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Date: Thu, 22 Feb 2024 11:31:07 -0000
From: "tip-bot2 for Nikolay Borisov" <tip-bot2@linutronix.de>
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Subject: [tip: x86/asm] x86/insn: Remove superfluous checks from instruction
 decoding routines
Cc: Nikolay Borisov <nik.borisov@suse.com>, Ingo Molnar <mingo@kernel.org>,
 Josh Poimboeuf <jpoimboe@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
 x86@kernel.org, linux-kernel@vger.kernel.org
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The following commit has been merged into the x86/asm branch of tip:

Commit-ID:     427e1646f1ef6c714a5bade30ca0302edc5d46a0
Gitweb:        https://git.kernel.org/tip/427e1646f1ef6c714a5bade30ca0302edc5d46a0
Author:        Nikolay Borisov <nik.borisov@suse.com>
AuthorDate:    Thu, 22 Feb 2024 13:16:35 +02:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 22 Feb 2024 12:23:04 +01:00

x86/insn: Remove superfluous checks from instruction decoding routines

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
---
 arch/x86/lib/insn.c       | 56 ++++++++++++++------------------------
 tools/arch/x86/lib/insn.c | 56 ++++++++++++++------------------------
 2 files changed, 42 insertions(+), 70 deletions(-)

diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 55e371c..3946bdc 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -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);
diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c
index 8fd63a0..5d81924 100644
--- a/tools/arch/x86/lib/insn.c
+++ b/tools/arch/x86/lib/insn.c
@@ -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);