From 126f21f0e8d46e2c0e9daafb67546dbfb316d325 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 10 Mar 2020 23:47:39 +0100 Subject: [PATCH] lib/smp_processor_id: Move it into noinstr section That code is already not traceable. Move it into the noinstr section so the objtool section validation does not trigger. Annotate the warning code as "safe". While it might be not under all circumstances, getting the information out is important enough. Should this ever trigger from the sensitive code which is shielded against instrumentation, e.g. low level entry, then the printk is the least of the worries. Addresses the objtool warnings: vmlinux.o: warning: objtool: context_tracking_recursion_enter()+0x7: call to __this_cpu_preempt_check() leaves .noinstr.text section vmlinux.o: warning: objtool: __context_tracking_exit()+0x17: call to __this_cpu_preempt_check() leaves .noinstr.text section vmlinux.o: warning: objtool: __context_tracking_enter()+0x2a: call to __this_cpu_preempt_check() leaves .noinstr.text section Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134340.902709267@linutronix.de --- lib/smp_processor_id.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index bd9571653288..525222e4f409 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -8,7 +8,7 @@ #include #include -notrace static nokprobe_inline +noinstr static unsigned int check_preemption_disabled(const char *what1, const char *what2) { int this_cpu = raw_smp_processor_id(); @@ -37,6 +37,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2) */ preempt_disable_notrace(); + instrumentation_begin(); if (!printk_ratelimit()) goto out_enable; @@ -45,6 +46,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2) printk("caller is %pS\n", __builtin_return_address(0)); dump_stack(); + instrumentation_end(); out_enable: preempt_enable_no_resched_notrace(); @@ -52,16 +54,14 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2) return this_cpu; } -notrace unsigned int debug_smp_processor_id(void) +noinstr unsigned int debug_smp_processor_id(void) { return check_preemption_disabled("smp_processor_id", ""); } EXPORT_SYMBOL(debug_smp_processor_id); -NOKPROBE_SYMBOL(debug_smp_processor_id); -notrace void __this_cpu_preempt_check(const char *op) +noinstr void __this_cpu_preempt_check(const char *op) { check_preemption_disabled("__this_cpu_", op); } EXPORT_SYMBOL(__this_cpu_preempt_check); -NOKPROBE_SYMBOL(__this_cpu_preempt_check);