[PATCH] Kernel .patches support

[Christian Hesse <mail@earthworm.de>]

Hi everybody,

every time I apply a patch to my kernel tree I (or my scripts) make an

echo $PATCHNAME $PATCHVERSION >> .patches

This patch makes the file accessible via /proc/patches.gz. I think this can be 
handy if you want to know what patches you (or your distributor) applied to 
your running kernel...

Most of the code is copy & past from CONFIG_IKCONFIG[_PROC].

Let me know what you think.

Regards,
-- 
Christian

diff -Nur linux-2.6.12+/include/linux/patches.h linux-2.6.12+-patches/include/linux/patches.h
--- linux-2.6.12+/include/linux/patches.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.12+-patches/include/linux/patches.h	2005-06-23 23:10:15.278685000 +0200
@@ -0,0 +1,6 @@
+#ifndef _LINUX_PATCHES_H
+#define _LINUX_PATCHES_H
+
+#include <linux/autoconf.h>
+
+#endif
diff -Nur linux-2.6.12+/init/Kconfig linux-2.6.12+-patches/init/Kconfig
--- linux-2.6.12+/init/Kconfig	2005-06-23 23:16:40.748685000 +0200
+++ linux-2.6.12+-patches/init/Kconfig	2005-06-23 23:10:16.928685000 +0200
@@ -226,6 +226,25 @@
 	  This option enables access to the kernel configuration file
 	  through /proc/config.gz.
 
+config IKPATCHES
+	bool "Kernel .patches support"
+	---help---
+	  This option enables the complete Linux kernel ".patches" file
+	  contents to be saved in the kernel. It provides documentation
+	  of which kernel patches are applied in a running kernel. This
+	  information can be extracted from the kernel image file with
+	  the script scripts/extract-ikpatches and used as input to
+	  rebuild the current kernel or to build another kernel.
+	  It can also be extracted from a running kernel by reading
+	  /proc/patches.gz if enabled (below).
+
+config IKPATCHES_PROC
+	bool "Enable access to .patches through /proc/patches.gz"
+	depends on IKPATCHES && PROC_FS
+	---help---
+	  This option enables access to the kernel patches file
+	  through /proc/patches.gz.
+
 config CPUSETS
 	bool "Cpuset support"
 	depends on SMP
diff -Nur linux-2.6.12+/kernel/Makefile linux-2.6.12+-patches/kernel/Makefile
--- linux-2.6.12+/kernel/Makefile	2005-06-23 23:17:13.248685000 +0200
+++ linux-2.6.12+-patches/kernel/Makefile	2005-06-23 23:10:17.218685000 +0200
@@ -21,6 +21,8 @@
 obj-$(CONFIG_CPUSETS) += cpuset.o
 obj-$(CONFIG_IKCONFIG) += configs.o
 obj-$(CONFIG_IKCONFIG_PROC) += configs.o
+obj-$(CONFIG_IKPATCHES) += patches.o
+obj-$(CONFIG_IKPATCHES_PROC) += patches.o
 obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
 obj-$(CONFIG_AUDIT) += audit.o
 obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
@@ -52,3 +54,17 @@
 targets += config_data.h
 $(obj)/config_data.h: $(obj)/config_data.gz FORCE
 	$(call if_changed,ikconfiggz)
+
+$(obj)/patches.o: $(obj)/patches_data.h
+
+# patches_data.h contains the same information as ikpatches.h but gzipped.
+# Info from patches_data can be extracted from /proc/patches*
+targets += patches_data.gz
+$(obj)/patches_data.gz: .patches FORCE
+	$(call if_changed,gzip)
+
+quiet_cmd_ikpatchesgz = IKPTC   $@
+      cmd_ikpatchesgz = (echo "static const char kernel_patches_data[] = MAGIC_START"; cat $< | scripts/bin2c; echo "MAGIC_END;") > $@
+targets += patches_data.h
+$(obj)/patches_data.h: $(obj)/patches_data.gz FORCE
+	$(call if_changed,ikpatchesgz)
diff -Nur linux-2.6.12+/kernel/patches.c linux-2.6.12+-patches/kernel/patches.c
--- linux-2.6.12+/kernel/patches.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.12+-patches/kernel/patches.c	2005-06-23 23:10:17.608685000 +0200
@@ -0,0 +1,115 @@
+/*
+ * kernel/patches.c
+ * Echo the kernel .patches file used to build the kernel
+ *
+ * Copyright (C) 2005 Christian Hesse <Christi@n-Hesse.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/patches.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+
+/**************************************************/
+/* the actual current patchesfile                 */
+
+/*
+ * Define kernel_patches_data and kernel_patches_data_size, which contains the
+ * wrapped and compressed patches file.  The file is first compressed
+ * with gzip and then bounded by two eight byte magic numbers to allow
+ * extraction from a binary kernel image:
+ *
+ *   IKPTC_ST
+ *   <image>
+ *   IKPTC_ED
+ */
+#define MAGIC_START	"IKPTC_ST"
+#define MAGIC_END	"IKPTC_ED"
+#include "patches_data.h"
+
+
+#define MAGIC_SIZE (sizeof(MAGIC_START) - 1)
+#define kernel_patches_data_size \
+	(sizeof(kernel_patches_data) - 1 - MAGIC_SIZE * 2)
+
+#ifdef CONFIG_IKPATCHES_PROC
+
+/**************************************************/
+/* globals and useful constants                   */
+
+static ssize_t
+ikpatches_read_current(struct file *file, char __user *buf,
+		      size_t len, loff_t * offset)
+{
+	loff_t pos = *offset;
+	ssize_t count;
+
+	if (pos >= kernel_patches_data_size)
+		return 0;
+
+	count = min(len, (size_t)(kernel_patches_data_size - pos));
+	if (copy_to_user(buf, kernel_patches_data + MAGIC_SIZE + pos, count))
+		return -EFAULT;
+
+	*offset += count;
+	return count;
+}
+
+static struct file_operations ikpatches_file_ops = {
+	.owner = THIS_MODULE,
+	.read = ikpatches_read_current,
+};
+
+/***************************************************/
+/* ikpatches_init: start up everything we need to */
+
+static int __init ikpatches_init(void)
+{
+	struct proc_dir_entry *entry;
+
+	/* create the current patches file */
+	entry = create_proc_entry("patches.gz", S_IFREG | S_IRUGO,
+				  &proc_root);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->proc_fops = &ikpatches_file_ops;
+	entry->size = kernel_patches_data_size;
+
+	return 0;
+}
+
+/***************************************************/
+/* ikpatches_cleanup: clean up our mess           */
+
+static void __exit ikpatches_cleanup(void)
+{
+	remove_proc_entry("patches.gz", &proc_root);
+}
+
+module_init(ikpatches_init);
+module_exit(ikpatches_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Hesse");
+MODULE_DESCRIPTION("Echo the kernel .patch file that lists applied patches");
+
+#endif /* CONFIG_IKPATCHES_PROC */

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