diff options
| author | John David Anglin | 2014-12-14 10:49:11 -0500 |
|---|---|---|
| committer | Helge Deller | 2014-12-26 17:47:01 +0100 |
| commit | 45db07382a5c78b0c43b3b0002b63757fb60e873 (patch) | |
| tree | 63d86170ec09f9d9181f40dd6caa091271b5116d | |
| parent | b2776bf7149bddd1f4161f14f79520f17fc1d71d (diff) | |
parisc: fix out-of-register compiler error in ldcw inline assembler function
The __ldcw macro has a problem when its argument needs to be reloaded from
memory. The output memory operand and the input register operand both need to
be reloaded using a register in class R1_REGS when generating 64-bit code.
This fails because there's only a single register in the class. Instead, use a
memory clobber. This also makes the __ldcw macro a compiler memory barrier.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> [3.13+]
Signed-off-by: Helge Deller <deller@gmx.de>
| -rw-r--r-- | arch/parisc/include/asm/ldcw.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/parisc/include/asm/ldcw.h b/arch/parisc/include/asm/ldcw.h index d2d11b7055ba..8121aa6db2ff 100644 --- a/arch/parisc/include/asm/ldcw.h +++ b/arch/parisc/include/asm/ldcw.h @@ -33,11 +33,18 @@ #endif /*!CONFIG_PA20*/ -/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. */ +/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. + We don't explicitly expose that "*a" may be written as reload + fails to find a register in class R1_REGS when "a" needs to be + reloaded when generating 64-bit PIC code. Instead, we clobber + memory to indicate to the compiler that the assembly code reads + or writes to items other than those listed in the input and output + operands. This may pessimize the code somewhat but __ldcw is + usually used within code blocks surrounded by memory barriors. */ #define __ldcw(a) ({ \ unsigned __ret; \ - __asm__ __volatile__(__LDCW " 0(%2),%0" \ - : "=r" (__ret), "+m" (*(a)) : "r" (a)); \ + __asm__ __volatile__(__LDCW " 0(%1),%0" \ + : "=r" (__ret) : "r" (a) : "memory"); \ __ret; \ }) |