perf_counter: fix type/event_id layout on big-endian systems
Impact: build fix for powerpc
Commit db3a944aca35ae61 ("perf_counter: revamp syscall input ABI")
expanded the hw_event.type field into a union of structs containing
bitfields. In particular it introduced a type field and a raw_type
field, with the intention that the 1-bit raw_type field should
overlay the most-significant bit of the 8-bit type field, and in fact
perf_counter_alloc() now assumes that (or at least, assumes that
raw_type doesn't overlay any of the bits that are 1 in the values of
PERF_TYPE_{HARDWARE,SOFTWARE,TRACEPOINT}).
Unfortunately this is not true on big-endian systems such as PowerPC,
where bitfields are laid out from left to right, i.e. from most
significant bit to least significant. This means that setting
hw_event.type = PERF_TYPE_SOFTWARE will set hw_event.raw_type to 1.
This fixes it by making the layout depend on whether or not
__BIG_ENDIAN_BITFIELD is defined. It's a bit ugly, but that's what
we get for using bitfields in a user/kernel ABI.
Also, that commit didn't fix up some places in arch/powerpc/kernel/
perf_counter.c where hw_event.raw and hw_event.event_id were used.
This fixes them too.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index a4b76c0..98f5990 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -15,6 +15,7 @@
#include <linux/types.h>
#include <linux/ioctl.h>
+#include <asm/byteorder.h>
/*
* User-space ABI bits:
@@ -86,6 +87,7 @@
*/
struct perf_counter_hw_event {
union {
+#ifndef __BIG_ENDIAN_BITFIELD
struct {
__u64 event_id : 56,
type : 8;
@@ -94,6 +96,16 @@
__u64 raw_event_id : 63,
raw_type : 1;
};
+#else
+ struct {
+ __u64 type : 8,
+ event_id : 56;
+ };
+ struct {
+ __u64 raw_type : 1,
+ raw_event_id : 63;
+ };
+#endif /* __BIT_ENDIAN_BITFIELD */
__u64 event_config;
};