From 028a58ec154257e618c27fb0eba8d9e30379bc3d Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Wed, 26 Mar 2025 22:03:04 -0400
Subject: [PATCH] tracing: Use _text and the kernel offset in last_boot_info
Instead of using kaslr_offset() just record the location of "_text". This
makes it possible for user space to use either the System.map or
/proc/kallsyms as what to map all addresses to functions with.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250326220304.38dbedcd@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index fa17397fdc1f..14c38fcd6f9e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -51,7 +51,7 @@
#include <linux/workqueue.h>
#include <linux/sort.h>
-#include <asm/setup.h> /* COMMAND_LINE_SIZE and kaslr_offset() */
+#include <asm/setup.h> /* COMMAND_LINE_SIZE */
#include "trace.h"
#include "trace_output.h"
@@ -5995,7 +5995,7 @@ struct trace_mod_entry {
};
struct trace_scratch {
- unsigned long kaslr_addr;
+ unsigned long text_addr;
unsigned long nr_entries;
struct trace_mod_entry entries[];
};
@@ -6133,11 +6133,7 @@ static void update_last_data(struct trace_array *tr)
kfree_rcu(module_delta, rcu);
/* Set the persistent ring buffer meta data to this address */
-#ifdef CONFIG_RANDOMIZE_BASE
- tscratch->kaslr_addr = kaslr_offset();
-#else
- tscratch->kaslr_addr = 0;
-#endif
+ tscratch->text_addr = (unsigned long)_text;
}
/**
@@ -6996,7 +6992,7 @@ static void show_last_boot_header(struct seq_file *m, struct trace_array *tr)
* should not be the same as the current boot.
*/
if (tscratch && (tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
- seq_printf(m, "%lx\t[kernel]\n", tscratch->kaslr_addr);
+ seq_printf(m, "%lx\t[kernel]\n", tscratch->text_addr);
else
seq_puts(m, "# Current\n");
}
@@ -9465,10 +9461,8 @@ static void setup_trace_scratch(struct trace_array *tr,
tr->scratch = tscratch;
tr->scratch_size = size;
-#ifdef CONFIG_RANDOMIZE_BASE
- if (tscratch->kaslr_addr)
- tr->text_delta = kaslr_offset() - tscratch->kaslr_addr;
-#endif
+ if (tscratch->text_addr)
+ tr->text_delta = (unsigned long)_text - tscratch->text_addr;
if (struct_size(tscratch, entries, tscratch->nr_entries) > size)
goto reset;
--
2.50.1