diff options
Diffstat (limited to '')
| -rw-r--r-- | kernel/trace/trace.c | 44 |
1 files changed, 29 insertions, 15 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8e28f19f5316..35b37c9aa26c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -502,6 +502,17 @@ static struct trace_array global_trace = { static struct trace_array *printk_trace = &global_trace; +static __always_inline bool printk_binsafe(struct trace_array *tr) +{ + /* + * The binary format of traceprintk can cause a crash if used + * by a buffer from another boot. Force the use of the + * non binary version of trace_printk if the trace_printk + * buffer is a boot mapped ring buffer. + */ + return !(tr->flags & TRACE_ARRAY_FL_BOOT); +} + void trace_set_ring_buffer_expanded(struct trace_array *tr) { if (!tr) @@ -1130,7 +1141,7 @@ EXPORT_SYMBOL_GPL(__trace_puts); */ int __trace_bputs(unsigned long ip, const char *str) { - struct trace_array *tr = printk_trace; + struct trace_array *tr = READ_ONCE(printk_trace); struct ring_buffer_event *event; struct trace_buffer *buffer; struct bputs_entry *entry; @@ -1138,6 +1149,9 @@ int __trace_bputs(unsigned long ip, const char *str) int size = sizeof(struct bputs_entry); int ret = 0; + if (!printk_binsafe(tr)) + return __trace_puts(ip, str, strlen(str)); + if (!(tr->trace_flags & TRACE_ITER_PRINTK)) return 0; @@ -3247,12 +3261,15 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) struct trace_event_call *call = &event_bprint; struct ring_buffer_event *event; struct trace_buffer *buffer; - struct trace_array *tr = printk_trace; + struct trace_array *tr = READ_ONCE(printk_trace); struct bprint_entry *entry; unsigned int trace_ctx; char *tbuffer; int len = 0, size; + if (!printk_binsafe(tr)) + return trace_vprintk(ip, fmt, args); + if (unlikely(tracing_selftest_running || tracing_disabled)) return 0; @@ -10560,20 +10577,17 @@ __init static void enable_instances(void) if (traceoff) tracer_tracing_off(tr); - if (traceprintk) { - /* - * The binary format of traceprintk can cause a crash if used - * by a buffer from another boot. Do not allow it for the - * memory mapped ring buffers. - */ - if (start) - pr_warn("Tracing: WARNING: memory mapped ring buffers cannot be used for trace_printk\n"); - else - printk_trace = tr; - } + if (traceprintk) + printk_trace = tr; - /* Only allow non mapped buffers to be deleted */ - if (!start) + /* + * If start is set, then this is a mapped buffer, and + * cannot be deleted by user space, so keep the reference + * to it. + */ + if (start) + tr->flags |= TRACE_ARRAY_FL_BOOT; + else trace_array_put(tr); while ((tok = strsep(&curr_str, ","))) { |