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or1k: Fix disassembly for little-endian binaries

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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>
This commit is contained in:
Stafford Horne
2025-06-15 05:15:40 +01:00
parent e4f71ccd5a
commit 7a23d8a826
2 changed files with 2 additions and 2 deletions
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2
cpu/or1k.opc
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@@ -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

2
opcodes/or1k-opc.h
View File

@@ -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