linux-kernel - [PATCH V3 3/9] x86/jump_label: Move checking code away from __jump_label

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Message-Id: <296d5a75c4aee4a957ee7923127c0604903f9daa.1545228276.git.bristot@redhat.com>
Date:   Fri, 21 Dec 2018 11:27:28 +0100
From:   Daniel Bristot de Oliveira <bristot@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Jiri Kosina <jkosina@...e.cz>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Chris von Recklinghausen <crecklin@...hat.com>,
        Jason Baron <jbaron@...mai.com>, Scott Wood <swood@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Clark Williams <williams@...hat.com>, x86@...nel.org
Subject: [PATCH V3 3/9] x86/jump_label: Move checking code away from __jump_label_transform()

Move the check of the current code, before updating an entry, to specialized
functions. No changes in the method, only code relocation.

Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>
Cc: Chris von Recklinghausen <crecklin@...hat.com>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Scott Wood <swood@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/kernel/jump_label.c | 60 +++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index aac0c1f7e354..7894080bd02f 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -37,16 +37,53 @@ static void bug_at(unsigned char *ip, int line)
 	BUG();
 }
 
+static inline void __jump_label_trans_check_enable(struct jump_entry *entry,
+						   enum jump_label_type type,
+						   const unsigned char *ideal_nop,
+						   int init)
+{
+	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
+	const void *expect;
+	int line;
+
+	if (init) {
+		expect = default_nop; line = __LINE__;
+	} else {
+		expect = ideal_nop; line = __LINE__;
+	}
+
+	if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
+		bug_at((void *)jump_entry_code(entry), line);
+}
+
+static inline void __jump_label_trans_check_disable(struct jump_entry *entry,
+						    enum jump_label_type type,
+						    union jump_code_union *jmp,
+						    int init)
+{
+	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
+	const void *expect;
+	int line;
+
+	if (init) {
+		expect = default_nop; line = __LINE__;
+	} else {
+		expect = jmp->code; line = __LINE__;
+	}
+
+	if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
+		bug_at((void *)jump_entry_code(entry), line);
+}
+
+
 static void __ref __jump_label_transform(struct jump_entry *entry,
 					 enum jump_label_type type,
 					 void *(*poker)(void *, const void *, size_t),
 					 int init)
 {
 	union jump_code_union jmp;
-	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
 	const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
-	const void *expect, *code;
-	int line;
+	const void *code;
 
 	jmp.jump = 0xe9;
 	jmp.offset = jump_entry_target(entry) -
@@ -56,26 +93,13 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
 		poker = text_poke_early;
 
 	if (type == JUMP_LABEL_JMP) {
-		if (init) {
-			expect = default_nop; line = __LINE__;
-		} else {
-			expect = ideal_nop; line = __LINE__;
-		}
-
+		__jump_label_trans_check_enable(entry, type, ideal_nop, init);
 		code = &jmp.code;
 	} else {
-		if (init) {
-			expect = default_nop; line = __LINE__;
-		} else {
-			expect = &jmp.code; line = __LINE__;
-		}
-
+		__jump_label_trans_check_disable(entry, type, &jmp, init);
 		code = ideal_nop;
 	}
 
-	if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
-		bug_at((void *)jump_entry_code(entry), line);
-
 	/*
 	 * Make text_poke_bp() a default fallback poker.
 	 *
-- 
2.17.1