ftrace: warn on failure to disable mcount callers (05736a42) · Commits · 戴 / test

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>

kernel/trace/ftrace.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

Admin message