On 10/21/2014 10:01 PM, John David Anglin wrote:
On 10/21/2014 3:46 PM, Helge Deller wrote:
/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. */
-#define __ldcw(a) ({ \
- unsigned __ret; \
- __asm__ __volatile__(__LDCW " 0(%2),%0" \
- : "=r" (__ret), "+m" (*(a)) : "r" (a)); \
- __ret; \
-})
+static inline unsigned int __ldcw(volatile unsigned int *address)
+{
+ unsigned int ret;
+ register volatile unsigned int *a = address;
+ __asm__ __volatile__(__LDCW " 0(%2),%0"
+ : "=r" (ret), "+m" (*(a)) : "r" (a));
+ return ret;
+}
You could keep the old macro version for 32-bit builds as the problem shouldn't occur there.
Attached is an updated patch/work-around which just reuses the existing register.
I don't like this patch much, but it's better than nothing for now.
Helge
diff --git a/arch/parisc/include/asm/ldcw.h b/arch/parisc/include/asm/ldcw.h
index d2d11b7..989595d 100644
--- a/arch/parisc/include/asm/ldcw.h
+++ b/arch/parisc/include/asm/ldcw.h
@@ -1,6 +1,8 @@
#ifndef __PARISC_LDCW_H
#define __PARISC_LDCW_H
+#include <linux/compiler.h>
+
#ifndef CONFIG_PA20
/* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data,
and GCC only guarantees 8-byte alignment for stack locals, we can't
@@ -34,12 +36,22 @@
#endif /*!CONFIG_PA20*/
/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. */
-#define __ldcw(a) ({ \
- unsigned __ret; \
- __asm__ __volatile__(__LDCW " 0(%2),%0" \
- : "=r" (__ret), "+m" (*(a)) : "r" (a)); \
- __ret; \
-})
+static inline unsigned int __ldcw(volatile unsigned int *address)
+{
+#if GCC_VERSION >= 40900
+ /* work around gcc-4.9 bug:
+ * error: can't find a register in class 'R1_REGS' while reloading 'asm'
+ */
+ __asm__ __volatile__(__LDCW " 0(%0),%0"
+ : "=r" (address), "+m" (*(address)) : "0" (address));
+ return (unsigned long) address;
+#else
+ unsigned int val;
+ __asm__ __volatile__(__LDCW " 0(%2),%0"
+ : "=r" (val), "+m" (*(address)) : "r" (address));
+ return val;
+#endif
+}
#ifdef CONFIG_SMP
# define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
