)
         b3 = word >> 8 & 0xff;
         b4 = word & 0xff;
 
+        zeros += (b1 == 0 ? 1 : 0);
+        zeros += (b2 == 0 ? 1 : 0);
+        zeros += (b3 == 0 ? 1 : 0);
+        zeros += (b4 == 0 ? 1 : 0);
+        if (zeros > 1) {
+            ml_printf("Error @ %p, more zeros than expected: %d, %d, %d, %d",
+                      ptr - 1, b1, b2, b3, b4);
+            return false;
+        }
+
         if ((b1 < b2 && b1 != 0) ||
             (b2 < b3 && b2 != 0) ||
             (b3 < b4 && b3 != 0)) {
@@ -238,6 +249,7 @@ static bool read_test_data_u64(int offset)
 
     for (i = 0; i < max; i++) {
         uint8_t b1, b2, b3, b4, b5, b6, b7, b8;
+        int zeros = 0;
         word = *ptr++;
 
         b1 = ((uint64_t) (word >> 56)) & 0xff;
@@ -249,6 +261,20 @@ static bool read_test_data_u64(int offset)
         b7 = (word >> 8)  & 0xff;
         b8 = (word >> 0)  & 0xff;
 
+        zeros += (b1 == 0 ? 1 : 0);
+        zeros += (b2 == 0 ? 1 : 0);
+        zeros += (b3 == 0 ? 1 : 0);
+        zeros += (b4 == 0 ? 1 : 0);
+        zeros += (b5 == 0 ? 1 : 0);
+        zeros += (b6 == 0 ? 1 : 0);
+        zeros += (b7 == 0 ? 1 : 0);
+        zeros += (b8 == 0 ? 1 : 0);
+        if (zeros > 1) {
+            ml_printf("Error @ %p, more zeros than expected: %d, %d, %d, %d, %d, %d, %d, %d",
+                      ptr - 1, b1, b2, b3, b4, b5, b6, b7, b8);
+            return false;
+        }
+
         if ((b1 < b2 && b1 != 0) ||
             (b2 < b3 && b2 != 0) ||
             (b3 < b4 && b3 != 0) ||
@@ -272,7 +298,7 @@ read_ufn read_ufns[] = { read_test_data_u16,
                          read_test_data_u32,
                          read_test_data_u64 };
 
-bool do_unsigned_reads(void)
+bool do_unsigned_reads(int start_off)
 {
     int i;
     bool ok = true;
@@ -280,11 +306,11 @@ bool do_unsigned_reads(void)
     for (i = 0; i < ARRAY_SIZE(read_ufns) && ok; i++) {
 #if CHECK_UNALIGNED
         int off;
-        for (off = 0; off < 8 && ok; off++) {
+        for (off = start_off; off < 8 && ok; off++) {
             ok = read_ufns[i](off);
         }
 #else
-        ok = read_ufns[i](0);
+        ok = read_ufns[i](start_off);
 #endif
     }
 
@@ -298,11 +324,11 @@ static bool do_unsigned_test(init_ufn fn)
     int i;
     for (i = 0; i < 8 && ok; i++) {
         fn(i);
-        ok = do_unsigned_reads();
+        ok = do_unsigned_reads(i);
     }
 #else
     fn(0);
-    return do_unsigned_reads();
+    return do_unsigned_reads(0);
 #endif
 }
 
-- 
2.20.1