[PATCH for-9.2] target/riscv: Avoid bad shift in riscv_cpu_do_interrupt()

[Peter Maydell]

In riscv_cpu_do_interrupt() we use the 'cause' value we got out of
cs->exception as a shift value.  However this value can be larger
than 31, which means that "1 << cause" is undefined behaviour,
because we do the shift on an 'int' type.

This causes the undefined behaviour sanitizer to complain
on one of the check-tcg tests:

$ UBSAN_OPTIONS=print_stacktrace=1:abort_on_error=1:halt_on_error=1 
./build/clang/qemu-system-riscv64 -M virt -semihosting -display none -device 
loader,file=build/clang/tests/tcg/riscv64-softmmu/issue1060
../../target/riscv/cpu_helper.c:1805:38: runtime error: shift exponent 63 is 
too large for 32-bit type 'int'
    #0 0x55f2dc026703 in riscv_cpu_do_interrupt 
/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../target/riscv/cpu_helper.c:1805:38
    #1 0x55f2dc3d170e in cpu_handle_exception 
/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../accel/tcg/cpu-exec.c:752:9

In this case cause is RISCV_EXCP_SEMIHOST, which is 0x3f.

Use 1ULL instead to ensure that the shift is in range.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/riscv/cpu_helper.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 0a3ead69eab..45806f5ab0f 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -1802,10 +1802,10 @@ void riscv_cpu_do_interrupt(CPUState *cs)
     bool async = !!(cs->exception_index & RISCV_EXCP_INT_FLAG);
     target_ulong cause = cs->exception_index & RISCV_EXCP_INT_MASK;
     uint64_t deleg = async ? env->mideleg : env->medeleg;
-    bool s_injected = env->mvip & (1 << cause) & env->mvien &&
-        !(env->mip & (1 << cause));
-    bool vs_injected = env->hvip & (1 << cause) & env->hvien &&
-        !(env->mip & (1 << cause));
+    bool s_injected = env->mvip & (1ULL << cause) & env->mvien &&
+        !(env->mip & (1ULL << cause));
+    bool vs_injected = env->hvip & (1ULL << cause) & env->hvien &&
+        !(env->mip & (1ULL << cause));
     target_ulong tval = 0;
     target_ulong tinst = 0;
     target_ulong htval = 0;
-- 
2.34.1