linux-kernel - [RFC][PATCH v3 12/16] printk: Register information into Kmemdump

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Message-ID: <20250912150855.2901211-13-eugen.hristev@linaro.org>
Date: Fri, 12 Sep 2025 18:08:51 +0300
From: Eugen Hristev <eugen.hristev@...aro.org>
To: linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	tglx@...utronix.de,
	andersson@...nel.org,
	pmladek@...e.com,
	rdunlap@...radead.org,
	corbet@....net,
	david@...hat.com,
	mhocko@...e.com
Cc: tudor.ambarus@...aro.org,
	mukesh.ojha@....qualcomm.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-hardening@...r.kernel.org,
	jonechou@...gle.com,
	rostedt@...dmis.org,
	linux-doc@...r.kernel.org,
	devicetree@...r.kernel.org,
	Eugen Hristev <eugen.hristev@...aro.org>
Subject: [RFC][PATCH v3 12/16] printk: Register information into Kmemdump

Kmemdump requires the prb, data, descriptors and info.
Add it inside the log_buf_vmcoreinfo_setup()

In the case when the log buffer is dynamically replaced by a runtime
allocated version, call kmemdump to register the data but call unregister
to remove the old registered data first.

Signed-off-by: Eugen Hristev <eugen.hristev@...aro.org>
---
 kernel/printk/printk.c | 47 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5aee9ffb16b9..f75489fd82df 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -49,6 +49,7 @@
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/panic.h>
+#include <linux/kmemdump.h>
 
 #include <linux/uaccess.h>
 #include <asm/sections.h>
@@ -964,6 +965,43 @@ const struct file_operations kmsg_fops = {
 };
 
 #ifdef CONFIG_VMCORE_INFO
+static void log_buf_vmcoreinfo_kmemdump_update(void *data, size_t data_size,
+					       void *descs, size_t descs_size,
+					       void *infos, size_t infos_size)
+{
+	kmemdump_unregister(KMEMDUMP_ID_COREIMAGE_prb_data);
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_data,
+			     (void *)data, data_size);
+
+	kmemdump_unregister(KMEMDUMP_ID_COREIMAGE_prb_descs);
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_descs,
+			     (void *)descs, descs_size);
+
+	kmemdump_unregister(KMEMDUMP_ID_COREIMAGE_prb_infos);
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_infos,
+			     (void *)infos, infos_size);
+}
+
+static void log_buf_vmcoreinfo_kmemdump(void)
+{
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb,
+			     (void *)&prb, sizeof(prb));
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_descs,
+			     (void *)&_printk_rb_static_descs,
+			     sizeof(_printk_rb_static_descs));
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_infos,
+			     (void *)&_printk_rb_static_infos,
+			     sizeof(_printk_rb_static_infos));
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_prb_data,
+			     (void *)&__log_buf, __LOG_BUF_LEN);
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_printk_rb_static,
+			     (void *)&printk_rb_static,
+			     sizeof(printk_rb_static));
+	kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_printk_rb_dynamic,
+			     (void *)&printk_rb_dynamic,
+			     sizeof(printk_rb_dynamic));
+}
+
 /*
  * This appends the listed symbols to /proc/vmcore
  *
@@ -1029,6 +1067,8 @@ void log_buf_vmcoreinfo_setup(void)
 
 	VMCOREINFO_STRUCT_SIZE(latched_seq);
 	VMCOREINFO_OFFSET(latched_seq, val);
+
+	log_buf_vmcoreinfo_kmemdump();
 }
 #endif
 
@@ -1214,6 +1254,11 @@ void __init setup_log_buf(int early)
 		 new_descs, ilog2(new_descs_count),
 		 new_infos);
 
+#ifdef CONFIG_VMCORE_INFO
+	log_buf_vmcoreinfo_kmemdump_update(new_log_buf, new_log_buf_len,
+					   new_descs, new_descs_size,
+					   new_infos, new_infos_size);
+#endif
 	local_irq_save(flags);
 
 	log_buf_len = new_log_buf_len;
@@ -1257,8 +1302,10 @@ void __init setup_log_buf(int early)
 	return;
 
 err_free_descs:
+	kmemdump_unregister(KMEMDUMP_ID_COREIMAGE_prb_descs);
 	memblock_free(new_descs, new_descs_size);
 err_free_log_buf:
+	kmemdump_unregister(KMEMDUMP_ID_COREIMAGE_prb_data);
 	memblock_free(new_log_buf, new_log_buf_len);
 out:
 	print_log_buf_usage_stats();
-- 
2.43.0