The patch titled
ftrace: warn on failure to disable mcount callers
has been added to the -mm tree. Its filename is
ftrace-warn-on-failure-to-disable-mcount-callers.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ftrace: warn on failure to disable mcount callers
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff -puN kernel/trace/ftrace.c~ftrace-warn-on-failure-to-disable-mcount-callers kernel/trace/ftrace.c
--- a/kernel/trace/ftrace.c~ftrace-warn-on-failure-to-disable-mcount-callers
+++ a/kernel/trace/ftrace.c
@@ -576,6 +576,16 @@ static void ftrace_shutdown_replenish(vo
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 *r
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;
}
_
Patches currently in -mm which might be from rostedt@xxxxxxxxxxx are
linux-next.patch
kbuild-ftrace-dont-assume-that-scripts-recordmcountpl-is-executable.patch
ftrace-warn-on-failure-to-disable-mcount-callers.patch
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