[PATCH for-7.1 v6 07/51] target/nios2: Fix BRET instruction

Richard Henderson posted 51 patches 3 years, 11 months ago
Maintainers: Chris Wulff <crwulff@gmail.com>, Marek Vasut <marex@denx.de>, Richard Henderson <richard.henderson@linaro.org>, Laurent Vivier <laurent@vivier.eu>, "Alex Bennée" <alex.bennee@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>
[PATCH for-7.1 v6 07/51] target/nios2: Fix BRET instruction
Posted by Richard Henderson 3 years, 11 months ago
We had failed to copy BSTATUS back to STATUS, and diagnose
supervisor-only.  The spec is light on the specifics of the
implementation of bret, but it is an easy assumption that
the restore into STATUS should work the same as eret.

Therefore, reuse the existing helper_eret.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/nios2/translate.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index 7c2c430e99..3f7bbd6d7b 100644
--- a/target/nios2/translate.c
+++ b/target/nios2/translate.c
@@ -407,12 +407,22 @@ static void ret(DisasContext *dc, uint32_t code, uint32_t flags)
     dc->base.is_jmp = DISAS_JUMP;
 }
 
-/* PC <- ba */
+/*
+ * status <- bstatus
+ * PC <- ba
+ */
 static void bret(DisasContext *dc, uint32_t code, uint32_t flags)
 {
-    tcg_gen_mov_tl(cpu_pc, cpu_R[R_BA]);
+    if (!gen_check_supervisor(dc)) {
+        return;
+    }
 
-    dc->base.is_jmp = DISAS_JUMP;
+#ifdef CONFIG_USER_ONLY
+    g_assert_not_reached();
+#else
+    gen_helper_eret(cpu_env, cpu_R[CR_BSTATUS], cpu_R[R_BA]);
+    dc->base.is_jmp = DISAS_NORETURN;
+#endif
 }
 
 /* PC <- rA */
-- 
2.25.1