[PATCH resend] Perf-tool/MIPS: support cross compiling of tools/perf for MIPS

[Deng-Cheng Zhu <dengcheng.zhu@gmail.com>]

(Directing this patch to Perf-events maintainers for review.)

With the kernel facility of Linux performance counters, we want the user
level tool tools/perf to be cross compiled for MIPS platform. To do this,
we need to include unistd.h, add rmb() and cpu_relax() in perf.h.

Your review comments are especially required for the definition of rmb():
In perf.h, we need to have a proper rmb() for _all_ MIPS platforms. And
we don't have CONFIG_* things for use in here. Looking at barrier.h,
rmb() goes into barrier() and __sync() for CAVIUM OCTEON and other CPUs,
respectively. What's more, __sync() has different versions as well.
Referring to BARRIER() in dump_tlb.c, I propose the "common" definition
for perf tool rmb() in this patch. Do you have any comments?

In addition, for testing the kernel part code I sent several days
ago, I was using the "particular" rmb() version for 24K/34K/74K cores:

#define rmb()           asm volatile(                           \
                                ".set   push\n\t"               \
                                ".set   noreorder\n\t"          \
                                ".set   mips2\n\t"              \
                                "sync\n\t"                      \
                                ".set   pop"                    \
                                : /* no output */               \
                                : /* no input */                \
                                : "memory")

This is the definition of __sync() for CONFIG_CPU_HAS_SYNC.


Thanks,

Deng-Cheng

Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 tools/perf/perf.h |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 6fb379b..cd05284 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -73,6 +73,18 @@
 #define cpu_relax()	asm volatile("":::"memory")
 #endif
 
+#ifdef __mips__
+#include "../../arch/mips/include/asm/unistd.h"
+#define rmb()		asm volatile(					\
+				".set	noreorder\n\t"			\
+				"nop;nop;nop;nop;nop;nop;nop\n\t"	\
+				".set	reorder"			\
+				: /* no output */			\
+				: /* no input */			\
+				: "memory")
+#define cpu_relax()	asm volatile("" ::: "memory")
+#endif
+
 #include <time.h>
 #include <unistd.h>
 #include <sys/types.h>