genode/repos/base-nova/src/base
Martin Stein ec6c19a487 base: memory barriers in lock implementations
The memory barrier prevents the compiler from changing the program order
of memory accesses in such a way that accesses to the guarded resource
get outside the guarded stage. As cmpxchg() defines the start of the
guarded stage it also represents an effective memory barrier.

On x86, the architecture ensures to not reorder writes with older reads,
writes to memory with other writes (except in cases that are not
relevant for our locks), or read/write instructions with I/O
instructions, locked instructions, and serializing instructions.

However on ARM, the architectural memory model allows not only that
memory accesses take local effect in another order as their program
order but also that different observers (components that can access
memory like data-busses, TLBs and branch predictors) observe these
effects each in another order. Thus, a correct program order isn't
sufficient for a correct observation order. An additional architectural
preservation of the memory barrier is needed to achieve this.

Fixes #692
2014-11-28 12:02:34 +01:00
..
console Move repositories to 'repos/' subdirectory 2014-05-14 16:08:00 +02:00
env Move repositories to 'repos/' subdirectory 2014-05-14 16:08:00 +02:00
ipc Move repositories to 'repos/' subdirectory 2014-05-14 16:08:00 +02:00
lock base: memory barriers in lock implementations 2014-11-28 12:02:34 +01:00
pager Fix race condition in page fault notification 2014-07-24 10:18:07 +02:00
server Move repositories to 'repos/' subdirectory 2014-05-14 16:08:00 +02:00
thread nova: re-throw uncatched exception of dying thread 2014-05-27 13:45:20 +02:00