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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-09-11 09:34:52 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-09-11 17:08:18 +0200 |
| commit | 6e8f580d1fcc18e290713984c379cb97131c015a (patch) | |
| tree | f4dc7a3e4310c64cacacae02d8c20476bc6f4c37 /arch | |
| parent | ARM: domains: thread_info.h no longer needs asm/domains.h (diff) | |
| download | linux-6e8f580d1fcc18e290713984c379cb97131c015a.tar.xz linux-6e8f580d1fcc18e290713984c379cb97131c015a.zip | |
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: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/domain.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h index e878129f2fee..fc8ba1663601 100644 --- a/arch/arm/include/asm/domain.h +++ b/arch/arm/include/asm/domain.h @@ -12,6 +12,7 @@ #ifndef __ASSEMBLY__ #include <asm/barrier.h> +#include <asm/thread_info.h> #endif /* @@ -89,7 +90,8 @@ 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; } @@ -98,7 +100,7 @@ static inline void set_domain(unsigned val) { asm volatile( "mcr p15, 0, %0, c3, c0 @ set domain" - : : "r" (val)); + : : "r" (val) : "memory"); isb(); } |