target/riscv: Make the priv register writable by GDB

Currently only PRV_U, PRV_S and PRV_M are supported, so this patch ensures that
the privilege mode is set to one of them. Once support for the H-extension is
added, this code will also need to properly update the virtualization status
when switching between VU/VS-modes and M-mode.

Signed-off-by: Jonathan Behrens <jonathan@fintelia.io>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
index 1f71604..1a7947e 100644 (file)
--- a/target/riscv/gdbstub.c
+++ b/target/riscv/gdbstub.c
@@ -387,6 +387,15 @@ static int riscv_gdb_get_virtual(CPURISCVState *cs, uint8_t *mem_buf, int n)
 
 static int riscv_gdb_set_virtual(CPURISCVState *cs, uint8_t *mem_buf, int n)
 {
+    if (n == 0) {
+#ifndef CONFIG_USER_ONLY
+        cs->priv = ldtul_p(mem_buf) & 0x3;
+        if (cs->priv == PRV_H) {
+            cs->priv = PRV_S;
+        }
+#endif
+        return sizeof(target_ulong);
+    }
     return 0;
 }