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perf, ARM: Modify kuser rmb() call to compile for Thumb-2 

The Thumb-2 instruction set does not provide an encoding
for sub pc, r0, #95 as present in the rmb() definition used
by perf. This results in compilation failure when using a
compiler targetting an instruction set other than ARM.

This patch redefines rmb() for ARM by casting the address
of the kuser helper to a function pointer, therefore getting
the compiler to take care of making the call.

Patch taken against tip/master.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Jamie Iles <jamie.iles@picochip.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1267616878-2154-1-git-send-email-will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Will Deacon 2010-03-03 11:47:58 +00:00 committed by Ingo Molnar
parent 4f16d4e0c9
commit da7196e1f9
1 changed files with 1 additions and 3 deletions
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4
tools/perf/perf.h
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@ -65,9 +65,7 @@
* Use the __kuser_memory_barrier helper in the CPU helper page. See
* arch/arm/kernel/entry-armv.S in the kernel source for details.
*/
#define rmb() asm volatile("mov r0, #0xffff0fff; mov lr, pc;" \
"sub pc, r0, #95" ::: "r0", "lr", "cc", \
"memory")
#define rmb() ((void(*)(void))0xffff0fa0)()
#define cpu_relax() asm volatile("":::"memory")
#endif