commit da1a679cde9b12d6e331f43d2d92a234f2d1f9b0
author Roland McGrath <roland@redhat.com> Thu Jul 19 01:48:39 2007 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> Thu Jul 19 10:04:47 2007 -0700
tree d8cf046a064a1f00443627a6d68b631789882f29
parent 86ead9caf9a9f265f6065c46080d046230e25d78

Add /sys/kernel/notes

This patch adds the /sys/kernel/notes magic file.  Reading this delivers the
contents of the kernel's .notes section.  This lets userland easily glean any
detailed information about the running kernel's build that was stored there at
compile time.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/ksysfs.c

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 559deca..2565e1b 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -62,6 +62,28 @@
 KERNEL_ATTR_RO(kexec_crash_loaded);
 #endif /* CONFIG_KEXEC */
 
+/*
+ * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
+ */
+extern const char __start_notes __attribute__((weak));
+extern const char __stop_notes __attribute__((weak));
+#define	notes_size (&__stop_notes - &__start_notes)
+
+static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
+			  char *buf, loff_t off, size_t count)
+{
+	memcpy(buf, &__start_notes + off, count);
+	return count;
+}
+
+static struct bin_attribute notes_attr = {
+	.attr = {
+		.name = "notes",
+		.mode = S_IRUGO,
+	},
+	.read = &notes_read,
+};
+
 decl_subsys(kernel, NULL, NULL);
 EXPORT_SYMBOL_GPL(kernel_subsys);
 
@@ -88,6 +110,12 @@
 		error = sysfs_create_group(&kernel_subsys.kobj,
 					   &kernel_attr_group);
 
+	if (!error && notes_size > 0) {
+		notes_attr.size = notes_size;
+		error = sysfs_create_bin_file(&kernel_subsys.kobj,
+					      &notes_attr);
+	}
+
 	return error;
 }