如何将程序加载到与目标地址不同的内存中？

Question

Generally the user program binaries will be loaded in low address (usually around 0x400000 ) in the programs address space which will be specified in the elf binary (in the case of linux).

Can we force a user binary to load at a high address, possibly within the 2GB range of addresses where libc or other such libraries are loaded?

I have tried finding a solution on the net but could not find any concrete solution for this.

(I am working on Ubuntu 12.10 64bit OS)

Thanks

Answer 1

Unless the binary is position-independent (PIE), this is not possible. Normal (non-PIE) binaries are hard-coded for a particular load address at link time, and during linking, the information necessary for relocating to a different address was already lost.

Edit: The above is assuming you're working with an existing binary. If you are producing the binary yourself, you can control the load address that's hard-coded into it with the following link options:

-Wl,-Ttext-segment,0x80000000

replacing 0x80000000 by your desired address. Certain addresses (such as those reserved for kernel use, typically beginning at 0xc0000000) will not work, and the address must be page-aligned (the last 3 hex digits must be 0).