diff options
| author | Mark Tomlinson | 2020-02-12 10:24:55 +1300 |
|---|---|---|
| committer | Paul Burton | 2020-02-15 12:44:03 -0800 |
| commit | 97e914b7de3c943011779b979b8093fdc0d85722 (patch) | |
| tree | fb2227ac71e85e7af279d57fb260fe0d37e11320 /arch/mips | |
| parent | 976c23af3ee5bd3447a7bfb6c356ceb4acf264a6 (diff) | |
MIPS: cavium_octeon: Fix syncw generation.
The Cavium Octeon CPU uses a special sync instruction for implementing
wmb, and due to a CPU bug, the instruction must appear twice. A macro
had been defined to hide this:
#define __SYNC_rpt(type) (1 + (type == __SYNC_wmb))
which was intended to evaluate to 2 for __SYNC_wmb, and 1 for any other
type of sync. However, this expression is evaluated by the assembler,
and not the compiler, and the result of '==' in the assembler is 0 or
-1, not 0 or 1 as it is in C. The net result was wmb() producing no code
at all. The simple fix in this patch is to change the '+' to '-'.
Fixes: bf92927251b3 ("MIPS: barrier: Add __SYNC() infrastructure")
Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | arch/mips/include/asm/sync.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/mips/include/asm/sync.h b/arch/mips/include/asm/sync.h index 7c6a1095f556..aabd097933fe 100644 --- a/arch/mips/include/asm/sync.h +++ b/arch/mips/include/asm/sync.h @@ -155,9 +155,11 @@ * effective barrier as noted by commit 6b07d38aaa52 ("MIPS: Octeon: Use * optimized memory barrier primitives."). Here we specify that the affected * sync instructions should be emitted twice. + * Note that this expression is evaluated by the assembler (not the compiler), + * and that the assembler evaluates '==' as 0 or -1, not 0 or 1. */ #ifdef CONFIG_CPU_CAVIUM_OCTEON -# define __SYNC_rpt(type) (1 + (type == __SYNC_wmb)) +# define __SYNC_rpt(type) (1 - (type == __SYNC_wmb)) #else # define __SYNC_rpt(type) 1 #endif |