[PATCH v5 1/2] target/xtensa: Use an exception for semihosting

[Richard Henderson <richard.henderson@linaro.org>]

Within do_interrupt, we hold the iothread lock, which
is required for Chardev access for the console, and for
the round trip for use_gdb_syscalls().

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/xtensa/cpu.h         | 2 ++
 target/xtensa/helper.h      | 3 ---
 target/xtensa/exc_helper.c  | 4 ++++
 target/xtensa/translate.c   | 3 ++-
 target/xtensa/xtensa-semi.c | 3 +--
 5 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index 579adcb769..ea66895e7f 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -260,6 +260,7 @@ enum {
     EXC_USER,
     EXC_DOUBLE,
     EXC_DEBUG,
+    EXC_SEMIHOST,
     EXC_MAX
 };
 
@@ -576,6 +577,7 @@ void xtensa_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr,
                                       unsigned size, MMUAccessType access_type,
                                       int mmu_idx, MemTxAttrs attrs,
                                       MemTxResult response, uintptr_t retaddr);
+void xtensa_semihosting(CPUXtensaState *env);
 #endif
 void xtensa_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr xtensa_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
diff --git a/target/xtensa/helper.h b/target/xtensa/helper.h
index ae938ceedb..531679cd86 100644
--- a/target/xtensa/helper.h
+++ b/target/xtensa/helper.h
@@ -11,9 +11,6 @@ DEF_HELPER_2(retw, void, env, i32)
 DEF_HELPER_3(window_check, noreturn, env, i32, i32)
 DEF_HELPER_1(restore_owb, void, env)
 DEF_HELPER_2(movsp, void, env, i32)
-#ifndef CONFIG_USER_ONLY
-DEF_HELPER_1(simcall, void, env)
-#endif
 
 #ifndef CONFIG_USER_ONLY
 DEF_HELPER_3(waiti, void, env, i32, i32)
diff --git a/target/xtensa/exc_helper.c b/target/xtensa/exc_helper.c
index d4823a65cd..d54a518875 100644
--- a/target/xtensa/exc_helper.c
+++ b/target/xtensa/exc_helper.c
@@ -219,6 +219,10 @@ void xtensa_cpu_do_interrupt(CPUState *cs)
     }
 
     switch (cs->exception_index) {
+    case EXC_SEMIHOST:
+        xtensa_semihosting(env);
+        return;
+
     case EXC_WINDOW_OVERFLOW4:
     case EXC_WINDOW_UNDERFLOW4:
     case EXC_WINDOW_OVERFLOW8:
diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 70e11eeb45..b65c8b8428 100644
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -2377,7 +2377,8 @@ static void translate_simcall(DisasContext *dc, const OpcodeArg arg[],
 {
 #ifndef CONFIG_USER_ONLY
     if (semihosting_enabled()) {
-        gen_helper_simcall(cpu_env);
+        tcg_gen_movi_i32(cpu_pc, dc->base.pc_next);
+        gen_exception(dc, EXC_SEMIHOST);
     }
 #endif
 }
diff --git a/target/xtensa/xtensa-semi.c b/target/xtensa/xtensa-semi.c
index fa21b7e11f..5375f106fc 100644
--- a/target/xtensa/xtensa-semi.c
+++ b/target/xtensa/xtensa-semi.c
@@ -28,7 +28,6 @@
 #include "qemu/osdep.h"
 #include "cpu.h"
 #include "chardev/char-fe.h"
-#include "exec/helper-proto.h"
 #include "semihosting/semihost.h"
 #include "qapi/error.h"
 #include "qemu/log.h"
@@ -188,7 +187,7 @@ void xtensa_sim_open_console(Chardev *chr)
     sim_console = &console;
 }
 
-void HELPER(simcall)(CPUXtensaState *env)
+void xtensa_semihosting(CPUXtensaState *env)
 {
     CPUState *cs = env_cpu(env);
     uint32_t *regs = env->regs;
-- 
2.34.1