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ftrace: warn on failure to disable mcount callers

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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>
This commit is contained in:
Steven Rostedt 2008-09-22 14:55:47 -07:00 committed by Ingo Molnar
parent 43a15386c4
commit 05736a427f
1 changed files with 27 additions and 0 deletions
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27
kernel/trace/ftrace.c
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@ -576,6 +576,16 @@ static void ftrace_shutdown_replenish(void)
ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL); 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 static int
ftrace_code_disable(struct dyn_ftrace *rec) 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); failed = ftrace_modify_code(ip, call, nop);
if (failed) { 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; rec->flags |= FTRACE_FL_FAILED;
return 0; return 0;
} }