Commit 8c19f96c authored by SeongJae Park's avatar SeongJae Park Committed by Zheng Zengkai
Browse files

mm/damon: hide kernel pointer from tracepoint event 

mainline inclusion
from mainline-v5.17-rc1
commit 76fd0285
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4RTX9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76fd0285b447991267e838842c0be7395eb454bb

--------------------------------

DAMON's virtual address spaces monitoring primitive uses 'struct pid *'
of the target process as its monitoring target id.  The kernel address
is exposed as-is to the user space via the DAMON tracepoint,
'damon_aggregated'.

Though primarily only privileged users are allowed to access that, it
would be better to avoid unnecessarily exposing kernel pointers so.
Because the trace result is only required to be able to distinguish each
target, we aren't need to use the pointer as-is.

This makes the tracepoint to use the index of the target in the
context's targets list as its id in the tracepoint, to hide the kernel
space address.

Link: https://lkml.kernel.org/r/20211229131016.23641-5-sj@kernel.org


Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 76fd0285)
Signed-off-by: default avatarYue Zou <zouyue3@huawei.com>
Reviewed-by: default avatarKefeng <Wang&lt;wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 4e519a65

include/trace/events/damon.h

+4 −4
Original line number Diff line number Diff line
@@ -11,10 +11,10 @@ 


TRACE_EVENT(damon_aggregated,



	TP_PROTO(struct damon_target *t, struct damon_region *r,

		unsigned int nr_regions),

	TP_PROTO(struct damon_target *t, unsigned int target_id,

		struct damon_region *r, unsigned int nr_regions),



	TP_ARGS(t, r, nr_regions),

	TP_ARGS(t, target_id, r, nr_regions),



	TP_STRUCT__entry(

		__field(unsigned long, target_id)
@@ -26,7 +26,7 @@ TRACE_EVENT(damon_aggregated, 
	),



	TP_fast_assign(

		__entry->target_id = t->id;

		__entry->target_id = target_id;

		__entry->nr_regions = nr_regions;

		__entry->start = r->ar.start;

		__entry->end = r->ar.end;

mm/damon/core.c

+3 −1
Original line number Diff line number Diff line
@@ -514,15 +514,17 @@ static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx) 
static void kdamond_reset_aggregated(struct damon_ctx *c)

{

	struct damon_target *t;

	unsigned int ti = 0;	/* target's index */



	damon_for_each_target(t, c) {

		struct damon_region *r;



		damon_for_each_region(r, t) {

			trace_damon_aggregated(t, r, damon_nr_regions(t));

			trace_damon_aggregated(t, ti, r, damon_nr_regions(t));

			r->last_nr_accesses = r->nr_accesses;

			r->nr_accesses = 0;

		}

		ti++;

	}

}