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Tue, 14 Jan 2025 05:36:02 GMT Received: from la-sh002-lnx.ap.qualcomm.com (10.80.80.8) by nasanex01c.na.qualcomm.com (10.45.79.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 13 Jan 2025 21:35:56 -0800 From: "Jiao, Joey" Date: Tue, 14 Jan 2025 13:34:34 +0800 Subject: [PATCH 4/7] kcov: introduce new kcov KCOV_TRACE_UNIQ_CMP mode MIME-Version: 1.0 Message-ID: <20250114-kcov-v1-4-004294b931a2@quicinc.com> References: <20250114-kcov-v1-0-004294b931a2@quicinc.com> In-Reply-To: <20250114-kcov-v1-0-004294b931a2@quicinc.com> To: Dmitry Vyukov , Andrey Konovalov , Jonathan Corbet , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , Catalin Marinas , Will Deacon CC: , , , , , , X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1736832942; l=6956; i=quic_jiangenj@quicinc.com; s=20250114; h=from:subject:message-id; bh=87rus4o59M/h6mbCeTYN+uwPYg3Cu8v5VQQt/ES6TT4=; b=dLbyxsjISwicFnHI2UlW7HXO0FqBJGbKRAtWrXffXPrseH1onOKQ7Uil5a0dOqyIK0G9Sonh3 Af14LF0A5HiDGL5/ZS9Y7gv/n6tgLyBJ6vxQua47w0wN4Ujd1sTIXzx X-Developer-Key: i=quic_jiangenj@quicinc.com; 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Signed-off-by: Jiao, Joey --- 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;