From: "H. Peter Anvin" <h...@linux.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 <h...@linux.intel.com> CC: Thomas Renninger <tr...@suse.de> Link: http://lkml.kernel.org/r/201203261651.29640.tr...@suse.de Signed-off-by: Thomas Renninger <tr...@suse.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
