diff options
| -rw-r--r-- | src/x86.c | 4 | ||||
| -rw-r--r-- | src/x86.h | 17 | ||||
| -rw-r--r-- | test/x86.test.c | 9 | ||||
| -rw-r--r-- | tools/x86test.c | 43 |
4 files changed, 63 insertions, 10 deletions
@@ -25,7 +25,6 @@ static int mrmsib(const uchar *p, int addrlen) { // But it's confusingly-written enough that the code I wrote before didn't // work, so with any luck nobody will need to refer to it again and this is // actually correct now. Fingers crossed. - if ((*p & 0xC6) == 0x06) return 3; // special case for disp16 if (addrlen == 4 || *p & 0xC0) { int sib = addrlen == 4 && *p < 0xC0 && (*p & 7) == 4; switch (*p & 0xC0) { @@ -41,7 +40,7 @@ static int mrmsib(const uchar *p, int addrlen) { case 0x80: return 1 + addrlen + sib; } } - if (addrlen == 2 && *p == 0x26) return 3; + if (addrlen == 2 && (*p & 0xC7) == 0x06) return 3; return 1; // note: include the mrm itself in the byte count } @@ -66,6 +65,7 @@ P: X86_SEG_PREFIXES(CASES) X86_OPS_1BYTE_NO(CASES) return pfxlen + 1; X86_OPS_1BYTE_I8(CASES) operandlen = 1; X86_OPS_1BYTE_IW(CASES) return pfxlen + 1 + operandlen; + X86_OPS_1BYTE_IWI(CASES) return pfxlen + 1 + addrlen; X86_OPS_1BYTE_I16(CASES) return pfxlen + 3; X86_OPS_1BYTE_MRM(CASES) return pfxlen + 1 + mrmsib(insn + 1, addrlen); X86_OPS_1BYTE_MRM_I8(CASES) operandlen = 1; @@ -25,6 +25,9 @@ */ // XXX: no BOUND (0x62): ambiguous with EVEX prefix - can't be arsed! +// XXX: no LES (0xC4) or DES (0xC5) either for similar reasons. better to report +// an unknown instruction than to potentially misinterpret an AVX thing. +// these are all legacy instructions that won't really be used much anyway. /* Instruction prefixes: segments */ #define X86_SEG_PREFIXES(X) \ @@ -188,10 +191,6 @@ X(X86_XOREAXI, 0x35) \ X(X86_CMPEAXI, 0x3D) \ X(X86_PUSHIW, 0x68) \ - X(X86_MOVALII, 0xA0) /* From offset (indirect) */ \ - X(X86_MOVEAXII, 0xA1) /* From offset (indirect) */ \ - X(X86_MOVIIAL, 0xA2) /* To offset (indirect) */ \ - X(X86_MOVIIEAX, 0xA3) /* To offset (indirect) */ \ X(X86_TESTEAXI, 0xA9) \ X(X86_MOVEAXI, 0xB8) \ X(X86_MOVECXI, 0xB9) \ @@ -204,6 +203,13 @@ X(X86_CALL, 0xE8) \ X(X86_JMPIW, 0xE9) +/* Single-byte opcodes with a word-sized immediate operand (indirect) */ +#define X86_OPS_1BYTE_IWI(X) \ + X(X86_MOVALII, 0xA0) /* From offset (indirect) */ \ + X(X86_MOVEAXII, 0xA1) /* From offset (indirect) */ \ + X(X86_MOVIIAL, 0xA2) /* To offset (indirect) */ \ + X(X86_MOVIIEAX, 0xA3) /* To offset (indirect) */ \ + /* Single-byte opcodes with 16-bit immediate operands, regardless of prefixes */ #define X86_OPS_1BYTE_I16(X) \ X(X86_RETI16, 0xC2) \ @@ -259,8 +265,6 @@ X(X86_LEA, 0x8D) \ X(X86_MOVSM, 0x8E) /* Store 4 bytes to segment register */ \ X(X86_POPM, 0x8F) \ - X(X86_LES, 0xC4) \ - X(X86_LDS, 0xC5) \ X(X86_SHIFTM18, 0xD0) /* Shift/roll by 1 place */ \ X(X86_SHIFTM1W, 0xD1) /* Shift/roll by 1 place */ \ X(X86_SHIFTMCL8, 0xD2) /* Shift/roll by CL places */ \ @@ -297,6 +301,7 @@ X86_OPS_1BYTE_NO(X) \ X86_OPS_1BYTE_I8(X) \ X86_OPS_1BYTE_IW(X) \ + X86_OPS_1BYTE_IWI(X) \ X86_OPS_1BYTE_I16(X) \ X86_OPS_1BYTE_MRM(X) \ X86_OPS_1BYTE_MRM_I8(X) \ diff --git a/test/x86.test.c b/test/x86.test.c index c0c825a..bf6e6e8 100644 --- a/test/x86.test.c +++ b/test/x86.test.c @@ -37,9 +37,14 @@ TEST("mov AL, moff8 instructions should be decoded correctly") { return true; } -TEST("fiadd [off16] instructions should be decoded correctly") { +TEST("16-bit MRM instructions should be decoded correctly") { const uchar fiadd_off16[] = HEXBYTES(67, DA, 06, DF, 11); - return x86_len(fiadd_off16) == 5; + const uchar fld_tword[] = HEXBYTES(67, DB, 2E, 99, C4); + const uchar add_off16_bl[] = HEXBYTES(67, 00, 1E, F5, BB); + if (x86_len(fiadd_off16) != 5) return false; + if (x86_len(fld_tword) != 5) return false; + if (x86_len(add_off16_bl) != 5) return false; + return true; } // vi: sw=4 ts=4 noet tw=80 cc=80 diff --git a/tools/x86test.c b/tools/x86test.c new file mode 100644 index 0000000..18fc72f --- /dev/null +++ b/tools/x86test.c @@ -0,0 +1,43 @@ +/* This file is dedicated to the public domain. */ + +#include <stdbool.h> +#include <stdio.h> + +#include "../src/udis86.h" +#include "../src/udis86.c" +#include "../src/intdefs.h" +#include "../src/x86.h" +#include "../src/x86.c" +#include "../src/os.h" +#include "../src/os.c" + +/* + * Quick hacked-up test program to more exhaustively test x86.c. This is not run + * as part of the build; it is just here for development and reference purposes. + */ + +int main(void) { + uchar buf[15]; + int bad = 0; + for (int i = 0; i < 100000000 && bad < 30; ++i) { + os_randombytes(buf, sizeof(buf)); + struct ud u; + ud_init(&u); + ud_set_mode(&u, 32); + ud_set_input_buffer(&u, buf, sizeof(buf)); + ud_set_syntax(&u, UD_SYN_INTEL); + int len = ud_disassemble(&u); + if (len && ud_insn_mnemonic(&u) != UD_Iinvalid) { + int mylen = x86_len(buf); + if (mylen != -1 && mylen != len) { + ++bad; + fprintf(stderr, "Uh oh! %s\nExp: %d\nGot: %d\nBytes:", + ud_insn_asm(&u), len, mylen); + for (int i = 0; i < len; ++i) fprintf(stderr, " %02X", buf[i]); + fputs("\n\n", stderr); + } + } + } + fprintf(stderr, "%d bad cases\n", bad); +} + |