[PATCH v3 1/3] perf: Add perf_event_attr::bp_priv

[Tiezhu Yang]

When developing hardware watchpoint on LoongArch, we want to set the
same privilege passed by the ptrace user data, but there is no bridge
to save this value like bp_addr, bp_type and bp_len. This is a common
issue for the archs which have privilege level of breakpoint.

Add a member "bp_priv" which lives in a union on config3 at the end
of the uapi struct perf_event_attr to make a bridge between ptrace
and hardware breakpoint.

This is preparation for later patch on some archs such as ARM, ARM64
and LoongArch which have privilege level of breakpoint.

Signed-off-by: Tiezhu Yang <yangtiezhu at loongson.cn>
---
 include/uapi/linux/perf_event.h | 5 ++++-
 kernel/events/hw_breakpoint.c   | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 3a64499b0f5d..abe8da7a1f60 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -521,7 +521,10 @@ struct perf_event_attr {
 	 */
 	__u64	sig_data;
 
-	__u64	config3; /* extension of config2 */
+	union {
+		__u8	bp_priv; /* privilege level of breakpoint */
+		__u64	config3; /* extension of config2 */
+	};
 };
 
 /*
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 6c2cb4e4f48d..3ad16b226e4f 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -754,6 +754,7 @@ static void hw_breakpoint_copy_attr(struct perf_event_attr *to,
 	to->bp_addr = from->bp_addr;
 	to->bp_type = from->bp_type;
 	to->bp_len  = from->bp_len;
+	to->bp_priv = from->bp_priv;
 	to->disabled = from->disabled;
 }
 
-- 
2.42.0