Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function

[Dave Hansen]

On 6/10/19 8:22 AM, Yu-cheng Yu wrote:
>> How does glibc know the linear address space size?  We donât want LA64 to
>> break old binaries because the address calculation changed.
> When an application starts, its highest stack address is determined.
> It uses that as the maximum the bitmap needs to cover.

Huh, I didn't think we ran code from the stack. ;)

Especially given the way that we implemented the new 5-level-paging
address space, I don't think that expecting code to be below the stack
is a good universal expectation.