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authorHeiko Carstens <heiko.carstens@de.ibm.com>2017-11-17 09:50:40 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-11-20 08:51:02 +0100
commitde35089cc82c33f8be1dec5a0c3d7a05cf91720d (patch)
treee47b55158cd1458151ad59f4171856810fd561bb /arch/s390
parent3241d3eb7d9bb7a134bedf49db196cf98b58834d (diff)
downloadlinux-de35089cc82c33f8be1dec5a0c3d7a05cf91720d.tar.gz
s390/disassembler: remove confusing code
When searching the opcode offset table within find_insn() the check "entry->opcode == 0" was intended to clarify that 1-byte opcodes, the first one being 0, are special. However there is no mnemonic for an illegal opcode starting with 0. Therefore there is also no opcode offset table entry that matches, which again means that the check never is true. Therefore just remove the confusing check, and add a comment which hopefully explains how this works. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kernel/dis.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
index 3be829721cf9..465d52b5e470 100644
--- a/arch/s390/kernel/dis.c
+++ b/arch/s390/kernel/dis.c
@@ -396,9 +396,14 @@ struct s390_insn *find_insn(unsigned char *code)
unsigned char opfrag;
int i;
+ /* Search the opcode offset table to find an entry which
+ * matches the beginning of the opcode. If there is no match
+ * the last entry will be used, which is the default entry for
+ * unknown instructions as well as 1-byte opcode instructions.
+ */
for (i = 0; i < ARRAY_SIZE(opcode_offset); i++) {
entry = &opcode_offset[i];
- if (entry->opcode == code[0] || entry->opcode == 0)
+ if (entry->opcode == code[0])
break;
}