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Date: Thu, 30 Aug 2012 11:29:16 +0200
From: Thomas Renninger <trenn@...e.de>
To: hpa@...or.com
Cc: linux-kernel@...r.kernel.org, lenb@...nel.org,
robert.moore@...el.com, ming.m.lin@...el.com,
initramfs@...r.kernel.org, bigeasy@...utronix.de, vojcek@...n.pl,
eric.piel@...mplin-utc.net, linux-acpi@...r.kernel.org,
yinghai@...nel.org, "H. Peter Anvin" <hpa@...ux.intel.com>,
Thomas Renninger <trenn@...e.de>
Subject: [PATCH 1/2] lib: Add early cpio decoder
From: "H. Peter Anvin" <hpa@...ux.intel.com>
Add a simple cpio decoder without library dependencies for the purpose
of extracting components from the initramfs blob for early kernel
uses. Intended consumers so far are microcode and ACPI override.
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
CC: Thomas Renninger <trenn@...e.de>
Link: http://lkml.kernel.org/r/201203261651.29640.trenn@suse.de
Signed-off-by: Thomas Renninger <trenn@...e.de>
---
include/linux/earlycpio.h | 13 ++++
lib/Makefile | 2 +-
lib/earlycpio.c | 173 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 187 insertions(+), 1 deletions(-)
create mode 100644 include/linux/earlycpio.h
create mode 100644 lib/earlycpio.c
diff --git a/include/linux/earlycpio.h b/include/linux/earlycpio.h
new file mode 100644
index 0000000..06db026
--- /dev/null
+++ b/include/linux/earlycpio.h
@@ -0,0 +1,13 @@
+#ifndef _LINUX_EARLYCPIO_H
+#define _LINUX_EARLYCPIO_H
+
+#include <linux/types.h>
+
+struct cpio_data {
+ void *data;
+ size_t size;
+};
+
+struct cpio_data find_cpio_data(const char *name, const void *data, size_t len);
+
+#endif /* _LINUX_EARLYCPIO_H */
diff --git a/lib/Makefile b/lib/Makefile
index 42d283e..0924041 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -12,7 +12,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
- is_single_threaded.o plist.o decompress.o
+ is_single_threaded.o plist.o decompress.o earlycpio.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/earlycpio.c b/lib/earlycpio.c
new file mode 100644
index 0000000..b16b80b
--- /dev/null
+++ b/lib/earlycpio.c
@@ -0,0 +1,173 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2012 Intel Corporation; author H. Peter Anvin
+ *
+ * This file is part of the Linux kernel, and is made available
+ * under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * earlycpio.c
+ *
+ * Find a specific cpio member; must precede any compressed content.
+ * This is used to locate data items in the initramfs used by the
+ * kernel itself during early boot (before the main initramfs is
+ * decompressed.) It is the responsibility of the initramfs creator
+ * to ensure that these items are uncompressed at the head of the
+ * blob. Depending on the boot loader or package tool that may be a
+ * separate file or part of the same file.
+ *
+ * For some architectures, e.g. i386, this file must compile to have
+ * no relocations and no library dependencies, so it can be called from
+ * a nonstandard environment. Therefore some normal library functions
+ * are inlined in this file.
+ */
+
+#include <linux/earlycpio.h>
+#include <linux/kernel.h>
+
+enum cpio_fields {
+ C_MAGIC,
+ C_INO,
+ C_MODE,
+ C_UID,
+ C_GID,
+ C_NLINK,
+ C_MTIME,
+ C_FILESIZE,
+ C_MAJ,
+ C_MIN,
+ C_RMAJ,
+ C_RMIN,
+ C_NAMESIZE,
+ C_CHKSUM,
+ C_NFIELDS
+};
+
+#ifdef CONFIG_X86
+static inline size_t strlen(const char *name)
+{
+ size_t n = -1;
+
+ asm("repne; scasb"
+ : "+D" (name), "+c" (n)
+ : "a" (0));
+
+ return -2 - n;
+}
+
+static inline int memcmp(const void *p1, const void *p2, size_t n)
+{
+ unsigned char rv;
+
+ asm("repe; cmpsb; setne %0"
+ : "=r" (rv), "+S" (p1), "+D" (p2), "+c" (n));
+
+ return rv;
+}
+#else
+static inline size_t strlen(const char *name)
+{
+ size_t n = 0;
+
+ while (*name++)
+ n++;
+
+ return n;
+}
+
+static inline int memcmp(const void *p1, const void *p2, size_t n)
+{
+ const unsigned char *u1 = p1;
+ const unsigned char *u2 = p2;
+ int d;
+
+ while (n--) {
+ d = *u2++ - *u1++;
+ if (d)
+ return d;
+ }
+ return 0;
+}
+#endif
+
+struct cpio_data __cpuinit find_cpio_data(const char *name,
+ const void *data, size_t len)
+{
+ const size_t cpio_header_len = 8*C_NFIELDS - 2;
+ struct cpio_data cd = { NULL, 0 };
+ const char *p, *dptr, *nptr;
+ unsigned int ch[C_NFIELDS], *chp, v;
+ unsigned char c, x;
+ size_t mynamesize = strlen(name) + 1;
+ int i, j;
+
+ p = data;
+
+ while (len > cpio_header_len) {
+ if (!*p) {
+ /* All cpio headers need to be 4-byte aligned */
+ p += 4;
+ len -= 4;
+ continue;
+ }
+
+ j = 6; /* The magic field is only 6 characters */
+ chp = ch;
+ for (i = C_NFIELDS; i; i--) {
+ v = 0;
+ while (j--) {
+ v <<= 4;
+ c = *p++;
+
+ x = c - '0';
+ if (x < 10) {
+ v += x;
+ continue;
+ }
+
+ x = (c | 0x20) - 'a';
+ if (x < 6) {
+ v += x + 10;
+ continue;
+ }
+
+ goto quit; /* Invalid hexadecimal */
+ }
+ *chp++ = v;
+ j = 8; /* All other fields are 8 characters */
+ }
+
+ if ((ch[C_MAGIC] - 0x070701) > 1)
+ goto quit; /* Invalid magic */
+
+ len -= cpio_header_len;
+
+ dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
+ nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
+
+ if (nptr > p + len || dptr < p || nptr < dptr)
+ goto quit; /* Buffer overrun */
+
+ if ((ch[C_MODE] & 0170000) == 0100000 &&
+ ch[C_NAMESIZE] == mynamesize &&
+ !memcmp(p, name, mynamesize)) {
+ cd.data = (void *)dptr;
+ cd.size = ch[C_FILESIZE];
+ return cd; /* Found it! */
+ }
+
+ len -= (nptr - p);
+ p = nptr;
+ }
+
+quit:
+ return cd;
+}
--
1.7.6.1
--
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