Drop % from register name used for register variable since it makes clang
unhappy.

ok deraadt@, visa@

Telling gcc the TCB pointer is in %r2 via the 'register asm' extension
tests out on powerpc and generates slightly better code

Use a Thread Information Block in both single and multi-threaded programs.
This stores errno, the cancelation flags, and related bits for each thread
and is allocated by ld.so or libc.a. This is an ABI break from 5.9-stable!

Make libpthread dlopen'able by moving the cancelation wrappers into libc
and doing locking and fork/errno handling via callbacks that libpthread
registers when it first initializes. 'errno' *must* be declared via
<errno.h> now!

Clean up libpthread's symbol exports like libc.

On powerpc, offset the TIB/TCB/TLS data from the register per the ELF spec.

Testing by various, particularly sthen@ and patrick@
ok kettenis@

It's been a quarter century: we can assume volatile is present with that name.

ok dlg@ mpi@ deraadt@

Add magic to use %r2 as the userland thread register.

ok guenther@

Specify the TLS variant for each platform.

Telling gcc the TCB pointer is in %r2 via the 'register asm' extension
tests out on powerpc and generates slightly better code

Use a Thread Information Block in both single and multi-threaded programs.
This stores errno, the cancelation flags, and related bits for each thread
and is allocated by ld.so or libc.a. This is an ABI break from 5.9-stable!

Make libpthread dlopen'able by moving the cancelation wrappers into libc
and doing locking and fork/errno handling via callbacks that libpthread
registers when it first initializes. 'errno' *must* be declared via
<errno.h> now!

Clean up libpthread's symbol exports like libc.

On powerpc, offset the TIB/TCB/TLS data from the register per the ELF spec.

Testing by various, particularly sthen@ and patrick@
ok kettenis@

It's been a quarter century: we can assume volatile is present with that name.

ok dlg@ mpi@ deraadt@

Add magic to use %r2 as the userland thread register.

ok guenther@

Specify the TLS variant for each platform.