The Official Rizin Book

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 rizin 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 - RzAsm and RzAnalysis. 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 RzAnalysis plugin looks like

RzAnalysisPlugin rz_analysis_plugin_v810 = {
	.name = "mycpu",
	.desc = "MYCPU code analysis plugin",
	.license = "LGPL3",
	.arch = "mycpu",
	.bits = 32,
	.op = mycpu_op,
	.esil = true,
	.set_reg_profile = set_reg_profile,
};

Like with disassembly plugin there is a key function - mycpu_op which scans the opcode and builds RzAnalysisOp 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 RzAnalysisOp 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

NAME=analysis_snes
RZ_PLUGIN_PATH=$(shell rizin -H RZ_USER_PLUGINS)
LIBEXT=$(shell rizin -H LIBEXT)
CFLAGS=-g -fPIC $(shell pkg-config --cflags rz_analysis)
LDFLAGS=-shared $(shell pkg-config --libs rz_analysis)
OBJS=$(NAME).o
LIB=$(NAME).$(LIBEXT)

all: $(LIB)

clean:
	rm -f $(LIB) $(OBJS)

$(LIB): $(OBJS)
	$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)

install:
	cp -f analysis_snes.$(SO_EXT) $(RZ_PLUGIN_PATH)

uninstall:
	rm -f $(RZ_PLUGIN_PATH)/analysis_snes.$(SO_EXT)

analysis_snes.c:

/* rizin - LGPL - Copyright 2015 - condret */

#include <string.h>
#include <rz_types.h>
#include <rz_lib.h>
#include <rz_asm.h>
#include <rz_analysis.h>
#include "snes_op_table.h"

static int snes_anop(RzAnalysis *anal, RzAnalysisOp *op, ut64 addr, const ut8 *data, int len) {
	memset (op, '\0', sizeof (RzAnalysisOp));
	op->size = snes_op[data[0]].len;
	op->addr = addr;
	op->type = RZ_ANALYSIS_OP_TYPE_UNK;
	switch (data[0]) {
		case 0xea:
			op->type = RZ_ANALYSIS_OP_TYPE_NOP;
			break;
	}
	return op->size;
}

struct rz_analysis_plugin_t rz_analysis_plugin_snes = {
	.name = "snes",
	.desc = "SNES analysis plugin",
	.license = "LGPL3",
	.arch = RZ_SYS_ARCH_NONE,
	.bits = 16,
	.init = NULL,
	.fini = NULL,
	.op = &snes_anop,
	.set_reg_profile = NULL,
	.fingerprint_bb = NULL,
	.fingerprint_fcn = NULL,
	.diff_bb = NULL,
	.diff_fcn = NULL,
	.diff_eval = NULL
};

#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
	.type = RZ_LIB_TYPE_ANALYSIS,
	.data = &rz_analysis_plugin_snes,
	.version = RZ_VERSION
};
#endif

After compiling rizin will list this plugin in the output:

_dA_  _8_16      snes        LGPL3   SuperNES CPU

snes_op_table.h: https://github.com/rizinorg/rizin/blob/master/librz/asm/arch/snes/snes_op_table.h

Example:

• 6502: https://github.com/rizinorg/rizin/commit/64636e9505f9ca8b408958d3c01ac8e3ce254a9b
• SNES: https://github.com/rizinorg/rizin/commit/60d6e5a1b9d244c7085b22ae8985d00027624b49