Could we just use GCC intrinsics in C? On Jul 31, 2013 9:08 AM, "Artturi Alm" <artturi....@gmail.com> wrote:
> On 07/31/13 16:37, Artturi Alm wrote: > >> On 07/31/13 08:57, Richard Allen wrote: >> >>> Hi, >>> >>> I just wanted to let you know that _atomic_lock(), from _atomic_lock.c, >>> as used by librthread should probably have a barrier instruction added >>> to prevent the processor from reordering loads/stores around the >>> atomic_lock. >>> >>> For more information about barriers on ARM, see: >>> http://infocenter.arm.com/**help/index.jsp?topic=/com.arm.** >>> doc.dui0489c/CIHGHHIE.html<http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/CIHGHHIE.html> >>> >>> >>> For some examples, see sections 7.2.1 and 7.2.2 >>> http://infocenter.arm.com/**help/topic/com.arm.doc.** >>> genc007826/Barrier_Litmus_**Tests_and_Cookbook_A08.pdf<http://infocenter.arm.com/help/topic/com.arm.doc.genc007826/Barrier_Litmus_Tests_and_Cookbook_A08.pdf> >>> >>> >>> -Richard >>> >>> >> Hi, >> >> I'm not sure what the diff against _atomic_lock.c would look like, >> since i'm guessing it might not be supported, and i don't like >> inline asm so i'll leave it to someone else, however, diff for >> using it in cpufunc_asm_armv7.S would be something like below >> >> > Wow, that was unclear. what i meant with 'it' was of course the dmb > instruction, and fwiw freebsd uses it exclusively in atomic.h inlines. > > >> -Artturi >> >> >> >> Index: cpufunc_asm_armv7.S >> ==============================**==============================**======= >> RCS file: /cvs/src/sys/arch/arm/arm/**cpufunc_asm_armv7.S,v >> retrieving revision 1.6 >> diff -u -p -r1.6 cpufunc_asm_armv7.S >> --- cpufunc_asm_armv7.S 30 Mar 2013 01:30:30 -0000 1.6 >> +++ cpufunc_asm_armv7.S 31 Jul 2013 13:26:18 -0000 >> @@ -19,6 +19,7 @@ >> #include <machine/asm.h> >> >> #define DSB .long 0xf57ff040 >> +#define DMB .long 0xf57ff050 >> #define ISB .long 0xf57ff060 >> #define WFI .long 0xe320f003
