Messages in this thread Patch in this message | | | Date | Thu, 21 Aug 2008 10:31:53 -0400 (EDT) | From | Steven Rostedt <> | Subject | [PATCH v2] ftrace: warn on failure to disable mcount callers |
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On Thu, 21 Aug 2008, Ingo Molnar wrote:
> > * Steven Rostedt <rostedt@goodmis.org> wrote: > > > + pr_info("WARNING: ftrace faulted on modifying "); > > + print_ip_sym(ip); > > please use the WARN() API, so that it gets picked up by automation. > > Ingo >
[ Added WARN_ON as requested above. ]
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> --- kernel/trace/ftrace.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)
Index: linux-tip.git/kernel/trace/ftrace.c =================================================================== --- linux-tip.git.orig/kernel/trace/ftrace.c 2008-08-20 21:58:19.000000000 -0400 +++ linux-tip.git/kernel/trace/ftrace.c 2008-08-21 10:19:09.000000000 -0400 @@ -574,6 +574,16 @@ 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) { @@ -588,6 +598,23 @@ 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; }
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