linux-kernel - [PATCH v3 1/6] powerpc/perf: Define big-endian version of perf_mem_data

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Message-Id: <1491875470-17904-2-git-send-email-maddy@linux.vnet.ibm.com>
Date:   Tue, 11 Apr 2017 07:21:05 +0530
From:   Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
To:     mpe@...erman.id.au
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        benh@...nel.crashing.org, paulus@...ba.org,
        sukadev@...ux.vnet.ibm.com, andrew.donnellan@....ibm.com,
        peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, wangnan0@...wei.com,
        ast@...nel.org, eranian@...gle.com,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
Subject: [PATCH v3 1/6] powerpc/perf: Define big-endian version of perf_mem_data_src

From: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>

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 (Which is broken now), we also need a big-endian represenation
of perf_mem_data_src. i.e, in a big endian system, if user request
PERF_SAMPLE_DATA_SRC (perf report -d), will get the default value from
perf_sample_data_init(), which is PERF_MEM_NA. Value for PERF_MEM_NA
is constructed using shifts:

  /* TLB access */
  #define PERF_MEM_TLB_NA		0x01 /* not available */
  ...
  #define PERF_MEM_TLB_SHIFT	26

  #define PERF_MEM_S(a, s) \
	(((__u64)PERF_MEM_##a##_##s) << PERF_MEM_##a##_SHIFT)

  #define PERF_MEM_NA (PERF_MEM_S(OP, NA)   |\
		    PERF_MEM_S(LVL, NA)   |\
		    PERF_MEM_S(SNOOP, NA) |\
		    PERF_MEM_S(LOCK, NA)  |\
		    PERF_MEM_S(TLB, NA))

Which works out as:

  ((0x01 << 0) | (0x01 << 5) | (0x01 << 19) | (0x01 << 24) | (0x01 << 26))

Which means the PERF_MEM_NA value comes out of the kernel as 0x5080021
in CPU endian.

But then in the perf tool, the code uses the bitfields to inspect the
value, and currently the bitfields are defined using little endian
ordering.

So eg. in perf_mem__tlb_scnprintf() we see:
  data_src->val = 0x5080021
             op = 0x0
            lvl = 0x0
          snoop = 0x0
           lock = 0x0
           dtlb = 0x0
           rsvd = 0x5080021

Patch does a minimal fix of adding big endian definition of the bitfields
to match the values that are already exported by the kernel on big endian.
And it makes no change on little endian.

Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
---
 include/uapi/linux/perf_event.h       | 16 ++++++++++++++++
 tools/include/uapi/linux/perf_event.h | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index c66a485a24ac..c4af1159a200 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -891,6 +891,7 @@ enum perf_callchain_context {
 #define PERF_FLAG_PID_CGROUP		(1UL << 2) /* pid=cgroup id, per-cpu mode only */
 #define PERF_FLAG_FD_CLOEXEC		(1UL << 3) /* O_CLOEXEC */
 
+#if defined(__LITTLE_ENDIAN_BITFIELD)
 union perf_mem_data_src {
 	__u64 val;
 	struct {
@@ -902,6 +903,21 @@ union perf_mem_data_src {
 			mem_rsvd:31;
 	};
 };
+#elif defined(__BIG_ENDIAN_BITFIELD)
+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 */
+	};
+};
+#else
+#error "Unknown endianness"
+#endif
 
 /* type of opcode (load/store/prefetch,code) */
 #define PERF_MEM_OP_NA		0x01 /* not available */
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index c66a485a24ac..c4af1159a200 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -891,6 +891,7 @@ enum perf_callchain_context {
 #define PERF_FLAG_PID_CGROUP		(1UL << 2) /* pid=cgroup id, per-cpu mode only */
 #define PERF_FLAG_FD_CLOEXEC		(1UL << 3) /* O_CLOEXEC */
 
+#if defined(__LITTLE_ENDIAN_BITFIELD)
 union perf_mem_data_src {
 	__u64 val;
 	struct {
@@ -902,6 +903,21 @@ union perf_mem_data_src {
 			mem_rsvd:31;
 	};
 };
+#elif defined(__BIG_ENDIAN_BITFIELD)
+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 */
+	};
+};
+#else
+#error "Unknown endianness"
+#endif
 
 /* type of opcode (load/store/prefetch,code) */
 #define PERF_MEM_OP_NA		0x01 /* not available */
-- 
2.7.4