[PATCH] Kernel .patches support

Christian Hesse
2005-06-23T22:06:35Z

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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

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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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