[PULL 18/18] target/ppc: fix vector registers access in gdbstub for little-endian

[David Gibson <david@gibson.dropbear.id.au>]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

As vector registers are stored in host endianness, we shouldn't swap its
64-bit elements in user mode. Add a 16-byte case in
ppc_maybe_bswap_register to handle the reordering of elements in softmmu
and remove avr_need_swap which is now unused.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20210826145656.2507213-3-matheus.ferst@eldorado.org.br>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 target/ppc/gdbstub.c | 32 +++++++-------------------------
 1 file changed, 7 insertions(+), 25 deletions(-)

diff --git a/target/ppc/gdbstub.c b/target/ppc/gdbstub.c
index 09ff1328d4..1808a150e4 100644
--- a/target/ppc/gdbstub.c
+++ b/target/ppc/gdbstub.c
@@ -101,6 +101,8 @@ void ppc_maybe_bswap_register(CPUPPCState *env, uint8_t *mem_buf, int len)
         bswap32s((uint32_t *)mem_buf);
     } else if (len == 8) {
         bswap64s((uint64_t *)mem_buf);
+    } else if (len == 16) {
+        bswap128s((Int128 *)mem_buf);
     } else {
         g_assert_not_reached();
     }
@@ -389,15 +391,6 @@ const char *ppc_gdb_get_dynamic_xml(CPUState *cs, const char *xml_name)
 }
 #endif
 
-static bool avr_need_swap(CPUPPCState *env)
-{
-#ifdef HOST_WORDS_BIGENDIAN
-    return msr_le;
-#else
-    return !msr_le;
-#endif
-}
-
 #if !defined(CONFIG_USER_ONLY)
 static int gdb_find_spr_idx(CPUPPCState *env, int n)
 {
@@ -486,14 +479,9 @@ static int gdb_get_avr_reg(CPUPPCState *env, GByteArray *buf, int n)
 
     if (n < 32) {
         ppc_avr_t *avr = cpu_avr_ptr(env, n);
-        if (!avr_need_swap(env)) {
-            gdb_get_reg128(buf, avr->u64[0] , avr->u64[1]);
-        } else {
-            gdb_get_reg128(buf, avr->u64[1] , avr->u64[0]);
-        }
+        gdb_get_reg128(buf, avr->VsrD(0), avr->VsrD(1));
         mem_buf = gdb_get_reg_ptr(buf, 16);
-        ppc_maybe_bswap_register(env, mem_buf, 8);
-        ppc_maybe_bswap_register(env, mem_buf + 8, 8);
+        ppc_maybe_bswap_register(env, mem_buf, 16);
         return 16;
     }
     if (n == 32) {
@@ -515,15 +503,9 @@ static int gdb_set_avr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
 {
     if (n < 32) {
         ppc_avr_t *avr = cpu_avr_ptr(env, n);
-        ppc_maybe_bswap_register(env, mem_buf, 8);
-        ppc_maybe_bswap_register(env, mem_buf + 8, 8);
-        if (!avr_need_swap(env)) {
-            avr->u64[0] = ldq_p(mem_buf);
-            avr->u64[1] = ldq_p(mem_buf + 8);
-        } else {
-            avr->u64[1] = ldq_p(mem_buf);
-            avr->u64[0] = ldq_p(mem_buf + 8);
-        }
+        ppc_maybe_bswap_register(env, mem_buf, 16);
+        avr->VsrD(0) = ldq_p(mem_buf);
+        avr->VsrD(1) = ldq_p(mem_buf + 8);
         return 16;
     }
     if (n == 32) {
-- 
2.31.1