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Commit e35795d9 authored by Russell King's avatar Russell King Committed by Amit Pundir
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UPSTREAM: ARM: domains: add memory dependencies to get_domain/set_domain 



We need to have memory dependencies on get_domain/set_domain to avoid
the compiler over-optimising these inline assembly instructions.

Loads/stores must not be reordered across a set_domain(), so introduce
a compiler barrier for that assembly.

The value of get_domain() must not be cached across a set_domain(), but
we still want to allow the compiler to optimise it away.  Introduce a
dependency on current_thread_info()->cpu_domain to avoid this; the new
memory clobber in set_domain() should therefore cause the compiler to
re-load this.  The other advantage of using this is we should have its
address in the register set already, or very soon after at most call
sites.

Tested-by: default avatarRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>

Change-Id: I150e9680f534aa064d002a187df452decf71be49
(cherry picked from commit 6e8f580d1fcc18e290713984c379cb97131c015a)
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
parent a49a528c

arch/arm/include/asm/domain.h

+4 −2
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 


#ifndef __ASSEMBLY__

#include <asm/barrier.h>

#include <asm/thread_info.h>

#endif



/*
@@ -71,7 +72,8 @@ static inline unsigned int get_domain(void) 


	asm(

	"mrc	p15, 0, %0, c3, c0	@ get domain"

	 : "=r" (domain));

	 : "=r" (domain)

	 : "m" (current_thread_info()->cpu_domain));



	return domain;

}
@@ -81,7 +83,7 @@ static inline void set_domain(unsigned val) 
{

	asm volatile(

	"mcr	p15, 0, %0, c3, c0	@ set domain"

	  : : "r" (val));

	  : : "r" (val) : "memory");

	isb();

}