Re: [PATCH v2 6/6] kexec, x86_64: put 64bit bzImage high

Eric W. Biederman
2012-11-19T17:28:32Z

Yinghai Lu <yinghai@kernel.org> writes:

> need to make sure pass right 64bit start address to go there directly
> later.

Instead of playing games with the definition of add_buffer and calling
add_buffer multiple times you can directly call locate_hole, to find
the hole you want and then you can call add_buffer when you have
found the hole you want to load the kernel in with very tight min
and max values that you will know will work.

Eric

> -v2: add kexec-bzImage64.c according to Eric.
> -v3: don't need to purgatory under 2g after Eric's change to purgatory code.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> ---
> kexec/arch/x86_64/Makefile | 1 +
> kexec/arch/x86_64/kexec-bzImage64.c | 316 +++++++++++++++++++++++++++++++++++
> kexec/arch/x86_64/kexec-x86_64.c | 1 +
> kexec/arch/x86_64/kexec-x86_64.h | 5 +
> 4 files changed, 323 insertions(+), 0 deletions(-)
> create mode 100644 kexec/arch/x86_64/kexec-bzImage64.c
>
> diff --git a/kexec/arch/x86_64/Makefile b/kexec/arch/x86_64/Makefile
> index 405bdf5..1cf10f9 100644
> --- a/kexec/arch/x86_64/Makefile
> +++ b/kexec/arch/x86_64/Makefile
> @@ -13,6 +13,7 @@ x86_64_KEXEC_SRCS += kexec/arch/i386/crashdump-x86.c
> x86_64_KEXEC_SRCS_native = kexec/arch/x86_64/kexec-x86_64.c
> x86_64_KEXEC_SRCS_native += kexec/arch/x86_64/kexec-elf-x86_64.c
> x86_64_KEXEC_SRCS_native += kexec/arch/x86_64/kexec-elf-rel-x86_64.c
> +x86_64_KEXEC_SRCS_native += kexec/arch/x86_64/kexec-bzImage64.c
>
> x86_64_KEXEC_SRCS += $(x86_64_KEXEC_SRCS_native)
>
> diff --git a/kexec/arch/x86_64/kexec-bzImage64.c b/kexec/arch/x86_64/kexec-bzImage64.c
> new file mode 100644
> index 0000000..6835ef6
> --- /dev/null
> +++ b/kexec/arch/x86_64/kexec-bzImage64.c
> @@ -0,0 +1,316 @@
> +/*
> + * kexec: Linux boots Linux
> + *
> + * Copyright (C) 2003-2010 Eric Biederman (ebiederm@xmission.com)
> + *
> + * 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 (version 2 of the License).
> + *
> + * 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. 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.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stddef.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <limits.h>
> +#include <stdlib.h>
> +#include <errno.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <unistd.h>
> +#include <getopt.h>
> +#include <elf.h>
> +#include <boot/elf_boot.h>
> +#include <ip_checksum.h>
> +#include <x86/x86-linux.h>
> +#include "../../kexec.h"
> +#include "../../kexec-elf.h"
> +#include "../../kexec-syscall.h"
> +#include "kexec-x86_64.h"
> +#include "../i386/x86-linux-setup.h"
> +#include "../i386/crashdump-x86.h"
> +#include <arch/options.h>
> +
> +static const int probe_debug = 0;
> +
> +int bzImage64_probe(const char *buf, off_t len)
> +{
> + const struct x86_linux_header *header;
> + if ((uintmax_t)len < (uintmax_t)(2 * 512)) {
> + if (probe_debug) {
> + fprintf(stderr, "File is too short to be a bzImage!\n");
> + }
> + return -1;
> + }
> + header = (const struct x86_linux_header *)buf;
> + if (memcmp(header->header_magic, "HdrS", 4) != 0) {
> + if (probe_debug) {
> + fprintf(stderr, "Not a bzImage\n");
> + }
> + return -1;
> + }
> + if (header->boot_sector_magic != 0xAA55) {
> + if (probe_debug) {
> + fprintf(stderr, "No x86 boot sector present\n");
> + }
> + /* No x86 boot sector present */
> + return -1;
> + }
> + if (header->protocol_version < 0x020C) {
> + if (probe_debug) {
> + fprintf(stderr, "Must be at least protocol version 2.12\n");
> + }
> + /* Must be at least protocol version 2.12 */
> + return -1;
> + }
> + if ((header->loadflags & 1) == 0) {
> + if (probe_debug) {
> + fprintf(stderr, "zImage not a bzImage\n");
> + }
> + /* Not a bzImage */
> + return -1;
> + }
> + if (!header->code64_start_offset) {
> + if (probe_debug) {
> + fprintf(stderr, "Not a bzImage64\n");
> + }
> + /* Must have non zero offset */
> + return -1;
> + }
> + if (!header->relocatable_kernel) {
> + if (probe_debug) {
> + fprintf(stderr, "Not a relocatable bzImage64\n");
> + }
> + /* Must be relocatable */
> + return -1;
> + }
> + /* I've got a bzImage64 */
> + if (probe_debug) {
> + fprintf(stderr, "It's a relocatable bzImage64\n");
> + }
> + return 0;
> +}
> +
> +void bzImage64_usage(void)
> +{
> + printf( " --command-line=STRING Set the kernel command line to STRING.\n"
> + " --append=STRING Set the kernel command line to STRING.\n"
> + " --reuse-cmdline Use kernel command line from running system.\n"
> + " --initrd=FILE Use FILE as the kernel's initial ramdisk.\n"
> + " --ramdisk=FILE Use FILE as the kernel's initial ramdisk.\n"
> + );
> +}
> +
> +static int do_bzImage64_load(struct kexec_info *info,
> + const char *kernel, off_t kernel_len,
> + const char *command_line, off_t command_line_len,
> + const char *initrd, off_t initrd_len)
> +{
> + struct x86_linux_header setup_header;
> + struct x86_linux_param_header *real_mode;
> + int setup_sects;
> + size_t size;
> + int kern16_size;
> + unsigned long setup_base, setup_size;
> + struct entry64_regs regs64;
> + char *modified_cmdline;
> + unsigned long cmdline_end;
> + unsigned long code64_start_offset = 0;
> + unsigned long kernel64_load_addr = 0;
> +
> + /*
> + * Find out about the file I am about to load.
> + */
> + if ((uintmax_t)kernel_len < (uintmax_t)(2 * 512))
> + return -1;
> +
> + memcpy(&setup_header, kernel, sizeof(setup_header));
> + setup_sects = setup_header.setup_sects;
> + if (setup_sects == 0)
> + setup_sects = 4;
> +
> + kern16_size = (setup_sects +1) *512;
> + if (kernel_len < kern16_size) {
> + fprintf(stderr, "BzImage truncated?\n");
> + return -1;
> + }
> +
> + if ((uintmax_t)command_line_len > (uintmax_t)setup_header.cmdline_size) {
> + dbgprintf("Kernel command line too long for kernel!\n");
> + return -1;
> + }
> +
> + dbgprintf("bzImage is relocatable\n");
> +
> + code64_start_offset = setup_header.code64_start_offset;
> + dbgprintf("code64_start_offset: 0x%lx\n", code64_start_offset);
> +
> + /* Need to append some command line parameters internally in case of
> + * taking crash dumps.
> + */
> + if (info->kexec_flags & (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT)) {
> + modified_cmdline = xmalloc(COMMAND_LINE_SIZE);
> + memset((void *)modified_cmdline, 0, COMMAND_LINE_SIZE);
> + if (command_line) {
> + strncpy(modified_cmdline, command_line,
> + COMMAND_LINE_SIZE);
> + modified_cmdline[COMMAND_LINE_SIZE - 1] = '\0';
> + }
> +
> + /* If panic kernel is being loaded, additional segments need
> + * to be created. load_crashdump_segments will take care of
> + * loading the segments as high in memory as possible, hence
> + * in turn as away as possible from kernel to avoid being
> + * stomped by the kernel.
> + */
> + if (load_crashdump_segments(info, modified_cmdline, -1, 0) < 0)
> + return -1;
> +
> + /* Use new command line buffer */
> + command_line = modified_cmdline;
> + command_line_len = strlen(command_line) +1;
> + }
> +
> + /* x86_64 purgatory could be anywhere */
> + elf_rel_build_load(info, &info->rhdr, purgatory, purgatory_size,
> + 0x3000, -1, -1, 0);
> + dbgprintf("Loaded purgatory at addr 0x%lx\n", info->rhdr.rel_addr);
> + /* The argument/parameter segment */
> + setup_size = kern16_size + command_line_len + PURGATORY_CMDLINE_SIZE;
> + real_mode = xmalloc(setup_size);
> + memcpy(real_mode, kernel, kern16_size);
> +
> + /* No real mode code will be executing. setup segment can be loaded
> + * anywhere as we will be just reading command line.
> + */
> + setup_base = add_buffer(info, real_mode, setup_size, setup_size,
> + 16, 0x3000, -1, -1);
> +
> + dbgprintf("Loaded setup data and command line at 0x%lx\n",
> + setup_base);
> +
> + /* The main kernel segment */
> + size = kernel_len - kern16_size;
> +
> + /* align to 1G to avoid cross the PUD_SIZE boundary */
> + /* try above 4G at first */
> + kernel64_load_addr = add_buffer(info, kernel + kern16_size,
> + size, size, 1UL<<30,
> + 1UL<<32, ULONG_MAX,
> + -1);
> +
> + /* 1G to 4G */
> + if (!kernel64_load_addr)
> + kernel64_load_addr = add_buffer(info, kernel + kern16_size,
> + size, size, 1UL<<30,
> + 1UL<<30, 1UL<<32,
> + -1);
> +
> + /* under 1g */
> + if (!kernel64_load_addr)
> + kernel64_load_addr = add_buffer(info, kernel + kern16_size,
> + size, size,
> + real_mode->kernel_alignment,
> + 0x100000, 1UL<<30,
> + 1);
> + if (kernel64_load_addr)
> + dbgprintf("Loaded 64bit kernel at 0x%lx\n", kernel64_load_addr);
> + else
> + die("can not load bzImage64");
> +
> + /* Tell the kernel what is going on */
> + setup_linux_bootloader_parameters(info, real_mode, setup_base,
> + kern16_size, command_line, command_line_len,
> + initrd, initrd_len);
> +
> + elf_rel_get_symbol(&info->rhdr, "entry64_regs", &regs64, sizeof(regs64));
> + regs64.rbx = 0; /* Bootstrap processor */
> + regs64.rsi = setup_base; /* Pointer to the parameters */
> + regs64.rip = kernel64_load_addr + code64_start_offset; /* the entry point */
> + regs64.rsp = elf_rel_get_addr(&info->rhdr, "stack_end"); /* Stack, unused */
> + elf_rel_set_symbol(&info->rhdr, "entry64_regs", &regs64, sizeof(regs64));
> +
> + cmdline_end = setup_base + kern16_size + command_line_len - 1;
> + elf_rel_set_symbol(&info->rhdr, "cmdline_end", &cmdline_end,
> + sizeof(unsigned long));
> +
> + /* Fill in the information BIOS calls would normally provide. */
> + setup_linux_system_parameters(real_mode, info->kexec_flags);
> +
> + return 0;
> +}
> +
> +int bzImage64_load(int argc, char **argv, const char *buf, off_t len,
> + struct kexec_info *info)
> +{
> + char *command_line = NULL;
> + const char *ramdisk, *append = NULL;
> + char *ramdisk_buf;
> + off_t ramdisk_length;
> + int command_line_len;
> + int opt;
> + int result;
> +
> + /* See options.h -- add any more there, too. */
> + static const struct option options[] = {
> + KEXEC_ARCH_OPTIONS
> + { "command-line", 1, 0, OPT_APPEND },
> + { "append", 1, 0, OPT_APPEND },
> + { "reuse-cmdline", 0, 0, OPT_REUSE_CMDLINE },
> + { "initrd", 1, 0, OPT_RAMDISK },
> + { "ramdisk", 1, 0, OPT_RAMDISK },
> + { 0, 0, 0, 0 },
> + };
> + static const char short_options[] = KEXEC_ARCH_OPT_STR "d";
> +
> + ramdisk = 0;
> + ramdisk_length = 0;
> + while((opt = getopt_long(argc, argv, short_options, options, 0)) != -1) {
> + switch(opt) {
> + default:
> + /* Ignore core options */
> + if (opt < OPT_ARCH_MAX) {
> + break;
> + }
> + case '?':
> + usage();
> + return -1;
> + break;
> + case OPT_APPEND:
> + append = optarg;
> + break;
> + case OPT_REUSE_CMDLINE:
> + command_line = get_command_line();
> + break;
> + case OPT_RAMDISK:
> + ramdisk = optarg;
> + break;
> + }
> + }
> + command_line = concat_cmdline(command_line, append);
> + command_line_len = 0;
> + if (command_line) {
> + command_line_len = strlen(command_line) +1;
> + }
> + ramdisk_buf = 0;
> + if (ramdisk) {
> + ramdisk_buf = slurp_file(ramdisk, &ramdisk_length);
> + }
> + result = do_bzImage64_load(info,
> + buf, len,
> + command_line, command_line_len,
> + ramdisk_buf, ramdisk_length);
> +
> + free(command_line);
> + return result;
> +}
> diff --git a/kexec/arch/x86_64/kexec-x86_64.c b/kexec/arch/x86_64/kexec-x86_64.c
> index 6c42c32..5c23e01 100644
> --- a/kexec/arch/x86_64/kexec-x86_64.c
> +++ b/kexec/arch/x86_64/kexec-x86_64.c
> @@ -37,6 +37,7 @@ struct file_type file_type[] = {
> { "multiboot-x86", multiboot_x86_probe, multiboot_x86_load,
> multiboot_x86_usage },
> { "elf-x86", elf_x86_probe, elf_x86_load, elf_x86_usage },
> + { "bzImage64", bzImage64_probe, bzImage64_load, bzImage64_usage },
> { "bzImage", bzImage_probe, bzImage_load, bzImage_usage },
> { "beoboot-x86", beoboot_probe, beoboot_load, beoboot_usage },
> { "nbi-x86", nbi_probe, nbi_load, nbi_usage },
> diff --git a/kexec/arch/x86_64/kexec-x86_64.h b/kexec/arch/x86_64/kexec-x86_64.h
> index a97cd71..b820ae8 100644
> --- a/kexec/arch/x86_64/kexec-x86_64.h
> +++ b/kexec/arch/x86_64/kexec-x86_64.h
> @@ -28,4 +28,9 @@ int elf_x86_64_load(int argc, char **argv, const char *buf, off_t len,
> struct kexec_info *info);
> void elf_x86_64_usage(void);
>
> +int bzImage64_probe(const char *buf, off_t len);
> +int bzImage64_load(int argc, char **argv, const char *buf, off_t len,
> + struct kexec_info *info);
> +void bzImage64_usage(void);
> +
> #endif /* KEXEC_X86_64_H */