On Wed, 2022-03-30 at 13:05 -0700, Reinette Chatre wrote: > > > On 3/30/2022 12:03 PM, Jarkko Sakkinen wrote: > > On Wed, 2022-03-30 at 10:40 -0700, Reinette Chatre wrote: > > > Could you please elaborate how the compiler will fix it up? > > > > Sure. > > > > Here's the disassembly of the RBX version: > > > > [0x000021a9]> pi 1 > > lea rax, [rbx + loc.encl_stack] > > > > Here's the same with s/RBX/RIP/: > > > > [0x000021a9]> pi 5 > > lea rax, loc.encl_stack > > > > Compiler will substitute correct offset relative to the RIP, > > well, because it can and it makes sense. > > It does not make sense to me because, as proven with my test, > the two threads end up sharing the same stack memory. I see, I need to correct my patch, thanks! RBX gives correct results because of the binary organization, i.e. TCS's are placed to zero offset and forward, and unrelocated symbol is just compiled in as an untranslated offset. RPI is given correct results but how the semantics work right now is incompatible. Still, even for kselftest, I would consider a switch because that way: 1. You can layout binary however you wan and things won't break. 2. You can point to any symbol not just stack, if ever need. I admit it works semantically but it just super unrobust. BR, Jarkko
