What is the reason for having read-only data defined in .text section?

Question

I am learning assembly and low-level programming itself and reading a book about it. It is said there that we can put any data inside the .text section of an elf file but of course we can't mutate it because of different permissions of pages/segments. But it was not told there, what was the reason for it, for having data inside .text section. I was also told by many C++ programmers that g++ compiler puts

static const char DATA[] = "SOME DATA";

inside the .text section too. I wonder, why not to put this data inside .rodata section, what is the purpose? And if .text is used, what to store in the .rodata then?

The main question is about this behaviour in long mode.

Answer 1

Traditionally, read-only data was placed in the text section for two reasons:

• the text section is not writable, so memory protection can catch accidental writes to read-only data and make your program crash instead
• with a memory-management unit (MMU), multiple instances of the same process can share one copy of the text section (as its guaranteed to be the same in all instances of the program), saving memory

On ELF targets, this scheme was modified a bit. Read-only data is now placed in the new .rodata section which is like the .text section except it also cannot be executed, preventing certain attack vectors. The advantages remain.