target/s390x: Add support for the TEST BLOCK instruction

TEST BLOCK was likely once used to execute basic memory
tests, but nowadays it's just a (slow) way to clear a page.

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1495128400-23759-1-git-send-email-thuth@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 28 insertions, 0 deletions

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index f6e5bcec5d..0c6a0d9612 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -20,6 +20,7 @@
 
 #include "qemu/osdep.h"
 #include "cpu.h"
+#include "exec/address-spaces.h"
 #include "exec/helper-proto.h"
 #include "exec/exec-all.h"
 #include "exec/cpu_ldst.h"
@@ -973,6 +974,33 @@ void HELPER(stctl)(CPUS390XState *env, uint32_t r1, uint64_t a2, uint32_t r3)
     }
 }
 
+uint32_t HELPER(testblock)(CPUS390XState *env, uint64_t real_addr)
+{
+    CPUState *cs = CPU(s390_env_get_cpu(env));
+    uint64_t abs_addr;
+    int i;
+
+    real_addr = fix_address(env, real_addr);
+    abs_addr = mmu_real2abs(env, real_addr) & TARGET_PAGE_MASK;
+    if (!address_space_access_valid(&address_space_memory, abs_addr,
+                                    TARGET_PAGE_SIZE, true)) {
+        program_interrupt(env, PGM_ADDRESSING, 4);
+        return 1;
+    }
+
+    /* Check low-address protection */
+    if ((env->cregs[0] & CR0_LOWPROT) && real_addr < 0x2000) {
+        program_interrupt(env, PGM_PROTECTION, 4);
+        return 1;
+    }
+
+    for (i = 0; i < TARGET_PAGE_SIZE; i += 8) {
+        stq_phys(cs->as, abs_addr + i, 0);
+    }
+
+    return 0;
+}
+
 uint32_t HELPER(tprot)(uint64_t a1, uint64_t a2)
 {
     /* XXX implement */