From: Anders Roxell <anders.roxell@xxxxxxxxxx> Subject: kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace Since __sanitizer_cov_trace_pc() is marked as notrace, function calls in __sanitizer_cov_trace_pc() shouldn't be traced either. ftrace_graph_caller() gets called for each function that isn't marked 'notrace', like canonicalize_ip(). This is the call trace from a run: [ 139.644550] ftrace_graph_caller+0x1c/0x24 [ 139.648352] canonicalize_ip+0x18/0x28 [ 139.652313] __sanitizer_cov_trace_pc+0x14/0x58 [ 139.656184] sched_clock+0x34/0x1e8 [ 139.659759] trace_clock_local+0x40/0x88 [ 139.663722] ftrace_push_return_trace+0x8c/0x1f0 [ 139.667767] prepare_ftrace_return+0xa8/0x100 [ 139.671709] ftrace_graph_caller+0x1c/0x24 Rework so that check_kcov_mode() and canonicalize_ip() that are called from __sanitizer_cov_trace_pc() are also marked as notrace. Link: http://lkml.kernel.org/r/20181128081239.18317-1-anders.roxell@xxxxxxxxxx Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Signen-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx> Co-developed-by: Arnd Bergmann <arnd@xxxxxxxx> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/kcov.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/kcov.c~kernel-kcovc-mark-funcs-in-__sanitizer_cov_trace_pc-as-notrace +++ a/kernel/kcov.c @@ -56,7 +56,7 @@ struct kcov { struct task_struct *t; }; -static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) +static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) { unsigned int mode; @@ -78,7 +78,7 @@ static bool check_kcov_mode(enum kcov_mo return mode == needed_mode; } -static unsigned long canonicalize_ip(unsigned long ip) +static notrace unsigned long canonicalize_ip(unsigned long ip) { #ifdef CONFIG_RANDOMIZE_BASE ip -= kaslr_offset(); _
