Re: [PATCH] [AArch64 Linux] Get rid of top byte from tagged address

Pedro Alves
2017-10-19T11:21:30Z

On 10/19/2017 09:08 AM, Yao Qi wrote:
> ARMv8 supports tagged address, that is, the top one byte in address
> is ignored. It is always enabled on aarch64-linux. The patch clear
> the top byte of the virtual address, at the point before GDB/GDBserver
> pass the address to /proc or ptrace syscall. The top byte of address is
> still retained in the rest of GDB, because these bits can be used by
> different applications in different ways. That is reason I didn't
> implement gdbarch method addr_bits_remove to get rid of them.

Something else that came to mind -- do we need to make GDB's
stack/code caches aware of this? I.e., for the case of
writing through a tagged address and reading via a non-tagged
address, and vice-versa.

Thanks,
Pedro Alves