[Qemu-devel] [PATCH 2/3] target-mips: Misaligned Memory Accesses for R6

[Yongbok Kim <yongbok.kim@imgtec.com>]

Release 6 requires misaligned memory access support for all ordinary memory
access instructions (for example, LW/SW, LWC1/SWC1).
However misaligned support is not provided for certain special memory accesses
such as atomics (for example, LL/SC).

In the mips_cpu_do_unaligned_access() callback, if it is R6 core it checks further
whether the address is valid.

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
---
 target-mips/cpu.h            |    2 ++
 target-mips/helper.c         |   36 ++++++++++++++++++++++++++++++++++++
 target-mips/op_helper.c      |   13 +++++++++++++
 target-mips/translate_init.c |    2 +-
 4 files changed, 52 insertions(+), 1 deletions(-)

diff --git a/target-mips/cpu.h b/target-mips/cpu.h
index f9d2b4c..6586d89 100644
--- a/target-mips/cpu.h
+++ b/target-mips/cpu.h
@@ -760,6 +760,8 @@ int mips_cpu_handle_mmu_fault(CPUState *cpu, vaddr address, int rw,
 void r4k_invalidate_tlb (CPUMIPSState *env, int idx, int use_extra);
 hwaddr cpu_mips_translate_address (CPUMIPSState *env, target_ulong address,
 		                               int rw);
+bool cpu_mips_validate_access(CPUMIPSState *env, target_ulong address,
+                            target_ulong badvaddr, unsigned data_size, int rw);
 #endif
 target_ulong exception_resume_pc (CPUMIPSState *env);
 
diff --git a/target-mips/helper.c b/target-mips/helper.c
index 8e3204a..6c44124 100644
--- a/target-mips/helper.c
+++ b/target-mips/helper.c
@@ -391,6 +391,42 @@ hwaddr cpu_mips_translate_address(CPUMIPSState *env, target_ulong address, int r
     }
 }
 
+bool cpu_mips_validate_access(CPUMIPSState *env, target_ulong address,
+                            target_ulong badvaddr, unsigned data_size, int rw)
+{
+    hwaddr physical;
+    int prot;
+    int access_type = ACCESS_INT;
+    int ret;
+    target_ulong addr;
+
+    addr = address & ~((target_ulong) data_size - 1);
+    ret = get_physical_address(env, &physical, &prot,
+            addr, rw, access_type);
+    if (ret != TLBRET_MATCH) {
+        if (ret != TLBRET_BADADDR && addr > badvaddr) {
+            badvaddr = addr;
+        }
+        raise_mmu_exception(env, badvaddr, rw, ret);
+        return false;
+    }
+    if ((data_size > 1)
+        && unlikely(((address & ~TARGET_PAGE_MASK) + data_size - 1)
+                    >= TARGET_PAGE_SIZE)) {
+        addr += data_size;
+        ret = get_physical_address(env, &physical, &prot, addr, rw,
+              access_type);
+        if (ret != TLBRET_MATCH) {
+            if (ret != TLBRET_BADADDR) {
+                badvaddr = addr;
+            }
+            raise_mmu_exception(env, badvaddr, rw, ret);
+            return false;
+        }
+    }
+    return true;
+}
+
 static const char * const excp_names[EXCP_LAST + 1] = {
     [EXCP_RESET] = "reset",
     [EXCP_SRESET] = "soft reset",
diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
index ca5fe43..dacc92b 100644
--- a/target-mips/op_helper.c
+++ b/target-mips/op_helper.c
@@ -2215,6 +2215,19 @@ void mips_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
     int error_code = 0;
     int excp;
 
+    if (env->insn_flags & ISA_MIPS32R6) {
+        /* Release 6 provides support for misaligned memory access for
+         * all ordinary memory reference instructions
+         * */
+        if (!cpu_mips_validate_access(env, addr, addr, size, access_type)) {
+            CPUState *cs = CPU(mips_env_get_cpu(env));
+            do_raise_exception_err(env, cs->exception_index,
+                                   env->error_code, retaddr);
+            return;
+        }
+        return;
+    }
+
     env->CP0_BadVAddr = addr;
 
     if (access_type == MMU_DATA_STORE) {
diff --git a/target-mips/translate_init.c b/target-mips/translate_init.c
index 85a65e7..ec54fef 100644
--- a/target-mips/translate_init.c
+++ b/target-mips/translate_init.c
@@ -607,7 +607,7 @@ static const mips_def_t mips_defs[] =
     },
     {
         /* A generic CPU supporting MIPS64 Release 6 ISA.
-           FIXME: Support IEEE 754-2008 FP and misaligned memory accesses.
+           FIXME: Support IEEE 754-2008 FP.
                   Eventually this should be replaced by a real CPU model. */
         .name = "MIPS64R6-generic",
         .CP0_PRid = 0x00010000,
-- 
1.7.5.4