[for-next][PATCH 3/3] tracing/fgraph: Have fgraph handle previous boot function addresses

Steven Rostedt
2024-08-15T16:57:56Z

From: Steven Rostedt <rostedt@goodmis.org>

Update the function graph code to modify the function addresses for a
previous boot buffer so that it matches the current kallsyms (note this
does not handle module addresses, yet).

After a reboot, instead of seeing:

# trace-cmd show -B boot_mapped | tail -n30
swapper/0-1 [000] d..2. 56.286470: 0) 0.481 us | 0xffffffff925da5c4();
swapper/0-1 [000] d.... 56.286471: 0) 4.065 us | }
swapper/0-1 [000] d.... 56.286471: 0) 4.920 us | }
swapper/0-1 [000] d..1. 56.286472: 0) | 0xffffffff92536254() {
swapper/0-1 [000] d..1. 56.286472: 0) + 28.974 us | 0xffffffff92534e30();
swapper/0-1 [000] d.... 56.286516: 0) + 43.881 us | }
swapper/0-1 [000] d..1. 56.286517: 0) | 0xffffffff925136c4() {
swapper/0-1 [000] d..1. 56.286518: 0) | 0xffffffff92514a14() {
swapper/0-1 [000] d..1. 56.286518: 0) 6.003 us | 0xffffffff92514200();
swapper/0-1 [000] d.... 56.286529: 0) + 11.510 us | }
swapper/0-1 [000] d.... 56.286529: 0) + 12.895 us | }
swapper/0-1 [000] d.... 56.286530: 0) ! 382.884 us | }
swapper/0-1 [000] d..1. 56.286530: 0) | 0xffffffff92536444() {
swapper/0-1 [000] d..1. 56.286531: 0) | 0xffffffff92536254() {
swapper/0-1 [000] d..1. 56.286531: 0) + 26.335 us | 0xffffffff92534e30();
swapper/0-1 [000] d.... 56.286560: 0) + 29.511 us | }
swapper/0-1 [000] d.... 56.286561: 0) + 30.452 us | }
swapper/0-1 [000] d..1. 56.286562: 0) | 0xffffffff9253c014() {
swapper/0-1 [000] d..1. 56.286562: 0) | 0xffffffff9253bed4() {
swapper/0-1 [000] d..1. 56.286563: 0) + 13.465 us | 0xffffffff92536684();
swapper/0-1 [000] d.... 56.286577: 0) + 14.651 us | }
swapper/0-1 [000] d.... 56.286577: 0) + 15.821 us | }
swapper/0-1 [000] d..1. 56.286578: 0) 0.667 us | 0xffffffff92547074();
swapper/0-1 [000] d..1. 56.286579: 0) 0.453 us | 0xffffffff924f35c4();
swapper/0-1 [000] d.... 56.286580: 0) # 3906.348 us | }
swapper/0-1 [000] d..1. 56.286581: 0) | 0xffffffff92531a14() {
swapper/0-1 [000] d..1. 56.286581: 0) 0.518 us | 0xffffffff92505cb4();
swapper/0-1 [000] d..1. 56.286595: 0) | 0xffffffff92db83c4() {
swapper/0-1 [000] d..1. 56.286596: 0) | 0xffffffff92dec2e4() {
swapper/0-1 [000] d..1. 56.286597: 0) | 0xffffffff92db5304() {

It now shows:

# trace-cmd show -B boot_mapped | tail -n30
swapper/0-1 [000] d..2. 363.079099: 0) 0.483 us | preempt_count_sub();
swapper/0-1 [000] d.... 363.079100: 0) 4.112 us | }
swapper/0-1 [000] d.... 363.079101: 0) 4.979 us | }
swapper/0-1 [000] d..1. 363.079101: 0) | disable_local_APIC() {
swapper/0-1 [000] d..1. 363.079102: 0) + 29.153 us | clear_local_APIC.part.0();
swapper/0-1 [000] d.... 363.079148: 0) + 46.517 us | }
swapper/0-1 [000] d..1. 363.079149: 0) | mcheck_cpu_clear() {
swapper/0-1 [000] d..1. 363.079149: 0) | mce_intel_feature_clear() {
swapper/0-1 [000] d..1. 363.079150: 0) 5.871 us | lmce_supported();
swapper/0-1 [000] d.... 363.079161: 0) + 11.340 us | }
swapper/0-1 [000] d.... 363.079161: 0) + 12.638 us | }
swapper/0-1 [000] d.... 363.079162: 0) ! 383.518 us | }
swapper/0-1 [000] d..1. 363.079162: 0) | lapic_shutdown() {
swapper/0-1 [000] d..1. 363.079163: 0) | disable_local_APIC() {
swapper/0-1 [000] d..1. 363.079163: 0) + 26.144 us | clear_local_APIC.part.0();
swapper/0-1 [000] d.... 363.079192: 0) + 29.424 us | }
swapper/0-1 [000] d.... 363.079192: 0) + 30.376 us | }
swapper/0-1 [000] d..1. 363.079193: 0) | restore_boot_irq_mode() {
swapper/0-1 [000] d..1. 363.079194: 0) | native_restore_boot_irq_mode() {
swapper/0-1 [000] d..1. 363.079194: 0) + 13.863 us | disconnect_bsp_APIC();
swapper/0-1 [000] d.... 363.079209: 0) + 14.933 us | }
swapper/0-1 [000] d.... 363.079209: 0) + 16.009 us | }
swapper/0-1 [000] d..1. 363.079210: 0) 0.694 us | hpet_disable();
swapper/0-1 [000] d..1. 363.079211: 0) 0.511 us | iommu_shutdown_noop();
swapper/0-1 [000] d.... 363.079212: 0) # 3980.260 us | }
swapper/0-1 [000] d..1. 363.079212: 0) | native_machine_emergency_restart() {
swapper/0-1 [000] d..1. 363.079213: 0) 0.495 us | tboot_shutdown();
swapper/0-1 [000] d..1. 363.079230: 0) | acpi_reboot() {
swapper/0-1 [000] d..1. 363.079231: 0) | acpi_reset() {
swapper/0-1 [000] d..1. 363.079232: 0) | acpi_os_write_port() {

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/20240813171257.478901820@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_functions_graph.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 13d0387ac6a6..a569daaac4c4 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -544,6 +544,8 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
struct trace_seq *s = &iter->seq;
struct trace_entry *ent = iter->ent;

+ addr += iter->tr->text_delta;
+
if (addr < (unsigned long)__irqentry_text_start ||
addr >= (unsigned long)__irqentry_text_end)
return;
@@ -710,6 +712,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
struct ftrace_graph_ret *graph_ret;
struct ftrace_graph_ent *call;
unsigned long long duration;
+ unsigned long func;
int cpu = iter->cpu;
int i;

@@ -717,6 +720,8 @@ print_graph_entry_leaf(struct trace_iterator *iter,
call = &entry->graph_ent;
duration = graph_ret->rettime - graph_ret->calltime;

+ func = call->func + iter->tr->text_delta;
+
if (data) {
struct fgraph_cpu_data *cpu_data;

@@ -747,10 +752,10 @@ print_graph_entry_leaf(struct trace_iterator *iter,
* enabled.
*/
if (flags & __TRACE_GRAPH_PRINT_RETVAL)
- print_graph_retval(s, graph_ret->retval, true, (void *)call->func,
+ print_graph_retval(s, graph_ret->retval, true, (void *)func,
!!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
else
- trace_seq_printf(s, "%ps();\n", (void *)call->func);
+ trace_seq_printf(s, "%ps();\n", (void *)func);

print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET,
cpu, iter->ent->pid, flags);
@@ -766,6 +771,7 @@ print_graph_entry_nested(struct trace_iterator *iter,
struct ftrace_graph_ent *call = &entry->graph_ent;
struct fgraph_data *data = iter->private;
struct trace_array *tr = iter->tr;
+ unsigned long func;
int i;

if (data) {
@@ -788,7 +794,9 @@ print_graph_entry_nested(struct trace_iterator *iter,
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');

- trace_seq_printf(s, "%ps() {\n", (void *)call->func);
+ func = call->func + iter->tr->text_delta;
+
+ trace_seq_printf(s, "%ps() {\n", (void *)func);

if (trace_seq_has_overflowed(s))
return TRACE_TYPE_PARTIAL_LINE;
@@ -863,6 +871,8 @@ check_irq_entry(struct trace_iterator *iter, u32 flags,
int *depth_irq;
struct fgraph_data *data = iter->private;

+ addr += iter->tr->text_delta;
+
/*
* If we are either displaying irqs, or we got called as
* a graph event and private data does not exist,
@@ -990,11 +1000,14 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
unsigned long long duration = trace->rettime - trace->calltime;
struct fgraph_data *data = iter->private;
struct trace_array *tr = iter->tr;
+ unsigned long func;
pid_t pid = ent->pid;
int cpu = iter->cpu;
int func_match = 1;
int i;

+ func = trace->func + iter->tr->text_delta;
+
if (check_irq_return(iter, flags, trace->depth))
return TRACE_TYPE_HANDLED;

@@ -1033,7 +1046,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
* function-retval option is enabled.
*/
if (flags & __TRACE_GRAPH_PRINT_RETVAL) {
- print_graph_retval(s, trace->retval, false, (void *)trace->func,
+ print_graph_retval(s, trace->retval, false, (void *)func,
!!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
} else {
/*
@@ -1046,7 +1059,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
trace_seq_puts(s, "}\n");
else
- trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
+ trace_seq_printf(s, "} /* %ps */\n", (void *)func);
}

/* Overrun */
--
2.43.0