That convention requires the instruction immediately preceding SYSCALL
to initialize $v0 with the syscall number. Then if a restart triggers,
$v0 will have been clobbered by the syscall interrupted, and needs to be
reinititalized. The kernel will decrement the PC by 4 before switching
back to the user mode so that $v0 has been reloaded before SYSCALL is
executed again. This implies the place $v0 is loaded from must be
preserved across a syscall, e.g. an immediate, static register, stack
slot, etc.
The restriction was lifted with Linux 2.6.36 kernel release and no
special requirements are placed around the SYSCALL instruction anymore,
however we still support older kernel binaries.
* sysdeps/sparc/sparc32/sparcv9/bits/atomic.h
(__arch_compare_and_exchange_val_32_acq): Use %g0 as second
argument of CAS if possible.
* sysdeps/sparc/sparc64/bits/atomic.h
(__arch_compare_and_exchange_val_32_acq): Likewise.
(__arch_compare_and_exchange_val_64_acq): Likewise.
The bsd implementation of ulimit produces wrong return values, so remove it
in favour of the posix implementation.
The only regression for non-Linux implementations using bsd sysdeps and not
providing an own ulimit is that the __UL_GETMAXBRK case (which is non-standard)
is left unimplemented (giving EINVAL).
In order for the __kernel_get_tbfreq vDSO call to work the
INTERNAL_VSYSCALL_NCS macro needed to be updated to prevent it from
assuming an integer return type (since the timebase frequency is a 64-bit
value) by specifying the type of the return type as a macro parameter. The
macro then specifically declares the return value as a 'register' (or
implied pair) of the denoted type. The compiler is then informed that this
register (or implied pair) is to be used for the return value.
Introduce (only on Linux) and use a HAVE_MREMAP symbol to advertize mremap
availability.
Move the malloc-sysdep.h include from arena.c to malloc.c, since what is
provided by malloc-sysdep.h is needed earlier in malloc.c, before the inclusion
of arena.c.