kprobes/x86: Make boostable flag boolean

Make arch_specific_insn.boostable to boolean, since it has
only 2 states, boostable or not. So it is better to use
boolean from the viewpoint of code readability.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/149076368566.22469.6322906866458231844.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/kprobes.h

@@ -72,14 +72,13 @@ struct arch_specific_insn {
 	/* copy of the original instruction */
 	kprobe_opcode_t *insn;
 	/*
-	 * boostable = -1: This instruction type is not boostable.
-	 * boostable = 0: This instruction type is boostable.
-	 * boostable = 1: This instruction has been boosted: we have
+	 * boostable = false: This instruction type is not boostable.
+	 * boostable = true: This instruction has been boosted: we have
 	 * added a relative jump after the instruction copy in insn,
 	 * so no single-step and fixup are needed (unless there's
 	 * a post_handler or break_handler).
 	 */
-	int boostable;
+	bool boostable;
 	bool if_modifier;
 };
 

arch/x86/kernel/kprobes/core.c

@@ -409,9 +409,9 @@ static void prepare_boost(struct kprobe *p, int length)
 		 * jumps back to correct address.
 		 */
 		synthesize_reljump(p->ainsn.insn + length, p->addr + length);
-		p->ainsn.boostable = 1;
+		p->ainsn.boostable = true;
 	} else {
-		p->ainsn.boostable = -1;
+		p->ainsn.boostable = false;
 	}
 }
 
@@ -467,7 +467,7 @@ void arch_disarm_kprobe(struct kprobe *p)
 void arch_remove_kprobe(struct kprobe *p)
 {
 	if (p->ainsn.insn) {
-		free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
+		free_insn_slot(p->ainsn.insn, p->ainsn.boostable);
 		p->ainsn.insn = NULL;
 	}
 }
@@ -539,7 +539,7 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
 		return;
 
 #if !defined(CONFIG_PREEMPT)
-	if (p->ainsn.boostable == 1 && !p->post_handler) {
+	if (p->ainsn.boostable && !p->post_handler) {
 		/* Boost up -- we can execute copied instructions directly */
 		if (!reenter)
 			reset_current_kprobe();
@@ -859,7 +859,7 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs,
 	case 0xcf:
 	case 0xea:	/* jmp absolute -- ip is correct */
 		/* ip is already adjusted, no more changes required */
-		p->ainsn.boostable = 1;
+		p->ainsn.boostable = true;
 		goto no_change;
 	case 0xe8:	/* call relative - Fix return addr */
 		*tos = orig_ip + (*tos - copy_ip);
@@ -884,7 +884,7 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs,
 			 * jmp near and far, absolute indirect
 			 * ip is correct. And this is boostable
 			 */
-			p->ainsn.boostable = 1;
+			p->ainsn.boostable = true;
 			goto no_change;
 		}
 	default:

arch/x86/kernel/kprobes/ftrace.c

@@ -94,6 +94,6 @@ NOKPROBE_SYMBOL(kprobe_ftrace_handler);
 int arch_prepare_kprobe_ftrace(struct kprobe *p)
 {
 	p->ainsn.insn = NULL;
-	p->ainsn.boostable = -1;
+	p->ainsn.boostable = false;
 	return 0;
 }