When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.
We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves. (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)
With copy relocation, address of protected data defined in the shared
library may be external. Compiler shouldn't asssume protected data will
be local. But due to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248
__attribute__((visibility("protected"))) doesn't work correctly, we need
to use asm (".protected xxx") instead.
* elf/ifuncdep2.c (global): Replace
__attribute__((visibility("protected"))) with
asm (".protected global").
* elf/ifuncmod1.c (global): Likewise.
* elf/ifuncmod5.c (global): Likewise.
Nick Alcock
H.J. Lu
Joseph Myers
Alan Modra
H.J. Lu