问题
I am writing a 64-bit application in C (with GCC) and NASM under Linux.
Is there a way to specify, where I want my heap and stack to be located. Specifically, I want all my malloc'ed data to be anywhere in range 0x00000000-0x7FFFFFFF. This can be done at either compile time, linking or runtime, via C code or otherwise. It doesn't matter.
If this is not possible, please explain, why.
P.S. For those interested, what the heck I am doing:
The program I am working on is written in C. During runtime it generates NASM code, compiles it and dynamically links to the already running program. This is needed for extreme optimization, because that code will be run thousands-if-not-billions of times, and is not known at compile time. So the reason I need 0x00000000-0x7FFFFFFF addresses is because they fit in immediates in assembler code. If I don't need to load the addresses separately, I can just about half the number of memory accesses needed and increase locality.
回答1:
For Linux, the standard way of acquiring any Virtual Address range is using the mmap(2) function.
You can specify the starting virtual address and the size. If the address is not already in use and it not reserved by prior calls (or by the kernel) you will get access to the virtual address.
The success of this call can be checked by comparing the return value to the start address you passed. If the call fails, the function returns NULL.
In general mmap is used to map virtual addresses to file descriptors. But this mapping has to happen through physical pages on the RAM. Since the applications cannot directly access the disk.
Since you do not want any file backing, you can use the MAP_ANONYMOUS flag in the mmap call (also pass -1 as the fd).
This is the excerpt for the related part of the man-page -
MAP_ANONYMOUS
The mapping is not backed by any file; its contents are initialized to zero. The fd argument is ignored; however, some implementations require fd to be -1 if MAP_ANONYMOUS (or MAP_ANON) is specified, and portable applications should ensure this. The offset argument should be zero. The use of MAP_ANONYMOUS in conjunction with MAP_SHARED is supported on Linux only since kernel 2.4.
来源：https://stackoverflow.com/questions/45475282/custom-heap-memory-allocation-ranges