linux-kernel - [PATCH V3 4/9] x86/jump_label: Add __jump_label_set_jump

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Message-Id: <eb97675f0d139aa6f78874db3abc81fcdba7a80f.1545228276.git.bristot@redhat.com>
Date:   Fri, 21 Dec 2018 11:27:29 +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 4/9] x86/jump_label: Add __jump_label_set_jump_code() helper

Move the definition of the code to be written from
__jump_label_transform() to a specialized function. No change in the
method, code relocation only.

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 | 38 +++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 7894080bd02f..a039ac4ca5bf 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -75,30 +75,36 @@ static inline void __jump_label_trans_check_disable(struct jump_entry *entry,
 		bug_at((void *)jump_entry_code(entry), line);
 }
 
+static void __jump_label_set_jump_code(struct jump_entry *entry,
+				       enum jump_label_type type,
+				       union jump_code_union *code,
+				       int init)
+{
+	const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
+
+	code->jump = 0xe9;
+	code->offset = jump_entry_target(entry) -
+		     (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
+
+	if (type == JUMP_LABEL_JMP) {
+		__jump_label_trans_check_enable(entry, type, ideal_nop, init);
+	} else {
+		__jump_label_trans_check_disable(entry, type, code, init);
+		memcpy(code, ideal_nop, JUMP_LABEL_NOP_SIZE);
+	}
+}
 
 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 *ideal_nop = ideal_nops[NOP_ATOMIC5];
-	const void *code;
-
-	jmp.jump = 0xe9;
-	jmp.offset = jump_entry_target(entry) -
-		     (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
+	union jump_code_union code;
 
 	if (early_boot_irqs_disabled)
 		poker = text_poke_early;
 
-	if (type == JUMP_LABEL_JMP) {
-		__jump_label_trans_check_enable(entry, type, ideal_nop, init);
-		code = &jmp.code;
-	} else {
-		__jump_label_trans_check_disable(entry, type, &jmp, init);
-		code = ideal_nop;
-	}
+	__jump_label_set_jump_code(entry, type, &code, init);
 
 	/*
 	 * Make text_poke_bp() a default fallback poker.
@@ -109,12 +115,12 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
 	 *
 	 */
 	if (poker) {
-		(*poker)((void *)jump_entry_code(entry), code,
+		(*poker)((void *)jump_entry_code(entry), &code,
 			 JUMP_LABEL_NOP_SIZE);
 		return;
 	}
 
-	text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,
+	text_poke_bp((void *)jump_entry_code(entry), &code, JUMP_LABEL_NOP_SIZE,
 		     (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 }
 
-- 
2.17.1