linux-kernel - [PATCH 2/2] kprobes: compile out IPMODIFY support if ftrace doesn't support it

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Date:	Wed, 14 Jan 2015 09:48:30 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	linux-next@...r.kernel.org
Subject: [PATCH 2/2] kprobes: compile out IPMODIFY support if ftrace doesn't
 support it

If ftrace doesn't claim to support IPMODIFY support, there is no need to 
compile IPMODIFY support in kprobes either.

Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
 kernel/kprobes.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 06f5830..49a69d7 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -912,7 +912,7 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 }
 #endif /* CONFIG_OPTPROBES */
 
-#ifdef CONFIG_KPROBES_ON_FTRACE
+#if defined(CONFIG_KPROBES_ON_FTRACE) && (ftrace_ipmodify_supported == 1)
 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 	.func = kprobe_ftrace_handler,
 	.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
@@ -957,7 +957,7 @@ static void disarm_kprobe_ftrace(struct kprobe *p)
 			   (unsigned long)p->addr, 1, 0);
 	WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 }
-#else	/* !CONFIG_KPROBES_ON_FTRACE */
+#else	/* !CONFIG_KPROBES_ON_FTRACE || ftrace_ipmodify_supported == 0 */
 #define prepare_kprobe(p)	arch_prepare_kprobe(p)
 #define arm_kprobe_ftrace(p)	do {} while (0)
 #define disarm_kprobe_ftrace(p)	do {} while (0)
@@ -1416,12 +1416,12 @@ int __weak arch_check_ftrace_location(struct kprobe *p)
 
 	ftrace_addr = ftrace_location((unsigned long)p->addr);
 	if (ftrace_addr) {
-#ifdef CONFIG_KPROBES_ON_FTRACE
+#if defined(CONFIG_KPROBES_ON_FTRACE) && (ftrace_ipmodify_supported == 1)
 		/* Given address is not on the instruction boundary */
 		if ((unsigned long)p->addr != ftrace_addr)
 			return -EILSEQ;
 		p->flags |= KPROBE_FLAG_FTRACE;
-#else	/* !CONFIG_KPROBES_ON_FTRACE */
+#else	/* !CONFIG_KPROBES_ON_FTRACE || ftrace_ipmodify_supported == 0 */
 		return -EINVAL;
 #endif
 	}

-- 
Jiri Kosina
SUSE Labs

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