From patchwork Wed Oct 23 15:24:29 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 11207027 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 994BE1951 for ; Wed, 23 Oct 2019 15:25:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C6F321928 for ; Wed, 23 Oct 2019 15:25:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vdU45X1q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390590AbfJWPZE (ORCPT ); Wed, 23 Oct 2019 11:25:04 -0400 Received: from mail-wr1-f74.google.com ([209.85.221.74]:48030 "EHLO mail-wr1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406681AbfJWPYm (ORCPT ); Wed, 23 Oct 2019 11:24:42 -0400 Received: by mail-wr1-f74.google.com with SMTP id 92so5846510wro.14 for ; Wed, 23 Oct 2019 08:24:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=QEWok5XzYtqqso1VZwcCBlXTZxUGFCIPb4s7g3hvBiY=; b=vdU45X1qI1SPQIwqFB2P3CsFq1aw79uRooHnC0Lkplyf/8ekhc9prAYo5Wr/DZOkaN CWSuhHd87FjaN7oPX04E2hgEZYr+NKYFYfqdsgiAOhVOYKJER3OlYmbPcZYDF/tAmi8p yPjdAi9blln+d4Uf+x01xV91rGhSPygELcDRyO4IPQudZyHwhfilKWDv4LZ638ZTr6nr HeyBTjMqOG55o0kvy/sVH+oOtkMdoZSPE2XAgHb8oOb3yq7btXOuRcmzk7g4+/Q86pxZ e+reMgYA++g5Sled6JnQdV/gh+WbSrGtbL8Hq6rK7rsc1Rngsk3Y/6sa7MCqMYOhwp+n E0Cg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=QEWok5XzYtqqso1VZwcCBlXTZxUGFCIPb4s7g3hvBiY=; b=MjAJBwfGclvyfjLsnhXwE/Ptz5wHwVOJ+ZPUuOfeoPbO9jyP2iEAnOqmqk8HovZ6Ua Zt+69vMWP6YnoYsqEUVROMdg/ljvjyAOHEgcAA9Crhrl/m+MjejhBpl1qsNHH9JrimVq PuiZ9DrsykPEBo3q/iAlPQuyvzoc77ZB8z1a8UhELeN80N0EXQJwqZz9cBXh8ktvClWF 4uOjCQLkInqn5777pTCEnKw0LkCRKE+g15q64Mda2Bw/qKAlTmWhEuOk+lelJB3gA9pU Qu0GUt+LecOVC1aCQ8PB0cj51hc+qpLnOLPYX/Q1Tb1Ru2Jp6jAmoX4LjZgUya/uPmOX gq4A== X-Gm-Message-State: APjAAAVVxZS5IqHvc+CRnk8xqrN9wf52RTcpsn0HdPLX6dbWX1fVY4dP 16i2EXD9z4xeJhydEU3foa+0fjANAfLbAThq+sXJdWET01g89P/rHhcpFlGl1zo85JHPfpL3xpS oebbEkhJf85445dwzBpyiPJwdg3FPAxQ9IaXODs6L0L54kOpq621P+BC+qZvRon4wG/dxKZK2xH a3 X-Google-Smtp-Source: APXvYqwZKhKN1SJ+sA9bxS3UfAxxydol53Yhl+Y5tllj2eT1BNWf31IGlf8fxR2T9vCUVEbAH1mzbAFB+K4wtMIw X-Received: by 2002:a5d:4847:: with SMTP id n7mr8847419wrs.398.1571844278984; Wed, 23 Oct 2019 08:24:38 -0700 (PDT) Date: Wed, 23 Oct 2019 17:24:29 +0200 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 1/3] kcov: remote coverage support From: Andrey Konovalov To: linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Vyukov , Greg Kroah-Hartman , Alan Stern , "Michael S . Tsirkin" , Jason Wang Cc: Andrew Morton , Arnd Bergmann , Steven Rostedt , David Windsor , Elena Reshetova , Anders Roxell , Alexander Potapenko , Marco Elver , Andrey Konovalov Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org This patch adds background thread coverage collection ability to kcov. With KCOV_ENABLE coverage is collected only for syscalls that are issued from the current process. With KCOV_REMOTE_ENABLE it's possible to collect coverage for arbitrary parts of the kernel code, provided that those parts are annotated with kcov_remote_start()/kcov_remote_stop(). This allows to collect coverage from two types of kernel background threads: the global ones, that are spawned during kernel boot and are always running (e.g. USB hub_event()); and the local ones, that are spawned when a user interacts with some kernel interface (e.g. vhost workers). To enable collecting coverage from a global background thread, a unique global handle must be assigned and passed to the corresponding kcov_remote_start() call. Then a userspace process can pass a list of such handles to the KCOV_REMOTE_ENABLE ioctl in the handles array field of the kcov_remote_arg struct. This will attach the used kcov device to the code sections, that are referenced by those handles. Since there might be many local background threads spawned from different userspace processes, we can't use a single global handle per annotation. Instead, the userspace process passes a non-zero handle through the common_handle field of the kcov_remote_arg struct. This common handle gets saved to the kcov_handle field in the current task_struct and needs to be passed to the newly spawned threads via custom annotations. Those threads should in turn be annotated with kcov_remote_start()/kcov_remote_stop(). Internally kcov stores handles as u64 integers. The top byte of a handle is used to denote the id of a subsystem that this handle belongs to, and the lower 4 bytes are used to denote a handle id within that subsystem. A reserved value 0 is used as a subsystem id for common handles as they don't belong to a particular subsystem. The bytes 4-7 are currently reserved and must be zero. In the future the number of bytes used for the subsystem or handle ids might be increased. When a particular userspace proccess collects coverage by via a common handle, kcov will collect coverage for each code section that is annotated to use the common handle obtained as kcov_handle from the current task_struct. However non common handles allow to collect coverage selectively from different subsystems. Signed-off-by: Andrey Konovalov Reviewed-by: Dmitry Vyukov --- Documentation/dev-tools/kcov.rst | 128 +++++++++ include/linux/kcov.h | 23 ++ include/linux/sched.h | 6 + include/uapi/linux/kcov.h | 25 ++ kernel/kcov.c | 480 ++++++++++++++++++++++++++++--- 5 files changed, 627 insertions(+), 35 deletions(-) diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst index 42b612677799..80536ffe784a 100644 --- a/Documentation/dev-tools/kcov.rst +++ b/Documentation/dev-tools/kcov.rst @@ -34,6 +34,7 @@ Profiling data will only become accessible once debugfs has been mounted:: Coverage collection ------------------- + The following program demonstrates coverage collection from within a test program using kcov: @@ -128,6 +129,7 @@ only need to enable coverage (disable happens automatically on thread end). Comparison operands collection ------------------------------ + Comparison operands collection is similar to coverage collection: .. code-block:: c @@ -202,3 +204,129 @@ Comparison operands collection is similar to coverage collection: Note that the kcov modes (coverage collection or comparison operands) are mutually exclusive. + +Remote coverage collection +-------------------------- + +With KCOV_ENABLE coverage is collected only for syscalls that are issued from +the current process. With KCOV_REMOTE_ENABLE it's possible to collect coverage +for arbitrary parts of the kernel code, provided that those parts are annotated +with kcov_remote_start()/kcov_remote_stop(). + +This allows to collect coverage from two types of kernel background threads: +the global ones, that are spawned during kernel boot and are always running +(e.g. USB hub_event()); and the local ones, that are spawned when a user +interacts with some kernel interface (e.g. vhost workers). + +To enable collecting coverage from a global background thread, a unique global +handle must be assigned and passed to the corresponding kcov_remote_start() +call. Then a userspace process can pass a list of such handles to the +KCOV_REMOTE_ENABLE ioctl in the handles array field of the kcov_remote_arg +struct. This will attach the used kcov device to the code sections, that are +referenced by those handles. + +Since there might be many local background threads spawned from different +userspace processes, we can't use a single global handle per annotation. +Instead, the userspace process passes a non-zero handle through the +common_handle field of the kcov_remote_arg struct. This common handle gets +saved to the kcov_handle field in the current task_struct and needs to be +passed to the newly spawned threads via custom annotations. Those threads +should in turn be annotated with kcov_remote_start()/kcov_remote_stop(). + +Internally kcov stores handles as u64 integers. The top byte of a handle is +used to denote the id of a subsystem that this handle belongs to, and the lower +4 bytes are used to denote a handle id within that subsystem. A reserved value +0 is used as a subsystem id for common handles as they don't belong to a +particular subsystem. The bytes 4-7 are currently reserved and must be zero. +In the future the number of bytes used for the subsystem or handle ids might +be increased. + +When a particular userspace proccess collects coverage by via a common handle, +kcov will collect coverage for each code section that is annotated to use the +common handle obtained as kcov_handle from the current task_struct. However +non common handles allow to collect coverage selectively from different +subsystems. + +.. code-block:: c + + struct kcov_remote_arg { + unsigned trace_mode; + unsigned area_size; + unsigned num_handles; + uint64_t common_handle; + uint64_t handles[0]; + }; + + #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long) + #define KCOV_DISABLE _IO('c', 101) + #define KCOV_REMOTE_ENABLE _IOW('c', 102, struct kcov_remote_arg) + + #define COVER_SIZE (64 << 10) + + #define KCOV_TRACE_PC 0 + + #define KCOV_SUBSYSTEM_COMMON (0x00ull << 56) + #define KCOV_SUBSYSTEM_USB (0x01ull << 56) + + #define KCOV_SUBSYSTEM_MASK (0xffull << 56) + #define KCOV_HANDLE_ID_MASK (0xffffffffull) + + static inline __u64 kcov_remote_handle(__u64 subsys, __u64 id) + { + if (subsys & ~KCOV_SUBSYSTEM_MASK || id & ~KCOV_HANDLE_ID_MASK) + return 0; + return subsys | id; + } + + #define KCOV_COMMON_ID 0x42 + #define KCOV_USB_BUS_NUM 1 + + int main(int argc, char **argv) + { + int fd; + unsigned long *cover, n, i; + struct kcov_remote_arg *arg; + + fd = open("/sys/kernel/debug/kcov", O_RDWR); + if (fd == -1) + perror("open"), exit(1); + if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE)) + perror("ioctl"), exit(1); + cover = (unsigned long*)mmap(NULL, COVER_SIZE * sizeof(unsigned long), + PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if ((void*)cover == MAP_FAILED) + perror("mmap"), exit(1); + + /* Enable coverage collection via common handle and from USB bus #1. */ + arg = calloc(1, sizeof(*arg) + sizeof(uint64_t)); + if (!arg) + perror("calloc"), exit(1); + arg->trace_mode = KCOV_TRACE_PC; + arg->area_size = COVER_SIZE; + arg->num_handles = 1; + arg->common_handle = kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, + KCOV_COMMON_ID); + arg->handles[0] = kcov_remote_handle(KCOV_SUBSYSTEM_USB, + KCOV_USB_BUS_NUM); + if (ioctl(fd, KCOV_REMOTE_ENABLE, arg)) + perror("ioctl"), free(arg), exit(1); + free(arg); + + /* + * Here the user needs to trigger execution of a kernel code section + * that is either annotated with the common handle, or to trigger some + * activity on USB bus #1. + */ + sleep(2); + + n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED); + for (i = 0; i < n; i++) + printf("0x%lx\n", cover[i + 1]); + if (ioctl(fd, KCOV_DISABLE, 0)) + perror("ioctl"), exit(1); + if (munmap(cover, COVER_SIZE * sizeof(unsigned long))) + perror("munmap"), exit(1); + if (close(fd)) + perror("close"), exit(1); + return 0; + } diff --git a/include/linux/kcov.h b/include/linux/kcov.h index b76a1807028d..a10e84707d82 100644 --- a/include/linux/kcov.h +++ b/include/linux/kcov.h @@ -37,12 +37,35 @@ do { \ (t)->kcov_mode &= ~KCOV_IN_CTXSW; \ } while (0) +/* See Documentation/dev-tools/kcov.rst for usage details. */ +void kcov_remote_start(u64 handle); +void kcov_remote_stop(void); +u64 kcov_common_handle(void); + +static inline void kcov_remote_start_common(u64 id) +{ + kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id)); +} + +static inline void kcov_remote_start_usb(u64 id) +{ + kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_USB, id)); +} + #else static inline void kcov_task_init(struct task_struct *t) {} static inline void kcov_task_exit(struct task_struct *t) {} static inline void kcov_prepare_switch(struct task_struct *t) {} static inline void kcov_finish_switch(struct task_struct *t) {} +static inline void kcov_remote_start(u64 handle) {} +static inline void kcov_remote_stop(void) {} +static inline u64 kcov_common_handle(void) +{ + return 0; +} +static inline void kcov_remote_start_common(u64 id) {} +static inline void kcov_remote_start_usb(u64 id) {} #endif /* CONFIG_KCOV */ #endif /* _LINUX_KCOV_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 67a1d86981a9..b0f9534b971e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1214,6 +1214,12 @@ struct task_struct { /* KCOV descriptor wired with this task or NULL: */ struct kcov *kcov; + + /* KCOV common handle for remote coverage collection: */ + u64 kcov_handle; + + /* KCOV sequence number, see kernel/kcov.c for details: */ + int kcov_sequence; #endif #ifdef CONFIG_MEMCG diff --git a/include/uapi/linux/kcov.h b/include/uapi/linux/kcov.h index 9529867717a8..1236847b2356 100644 --- a/include/uapi/linux/kcov.h +++ b/include/uapi/linux/kcov.h @@ -4,9 +4,21 @@ #include +/* See Documentation/dev-tools/kcov.rst for usage details. */ +struct kcov_remote_arg { + unsigned int trace_mode; /* KCOV_TRACE_PC or KCOV_TRACE_CMP */ + unsigned int area_size; /* Length of coverage buffer in words */ + unsigned int num_handles; /* Size of handles array */ + __u64 common_handle; + __u64 handles[0]; +}; + +#define KCOV_REMOTE_MAX_HANDLES 0x10000 + #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long) #define KCOV_ENABLE _IO('c', 100) #define KCOV_DISABLE _IO('c', 101) +#define KCOV_REMOTE_ENABLE _IOW('c', 102, struct kcov_remote_arg) enum { /* @@ -32,4 +44,17 @@ enum { #define KCOV_CMP_SIZE(n) ((n) << 1) #define KCOV_CMP_MASK KCOV_CMP_SIZE(3) +#define KCOV_SUBSYSTEM_COMMON (0x00ull << 56) +#define KCOV_SUBSYSTEM_USB (0x01ull << 56) + +#define KCOV_SUBSYSTEM_MASK (0xffull << 56) +#define KCOV_HANDLE_ID_MASK (0xffffffffull) + +static inline __u64 kcov_remote_handle(__u64 subsys, __u64 id) +{ + if (subsys & ~KCOV_SUBSYSTEM_MASK || id & ~KCOV_HANDLE_ID_MASK) + return 0; + return subsys | id; +} + #endif /* _LINUX_KCOV_IOCTLS_H */ diff --git a/kernel/kcov.c b/kernel/kcov.c index 2ee38727844a..a79d2351212b 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -23,6 +24,8 @@ #include #include +#define kcov_debug(fmt, ...) pr_debug("%s: " fmt, __func__, ##__VA_ARGS__) + /* Number of 64-bit words written per one comparison: */ #define KCOV_WORDS_PER_CMP 4 @@ -44,19 +47,97 @@ struct kcov { * Reference counter. We keep one for: * - opened file descriptor * - task with enabled coverage (we can't unwire it from another task) + * - each code section for remote coverage collection */ refcount_t refcount; /* The lock protects mode, size, area and t. */ spinlock_t lock; enum kcov_mode mode; - /* Size of arena (in long's for KCOV_MODE_TRACE). */ - unsigned size; + /* Size of arena (in long's). */ + unsigned int size; /* Coverage buffer shared with user space. */ void *area; /* Task for which we collect coverage, or NULL. */ struct task_struct *t; + /* Collecting coverage from remote threads. */ + bool remote; + /* Size of remote arena (in long's). */ + unsigned int remote_size; + /* + * Sequence is incremented each time kcov is reenabled, used by + * kcov_remote_stop(), see the comment there. + */ + int sequence; }; +struct kcov_remote_area { + struct list_head list; + unsigned int size; +}; + +struct kcov_remote { + u64 handle; + struct kcov *kcov; + struct hlist_node hnode; +}; + +static DEFINE_SPINLOCK(kcov_remote_lock); +static DEFINE_HASHTABLE(kcov_remote_map, 4); +static struct list_head kcov_remote_areas = LIST_HEAD_INIT(kcov_remote_areas); + +static struct kcov_remote *kcov_remote_find(u64 handle) +{ + struct kcov_remote *remote; + + hash_for_each_possible(kcov_remote_map, remote, hnode, handle) { + if (remote->handle == handle) + return remote; + } + return NULL; +} + +static struct kcov_remote *kcov_remote_add(struct kcov *kcov, u64 handle) +{ + struct kcov_remote *remote; + + if (kcov_remote_find(handle)) + return ERR_PTR(-EEXIST); + remote = kmalloc(sizeof(*remote), GFP_ATOMIC); + if (!remote) + return ERR_PTR(-ENOMEM); + remote->handle = handle; + remote->kcov = kcov; + hash_add(kcov_remote_map, &remote->hnode, handle); + return remote; +} + +static struct kcov_remote_area *kcov_remote_area_get(unsigned int size) +{ + struct kcov_remote_area *area; + struct list_head *pos; + + kcov_debug("size = %u\n", size); + list_for_each(pos, &kcov_remote_areas) { + area = list_entry(pos, struct kcov_remote_area, list); + if (area->size == size) { + list_del(&area->list); + kcov_debug("rv = %px\n", area); + return area; + } + } + kcov_debug("rv = NULL\n"); + return NULL; +} + +static void kcov_remote_area_put(struct kcov_remote_area *area, + unsigned int size) +{ + kcov_debug("area = %px, size = %u\n", area, size); + INIT_LIST_HEAD(&area->list); + area->size = size; + list_add(&area->list, &kcov_remote_areas); +} + static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) { unsigned int mode; @@ -73,7 +154,7 @@ static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_stru * in_interrupt() returns false (e.g. preempt_schedule_irq()). * READ_ONCE()/barrier() effectively provides load-acquire wrt * interrupts, there are paired barrier()/WRITE_ONCE() in - * kcov_ioctl_locked(). + * kcov_start(). */ barrier(); return mode == needed_mode; @@ -227,6 +308,78 @@ void notrace __sanitizer_cov_trace_switch(u64 val, u64 *cases) EXPORT_SYMBOL(__sanitizer_cov_trace_switch); #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ +static void kcov_start(struct task_struct *t, unsigned int size, + void *area, enum kcov_mode mode, int sequence) +{ + kcov_debug("t = %px, size = %u, area = %px\n", t, size, area); + /* Cache in task struct for performance. */ + t->kcov_size = size; + t->kcov_area = area; + /* See comment in check_kcov_mode(). */ + barrier(); + WRITE_ONCE(t->kcov_mode, mode); + t->kcov_sequence = sequence; +} + +static void kcov_stop(struct task_struct *t) +{ + WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); + barrier(); + t->kcov_size = 0; + t->kcov_area = NULL; +} + +static void kcov_task_reset(struct task_struct *t) +{ + kcov_stop(t); + t->kcov = NULL; + t->kcov_sequence = 0; + t->kcov_handle = 0; +} + +void kcov_task_init(struct task_struct *t) +{ + kcov_task_reset(t); + t->kcov_handle = current->kcov_handle; +} + +static void kcov_reset(struct kcov *kcov) +{ + kcov->t = NULL; + kcov->mode = KCOV_MODE_INIT; + kcov->remote = false; + kcov->remote_size = 0; + kcov->sequence++; +} + +static void kcov_remote_reset(struct kcov *kcov) +{ + int bkt; + struct kcov_remote *remote; + struct hlist_node *tmp; + + spin_lock(&kcov_remote_lock); + hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { + if (remote->kcov != kcov) + continue; + kcov_debug("removing handle %llx\n", remote->handle); + hash_del(&remote->hnode); + kfree(remote); + } + /* Do reset before unlock to prevent races with kcov_remote_start(). */ + kcov_reset(kcov); + spin_unlock(&kcov_remote_lock); +} + +static void kcov_disable(struct task_struct *t, struct kcov *kcov) +{ + kcov_task_reset(t); + if (kcov->remote) + kcov_remote_reset(kcov); + else + kcov_reset(kcov); +} + static void kcov_get(struct kcov *kcov) { refcount_inc(&kcov->refcount); @@ -235,20 +388,12 @@ static void kcov_get(struct kcov *kcov) static void kcov_put(struct kcov *kcov) { if (refcount_dec_and_test(&kcov->refcount)) { + kcov_remote_reset(kcov); vfree(kcov->area); kfree(kcov); } } -void kcov_task_init(struct task_struct *t) -{ - WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); - barrier(); - t->kcov_size = 0; - t->kcov_area = NULL; - t->kcov = NULL; -} - void kcov_task_exit(struct task_struct *t) { struct kcov *kcov; @@ -256,15 +401,23 @@ void kcov_task_exit(struct task_struct *t) kcov = t->kcov; if (kcov == NULL) return; + spin_lock(&kcov->lock); + kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t); + /* + * If !kcov->remote, this checks that t->kcov->t == t. + * If kcov->remote == true then the exiting task is either: + * 1. a remote task between kcov_remote_start() and kcov_remote_stop(), + * in this case t != kcov->t and we'll print a warning; or + * 2. the task that created kcov exiting without calling KCOV_DISABLE, + * in this case t == kcov->t and no warning is printed. + */ if (WARN_ON(kcov->t != t)) { spin_unlock(&kcov->lock); return; } /* Just to not leave dangling references behind. */ - kcov_task_init(t); - kcov->t = NULL; - kcov->mode = KCOV_MODE_INIT; + kcov_disable(t, kcov); spin_unlock(&kcov->lock); kcov_put(kcov); } @@ -313,6 +466,7 @@ static int kcov_open(struct inode *inode, struct file *filep) if (!kcov) return -ENOMEM; kcov->mode = KCOV_MODE_DISABLED; + kcov->sequence = 1; refcount_set(&kcov->refcount, 1); spin_lock_init(&kcov->lock); filep->private_data = kcov; @@ -325,6 +479,20 @@ static int kcov_close(struct inode *inode, struct file *filep) return 0; } +static int kcov_get_mode(unsigned long arg) +{ + if (arg == KCOV_TRACE_PC) + return KCOV_MODE_TRACE_PC; + else if (arg == KCOV_TRACE_CMP) +#ifdef CONFIG_KCOV_ENABLE_COMPARISONS + return KCOV_MODE_TRACE_CMP; +#else + return -ENOTSUPP; +#endif + else + return -EINVAL; +} + /* * Fault in a lazily-faulted vmalloc area before it can be used by * __santizer_cov_trace_pc(), to avoid recursion issues if any code on the @@ -340,14 +508,35 @@ static void kcov_fault_in_area(struct kcov *kcov) READ_ONCE(area[offset]); } +static inline bool kcov_check_handle(u64 handle, bool common_valid, + bool uncommon_valid, bool zero_valid) +{ + if (handle & ~(KCOV_SUBSYSTEM_MASK | KCOV_HANDLE_ID_MASK)) + return false; + switch (handle & KCOV_SUBSYSTEM_MASK) { + case KCOV_SUBSYSTEM_COMMON: + return (handle & KCOV_HANDLE_ID_MASK) ? + common_valid : zero_valid; + case KCOV_SUBSYSTEM_USB: + return uncommon_valid; + default: + return false; + } + return false; +} + static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, unsigned long arg) { struct task_struct *t; unsigned long size, unused; + int mode, i; + struct kcov_remote_arg *remote_arg; + struct kcov_remote *remote; switch (cmd) { case KCOV_INIT_TRACE: + kcov_debug("KCOV_INIT_TRACE\n"); /* * Enable kcov in trace mode and setup buffer size. * Must happen before anything else. @@ -366,6 +555,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, kcov->mode = KCOV_MODE_INIT; return 0; case KCOV_ENABLE: + kcov_debug("KCOV_ENABLE\n"); /* * Enable coverage for the current task. * At this point user must have been enabled trace mode, @@ -378,29 +568,20 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, t = current; if (kcov->t != NULL || t->kcov != NULL) return -EBUSY; - if (arg == KCOV_TRACE_PC) - kcov->mode = KCOV_MODE_TRACE_PC; - else if (arg == KCOV_TRACE_CMP) -#ifdef CONFIG_KCOV_ENABLE_COMPARISONS - kcov->mode = KCOV_MODE_TRACE_CMP; -#else - return -ENOTSUPP; -#endif - else - return -EINVAL; + mode = kcov_get_mode(arg); + if (mode < 0) + return mode; kcov_fault_in_area(kcov); - /* Cache in task struct for performance. */ - t->kcov_size = kcov->size; - t->kcov_area = kcov->area; - /* See comment in check_kcov_mode(). */ - barrier(); - WRITE_ONCE(t->kcov_mode, kcov->mode); + kcov->mode = mode; + kcov_start(t, kcov->size, kcov->area, kcov->mode, + kcov->sequence); t->kcov = kcov; kcov->t = t; - /* This is put either in kcov_task_exit() or in KCOV_DISABLE. */ + /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ kcov_get(kcov); return 0; case KCOV_DISABLE: + kcov_debug("KCOV_DISABLE\n"); /* Disable coverage for the current task. */ unused = arg; if (unused != 0 || current->kcov != kcov) @@ -408,11 +589,65 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, t = current; if (WARN_ON(kcov->t != t)) return -EINVAL; - kcov_task_init(t); - kcov->t = NULL; - kcov->mode = KCOV_MODE_INIT; + kcov_disable(t, kcov); kcov_put(kcov); return 0; + case KCOV_REMOTE_ENABLE: + kcov_debug("KCOV_REMOTE_ENABLE\n"); + if (kcov->mode != KCOV_MODE_INIT || !kcov->area) + return -EINVAL; + t = current; + if (kcov->t != NULL || t->kcov != NULL) + return -EBUSY; + remote_arg = (struct kcov_remote_arg *)arg; + mode = kcov_get_mode(remote_arg->trace_mode); + if (mode < 0) + return mode; + if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long)) + return -EINVAL; + kcov->mode = mode; + t->kcov = kcov; + kcov->t = t; + kcov->remote = true; + kcov->remote_size = remote_arg->area_size; + spin_lock(&kcov_remote_lock); + for (i = 0; i < remote_arg->num_handles; i++) { + kcov_debug("handle %llx\n", remote_arg->handles[i]); + if (!kcov_check_handle(remote_arg->handles[i], + false, true, false)) { + spin_unlock(&kcov_remote_lock); + kcov_disable(t, kcov); + return -EINVAL; + } + remote = kcov_remote_add(kcov, remote_arg->handles[i]); + if (IS_ERR(remote)) { + spin_unlock(&kcov_remote_lock); + kcov_disable(t, kcov); + return PTR_ERR(remote); + } + } + if (remote_arg->common_handle) { + kcov_debug("common handle %llx\n", + remote_arg->common_handle); + if (!kcov_check_handle(remote_arg->common_handle, + true, false, false)) { + spin_unlock(&kcov_remote_lock); + kcov_disable(t, kcov); + return -EINVAL; + } + remote = kcov_remote_add(kcov, + remote_arg->common_handle); + if (IS_ERR(remote)) { + spin_unlock(&kcov_remote_lock); + kcov_disable(t, kcov); + return PTR_ERR(remote); + } + t->kcov_handle = remote_arg->common_handle; + } + spin_unlock(&kcov_remote_lock); + /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ + kcov_get(kcov); + return 0; default: return -ENOTTY; } @@ -422,11 +657,35 @@ static long kcov_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { struct kcov *kcov; int res; + struct kcov_remote_arg *remote_arg = NULL; + unsigned int remote_num_handles; + unsigned long remote_arg_size; + + if (cmd == KCOV_REMOTE_ENABLE) { + if (get_user(remote_num_handles, (unsigned __user *)(arg + + offsetof(struct kcov_remote_arg, num_handles)))) + return -EFAULT; + if (remote_num_handles > KCOV_REMOTE_MAX_HANDLES) + return -EINVAL; + remote_arg_size = struct_size(remote_arg, handles, + remote_num_handles); + remote_arg = memdup_user((void __user *)arg, remote_arg_size); + if (IS_ERR(remote_arg)) + return PTR_ERR(remote_arg); + if (remote_arg->num_handles != remote_num_handles) { + kfree(remote_arg); + return -EINVAL; + } + arg = (unsigned long)remote_arg; + } kcov = filep->private_data; spin_lock(&kcov->lock); res = kcov_ioctl_locked(kcov, cmd, arg); spin_unlock(&kcov->lock); + + kfree(remote_arg); + return res; } @@ -438,6 +697,157 @@ static const struct file_operations kcov_fops = { .release = kcov_close, }; +u64 kcov_common_handle(void) +{ + return current->kcov_handle; +} + +void kcov_remote_start(u64 handle) +{ + struct kcov_remote *remote; + void *area; + struct task_struct *t; + unsigned int size; + enum kcov_mode mode; + int sequence; + + if (WARN_ON(!kcov_check_handle(handle, true, true, true))) + return; + if (WARN_ON(!in_task())) + return; + t = current; + /* + * Check that kcov_remote_start is not called twice + * nor called by user tasks (with enabled kcov). + */ + if (WARN_ON(t->kcov)) + return; + + kcov_debug("handle = %llx\n", handle); + + spin_lock(&kcov_remote_lock); + remote = kcov_remote_find(handle); + if (!remote) { + kcov_debug("no remote found"); + spin_unlock(&kcov_remote_lock); + return; + } + /* Put in kcov_remote_stop(). */ + kcov_get(remote->kcov); + t->kcov = remote->kcov; + /* + * Read kcov fields before unlock to prevent races with + * KCOV_DISABLE / kcov_remote_reset(). + */ + size = remote->kcov->remote_size; + mode = remote->kcov->mode; + sequence = remote->kcov->sequence; + area = kcov_remote_area_get(size); + spin_unlock(&kcov_remote_lock); + + if (!area) { + area = vmalloc(size * sizeof(unsigned long)); + if (!area) { + t->kcov = NULL; + kcov_put(remote->kcov); + return; + } + } + /* Reset coverage size. */ + *(u64 *)area = 0; + + kcov_debug("area = %px, size = %u", area, size); + + kcov_start(t, size, area, mode, sequence); + +} + +static void kcov_move_area(enum kcov_mode mode, void *dst_area, + unsigned int dst_area_size, void *src_area) +{ + u64 word_size = sizeof(unsigned long); + u64 count_size, entry_size; + u64 dst_len, src_len; + void *dst_entries, *src_entries; + u64 dst_occupied, dst_free, bytes_to_move, entries_moved; + + kcov_debug("%px %u <= %px %lu\n", + dst_area, dst_area_size, src_area, *(unsigned long *)src_area); + + switch (mode) { + case KCOV_MODE_TRACE_PC: + dst_len = READ_ONCE(*(unsigned long *)dst_area); + src_len = *(unsigned long *)src_area; + count_size = sizeof(unsigned long); + entry_size = sizeof(unsigned long); + break; + case KCOV_MODE_TRACE_CMP: + dst_len = READ_ONCE(*(u64 *)dst_area); + src_len = *(u64 *)src_area; + count_size = sizeof(u64); + entry_size = sizeof(u64) * KCOV_WORDS_PER_CMP; + break; + default: + WARN_ON(1); + return; + } + + if (dst_len > (dst_area_size * word_size - count_size) / entry_size) + return; + dst_occupied = count_size + dst_len * entry_size; + dst_free = dst_area_size * word_size - dst_occupied; + bytes_to_move = min(dst_free, src_len * entry_size); + dst_entries = dst_area + dst_occupied; + src_entries = src_area + count_size; + memcpy(dst_entries, src_entries, bytes_to_move); + entries_moved = bytes_to_move / entry_size; + + switch (mode) { + case KCOV_MODE_TRACE_PC: + WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved); + break; + case KCOV_MODE_TRACE_CMP: + WRITE_ONCE(*(u64 *)dst_area, dst_len + entries_moved); + break; + default: + break; + } +} + +void kcov_remote_stop(void) +{ + struct task_struct *t = current; + struct kcov *kcov = t->kcov; + void *area = t->kcov_area; + unsigned int size = t->kcov_size; + int sequence = t->kcov_sequence; + + if (!kcov) { + kcov_debug("no kcov found\n"); + return; + } + + kcov_stop(t); + t->kcov = NULL; + + spin_lock(&kcov->lock); + /* + * KCOV_DISABLE could have been called between kcov_remote_start() + * and kcov_remote_stop(), hence the check. + */ + kcov_debug("move if: %d == %d && %d\n", + sequence, kcov->sequence, (int)kcov->remote); + if (sequence == kcov->sequence && kcov->remote) + kcov_move_area(kcov->mode, kcov->area, kcov->size, area); + spin_unlock(&kcov->lock); + + spin_lock(&kcov_remote_lock); + kcov_remote_area_put(area, size); + spin_unlock(&kcov_remote_lock); + + kcov_put(kcov); +} + static int __init kcov_init(void) { /* From patchwork Wed Oct 23 15:24:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 11207019 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 081FA13BD for ; Wed, 23 Oct 2019 15:25:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB0D921872 for ; Wed, 23 Oct 2019 15:25:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rM5CCQ6Q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406743AbfJWPZA (ORCPT ); Wed, 23 Oct 2019 11:25:00 -0400 Received: from mail-ua1-f73.google.com ([209.85.222.73]:47502 "EHLO mail-ua1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406692AbfJWPYn (ORCPT ); Wed, 23 Oct 2019 11:24:43 -0400 Received: by mail-ua1-f73.google.com with SMTP id 4so2446741uay.14 for ; Wed, 23 Oct 2019 08:24:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=+fsowxQJsoipiOcnYQh/aAOpnyB04Lo2+yDsb2t+OXI=; b=rM5CCQ6QwHb40lD+8V+d3DREorqYK5DjOVpuv3ArZyGAQ516U+qeieYBqLgPg/xCCK UAjub/EHsWLgM2LRDliKIF+uBvQ/JLIyFqbB4P8PCFH2x5ojoCa0GTnMm7AwA84gXKV+ kZMFiWnZrMW7me+aEiFoCKyx0Zg9KGlJpjayMWrLM/C4QjFy49U7YDeOOlyQRvjPEUhb 7eRgQp1jx6Zkg5prYydvLpCIKKUNKxau5Flcl2aoiu02/1k6+a2awvXc/lfyJ2JFlgjD wJ1xx+GsUvq738BGFcz8U+DTA9duDH1CnWnU5lcaa/rUxJ8X2VmIijtBB1WemnynjuMk NdXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=+fsowxQJsoipiOcnYQh/aAOpnyB04Lo2+yDsb2t+OXI=; b=eMQW8AsG7tAFQj67ux3OYJvKl4hBZHDQyUEvzZsYnhmUp5IzKUtm05sXNs8f0+urNw nkyOhrmNTgSf7ZzgxL80Cv3CW47TB0rbQEwPJfpfrbc67DOJvGH+iQwXHK7JBwLH6q93 QVpVdyCeQeN6SYk3J1qUj1uwgX4ZnYS03IH43T4DIwDFKItjCluH74j0drXHOMtqv60Q zSelDVYBRd/hkjVGAv+EkwVGcIvjzo/rfy8/88KpvOgjrcJDBuN0M77FHXZ+FyMAFNbx LEo9+bUtvT/Jfm2BdD8lF1Xi6Comt0atv7MCB56cG9pO1wOyiran4RjB61RWs0cwawea N8Pw== X-Gm-Message-State: APjAAAUtkDKaWbDpJNzyA208EdPebM2Dt58hb2udXsMm9NnYLCD1UEKZ qFn2lsrfT5FubPJ1qaRTDeTsEEsOLf5gzvMTKZr3GT89qB3o0HEY2XR8iP/ncec/i4Mi6qsnLJe I6p4jpDv8+clGtLNDl3vmYOb4wtQOEWE9FRihnrgEE65sg0KU0lHrNdoH7iA0qGtr4vra5O2mQV 3H X-Google-Smtp-Source: APXvYqyVi59fXRYgZbs3IqAwnhV+t83pyUg453y+vcRDf4p6UDsgQ0xoylaSfeVaF4BAxV8813MNkxvSMM0JesNv X-Received: by 2002:a1f:97c2:: with SMTP id z185mr5634334vkd.0.1571844282053; Wed, 23 Oct 2019 08:24:42 -0700 (PDT) Date: Wed, 23 Oct 2019 17:24:30 +0200 In-Reply-To: Message-Id: <7ac106f30b2c1dab4809c75c5ae6efb91b531cce.1571844200.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 2/3] usb, kcov: collect coverage from hub_event From: Andrey Konovalov To: linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Vyukov , Greg Kroah-Hartman , Alan Stern , "Michael S . Tsirkin" , Jason Wang Cc: Andrew Morton , Arnd Bergmann , Steven Rostedt , David Windsor , Elena Reshetova , Anders Roxell , Alexander Potapenko , Marco Elver , Andrey Konovalov Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org This patch adds kcov_remote_start()/kcov_remote_stop() annotations to the hub_event() function, which is responsible for processing events on USB buses, in particular events that happen during USB device enumeration. Since hub_event() is run in a global background kernel thread (see Documentation/dev-tools/kcov.rst for details), each USB bus gets a unique global handle id from the USB subsystem kcov handle id range. As the result kcov can now be used to collect coverage from events that happen on a particular USB bus. Signed-off-by: Andrey Konovalov --- drivers/usb/core/hub.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 236313f41f4a..823dd675f6db 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include @@ -5374,6 +5375,8 @@ static void hub_event(struct work_struct *work) hub_dev = hub->intfdev; intf = to_usb_interface(hub_dev); + kcov_remote_start_usb((u64)hdev->bus->busnum); + dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n", hdev->state, hdev->maxchild, /* NOTE: expects max 15 ports... */ @@ -5480,6 +5483,8 @@ static void hub_event(struct work_struct *work) /* Balance the stuff in kick_hub_wq() and allow autosuspend */ usb_autopm_put_interface(intf); kref_put(&hub->kref, hub_release); + + kcov_remote_stop(); } static const struct usb_device_id hub_id_table[] = { From patchwork Wed Oct 23 15:24:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 11207015 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 986E71515 for ; Wed, 23 Oct 2019 15:24:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 776FE2173B for ; Wed, 23 Oct 2019 15:24:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="amtMxUQE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406725AbfJWPYr (ORCPT ); Wed, 23 Oct 2019 11:24:47 -0400 Received: from mail-wr1-f74.google.com ([209.85.221.74]:41476 "EHLO mail-wr1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406683AbfJWPYq (ORCPT ); Wed, 23 Oct 2019 11:24:46 -0400 Received: by mail-wr1-f74.google.com with SMTP id r8so3918885wrx.8 for ; Wed, 23 Oct 2019 08:24:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=5pfhpJx7UO/QNtR11zCiFnLuGkt6GlpMBjgSmMf75Tg=; b=amtMxUQEE/NOaMMB3lVYFv0UVIN4cbxrFTOMtC+0gOEicg9d0fwN7TprkrYhLBo/Qw 2EleEu8IMAhzGJRgyAUacDO8oPPKbhqpC3R4dWMwut0HBsgzzBVDlz/ApsLhBcXyyTSm /eCD/zfLTh6s5SMDIXOKsRL2wDTNqNpwZqeVIVU9EF9beg2ShlZJPx/wjpr4r121AD4r J1naSOk9REiJ+0ShRF4cS702lhMN4FFHmRcdPJ6qvufDuGYARjHTD2Xpz5IW00jpiKBW 8cijMl+bWToufDsT5R/eF6fNtOFNqFoN96aYFdTgT2zM1evjQCf9Rb/TDN7b5jUJEzw0 AyTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=5pfhpJx7UO/QNtR11zCiFnLuGkt6GlpMBjgSmMf75Tg=; b=V8YeqY8AgWRu7XFzz6zSTvdyDAsxztJhpbR5Te7QxGJ1HzHKszghijnUnynfEtS/rp Bfbqf8VDEm7Vzf8GkW/lrDCYYgEwJBIwscVIq4cV5rONNEQ8LlmulcSKnMqaiZNynJfm 0VXF+5qTmXz1lUYFtWHwuk4QFU9+GEei4WIPTK8FdPC81FG4WEVyAlZ3NzLkotjQgrT+ 4Gj9iFLbWUX36vdmNfQNawHIQKuW0doQbjyo5ozFtjKZVPUu6YQJ29tVbsS5x8yborZI 2k3R/HlpHfH9EQVlGB0IxUVRkbQhuPdTxsYAGnYmSRTol+46sQTWLCOMgLVA9HhoA9kD a5/A== X-Gm-Message-State: APjAAAUA/K7KBZCg5DkiDUF2xmw04mw5QmHGxVWCH/iPnwUDv4itDGQM BlhFdmBqassUGHseAwcF1/TfCSse1er8DB8cYFKKcNIUDXQ4oGxP3MA0R4WZu5b/vOVP9Vtq08P GrkiVOVCao0EoiYBk4kdjSV6u7C9LelBhFCc+P5hQwC8zjASpro5Hqsj+MRVmYADbYBdSAEXHCE Xf X-Google-Smtp-Source: APXvYqzdi2O+812zGiyp5RRX+hLIIZ845MysjmhOziDahGLFuGnRWQ7rOw8CUUpGv+5aE1gSW2A1zPgWo9uj7H6o X-Received: by 2002:a5d:6ac3:: with SMTP id u3mr9376179wrw.206.1571844285109; Wed, 23 Oct 2019 08:24:45 -0700 (PDT) Date: Wed, 23 Oct 2019 17:24:31 +0200 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 3/3] vhost, kcov: collect coverage from vhost_worker From: Andrey Konovalov To: linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Vyukov , Greg Kroah-Hartman , Alan Stern , "Michael S . Tsirkin" , Jason Wang Cc: Andrew Morton , Arnd Bergmann , Steven Rostedt , David Windsor , Elena Reshetova , Anders Roxell , Alexander Potapenko , Marco Elver , Andrey Konovalov Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org This patch adds kcov_remote_start()/kcov_remote_stop() annotations to the vhost_worker() function, which is responsible for processing vhost works. Since vhost_worker() threads are spawned per vhost device instance the common kcov handle is used for kcov_remote_start()/stop() annotations (see Documentation/dev-tools/kcov.rst for details). As the result kcov can now be used to collect coverage from vhost worker threads. Signed-off-by: Andrey Konovalov --- drivers/vhost/vhost.c | 6 ++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 7 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 36ca2cf419bf..f44340b41494 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "vhost.h" @@ -357,7 +358,9 @@ static int vhost_worker(void *data) llist_for_each_entry_safe(work, work_next, node, node) { clear_bit(VHOST_WORK_QUEUED, &work->flags); __set_current_state(TASK_RUNNING); + kcov_remote_start_common(dev->kcov_handle); work->fn(work); + kcov_remote_stop(); if (need_resched()) schedule(); } @@ -546,6 +549,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev) /* No owner, become one */ dev->mm = get_task_mm(current); + dev->kcov_handle = kcov_common_handle(); worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); if (IS_ERR(worker)) { err = PTR_ERR(worker); @@ -571,6 +575,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev) if (dev->mm) mmput(dev->mm); dev->mm = NULL; + dev->kcov_handle = 0; err_mm: return err; } @@ -682,6 +687,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev) if (dev->worker) { kthread_stop(dev->worker); dev->worker = NULL; + dev->kcov_handle = 0; } if (dev->mm) mmput(dev->mm); diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index e9ed2722b633..a123fd70847e 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -173,6 +173,7 @@ struct vhost_dev { int iov_limit; int weight; int byte_weight; + u64 kcov_handle; }; bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);