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x86/insn: Remove superfluous checks from instruction decoding routines

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It's pointless checking if a particular part of an instruction is
decoded before calling the routine responsible for decoding it as this
check is duplicated in the routines itself. Streamline the code by
removing the superfluous checks. No functional difference.

Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240222111636.2214523-2-nik.borisov@suse.com
This commit is contained in:
Nikolay Borisov 2024-02-22 13:16:35 +02:00 committed by Ingo Molnar
parent b401b62175
commit 427e1646f1
2 changed files with 42 additions and 70 deletions
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56
arch/x86/lib/insn.c
View File

@ -268,11 +268,9 @@ int insn_get_opcode(struct insn *insn)
if (opcode->got)
return 0;
if (!insn->prefixes.got) {
ret = insn_get_prefixes(insn);
if (ret)
return ret;
}
ret = insn_get_prefixes(insn);
if (ret)
return ret;
/* Get first opcode */
op = get_next(insn_byte_t, insn);
@ -339,11 +337,9 @@ int insn_get_modrm(struct insn *insn)
if (modrm->got)
return 0;
if (!insn->opcode.got) {
ret = insn_get_opcode(insn);
if (ret)
return ret;
}
ret = insn_get_opcode(insn);
if (ret)
return ret;
if (inat_has_modrm(insn->attr)) {
mod = get_next(insn_byte_t, insn);
@ -386,11 +382,9 @@ int insn_rip_relative(struct insn *insn)
if (!insn->x86_64)
return 0;
if (!modrm->got) {
ret = insn_get_modrm(insn);
if (ret)
return 0;
}
ret = insn_get_modrm(insn);
if (ret)
return 0;
/*
* For rip-relative instructions, the mod field (top 2 bits)
* is zero and the r/m field (bottom 3 bits) is 0x5.
@ -417,11 +411,9 @@ int insn_get_sib(struct insn *insn)
if (insn->sib.got)
return 0;
if (!insn->modrm.got) {
ret = insn_get_modrm(insn);
if (ret)
return ret;
}
ret = insn_get_modrm(insn);
if (ret)
return ret;
if (insn->modrm.nbytes) {
modrm = insn->modrm.bytes[0];
@ -460,11 +452,9 @@ int insn_get_displacement(struct insn *insn)
if (insn->displacement.got)
return 0;
if (!insn->sib.got) {
ret = insn_get_sib(insn);
if (ret)
return ret;
}
ret = insn_get_sib(insn);
if (ret)
return ret;
if (insn->modrm.nbytes) {
/*
@ -628,11 +618,9 @@ int insn_get_immediate(struct insn *insn)
if (insn->immediate.got)
return 0;
if (!insn->displacement.got) {
ret = insn_get_displacement(insn);
if (ret)
return ret;
}
ret = insn_get_displacement(insn);
if (ret)
return ret;
if (inat_has_moffset(insn->attr)) {
if (!__get_moffset(insn))
@ -703,11 +691,9 @@ int insn_get_length(struct insn *insn)
if (insn->length)
return 0;
if (!insn->immediate.got) {
ret = insn_get_immediate(insn);
if (ret)
return ret;
}
ret = insn_get_immediate(insn);
if (ret)
return ret;
insn->length = (unsigned char)((unsigned long)insn->next_byte
- (unsigned long)insn->kaddr);

56
tools/arch/x86/lib/insn.c
View File

@ -268,11 +268,9 @@ int insn_get_opcode(struct insn *insn)
if (opcode->got)
return 0;
if (!insn->prefixes.got) {
ret = insn_get_prefixes(insn);
if (ret)
return ret;
}
ret = insn_get_prefixes(insn);
if (ret)
return ret;
/* Get first opcode */
op = get_next(insn_byte_t, insn);
@ -339,11 +337,9 @@ int insn_get_modrm(struct insn *insn)
if (modrm->got)
return 0;
if (!insn->opcode.got) {
ret = insn_get_opcode(insn);
if (ret)
return ret;
}
ret = insn_get_opcode(insn);
if (ret)
return ret;
if (inat_has_modrm(insn->attr)) {
mod = get_next(insn_byte_t, insn);
@ -386,11 +382,9 @@ int insn_rip_relative(struct insn *insn)
if (!insn->x86_64)
return 0;
if (!modrm->got) {
ret = insn_get_modrm(insn);
if (ret)
return 0;
}
ret = insn_get_modrm(insn);
if (ret)
return 0;
/*
* For rip-relative instructions, the mod field (top 2 bits)
* is zero and the r/m field (bottom 3 bits) is 0x5.
@ -417,11 +411,9 @@ int insn_get_sib(struct insn *insn)
if (insn->sib.got)
return 0;
if (!insn->modrm.got) {
ret = insn_get_modrm(insn);
if (ret)
return ret;
}
ret = insn_get_modrm(insn);
if (ret)
return ret;
if (insn->modrm.nbytes) {
modrm = insn->modrm.bytes[0];
@ -460,11 +452,9 @@ int insn_get_displacement(struct insn *insn)
if (insn->displacement.got)
return 0;
if (!insn->sib.got) {
ret = insn_get_sib(insn);
if (ret)
return ret;
}
ret = insn_get_sib(insn);
if (ret)
return ret;
if (insn->modrm.nbytes) {
/*
@ -628,11 +618,9 @@ int insn_get_immediate(struct insn *insn)
if (insn->immediate.got)
return 0;
if (!insn->displacement.got) {
ret = insn_get_displacement(insn);
if (ret)
return ret;
}
ret = insn_get_displacement(insn);
if (ret)
return ret;
if (inat_has_moffset(insn->attr)) {
if (!__get_moffset(insn))
@ -703,11 +691,9 @@ int insn_get_length(struct insn *insn)
if (insn->length)
return 0;
if (!insn->immediate.got) {
ret = insn_get_immediate(insn);
if (ret)
return ret;
}
ret = insn_get_immediate(insn);
if (ret)
return ret;
insn->length = (unsigned char)((unsigned long)insn->next_byte
- (unsigned long)insn->kaddr);