linux-kernel - [PATCH v2 06/18] perf/hw_breakpoint: add arch-independent hw_breakpoint_modify

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Message-ID: <20250904002126.1514566-7-wangjinchao600@gmail.com>
Date: Thu,  4 Sep 2025 08:21:03 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	"Naveen N . Rao" <naveen@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	David Hildenbrand <david@...hat.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	linux-perf-users@...r.kernel.org,
	linux-mm@...ck.org,
	linux-trace-kernel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v2 06/18] perf/hw_breakpoint: add arch-independent hw_breakpoint_modify_local()

Introduce hw_breakpoint_modify_local() as a generic helper to modify an
existing hardware breakpoint. The function invokes
hw_breakpoint_arch_parse() and delegates the reinstall step to the
architecture via arch_reinstall_hw_breakpoint().

A weak default implementation of arch_reinstall_hw_breakpoint() is
provided, returning -EOPNOTSUPP on architectures without support.

This makes the interface arch-independent while allowing x86 (and others)
to provide their own implementation.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 include/linux/hw_breakpoint.h |  1 +
 kernel/events/hw_breakpoint.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index db199d653dd1..9453b5bdb443 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -67,6 +67,7 @@ extern int
 modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *attr,
 				bool check);
 
+int hw_breakpoint_modify_local(struct perf_event *bp, struct perf_event_attr *attr);
 /*
  * Kernel breakpoints are not associated with any particular thread.
  */
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 8ec2cb688903..ff428739f71e 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -983,6 +983,24 @@ static void hw_breakpoint_del(struct perf_event *bp, int flags)
 	arch_uninstall_hw_breakpoint(bp);
 }
 
+int hw_breakpoint_modify_local(struct perf_event *bp, struct perf_event_attr *attr)
+{
+	int err;
+
+	err = hw_breakpoint_arch_parse(bp, attr, counter_arch_bp(bp));
+	if (err)
+		return err;
+
+	return arch_reinstall_hw_breakpoint(bp);
+}
+EXPORT_SYMBOL(hw_breakpoint_modify_local);
+
+/* weak fallback for arches without support */
+__weak int arch_reinstall_hw_breakpoint(struct perf_event *bp)
+{
+	return -EOPNOTSUPP;
+}
+
 static void hw_breakpoint_start(struct perf_event *bp, int flags)
 {
 	bp->hw.state = 0;
-- 
2.43.0