From b3aa557722b3d5858f14ca559e03461c24125aaf Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 31 Oct 2008 15:44:07 -0400 Subject: [PATCH] ftrace: use kretprobe trampoline name to test in output Impact: ia64+tracing build fix When a function is kprobed, the return address is set to the kprobe_trampoline, or something similar. This caused the output of the trace to look confusing when the parent seemed to be this "kprobe_trampoline" function. To fix this, Abhishek Sagar added a test of the instruction pointer of the parent to see if it matched the kprobe_trampoline. If it did, the output would print a "[unknown/kretprobe'd]" instead. Unfortunately, not all archs do this the same way, and the trampoline function may not be exported, which causes failures in builds. This patch will compare the name instead of the pointer to see if it matches. This prevents us from depending on a function from being exported, and should work on all archs. The worst that can happen is that an arch might use a different name and then we go back to the confusing output. At least the arch will still build. Reported-by: Abhishek Sagar Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar Tested-by: Abhishek Sagar Acked-by: Abhishek Sagar --- kernel/trace/trace.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 85bee775a03e..9f3b478f9171 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1088,17 +1088,20 @@ static void s_stop(struct seq_file *m, void *p) mutex_unlock(&trace_types_lock); } -#define KRETPROBE_MSG "[unknown/kretprobe'd]" - #ifdef CONFIG_KRETPROBES -static inline int kretprobed(unsigned long addr) +static inline const char *kretprobed(const char *name) { - return addr == (unsigned long)kretprobe_trampoline; + static const char tramp_name[] = "kretprobe_trampoline"; + int size = sizeof(tramp_name); + + if (strncmp(tramp_name, name, size) == 0) + return "[unknown/kretprobe'd]"; + return name; } #else -static inline int kretprobed(unsigned long addr) +static inline const char *kretprobed(const char *name) { - return 0; + return name; } #endif /* CONFIG_KRETPROBES */ @@ -1107,10 +1110,13 @@ seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address) { #ifdef CONFIG_KALLSYMS char str[KSYM_SYMBOL_LEN]; + const char *name; kallsyms_lookup(address, NULL, NULL, NULL, str); - return trace_seq_printf(s, fmt, str); + name = kretprobed(str); + + return trace_seq_printf(s, fmt, name); #endif return 1; } @@ -1121,9 +1127,12 @@ seq_print_sym_offset(struct trace_seq *s, const char *fmt, { #ifdef CONFIG_KALLSYMS char str[KSYM_SYMBOL_LEN]; + const char *name; sprint_symbol(str, address); - return trace_seq_printf(s, fmt, str); + name = kretprobed(str); + + return trace_seq_printf(s, fmt, name); #endif return 1; } @@ -1377,10 +1386,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) seq_print_ip_sym(s, field->ip, sym_flags); trace_seq_puts(s, " ("); - if (kretprobed(field->parent_ip)) - trace_seq_puts(s, KRETPROBE_MSG); - else - seq_print_ip_sym(s, field->parent_ip, sym_flags); + seq_print_ip_sym(s, field->parent_ip, sym_flags); trace_seq_puts(s, ")\n"); break; } @@ -1496,12 +1502,9 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter) ret = trace_seq_printf(s, " <-"); if (!ret) return TRACE_TYPE_PARTIAL_LINE; - if (kretprobed(field->parent_ip)) - ret = trace_seq_puts(s, KRETPROBE_MSG); - else - ret = seq_print_ip_sym(s, - field->parent_ip, - sym_flags); + ret = seq_print_ip_sym(s, + field->parent_ip, + sym_flags); if (!ret) return TRACE_TYPE_PARTIAL_LINE; } -- GitLab