未知的arm linux内核图像格式

时间：2013-02-10 17:32:46

标签： linux kernel arm

我有一个ARM linux内核映像文件。但我不确定 究竟是什么样的格式...

'file'命令告诉我它是纯数据。

首先，我认为它是vmlinuz并尝试解压缩。

我搜索了'gzip'标题签名和 从那里解压缩。

但我得到的只是关注makefile脚本。

#
# Automatically generated make config: don't edit
# Linux/arm 2.6.38.7 Kernel Configuration
# Sat Apr 28 17:29:46 2012
#
CONFIG_ARM=y
CONFIG_SYS_SUPPORTS_APM_EMULATION=y
CONFIG_HAVE_SCHED_CLOCK=y
CONFIG_ARCH_SCHED_CLOCK=y
# CONFIG_ARCH_USES_GETTIMEOFFSET is not set
CONFIG_GENERIC_CLOCKEVENTS=y
CONFIG_GENERIC_CLOCKEVENTS_BROADCAST=y
CONFIG_KTIME_SCALAR=y
CONFIG_STACKTRACE_SUPPORT=y
CONFIG_LOCKDEP_SUPPORT=y
CONFIG_TRACE_IRQFLAGS_SUPPORT=y
CONFIG_HARDIRQS_SW_RESEND=y
CONFIG_GENERIC_IRQ_PROBE=y
CONFIG_RWSEM_GENERIC_SPINLOCK=y
CONFIG_ARCH_HAS_CPU_IDLE_WAIT=y
CONFIG_GENERIC_HWEIGHT=y
CONFIG_GENERIC_CALIBRATE_DELAY=y
CONFIG_NEED_DMA_MAP_STATE=y
CONFIG_VECTORS_BASE=0xffff0000
# CONFIG_ARM_PATCH_PHYS_VIRT is not set
CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
CONFIG_CONSTRUCTORS=y
CONFIG_HAVE_IRQ_WORK=y
CONFIG_IRQ_WORK=y

#
# General setup
#
CONFIG_EXPERIMENTAL=y
CONFIG_LOCK_KERNEL=y
CONFIG_INIT_ENV_ARG_LIMIT=32
CONFIG_CROSS_COMPILE=""
CONFIG_LOCALVERSION=""
# CONFIG_LOCALVERSION_AUTO is not set
CONFIG_HAVE_KERNEL_GZIP=y
CONFIG_HAVE_KERNEL_LZMA=y
CONFIG_HAVE_KERNEL_LZO=y
CONFIG_KERNEL_GZIP=y
# CONFIG_KERNEL_LZMA is not set
# CONFIG_KERNEL_LZO is not set
CONFIG_SWAP=y
CONFIG_SYSVIPC=y
CONFIG_SYSVIPC_SYSCTL=y
# CONFIG_BSD_PROCESS_ACCT is not set
CONFIG_HAVE_GENERIC_HARDIRQS=y

#
# IRQ subsystem
#
CONFIG_GENERIC_HARDIRQS=y
# CONFIG_GENERIC_HARDIRQS_NO_DEPRECATED is not set
CONFIG_HAVE_SPARSE_IRQ=y
CONFIG_GENERIC_IRQ_SHOW=y
# CONFIG_GENERIC_PENDING_IRQ is not set
# CONFIG_AUTO_IRQ_AFFINITY is not set
# CONFIG_IRQ_PER_CPU is not set
CONFIG_SPARSE_IRQ=y

#
# RCU Subsystem
#
CONFIG_TREE_RCU=y
# CONFIG_PREEMPT_RCU is not set
# CONFIG_RCU_TRACE is not set
CONFIG_RCU_FANOUT=32
# CONFIG_RCU_FANOUT_EXACT is not set
# CONFIG_TREE_RCU_TRACE is not set
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
# CONFIG_CGROUP_DEBUG is not set
# CONFIG_CGROUP_NS is not set
# CONFIG_CGROUP_FREEZER is not set
# CONFIG_CGROUP_DEVICE is not set
CONFIG_CPUSETS=y
CONFIG_PROC_PID_CPUSET=y
# CONFIG_CGROUP_CPUACCT is not set
# CONFIG_RESOURCE_COUNTERS is not set
# CONFIG_CGROUP_SCHED is not set
# CONFIG_BLK_CGROUP is not set
CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_IPC_NS is not set
# CONFIG_USER_NS is not set
# CONFIG_PID_NS is not set
# CONFIG_HAVE_GET_CYCLES is not set
# CONFIG_HAVE_TRACE_CLOCK is not set
CONFIG_HAVE_TRACE_CLOCK_GENERIC=y
CONFIG_HAVE_TRACE_CLOCK_32_TO_64=y
# CONFIG_HAVE_UNSYNCHRONIZED_TSC is not set
# CONFIG_SCHED_AUTOGROUP is not set
# CONFIG_SYSFS_DEPRECATED is not set
# CONFIG_RELAY is not set
CONFIG_BLK_DEV_INITRD=y
CONFIG_INITRAMFS_SOURCE=""
CONFIG_RD_GZIP=y
CONFIG_RD_BZIP2=y
CONFIG_RD_LZMA=y
CONFIG_RD_XZ=y
CONFIG_RD_LZO=y
# CONFIG_CC_OPTIMIZE_FOR_SIZE is not set
CONFIG_SYSCTL=y
CONFIG_ANON_INODES=y
# CONFIG_EXPERT is not set
# CONFIG_EMBEDDED is not set
CONFIG_UID16=y
CONFIG_SYSCTL_SYSCALL=y
CONFIG_KALLSYMS=y
# CONFIG_KALLSYMS_ALL is not set
# CONFIG_KALLSYMS_EXTRA_PASS is not set
CONFIG_HOTPLUG=y
CONFIG_PRINTK=y
CONFIG_BUG=y
CONFIG_ELF_CORE=y
CONFIG_BASE_FULL=y
CONFIG_FUTEX=y
CONFIG_EPOLL=y
CONFIG_SIGNALFD=y
CONFIG_TIMERFD=y
CONFIG_EVENTFD=y
CONFIG_SHMEM=y
CONFIG_AIO=y
CONFIG_HAVE_PERF_EVENTS=y
CONFIG_PERF_USE_VMALLOC=y

#
# Kernel Performance Events And Counters
#
CONFIG_PERF_EVENTS=y
# CONFIG_PERF_COUNTERS is not set
# CONFIG_DEBUG_PERF_USE_VMALLOC is not set
CONFIG_VM_EVENT_COUNTERS=y
CONFIG_SLUB_DEBUG=y
CONFIG_COMPAT_BRK=y
# CONFIG_SLAB is not set
CONFIG_SLUB=y
CONFIG_PROFILING=y
# CONFIG_MARKERS is not set
CONFIG_OPROFILE=y
CONFIG_HAVE_OPROFILE=y
# CONFIG_KPROBES is not set

我用hexdump彻底查看了二进制文件。 我认为这是一个纯ARM二进制文件。

前几个字节被反汇编如下

 msr    CPSR_c, #211    ; 0xd3
 mrc    15, 0, r9, cr0, cr0, {0}
 bl 0x000148e0
 movs   sl, r5
 beq    0x00014924
 add    r3, pc, #44 ; 0x2c
 ldm    r3, {r4, r8}
 sub    r4, r3, r4
 add    r8, r8, r4
 bl 0x00000154
 bl 0x0000018c
 bl 0x00000050
 ldr    sp, [pc, #12]   ; 0x00000044
 add    lr, pc, #4
 mov    r8, r4
 add    pc, sl, #16
 b  0x00014894
 andhi  r8, r0, r8, ror #3
 andhi  r8, r0, r8, asr #32
 andhi  r0, r0, r0
 add    r4, r8, #16384  ; 0x4000
 mov    r0, r4
 mov    r3, #0
 add    r6, r0, #16384  ; 0x4000
 str    r3, [r0], #4
 str    r3, [r0], #4
 str    r3, [r0], #4
 str    r3, [r0], #4
 teq    r0, r6
 bne    0x00000060
 ldr    r7, [sl, #8]
 add    r0, pc, #196    ; 0xc4
 ldm    r0, {r3, r5, r6}
 sub    r0, r0, r3
 add    r5, r5, r0
 add    r6, r6, r0
 lsr    r5, r5, #20
 lsr    r6, r6, #20
 orr    r3, r7, r5, lsl #20
 str    r3, [r4, r5, lsl #2]
 cmp    r5, r6
 addcc  r5, r5, #0
 bcc    0x00000098
 mov    r3, pc
 lsr    r3, r3, #20
 orr    r3, r7, r3, lsl #20
 add    r0, r4, #8192   ; 0x2000
 str    r3, [r0, #0]!
 ldr    r6, [pc, #124]  ; 0x00000144
 add    r0, r0, #4
 add    r6, r4, r6, lsr #18
 cmp    r0, r6
 add    r3, r3, #1048576    ; 0x100000
 strls  r3, [r0], #4
 bls    0x000000cc
 lsr    r0, r2, #20
 lsls   r0, r0, #20
 moveq  r0, r8
 sub    r3, r0, r8
 add    r3, r3, #-2147483648    ; 0x80000000
 add    r3, r4, r3, lsr #18
 orr    r6, r7, r0
 str    r6, [r3]
 mov    r7, #36864  ; 0x9000
 orr    r3, r7, #-134217728 ; 0xf8000000
 orr    r7, r7, #268435456  ; 0x10000000
 lsr    r3, r3, #20
 lsl    r3, r3, #2

...

这是用于启动过程的内核映像文件 用于ARM模拟器（SoC设计器）。它工作正常。

我想要的是这个内核的ELF文件 我可以像IDA那样用反汇编程序打开。

但我无法从此内核映像中检索原始ELF格式的文件...

一些帮助将不胜感激。

提前谢谢。

1 个答案:

答案 0 :(得分：5)

ARM Linux内核通常是自加载普通二进制文件，通过从中提取代码+ rdata部分并附加“piggy”加载器从原始ELF生成。它们由引导程序加载到内存中的某个位置，然后从那里运行。小猪装载机将主要有效载荷解包/复制到最终地址并跳转到它。

从二进制文件中恢复ELF可能是可能的（最终运行时地址通常固定为0xC0008000，您可以通过分析启动代码找到.data / .bss范围），但符号表比较棘手。最近的内核不按原样使用ELF符号表，而是使用压缩来节省空间。如果您可以启动内核，最简单的方法是阅读/proc/ksyms或/proc/kallsyms，因为它将具有未压缩格式的符号。否则，您必须在二进制文件decompress it manually中找到压缩表。

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