[PATCH 2/2] target/xtensa: Remove tswap() calls in semihosting simcall() helper

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

In preparation of heterogeneous emulation where cores with
different endianness can run concurrently, we need to remove
the tswap() calls -- which use a fixed per-binary endianness.

Get the endianness of the CPU accessed using the libisa
xtensa_isa_is_big_endian() call and replace the tswap() calls
by bswap() ones when necessary.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/xtensa/xtensa-semi.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/target/xtensa/xtensa-semi.c b/target/xtensa/xtensa-semi.c
index fa21b7e11fc..21d23e39de5 100644
--- a/target/xtensa/xtensa-semi.c
+++ b/target/xtensa/xtensa-semi.c
@@ -328,10 +328,17 @@ void HELPER(simcall)(CPUXtensaState *env)
             struct timeval tv = {0};
 
             if (target_tv) {
+                bool cpu_big_endian = xtensa_isa_is_big_endian(env->config->isa);
+                bool swap_needed = HOST_BIG_ENDIAN != cpu_big_endian;
+
                 cpu_memory_rw_debug(cs, target_tv,
                         (uint8_t *)target_tvv, sizeof(target_tvv), 0);
-                tv.tv_sec = (int32_t)tswap32(target_tvv[0]);
-                tv.tv_usec = (int32_t)tswap32(target_tvv[1]);
+                if (swap_needed) {
+                    bswap32s(&target_tvv[0]);
+                    bswap32s(&target_tvv[1]);
+                }
+                tv.tv_sec = (int32_t)target_tvv[0];
+                tv.tv_usec = (int32_t)target_tvv[1];
             }
             if (fd < 3 && sim_console) {
                 if ((fd == 1 || fd == 2) && rq == SELECT_ONE_WRITE) {
@@ -381,6 +388,8 @@ void HELPER(simcall)(CPUXtensaState *env)
             int argc = semihosting_get_argc();
             int str_offset = (argc + 1) * sizeof(uint32_t);
             int i;
+            bool cpu_big_endian = xtensa_isa_is_big_endian(env->config->isa);
+            bool swap_needed = HOST_BIG_ENDIAN != cpu_big_endian;
             uint32_t argptr;
 
             for (i = 0; i < argc; ++i) {
@@ -388,6 +397,9 @@ void HELPER(simcall)(CPUXtensaState *env)
                 int str_size = strlen(str) + 1;
 
                 argptr = tswap32(regs[3] + str_offset);
+                if (swap_needed) {
+                    bswap32s(&argptr);
+                }
 
                 cpu_memory_rw_debug(cs,
                                     regs[3] + i * sizeof(uint32_t),
-- 
2.45.2