On Mon, May 18, 2015 at 12:24:51PM +0930, Alan Modra wrote:
> + error ("%<-fsplit-stack%> currently only supported on PowerPC64
> GNU/Linux with glibc-2.18 or later");
I forgot to comment on this. 2.19 is actually when __private_ss
appeared in the ppc tcbhead_t, but I misread the commit date and
thought it was 2.18. I was going to correct that, but then wondered
if glibc allocates any spare bytes, and it looks like it does. We
have a struct pthread before tcbhead_t, and struct pthread is aligned
according to TCB_ALIGNMENT which is 16 for powerpc. So 2.18's 56
byte tcbhead_t, which is laid out so that the end coincides with
tp-0x7000, must be preceded by 8 bytes of padding. Enough for
__private_ss, and we don't care if it isn't initially zero.
--
Alan Modra
Australia Development Lab, IBM
