[PATCH 2/2 v3] kprobes: compile out IPMODIFY support if ftrace doesn't support it

From: Jiri Kosina
Date: Thu Jan 15 2015 - 04:50:27 EST


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@xxxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---

v1 -> v2: nothing
v2 -> v3: add Masami's ack and remove superfluous '== 1' comparsions

kernel/kprobes.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 06f5830..dfb296c 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)
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 */
#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)
/* 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 */
return -EINVAL;
#endif
}
--
Jiri Kosina
SUSE Labs
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