Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 05736a42 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

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: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 43a15386

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;

	}