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authorSteven Rostedt <rostedt@goodmis.org>2008-09-22 14:55:47 -0700
committerIngo Molnar <mingo@elte.hu>2008-10-14 10:38:11 +0200
commit05736a427f7e16be948ccbf39782bd3a6ae16b14 (patch)
tree6efd6991853918242947df308be60b14a6fa5e80 /kernel/trace/ftrace.c
parent43a15386c4faf913f7d70a47748c266d6210cd6e (diff)
ftrace: warn on failure to disable mcount callers
With the recent updates to ftrace, there should not be any failures when modifying the code. If there is, then we need to warn about it. This patch has a cleaned up version of the code that I used to discover that the weak symbols were causing failures. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/ftrace.c')
-rw-r--r--kernel/trace/ftrace.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7694f3e5979..4dda4f60a2a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -576,6 +576,16 @@ static void ftrace_shutdown_replenish(void)
ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
}
+static void print_ip_ins(const char *fmt, unsigned char *p)
+{
+ int i;
+
+ printk(KERN_CONT "%s", fmt);
+
+ for (i = 0; i < MCOUNT_INSN_SIZE; i++)
+ printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
+}
+
static int
ftrace_code_disable(struct dyn_ftrace *rec)
{
@@ -590,6 +600,23 @@ ftrace_code_disable(struct dyn_ftrace *rec)
failed = ftrace_modify_code(ip, call, nop);
if (failed) {
+ switch (failed) {
+ case 1:
+ WARN_ON_ONCE(1);
+ pr_info("ftrace faulted on modifying ");
+ print_ip_sym(ip);
+ break;
+ case 2:
+ WARN_ON_ONCE(1);
+ pr_info("ftrace failed to modify ");
+ print_ip_sym(ip);
+ print_ip_ins(" expected: ", call);
+ print_ip_ins(" actual: ", (unsigned char *)ip);
+ print_ip_ins(" replace: ", nop);
+ printk(KERN_CONT "\n");
+ break;
+ }
+
rec->flags |= FTRACE_FL_FAILED;
return 0;
}