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[PULL,18/68] target/nios2: Fix BRET instruction

Message ID 20220426181907.103691-19-richard.henderson@linaro.org
State New
Headers show
Series [PULL,01/68] linux-user/nios2: Hoist pc advance to the top of EXCP_TRAP | expand

Commit Message

Richard Henderson April 26, 2022, 6:18 p.m. UTC 
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>
Message-Id: <20220421151735.31996-19-richard.henderson@linaro.org>
---
 target/nios2/translate.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)
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Patch

diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index 53699ee088..3694f2503b 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 */