ext: add simple sifive cflush extension

just check the execution privilege

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

customext/cflush.cc

@@ -0,0 +1,41 @@
+#include "extension.h"
+#include <cstring>
+
+struct : public arg_t {
+  std::string to_string(insn_t insn) const {
+    return xpr_name[insn.rs1()];
+  }
+} xrs1;
+
+static reg_t custom_cflush(processor_t* p, insn_t insn, reg_t pc)
+{
+  require_privilege(PRV_M);
+
+  return pc + 4; \
+}
+
+class cflush_t : public extension_t
+{
+ public:
+  const char* name() { return "cflush"; }
+
+  cflush_t() {}
+
+  std::vector<insn_desc_t> get_instructions() {
+    std::vector<insn_desc_t> insns;
+    insns.push_back((insn_desc_t){0xFC000073, 0xFFF07FFF, custom_cflush, custom_cflush});
+    insns.push_back((insn_desc_t){0xFC200073, 0xFFF07FFF, custom_cflush, custom_cflush});
+    insns.push_back((insn_desc_t){0xFC100073, 0xFFF07FFF, custom_cflush, custom_cflush});
+    return insns;
+  }
+
+  std::vector<disasm_insn_t*> get_disasms() {
+    std::vector<disasm_insn_t*> insns;
+    insns.push_back(new disasm_insn_t("cflush.d.l1", 0xFC000073, 0xFFF07FFF, {&xrs1}));
+    insns.push_back(new disasm_insn_t("cdiscard.d.l1", 0xFC200073, 0xFFF07FFF, {&xrs1}));
+    insns.push_back(new disasm_insn_t("cflush.i.l1", 0xFC100073, 0xFFF07FFF, {&xrs1}));
+    return insns;
+  }
+};
+
+REGISTER_EXTENSION(cflush, []() { return new cflush_t; })

customext/customext.mk.in

@@ -5,6 +5,7 @@ customext_subproject_deps = \
 
 customext_srcs = \
 	dummy_rocc.cc \
+	cflush.cc \
 
 customext_CFLAGS = -fPIC