linux-kernel - [PATCH 5/7] powerpc/perf: Define big-endian version of perf_mem_data

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Message-ID: <20130810175153.GF15551@us.ibm.com>
Date:	Sat, 10 Aug 2013 10:51:54 -0700
From:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Cc:	Stephane Eranian <eranian@...gle.com>,
	Paul Mackerras <paulus@...ba.org>,
	Anton Blanchard <anton@....ibm.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Subject: [PATCH 5/7] powerpc/perf: Define big-endian version of
 perf_mem_data_src


[PATCH 5/7] powerpc/perf: Define big-endian version of perf_mem_data_src

perf_mem_data_src is an union that is initialized via the ->val field
and accessed via the bitmap fields. For this to work on big endian
platforms, we also need a big-endian represenation of perf_mem_data_src.

Cc: Stephane Eranian <eranian@...gle.com>
Cc: Paul Mckerras <paulus@...ba.org>
Cc: Michael Ellerman <michael@...erman.id.au>
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
---

Thanks to input from Stephane Eranian and Michael Ellerman.

 include/uapi/linux/perf_event.h |   55 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 55 insertions(+), 0 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 62c25a2..8497c51 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -19,6 +19,47 @@
 #include <asm/byteorder.h>
 
 /*
+ * Kernel and userspace check for endianness in incompatible ways.
+ * In user space, <endian.h> defines both __BIG_ENDIAN and __LITTLE_ENDIAN
+ * but sets __BYTE_ORDER to one or the other. So user space uses checks are:
+ *
+ *	#if __BYTE_ORDER == __LITTLE_ENDIAN
+ *
+ * In the kernel, __BYTE_ORDER is undefined, so using the above check doesn't
+ * work. Further, kernel code assumes that exactly one of __BIG_ENDIAN and
+ * __LITTLE_ENDIAN is defined.  So the kernel checks are like:
+ *
+ *	#if defined(__LITTLE_ENDIAN)
+ *
+ * But we can't use that check in user space since __LITTLE_ENDIAN (and
+ * __BIG_ENDIAN) are always defined.
+ *
+ * Since some perf data structures depend on endianness _and_ are shared
+ * between kernel and user, perf needs its own notion of endian macros (at
+ * least until user and kernel endian checks converge).
+ */
+#define __PERF_LE	1234
+#define __PERF_BE	4321
+
+#if defined(__KERNEL__)
+
+#if defined(__LITTLE_ENDIAN)
+#define __PERF_BYTE_ORDER	__PERF_LE
+#elif defined(__BIG_ENDIAN)
+#define __PERF_BYTE_ORDER	__PERF_BE
+#endif
+
+#else /* __KERNEL__ */
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define __PERF_BYTE_ORDER	__PERF_LE
+#elif __BYTE_ORDER == __BIG_ENDIAN
+#define __PERF_BYTE_ORDER	__PERF_BE
+#endif
+
+#endif /* __KERNEL__ */
+
+/*
  * User-space ABI bits:
  */
 
@@ -659,6 +700,7 @@ enum perf_callchain_context {
 #define PERF_FLAG_FD_OUTPUT		(1U << 1)
 #define PERF_FLAG_PID_CGROUP		(1U << 2) /* pid=cgroup id, per-cpu mode only */
 
+#if __PERF_BYTE_ORDER == __PERF_LE
 union perf_mem_data_src {
 	__u64 val;
 	struct {
@@ -670,6 +712,19 @@ union perf_mem_data_src {
 			mem_rsvd:31;
 	};
 };
+#elif __PERF_BYTE_ORDER == __PERF_BE
+union perf_mem_data_src {
+	__u64 val;
+	struct {
+		__u64	mem_rsvd:31,
+			mem_dtlb:7,	/* tlb access */
+			mem_lock:2,	/* lock instr */
+			mem_snoop:5,	/* snoop mode */
+			mem_lvl:14,	/* memory hierarchy level */
+			mem_op:5;	/* type of opcode */
+	};
+};
+#endif
 
 /* type of opcode (load/store/prefetch,code) */
 #define PERF_MEM_OP_NA		0x01 /* not available */
-- 
1.7.1

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