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Message-ID: <20250114-kcov-v1-4-004294b931a2@quicinc.com>
Date: Tue, 14 Jan 2025 13:34:34 +0800
From: "Jiao, Joey" <quic_jiangenj@...cinc.com>
To: Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Konovalov
<andreyknvl@...il.com>,
Jonathan Corbet <corbet@....net>,
Andrew Morton
<akpm@...ux-foundation.org>,
Dennis Zhou <dennis@...nel.org>, Tejun Heo
<tj@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Catalin Marinas
<catalin.marinas@....com>,
Will Deacon <will@...nel.org>
CC: <kasan-dev@...glegroups.com>, <linux-kernel@...r.kernel.org>,
<workflows@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-mm@...ck.org>, <linux-arm-kernel@...ts.infradead.org>,
<kernel@...cinc.com>
Subject: [PATCH 4/7] kcov: introduce new kcov KCOV_TRACE_UNIQ_CMP mode
Similar to KCOV_TRACE_CMP mode, KCOV_TRACE_UNIQ_CMP stores unique CMP data
into area.
Signed-off-by: Jiao, Joey <quic_jiangenj@...cinc.com>
---
include/linux/kcov.h | 2 +
include/uapi/linux/kcov.h | 2 +
kernel/kcov.c | 112 ++++++++++++++++++++++++++++++++--------------
3 files changed, 83 insertions(+), 33 deletions(-)
diff --git a/include/linux/kcov.h b/include/linux/kcov.h
index 56b858205ba16c47fc72bda9938c98f034503c8c..a78d78164bf75368c71a958a5438fc3ee68c95ca 100644
--- a/include/linux/kcov.h
+++ b/include/linux/kcov.h
@@ -27,6 +27,8 @@ enum kcov_mode {
KCOV_MODE_TRACE_UNIQ_PC = 16,
/* Collecting uniq edge mode. */
KCOV_MODE_TRACE_UNIQ_EDGE = 32,
+ /* Collecting uniq cmp mode. */
+ KCOV_MODE_TRACE_UNIQ_CMP = 64,
};
#define KCOV_IN_CTXSW (1 << 30)
diff --git a/include/uapi/linux/kcov.h b/include/uapi/linux/kcov.h
index 9b2019f0ab8b8cb5426d2d6b74472fa1a7293817..08abfca273c9624dc54a2c70b12a4a9302700f26 100644
--- a/include/uapi/linux/kcov.h
+++ b/include/uapi/linux/kcov.h
@@ -39,6 +39,8 @@ enum {
KCOV_TRACE_UNIQ_PC = 2,
/* Collecting uniq edge mode. */
KCOV_TRACE_UNIQ_EDGE = 4,
+ /* Collecting uniq CMP mode. */
+ KCOV_TRACE_UNIQ_CMP = 8,
};
/*
diff --git a/kernel/kcov.c b/kernel/kcov.c
index c04bbec9ac3186a5145240de8ac609ad8a7ca733..af73c40114d23adedab8318e8657d24bf36ae865 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -36,6 +36,11 @@
struct kcov_entry {
unsigned long ent;
+#ifdef CONFIG_KCOV_ENABLE_COMPARISONS
+ unsigned long type;
+ unsigned long arg1;
+ unsigned long arg2;
+#endif
struct hlist_node node;
};
@@ -44,7 +49,7 @@ struct kcov_entry {
#define MIN_POOL_ALLOC_ORDER ilog2(roundup_pow_of_two(sizeof(struct kcov_entry)))
/*
- * kcov hashmap to store uniq pc, prealloced mem for kcov_entry
+ * kcov hashmap to store uniq pc|edge|cmp, prealloced mem for kcov_entry
* and area shared between kernel and userspace.
*/
struct kcov_map {
@@ -87,7 +92,7 @@ struct kcov {
unsigned long prev_pc;
/* Coverage buffer shared with user space. */
void *area;
- /* Coverage hashmap for unique pc. */
+ /* Coverage hashmap for unique pc|cmp. */
struct kcov_map *map;
/* Edge hashmap for unique edge. */
struct kcov_map *map_edge;
@@ -289,14 +294,23 @@ static notrace inline void kcov_map_add(struct kcov_map *map, struct kcov_entry
struct kcov *kcov;
struct kcov_entry *entry;
unsigned int key = hash_key(ent);
- unsigned long pos, *area;
+ unsigned long pos, start_index, end_pos, max_pos, *area;
kcov = t->kcov;
- hash_for_each_possible_rcu(map->buckets, entry, node, key) {
- if (entry->ent == ent->ent)
- return;
- }
+ if ((mode == KCOV_MODE_TRACE_UNIQ_PC ||
+ mode == KCOV_MODE_TRACE_UNIQ_EDGE))
+ hash_for_each_possible_rcu(map->buckets, entry, node, key) {
+ if (entry->ent == ent->ent)
+ return;
+ }
+ else
+ hash_for_each_possible_rcu(map->buckets, entry, node, key) {
+ if (entry->ent == ent->ent && entry->type == ent->type &&
+ entry->arg1 == ent->arg1 && entry->arg2 == ent->arg2) {
+ return;
+ }
+ }
entry = (struct kcov_entry *)gen_pool_alloc(map->pool, 1 << MIN_POOL_ALLOC_ORDER);
if (unlikely(!entry))
@@ -306,16 +320,31 @@ static notrace inline void kcov_map_add(struct kcov_map *map, struct kcov_entry
memcpy(entry, ent, sizeof(*entry));
hash_add_rcu(map->buckets, &entry->node, key);
- if (mode == KCOV_MODE_TRACE_UNIQ_PC)
+ if (mode == KCOV_MODE_TRACE_UNIQ_PC || mode == KCOV_MODE_TRACE_UNIQ_CMP)
area = t->kcov_area;
else
area = kcov->map_edge->area;
pos = READ_ONCE(area[0]) + 1;
- if (likely(pos < t->kcov_size)) {
- WRITE_ONCE(area[0], pos);
- barrier();
- area[pos] = ent->ent;
+ if (mode == KCOV_MODE_TRACE_UNIQ_PC || mode == KCOV_MODE_TRACE_UNIQ_EDGE) {
+ if (likely(pos < t->kcov_size)) {
+ WRITE_ONCE(area[0], pos);
+ barrier();
+ area[pos] = ent->ent;
+ }
+ } else {
+ start_index = 1 + (pos - 1) * KCOV_WORDS_PER_CMP;
+ max_pos = t->kcov_size * sizeof(unsigned long);
+ end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
+ if (likely(end_pos <= max_pos)) {
+ /* See comment in __sanitizer_cov_trace_pc(). */
+ WRITE_ONCE(area[0], pos);
+ barrier();
+ area[start_index] = ent->type;
+ area[start_index + 1] = ent->arg1;
+ area[start_index + 2] = ent->arg2;
+ area[start_index + 3] = ent->ent;
+ }
}
}
@@ -384,33 +413,44 @@ static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
struct task_struct *t;
u64 *area;
u64 count, start_index, end_pos, max_pos;
+ struct kcov_entry entry = {0};
+ unsigned int mode;
t = current;
- if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t))
+ if (!check_kcov_mode(KCOV_MODE_TRACE_CMP | KCOV_MODE_TRACE_UNIQ_CMP, t))
return;
+ mode = t->kcov_mode;
ip = canonicalize_ip(ip);
- /*
- * We write all comparison arguments and types as u64.
- * The buffer was allocated for t->kcov_size unsigned longs.
- */
- area = (u64 *)t->kcov_area;
- max_pos = t->kcov_size * sizeof(unsigned long);
-
- count = READ_ONCE(area[0]);
-
- /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */
- start_index = 1 + count * KCOV_WORDS_PER_CMP;
- end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
- if (likely(end_pos <= max_pos)) {
- /* See comment in __sanitizer_cov_trace_pc(). */
- WRITE_ONCE(area[0], count + 1);
- barrier();
- area[start_index] = type;
- area[start_index + 1] = arg1;
- area[start_index + 2] = arg2;
- area[start_index + 3] = ip;
+ if (mode == KCOV_MODE_TRACE_CMP) {
+ /*
+ * We write all comparison arguments and types as u64.
+ * The buffer was allocated for t->kcov_size unsigned longs.
+ */
+ area = (u64 *)t->kcov_area;
+ max_pos = t->kcov_size * sizeof(unsigned long);
+
+ count = READ_ONCE(area[0]);
+
+ /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */
+ start_index = 1 + count * KCOV_WORDS_PER_CMP;
+ end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
+ if (likely(end_pos <= max_pos)) {
+ /* See comment in __sanitizer_cov_trace_pc(). */
+ WRITE_ONCE(area[0], count + 1);
+ barrier();
+ area[start_index] = type;
+ area[start_index + 1] = arg1;
+ area[start_index + 2] = arg2;
+ area[start_index + 3] = ip;
+ }
+ } else {
+ entry.type = type;
+ entry.arg1 = arg1;
+ entry.arg2 = arg2;
+ entry.ent = ip;
+ kcov_map_add(t->kcov->map, &entry, t, KCOV_MODE_TRACE_UNIQ_CMP);
}
}
@@ -730,6 +770,12 @@ static int kcov_get_mode(unsigned long arg)
mode |= KCOV_MODE_TRACE_UNIQ_PC;
if (arg & KCOV_TRACE_UNIQ_EDGE)
mode |= KCOV_MODE_TRACE_UNIQ_EDGE;
+ if (arg == KCOV_TRACE_UNIQ_CMP)
+#ifdef CONFIG_KCOV_ENABLE_COMPARISONS
+ mode = KCOV_MODE_TRACE_UNIQ_CMP;
+#else
+ return -EOPNOTSUPP;
+#endif
if (!mode)
return -EINVAL;
--
2.47.1
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