When kernel's binary becomes large enough (32M and more) errors
may occur during the final linkage stage. It happens because
the build system uses short relocations for ARC by default.
This problem may be easily resolved by passing -mlong-calls
option to GCC to use long absolute jumps (j) instead of short
relative branchs (b).
But there are fragments of pure assembler code exist which use
branchs in inappropriate places and cause a linkage error because
of relocations overflow.
First of these fragments is .fixup insertion in futex.h and
unaligned.c. It inserts a code in the separate section (.fixup)
with branch instruction. It leads to the linkage error when
kernel becomes large.
Second of these fragments is calling scheduler's functions
(common kernel code) from entry.S of ARC's code. When kernel's
binary becomes large it may lead to the linkage error because
scheduler may occur far enough from ARC's code in the final
binary.
Signed-off-by: Yuriy Kolerov <yuriy.kolerov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
W/o hardware assisted atomic r-m-w the best we can do is to disable
preemption.
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Callers of cmpxchg_futex_value_locked() in futex code expect bimodal
return value:
!0 (essentially -EFAULT as failure)
0 (success)
Before this patch, the success return value was old value of futex,
which could very well be non zero, causing caller to possibly take the
failure path erroneously.
Fix that by returning 0 for success
(This fix was done back in 2011 for all upstream arches, which ARC
obviously missed)
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The atomic ops on futex need to provide the full barrier just like
regular atomics in kernel.
Also remove pagefault_enable/disable in futex_atomic_cmpxchg_inatomic()
as core code already does that
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
