or1k: Fix disassembly for little-endian binaries

There are some OpenRISC CPUs that have their binaries stored in
little-endian format.  Using objdump to disassemble these is
problematic, as some instructions fail to disassemble, for example:

    objdump -D -b binary -EB -m or1k test_be.bin

       0:	18 60 07 27 	l.movhi r3,0x727
       4:	a8 63 0e 00 	l.ori r3,r3,0xe00
       8:	9c 63 ff ff 	l.addi r3,r3,-1
       c:	bc 43 00 00 	l.sfgtui r3,0
      10:	13 ff ff fe 	l.bf 0x8
      14:	44 00 48 00 	l.jr r9

    objdump -D -b binary -EL -m or1k test_le.bin

       0:	27 07 60 18 	*unknown*
       4:	00 0e 63 a8 	l.ori r3,r3,0xe00
       8:	ff ff 63 9c 	*unknown*
       c:	00 00 43 bc 	l.sfgtui r3,0
      10:	fe ff ff 13 	*unknown*
      14:	00 48 00 44 	l.jr r9

It was found that the hash function was using the still little-endian
buffer to extract the opcode used for the hash lookup.  This didn't work
as it was pulling the wrong hashcode causing instruction lookup to fail.

Fix the hash function by using the normalized/byte-swapped value instead
of the buffer.

Signed-off-by: Stafford Horne <shorne@gmail.com>

diff --git a/cpu/or1k.opc b/cpu/or1k.opc
index 5d20a1f33a709931962647b12b61751ed94c324d..748187edcdf4795bbccea88ee7c6fdc3638e778d 100644 (file)
--- a/cpu/or1k.opc
+++ b/cpu/or1k.opc
@@ -38,7 +38,7 @@
 #undef  CGEN_DIS_HASH_SIZE
 #define CGEN_DIS_HASH_SIZE 256
 #undef  CGEN_DIS_HASH
-#define CGEN_DIS_HASH(buffer, value) (((unsigned char *) (buffer))[0] >> 2)
+#define CGEN_DIS_HASH(buffer, value) ((value >> 26) & 0xff)
 
 /* Check applicability of instructions against machines.  */
 #define CGEN_VALIDATE_INSN_SUPPORTED

diff --git a/opcodes/or1k-opc.h b/opcodes/or1k-opc.h
index d3d084b1becb296ad0564206845347d1f240ac06..6eec8006828c39fc0f385ee0670df99d7d87983f 100644 (file)
--- a/opcodes/or1k-opc.h
+++ b/opcodes/or1k-opc.h
@@ -35,7 +35,7 @@ extern "C" {
 #undef  CGEN_DIS_HASH_SIZE
 #define CGEN_DIS_HASH_SIZE 256
 #undef  CGEN_DIS_HASH
-#define CGEN_DIS_HASH(buffer, value) (((unsigned char *) (buffer))[0] >> 2)
+#define CGEN_DIS_HASH(buffer, value) ((value >> 26) & 0xff)
 
 /* Check applicability of instructions against machines.  */
 #define CGEN_VALIDATE_INSN_SUPPORTED