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| author | Helge Deller <deller@gmx.de> | 2009-04-30 21:39:45 +0000 |
|---|---|---|
| committer | Kyle McMartin <kyle@mcmartin.ca> | 2009-07-03 03:34:07 +0000 |
| commit | 7d17e2763129ea307702fcdc91f6e9d114b65c2d (patch) | |
| tree | 7941bcdc08cce96bbd31b718a23d1c9431dde2b1 /arch/parisc | |
| parent | 4fb11781a044552dded5342e1a78cf92a74683db (diff) | |
| download | linux-7d17e2763129ea307702fcdc91f6e9d114b65c2d.tar.gz linux-7d17e2763129ea307702fcdc91f6e9d114b65c2d.tar.bz2 linux-7d17e2763129ea307702fcdc91f6e9d114b65c2d.zip | |
parisc: fix ldcw inline assembler
There are two reasons to expose the memory *a in the asm:
1) To prevent the compiler from discarding a preceeding write to *a, and
2) to prevent it from caching *a in a register over the asm.
The change has had a few days testing with a SMP build of 2.6.22.19
running on a rp3440.
This patch is about the correctness of the __ldcw() macro itself.
The use of the macro should be confined to small inline functions
to try to limit the effect of clobbering memory on GCC's optimization
of loads and stores.
Signed-off-by: Dave Anglin <dave.anglin@nrc-cnrc.gc.ca>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Diffstat (limited to 'arch/parisc')
| -rw-r--r-- | arch/parisc/include/asm/system.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/parisc/include/asm/system.h b/arch/parisc/include/asm/system.h index ee80c920b464..d91357bca5b4 100644 --- a/arch/parisc/include/asm/system.h +++ b/arch/parisc/include/asm/system.h @@ -168,8 +168,8 @@ static inline void set_eiem(unsigned long val) /* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. */ #define __ldcw(a) ({ \ unsigned __ret; \ - __asm__ __volatile__(__LDCW " 0(%1),%0" \ - : "=r" (__ret) : "r" (a)); \ + __asm__ __volatile__(__LDCW " 0(%2),%0" \ + : "=r" (__ret), "+m" (*(a)) : "r" (a)); \ __ret; \ }) |