[PATCH v2 3/6] target/ppc: Fix instruction loading endianness in alignment interrupt

[Nicholas Piggin <npiggin@gmail.com>]

powerpc ifetch endianness depends on MSR[LE] so it has to byteswap
after cpu_ldl_code(). This corrects DSISR bits in alignment
interrupts when running in little endian mode.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Since v1:
- Removed big endian ifdef [Fabiano review]
- Acaually use need_byswap helper.

 target/ppc/excp_helper.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 287659c74d..07729967b5 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -133,6 +133,24 @@ static void dump_hcall(CPUPPCState *env)
                   env->nip);
 }
 
+/* Return true iff byteswap is needed in a scalar memop */
+static inline bool need_byteswap(CPUArchState *env)
+{
+    /* SOFTMMU builds TARGET_BIG_ENDIAN. Need to swap when MSR[LE] is set */
+    return !!(env->msr & ((target_ulong)1 << MSR_LE));
+}
+
+static uint32_t ppc_ldl_code(CPUArchState *env, abi_ptr addr)
+{
+    uint32_t insn = cpu_ldl_code(env, addr);
+
+    if (need_byteswap(env)) {
+        insn = bswap32(insn);
+    }
+
+    return insn;
+}
+
 static void ppc_excp_debug_sw_tlb(CPUPPCState *env, int excp)
 {
     const char *es;
@@ -3097,7 +3115,7 @@ void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
 
     /* Restore state and reload the insn we executed, for filling in DSISR.  */
     cpu_restore_state(cs, retaddr);
-    insn = cpu_ldl_code(env, env->nip);
+    insn = ppc_ldl_code(env, env->nip);
 
     switch (env->mmu_model) {
     case POWERPC_MMU_SOFT_4xx:
-- 
2.37.2