Implementing a new analysis plugin

After implementing disassembly plugin, you might have noticed that output is far from being good - no proper highlighting, no reference lines and so on. This is because radare2 requires every architecture plugin to provide also analysis information about every opcode. At the moment the implementation of disassembly and opcodes analysis is separated between two modules - RAsm and RAnal. Thus we need to write an analysis plugin too. The principle is very similar - you just need to create a C file and corresponding Makefile.

They structure of RAnal plugin looks like

  1. RAnalPlugin r_anal_plugin_v810 = {
  2.     .name = "mycpu",
  3.     .desc = "MYCPU code analysis plugin",
  4.     .license = "LGPL3",
  5.     .arch = "mycpu",
  6.     .bits = 32,
  7.     .op = mycpu_op,
  8.     .esil = true,
  9.     .set_reg_profile = set_reg_profile,
  10. };

Like with disassembly plugin there is a key function - mycpu_op which scans the opcode and builds RAnalOp structure. On the other hand, in this example analysis plugins also performs uplifting to ESIL, which is enabled in .esil = true statement. Thus, mycpu_op obliged to fill the corresponding RAnalOp ESIL field for the opcodes. Second important thing for ESIL uplifting and emulation - register profile, like in debugger, which is set within set_reg_profile function.

Makefile

  1. NAME=anal_snes
  2. R2_PLUGIN_PATH=$(shell r2 -H R2_USER_PLUGINS)
  3. LIBEXT=$(shell r2 -H LIBEXT)
  4. CFLAGS=-g -fPIC $(shell pkg-config --cflags r_anal)
  5. LDFLAGS=-shared $(shell pkg-config --libs r_anal)
  6. OBJS=$(NAME).o
  7. LIB=$(NAME).$(LIBEXT)
  9. all: $(LIB)
  11. clean:
  12.     rm -f $(LIB) $(OBJS)
  14. $(LIB): $(OBJS)
  15.     $(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)
  17. install:
  18.     cp -f anal_snes.$(SO_EXT) $(R2_PLUGIN_PATH)
  20. uninstall:
  21.     rm -f $(R2_PLUGIN_PATH)/anal_snes.$(SO_EXT)

anal_snes.c:

  1. /* radare - LGPL - Copyright 2015 - condret */
  3. #include <string.h>
  4. #include <r_types.h>
  5. #include <r_lib.h>
  6. #include <r_asm.h>
  7. #include <r_anal.h>
  8. #include "snes_op_table.h"
  10. static int snes_anop(RAnal *anal, RAnalOp *op, ut64 addr, const ut8 *data, int len) {
  11.     memset (op, '\0', sizeof (RAnalOp));
  12.     op->size = snes_op[data[0]].len;
  13.     op->addr = addr;
  14.     op->type = R_ANAL_OP_TYPE_UNK;
  15.     switch (data[0]) {
  16.         case 0xea:
  17.             op->type = R_ANAL_OP_TYPE_NOP;
  18.             break;
  19.     }
  20.     return op->size;
  21. }
  23. struct r_anal_plugin_t r_anal_plugin_snes = {
  24.     .name = "snes",
  25.     .desc = "SNES analysis plugin",
  26.     .license = "LGPL3",
  27.     .arch = R_SYS_ARCH_NONE,
  28.     .bits = 16,
  29.     .init = NULL,
  30.     .fini = NULL,
  31.     .op = &snes_anop,
  32.     .set_reg_profile = NULL,
  33.     .fingerprint_bb = NULL,
  34.     .fingerprint_fcn = NULL,
  35.     .diff_bb = NULL,
  36.     .diff_fcn = NULL,
  37.     .diff_eval = NULL
  38. };
  40. #ifndef R2_PLUGIN_INCORE
  41. R_API RLibStruct radare_plugin = {
  42.     .type = R_LIB_TYPE_ANAL,
  43.     .data = &r_anal_plugin_snes,
  44.     .version = R2_VERSION
  45. };
  46. #endif

After compiling radare2 will list this plugin in the output:

  1. _dA_  _8_16      snes        LGPL3   SuperNES CPU

snes_op_table.h: https://github.com/radareorg/radare2/blob/master/libr/asm/arch/snes/snes\_op\_table.h

Example: