我用gcc编译链接了最基本的C程序，test.c:
int
main() {
}
正如预期的那样，输出是一个动态链接的可执行文件:
$ file test
test: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.26, BuildID[sha1]=0x0f806c099f74132a158d98aebde4639ae0998971, not stripped
运行 strace 给出以下输出:
$ strace -f ./test
execve("./test", ["./test"], [/* 31 vars */]) = 0
brk(0) = 0x248d000
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f77eeb27000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=109292, ...}) = 0
mmap(NULL, 109292, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f77eeb0c000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\300\357\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1595408, ...}) = 0
mmap(NULL, 3709016, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f77ee580000
mprotect(0x7f77ee700000, 2097152, PROT_NONE) = 0
mmap(0x7f77ee900000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x180000) = 0x7f77ee900000
mmap(0x7f77ee905000, 18520, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f77ee905000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f77eeb0b000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f77eeb0a000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f77eeb09000
arch_prctl(ARCH_SET_FS, 0x7f77eeb0a700) = 0
mprotect(0x7f77ee900000, 16384, PROT_READ) = 0
mprotect(0x7f77eeb29000, 4096, PROT_READ) = 0
munmap(0x7f77eeb0c000, 109292) = 0
exit_group(-292524312) = ?
根据 execve 手册，我期待在 strace 输出的某处看到“/lib64/ld-linux.so.2”:
If the executable is a dynamically linked ELF executable, the interpreter named in >the PT_INTERP segment is used to load the needed shared libraries. This interpreter >is typically /lib/ld-linux.so.2 for binaries linked with glibc 2
我的猜测是链接器/加载器 (/lib64/ld-linux.so.2) 调用是 execve 的一部分。有人可以确认吗？
最佳答案
My guess is that the linker/loader (/lib64/ld-linux.so.2) call is part of execve.
这在一定程度上是正确的。
内核首先查看主要的可执行段，然后mmap将它们放入新的“进程外壳”。
当它发现可执行文件有 PT_INTERP 段时，它也会mmap该文件的段，并将控制权交给它。
因此，在从execve()“返回”到用户模式时，解释器(通常是/lib64/ld-linux-x86-64.so.2在 Linux/x86_64 上)已经映射并正在运行。然后解释器的工作是重新定位自己，mmap 其余所需的共享库，初始化它们，最后将控制权转移到主可执行文件。
如果您想了解更多详情，请开始 here .
关于linux - execve如何调用动态链接器/加载器(ld-linux.so.2)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26876247/