2b279bd5 by Mark Charlebois Committed by Behan Webster

DO-NOT-UPSTREAM arm64, LLVMLinux: prfm

Fix for prfm error on AArch64

The following error is generated with the mainline clang compiler
for AArch64:

arch/arm64/include/asm/processor.h:149:15:
error: invalid operand in inline asm: 'prfm pldl1keep, ${0:a}
'

Per comments by Tim Northover on the LLVM Bug database:

"It's rather unclear how it's better than "prfm pstl1keep, [%0]" though.
Not all instructions can make use of any offset, so wouldn't we have to be
conservative and always map it to "[xN]"?

When %a0 is changed to [%x0] it uncovered a GCC bug:
https://bugs.linaro.org/show_bug.cgi?id=635

Changing the "p" to "r" resolves the issue for both clang and GCC.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>
1 parent 7776dc11
......@@ -147,13 +147,13 @@ extern struct task_struct *cpu_switch_to(struct task_struct *prev,
#define ARCH_HAS_PREFETCH
static inline void prefetch(const void *ptr)
{
asm volatile("prfm pldl1keep, %a0\n" : : "p" (ptr));
asm volatile("prfm pldl1keep, [%x0]\n" : : "r" (ptr));
}
#define ARCH_HAS_PREFETCHW
static inline void prefetchw(const void *ptr)
{
asm volatile("prfm pstl1keep, %a0\n" : : "p" (ptr));
asm volatile("prfm pstl1keep, [%x0]\n" : : "r" (ptr));
}
#define ARCH_HAS_SPINLOCK_PREFETCH
......