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| author | Cheng Jian <cj.chengjian@huawei.com> | 2020-05-15 13:08:28 +0300 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-05-20 04:08:01 +0300 |
| commit | c143b7753b308d5f7d03b165a7fdff1dda1f271d (patch) | |
| tree | d711efa0801557d5b217391bd711503ce8161db1 | |
| parent | b9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff) | |
| download | linux-c143b7753b308d5f7d03b165a7fdff1dda1f271d.tar.xz | |
ftrace: show debugging information when panic_on_warn set
When an anomaly is detected in the function call modification
code, ftrace_bug() is called to disable function tracing as well
as give some warn and information that may help debug the problem.
But currently, we call FTRACE_WARN_ON_ONCE() first in ftrace_bug(),
so when panic_on_warn is set, we can't see the debugging information
here. Call FTRACE_WARN_ON_ONCE() at the end of ftrace_bug() to ensure
that the debugging information is displayed first.
after this patch, the dmesg looks like:
------------[ ftrace bug ]------------
ftrace failed to modify
[<ffff800010081004>] bcm2835_handle_irq+0x4/0x58
actual: 1f:20:03:d5
Setting ftrace call site to call ftrace function
ftrace record flags: 80000001
(1)
expected tramp: ffff80001009d6f0
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1635 at kernel/trace/ftrace.c:2078 ftrace_bug+0x204/0x238
Kernel panic - not syncing: panic_on_warn set ...
CPU: 2 PID: 1635 Comm: sh Not tainted 5.7.0-rc5-00033-gb922183867f5 #14
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x1b0
show_stack+0x20/0x30
dump_stack+0xc0/0x10c
panic+0x16c/0x368
__warn+0x120/0x160
report_bug+0xc8/0x160
bug_handler+0x28/0x98
brk_handler+0x70/0xd0
do_debug_exception+0xcc/0x1ac
el1_sync_handler+0xe4/0x120
el1_sync+0x7c/0x100
ftrace_bug+0x204/0x238
Link: https://lkml.kernel.org/r/20200515100828.7091-1-cj.chengjian@huawei.com
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/ftrace.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index bd030b1b9514..cd39cbf3631a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2027,14 +2027,14 @@ void ftrace_bug(int failed, struct dyn_ftrace *rec) { unsigned long ip = rec ? rec->ip : 0; + pr_info("------------[ ftrace bug ]------------\n"); + switch (failed) { case -EFAULT: - FTRACE_WARN_ON_ONCE(1); pr_info("ftrace faulted on modifying "); print_ip_sym(ip); break; case -EINVAL: - FTRACE_WARN_ON_ONCE(1); pr_info("ftrace failed to modify "); print_ip_sym(ip); print_ip_ins(" actual: ", (unsigned char *)ip); @@ -2045,12 +2045,10 @@ void ftrace_bug(int failed, struct dyn_ftrace *rec) } break; case -EPERM: - FTRACE_WARN_ON_ONCE(1); pr_info("ftrace faulted on writing "); print_ip_sym(ip); break; default: - FTRACE_WARN_ON_ONCE(1); pr_info("ftrace faulted on unknown error "); print_ip_sym(ip); } @@ -2077,6 +2075,8 @@ void ftrace_bug(int failed, struct dyn_ftrace *rec) ip = ftrace_get_addr_curr(rec); pr_cont("\n expected tramp: %lx\n", ip); } + + FTRACE_WARN_ON_ONCE(1); } static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update) |