target/riscv: Set pc_succ_insn for !rvc illegal insn

Failure to set pc_succ_insn may result in a TB covering zero bytes,
which triggers an assert within the code generator.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1224Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NAlistair Francis <alistair.francis@wdc.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221203175744.151365-1-richard.henderson@linaro.org>
[ Changes by AF:
 - Add missing run-plugin-test-noc-% line
]
Signed-off-by: NAlistair Francis <alistair.francis@wdc.com>
(cherry picked from commit ec2918b4)
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

target/riscv/translate.c

@@ -1064,14 +1064,10 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
 
     /* Check for compressed insn */
     if (insn_len(opcode) == 2) {
-        if (!has_ext(ctx, RVC)) {
-            gen_exception_illegal(ctx);
-        } else {
-            ctx->opcode = opcode;
-            ctx->pc_succ_insn = ctx->base.pc_next + 2;
-            if (decode_insn16(ctx, opcode)) {
-                return;
-            }
+        ctx->opcode = opcode;
+        ctx->pc_succ_insn = ctx->base.pc_next + 2;
+        if (has_ext(ctx, RVC) && decode_insn16(ctx, opcode)) {
+            return;
         }
     } else {
         uint32_t opcode32 = opcode;

tests/tcg/Makefile.target

@@ -117,6 +117,8 @@ endif
 
 %: %.c
 	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
+%: %.S
+	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
 else
 # For softmmu targets we include a different Makefile fragement as the
 # build options for bare programs are usually pretty different. They

tests/tcg/riscv64/Makefile.target

@@ -4,3 +4,9 @@
 VPATH += $(SRC_PATH)/tests/tcg/riscv64
 TESTS += test-div
 TESTS += noexec
+
+# Disable compressed instructions for test-noc
+TESTS += test-noc
+test-noc: LDFLAGS = -nostdlib -static
+run-test-noc: QEMU_OPTS += -cpu rv64,c=false
+run-plugin-test-noc-%: QEMU_OPTS += -cpu rv64,c=false

tests/tcg/riscv64/test-noc.S

+#include <asm/unistd.h>
+
+	.text
+	.globl _start
+_start:
+	.option	norvc
+	li	a0, 4		/* SIGILL */
+	la	a1, sa
+	li	a2, 0
+	li	a3, 8
+	li	a7, __NR_rt_sigaction
+	scall
+
+	.option	rvc
+	li	a0, 1
+	j	exit
+	.option	norvc
+
+pass:
+	li	a0, 0
+exit:
+	li	a7, __NR_exit
+	scall
+
+	.data
+	/* struct kernel_sigaction sa = { .sa_handler = pass }; */
+	.type	sa, @object
+	.size	sa, 32
+sa:
+	.dword	pass
+	.zero	24
+