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![Arnd Bergmann](/assets/img/avatar_default.png)
A number of internal functions in kcov are only called from generated code and don't technically need a declaration, but 'make W=1' warns about global symbols without a prototype: kernel/kcov.c:199:14: error: no previous prototype for '__sanitizer_cov_trace_pc' [-Werror=missing-prototypes] kernel/kcov.c:264:14: error: no previous prototype for '__sanitizer_cov_trace_cmp1' [-Werror=missing-prototypes] kernel/kcov.c:270:14: error: no previous prototype for '__sanitizer_cov_trace_cmp2' [-Werror=missing-prototypes] kernel/kcov.c:276:14: error: no previous prototype for '__sanitizer_cov_trace_cmp4' [-Werror=missing-prototypes] kernel/kcov.c:282:14: error: no previous prototype for '__sanitizer_cov_trace_cmp8' [-Werror=missing-prototypes] kernel/kcov.c:288:14: error: no previous prototype for '__sanitizer_cov_trace_const_cmp1' [-Werror=missing-prototypes] kernel/kcov.c:295:14: error: no previous prototype for '__sanitizer_cov_trace_const_cmp2' [-Werror=missing-prototypes] kernel/kcov.c:302:14: error: no previous prototype for '__sanitizer_cov_trace_const_cmp4' [-Werror=missing-prototypes] kernel/kcov.c:309:14: error: no previous prototype for '__sanitizer_cov_trace_const_cmp8' [-Werror=missing-prototypes] kernel/kcov.c:316:14: error: no previous prototype for '__sanitizer_cov_trace_switch' [-Werror=missing-prototypes] Adding prototypes for these in a header solves that problem, but now there is a mismatch between the built-in type and the prototype on 64-bit architectures because they expect some functions to take a 64-bit 'unsigned long' argument rather than an 'unsigned long long' u64 type: include/linux/kcov.h:84:6: error: conflicting types for built-in function '__sanitizer_cov_trace_switch'; expected 'void(long long unsigned int, void *)' [-Werror=builtin-declaration-mismatch] 84 | void __sanitizer_cov_trace_switch(u64 val, u64 *cases); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avoid this as well with a custom type definition. Link: https://lkml.kernel.org/r/20230517124944.929997-1-arnd@kernel.org Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Rong Tao <rongtao@cestc.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1081 lines
29 KiB
C
1081 lines
29 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#define pr_fmt(fmt) "kcov: " fmt
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#define DISABLE_BRANCH_PROFILING
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#include <linux/atomic.h>
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/export.h>
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#include <linux/types.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/hashtable.h>
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#include <linux/init.h>
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#include <linux/kmsan-checks.h>
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#include <linux/mm.h>
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#include <linux/preempt.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/vmalloc.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/kcov.h>
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#include <linux/refcount.h>
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#include <linux/log2.h>
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#include <asm/setup.h>
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#define kcov_debug(fmt, ...) pr_debug("%s: " fmt, __func__, ##__VA_ARGS__)
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/* Number of 64-bit words written per one comparison: */
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#define KCOV_WORDS_PER_CMP 4
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/*
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* kcov descriptor (one per opened debugfs file).
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* State transitions of the descriptor:
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* - initial state after open()
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* - then there must be a single ioctl(KCOV_INIT_TRACE) call
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* - then, mmap() call (several calls are allowed but not useful)
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* - then, ioctl(KCOV_ENABLE, arg), where arg is
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* KCOV_TRACE_PC - to trace only the PCs
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* or
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* KCOV_TRACE_CMP - to trace only the comparison operands
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* - then, ioctl(KCOV_DISABLE) to disable the task.
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* Enabling/disabling ioctls can be repeated (only one task a time allowed).
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*/
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struct kcov {
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/*
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* Reference counter. We keep one for:
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* - opened file descriptor
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* - task with enabled coverage (we can't unwire it from another task)
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* - each code section for remote coverage collection
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*/
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refcount_t refcount;
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/* The lock protects mode, size, area and t. */
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spinlock_t lock;
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enum kcov_mode mode;
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/* Size of arena (in long's). */
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unsigned int size;
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/* Coverage buffer shared with user space. */
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void *area;
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/* Task for which we collect coverage, or NULL. */
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struct task_struct *t;
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/* Collecting coverage from remote (background) threads. */
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bool remote;
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/* Size of remote area (in long's). */
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unsigned int remote_size;
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/*
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* Sequence is incremented each time kcov is reenabled, used by
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* kcov_remote_stop(), see the comment there.
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*/
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int sequence;
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};
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struct kcov_remote_area {
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struct list_head list;
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unsigned int size;
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};
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struct kcov_remote {
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u64 handle;
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struct kcov *kcov;
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struct hlist_node hnode;
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};
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static DEFINE_SPINLOCK(kcov_remote_lock);
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static DEFINE_HASHTABLE(kcov_remote_map, 4);
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static struct list_head kcov_remote_areas = LIST_HEAD_INIT(kcov_remote_areas);
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struct kcov_percpu_data {
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void *irq_area;
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local_lock_t lock;
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unsigned int saved_mode;
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unsigned int saved_size;
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void *saved_area;
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struct kcov *saved_kcov;
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int saved_sequence;
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};
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static DEFINE_PER_CPU(struct kcov_percpu_data, kcov_percpu_data) = {
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.lock = INIT_LOCAL_LOCK(lock),
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};
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/* Must be called with kcov_remote_lock locked. */
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static struct kcov_remote *kcov_remote_find(u64 handle)
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{
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struct kcov_remote *remote;
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hash_for_each_possible(kcov_remote_map, remote, hnode, handle) {
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if (remote->handle == handle)
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return remote;
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}
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return NULL;
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}
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/* Must be called with kcov_remote_lock locked. */
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static struct kcov_remote *kcov_remote_add(struct kcov *kcov, u64 handle)
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{
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struct kcov_remote *remote;
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if (kcov_remote_find(handle))
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return ERR_PTR(-EEXIST);
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remote = kmalloc(sizeof(*remote), GFP_ATOMIC);
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if (!remote)
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return ERR_PTR(-ENOMEM);
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remote->handle = handle;
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remote->kcov = kcov;
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hash_add(kcov_remote_map, &remote->hnode, handle);
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return remote;
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}
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/* Must be called with kcov_remote_lock locked. */
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static struct kcov_remote_area *kcov_remote_area_get(unsigned int size)
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{
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struct kcov_remote_area *area;
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struct list_head *pos;
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list_for_each(pos, &kcov_remote_areas) {
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area = list_entry(pos, struct kcov_remote_area, list);
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if (area->size == size) {
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list_del(&area->list);
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return area;
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}
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}
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return NULL;
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}
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/* Must be called with kcov_remote_lock locked. */
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static void kcov_remote_area_put(struct kcov_remote_area *area,
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unsigned int size)
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{
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INIT_LIST_HEAD(&area->list);
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area->size = size;
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list_add(&area->list, &kcov_remote_areas);
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/*
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* KMSAN doesn't instrument this file, so it may not know area->list
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* is initialized. Unpoison it explicitly to avoid reports in
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* kcov_remote_area_get().
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*/
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kmsan_unpoison_memory(&area->list, sizeof(area->list));
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}
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static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
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{
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unsigned int mode;
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/*
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* We are interested in code coverage as a function of a syscall inputs,
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* so we ignore code executed in interrupts, unless we are in a remote
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* coverage collection section in a softirq.
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*/
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if (!in_task() && !(in_serving_softirq() && t->kcov_softirq))
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return false;
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mode = READ_ONCE(t->kcov_mode);
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/*
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* There is some code that runs in interrupts but for which
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* in_interrupt() returns false (e.g. preempt_schedule_irq()).
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* READ_ONCE()/barrier() effectively provides load-acquire wrt
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* interrupts, there are paired barrier()/WRITE_ONCE() in
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* kcov_start().
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*/
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barrier();
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return mode == needed_mode;
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}
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static notrace unsigned long canonicalize_ip(unsigned long ip)
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{
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#ifdef CONFIG_RANDOMIZE_BASE
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ip -= kaslr_offset();
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#endif
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return ip;
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}
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/*
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* Entry point from instrumented code.
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* This is called once per basic-block/edge.
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*/
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void notrace __sanitizer_cov_trace_pc(void)
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{
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struct task_struct *t;
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unsigned long *area;
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unsigned long ip = canonicalize_ip(_RET_IP_);
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unsigned long pos;
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t = current;
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if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t))
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return;
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area = t->kcov_area;
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/* The first 64-bit word is the number of subsequent PCs. */
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pos = READ_ONCE(area[0]) + 1;
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if (likely(pos < t->kcov_size)) {
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/* Previously we write pc before updating pos. However, some
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* early interrupt code could bypass check_kcov_mode() check
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* and invoke __sanitizer_cov_trace_pc(). If such interrupt is
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* raised between writing pc and updating pos, the pc could be
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* overitten by the recursive __sanitizer_cov_trace_pc().
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* Update pos before writing pc to avoid such interleaving.
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*/
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WRITE_ONCE(area[0], pos);
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barrier();
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area[pos] = ip;
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}
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_pc);
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#ifdef CONFIG_KCOV_ENABLE_COMPARISONS
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static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
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{
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struct task_struct *t;
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u64 *area;
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u64 count, start_index, end_pos, max_pos;
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t = current;
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if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t))
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return;
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ip = canonicalize_ip(ip);
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/*
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* We write all comparison arguments and types as u64.
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* The buffer was allocated for t->kcov_size unsigned longs.
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*/
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area = (u64 *)t->kcov_area;
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max_pos = t->kcov_size * sizeof(unsigned long);
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count = READ_ONCE(area[0]);
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/* Every record is KCOV_WORDS_PER_CMP 64-bit words. */
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start_index = 1 + count * KCOV_WORDS_PER_CMP;
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end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
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if (likely(end_pos <= max_pos)) {
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/* See comment in __sanitizer_cov_trace_pc(). */
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WRITE_ONCE(area[0], count + 1);
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barrier();
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area[start_index] = type;
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area[start_index + 1] = arg1;
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area[start_index + 2] = arg2;
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area[start_index + 3] = ip;
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}
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}
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void notrace __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(0), arg1, arg2, _RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1);
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void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(1), arg1, arg2, _RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2);
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void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4);
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void notrace __sanitizer_cov_trace_cmp8(kcov_u64 arg1, kcov_u64 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(3), arg1, arg2, _RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8);
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void notrace __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST, arg1, arg2,
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_RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1);
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void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST, arg1, arg2,
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_RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2);
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void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2,
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_RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4);
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void notrace __sanitizer_cov_trace_const_cmp8(kcov_u64 arg1, kcov_u64 arg2)
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{
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write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST, arg1, arg2,
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_RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8);
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void notrace __sanitizer_cov_trace_switch(kcov_u64 val, void *arg)
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{
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u64 i;
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u64 *cases = arg;
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u64 count = cases[0];
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u64 size = cases[1];
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u64 type = KCOV_CMP_CONST;
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switch (size) {
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case 8:
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type |= KCOV_CMP_SIZE(0);
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break;
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case 16:
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type |= KCOV_CMP_SIZE(1);
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break;
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case 32:
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type |= KCOV_CMP_SIZE(2);
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break;
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case 64:
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type |= KCOV_CMP_SIZE(3);
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break;
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default:
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return;
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}
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for (i = 0; i < count; i++)
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write_comp_data(type, cases[i + 2], val, _RET_IP_);
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}
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EXPORT_SYMBOL(__sanitizer_cov_trace_switch);
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#endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */
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static void kcov_start(struct task_struct *t, struct kcov *kcov,
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unsigned int size, void *area, enum kcov_mode mode,
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int sequence)
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{
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kcov_debug("t = %px, size = %u, area = %px\n", t, size, area);
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t->kcov = kcov;
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/* Cache in task struct for performance. */
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t->kcov_size = size;
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t->kcov_area = area;
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t->kcov_sequence = sequence;
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/* See comment in check_kcov_mode(). */
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barrier();
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WRITE_ONCE(t->kcov_mode, mode);
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}
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static void kcov_stop(struct task_struct *t)
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{
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WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED);
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barrier();
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t->kcov = NULL;
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t->kcov_size = 0;
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t->kcov_area = NULL;
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}
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static void kcov_task_reset(struct task_struct *t)
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{
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kcov_stop(t);
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t->kcov_sequence = 0;
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t->kcov_handle = 0;
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}
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void kcov_task_init(struct task_struct *t)
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{
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kcov_task_reset(t);
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t->kcov_handle = current->kcov_handle;
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}
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static void kcov_reset(struct kcov *kcov)
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{
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kcov->t = NULL;
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kcov->mode = KCOV_MODE_INIT;
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kcov->remote = false;
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kcov->remote_size = 0;
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kcov->sequence++;
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}
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static void kcov_remote_reset(struct kcov *kcov)
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{
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int bkt;
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struct kcov_remote *remote;
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struct hlist_node *tmp;
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unsigned long flags;
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spin_lock_irqsave(&kcov_remote_lock, flags);
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hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) {
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if (remote->kcov != kcov)
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continue;
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hash_del(&remote->hnode);
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kfree(remote);
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}
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/* Do reset before unlock to prevent races with kcov_remote_start(). */
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kcov_reset(kcov);
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spin_unlock_irqrestore(&kcov_remote_lock, flags);
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}
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static void kcov_disable(struct task_struct *t, struct kcov *kcov)
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{
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kcov_task_reset(t);
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if (kcov->remote)
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kcov_remote_reset(kcov);
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else
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kcov_reset(kcov);
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}
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static void kcov_get(struct kcov *kcov)
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{
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refcount_inc(&kcov->refcount);
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}
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static void kcov_put(struct kcov *kcov)
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{
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if (refcount_dec_and_test(&kcov->refcount)) {
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kcov_remote_reset(kcov);
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vfree(kcov->area);
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kfree(kcov);
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}
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}
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void kcov_task_exit(struct task_struct *t)
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{
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struct kcov *kcov;
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unsigned long flags;
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kcov = t->kcov;
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if (kcov == NULL)
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return;
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spin_lock_irqsave(&kcov->lock, flags);
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kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t);
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/*
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* For KCOV_ENABLE devices we want to make sure that t->kcov->t == t,
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* which comes down to:
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* WARN_ON(!kcov->remote && kcov->t != t);
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*
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* For KCOV_REMOTE_ENABLE devices, the exiting task is either:
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*
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* 1. A remote task between kcov_remote_start() and kcov_remote_stop().
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* In this case we should print a warning right away, since a task
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* shouldn't be exiting when it's in a kcov coverage collection
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|
* section. Here t points to the task that is collecting remote
|
|
* coverage, and t->kcov->t points to the thread that created the
|
|
* kcov device. Which means that to detect this case we need to
|
|
* check that t != t->kcov->t, and this gives us the following:
|
|
* WARN_ON(kcov->remote && kcov->t != t);
|
|
*
|
|
* 2. The task that created kcov exiting without calling KCOV_DISABLE,
|
|
* and then again we make sure that t->kcov->t == t:
|
|
* WARN_ON(kcov->remote && kcov->t != t);
|
|
*
|
|
* By combining all three checks into one we get:
|
|
*/
|
|
if (WARN_ON(kcov->t != t)) {
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
return;
|
|
}
|
|
/* Just to not leave dangling references behind. */
|
|
kcov_disable(t, kcov);
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
kcov_put(kcov);
|
|
}
|
|
|
|
static int kcov_mmap(struct file *filep, struct vm_area_struct *vma)
|
|
{
|
|
int res = 0;
|
|
struct kcov *kcov = vma->vm_file->private_data;
|
|
unsigned long size, off;
|
|
struct page *page;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&kcov->lock, flags);
|
|
size = kcov->size * sizeof(unsigned long);
|
|
if (kcov->area == NULL || vma->vm_pgoff != 0 ||
|
|
vma->vm_end - vma->vm_start != size) {
|
|
res = -EINVAL;
|
|
goto exit;
|
|
}
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
vm_flags_set(vma, VM_DONTEXPAND);
|
|
for (off = 0; off < size; off += PAGE_SIZE) {
|
|
page = vmalloc_to_page(kcov->area + off);
|
|
res = vm_insert_page(vma, vma->vm_start + off, page);
|
|
if (res) {
|
|
pr_warn_once("kcov: vm_insert_page() failed\n");
|
|
return res;
|
|
}
|
|
}
|
|
return 0;
|
|
exit:
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
return res;
|
|
}
|
|
|
|
static int kcov_open(struct inode *inode, struct file *filep)
|
|
{
|
|
struct kcov *kcov;
|
|
|
|
kcov = kzalloc(sizeof(*kcov), GFP_KERNEL);
|
|
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;
|
|
return nonseekable_open(inode, filep);
|
|
}
|
|
|
|
static int kcov_close(struct inode *inode, struct file *filep)
|
|
{
|
|
kcov_put(filep->private_data);
|
|
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
|
|
* vmalloc fault handling path is instrumented.
|
|
*/
|
|
static void kcov_fault_in_area(struct kcov *kcov)
|
|
{
|
|
unsigned long stride = PAGE_SIZE / sizeof(unsigned long);
|
|
unsigned long *area = kcov->area;
|
|
unsigned long offset;
|
|
|
|
for (offset = 0; offset < kcov->size; offset += stride)
|
|
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_INSTANCE_MASK))
|
|
return false;
|
|
switch (handle & KCOV_SUBSYSTEM_MASK) {
|
|
case KCOV_SUBSYSTEM_COMMON:
|
|
return (handle & KCOV_INSTANCE_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 flags, unused;
|
|
int mode, i;
|
|
struct kcov_remote_arg *remote_arg;
|
|
struct kcov_remote *remote;
|
|
|
|
switch (cmd) {
|
|
case KCOV_ENABLE:
|
|
/*
|
|
* Enable coverage for the current task.
|
|
* At this point user must have been enabled trace mode,
|
|
* and mmapped the file. Coverage collection is disabled only
|
|
* at task exit or voluntary by KCOV_DISABLE. After that it can
|
|
* be enabled for another task.
|
|
*/
|
|
if (kcov->mode != KCOV_MODE_INIT || !kcov->area)
|
|
return -EINVAL;
|
|
t = current;
|
|
if (kcov->t != NULL || t->kcov != NULL)
|
|
return -EBUSY;
|
|
mode = kcov_get_mode(arg);
|
|
if (mode < 0)
|
|
return mode;
|
|
kcov_fault_in_area(kcov);
|
|
kcov->mode = mode;
|
|
kcov_start(t, kcov, kcov->size, kcov->area, kcov->mode,
|
|
kcov->sequence);
|
|
kcov->t = t;
|
|
/* Put either in kcov_task_exit() or in KCOV_DISABLE. */
|
|
kcov_get(kcov);
|
|
return 0;
|
|
case KCOV_DISABLE:
|
|
/* Disable coverage for the current task. */
|
|
unused = arg;
|
|
if (unused != 0 || current->kcov != kcov)
|
|
return -EINVAL;
|
|
t = current;
|
|
if (WARN_ON(kcov->t != t))
|
|
return -EINVAL;
|
|
kcov_disable(t, kcov);
|
|
kcov_put(kcov);
|
|
return 0;
|
|
case KCOV_REMOTE_ENABLE:
|
|
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_irqsave(&kcov_remote_lock, flags);
|
|
for (i = 0; i < remote_arg->num_handles; i++) {
|
|
if (!kcov_check_handle(remote_arg->handles[i],
|
|
false, true, false)) {
|
|
spin_unlock_irqrestore(&kcov_remote_lock,
|
|
flags);
|
|
kcov_disable(t, kcov);
|
|
return -EINVAL;
|
|
}
|
|
remote = kcov_remote_add(kcov, remote_arg->handles[i]);
|
|
if (IS_ERR(remote)) {
|
|
spin_unlock_irqrestore(&kcov_remote_lock,
|
|
flags);
|
|
kcov_disable(t, kcov);
|
|
return PTR_ERR(remote);
|
|
}
|
|
}
|
|
if (remote_arg->common_handle) {
|
|
if (!kcov_check_handle(remote_arg->common_handle,
|
|
true, false, false)) {
|
|
spin_unlock_irqrestore(&kcov_remote_lock,
|
|
flags);
|
|
kcov_disable(t, kcov);
|
|
return -EINVAL;
|
|
}
|
|
remote = kcov_remote_add(kcov,
|
|
remote_arg->common_handle);
|
|
if (IS_ERR(remote)) {
|
|
spin_unlock_irqrestore(&kcov_remote_lock,
|
|
flags);
|
|
kcov_disable(t, kcov);
|
|
return PTR_ERR(remote);
|
|
}
|
|
t->kcov_handle = remote_arg->common_handle;
|
|
}
|
|
spin_unlock_irqrestore(&kcov_remote_lock, flags);
|
|
/* Put either in kcov_task_exit() or in KCOV_DISABLE. */
|
|
kcov_get(kcov);
|
|
return 0;
|
|
default:
|
|
return -ENOTTY;
|
|
}
|
|
}
|
|
|
|
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;
|
|
unsigned long size, flags;
|
|
void *area;
|
|
|
|
kcov = filep->private_data;
|
|
switch (cmd) {
|
|
case KCOV_INIT_TRACE:
|
|
/*
|
|
* Enable kcov in trace mode and setup buffer size.
|
|
* Must happen before anything else.
|
|
*
|
|
* First check the size argument - it must be at least 2
|
|
* to hold the current position and one PC.
|
|
*/
|
|
size = arg;
|
|
if (size < 2 || size > INT_MAX / sizeof(unsigned long))
|
|
return -EINVAL;
|
|
area = vmalloc_user(size * sizeof(unsigned long));
|
|
if (area == NULL)
|
|
return -ENOMEM;
|
|
spin_lock_irqsave(&kcov->lock, flags);
|
|
if (kcov->mode != KCOV_MODE_DISABLED) {
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
vfree(area);
|
|
return -EBUSY;
|
|
}
|
|
kcov->area = area;
|
|
kcov->size = size;
|
|
kcov->mode = KCOV_MODE_INIT;
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
return 0;
|
|
case 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;
|
|
fallthrough;
|
|
default:
|
|
/*
|
|
* All other commands can be normally executed under a spin lock, so we
|
|
* obtain and release it here in order to simplify kcov_ioctl_locked().
|
|
*/
|
|
spin_lock_irqsave(&kcov->lock, flags);
|
|
res = kcov_ioctl_locked(kcov, cmd, arg);
|
|
spin_unlock_irqrestore(&kcov->lock, flags);
|
|
kfree(remote_arg);
|
|
return res;
|
|
}
|
|
}
|
|
|
|
static const struct file_operations kcov_fops = {
|
|
.open = kcov_open,
|
|
.unlocked_ioctl = kcov_ioctl,
|
|
.compat_ioctl = kcov_ioctl,
|
|
.mmap = kcov_mmap,
|
|
.release = kcov_close,
|
|
};
|
|
|
|
/*
|
|
* kcov_remote_start() and kcov_remote_stop() can be used to annotate a section
|
|
* of code in a kernel background thread or in a softirq to allow kcov to be
|
|
* used to collect coverage from that part of code.
|
|
*
|
|
* The handle argument of kcov_remote_start() identifies a code section that is
|
|
* used for coverage collection. A userspace process passes this handle to
|
|
* KCOV_REMOTE_ENABLE ioctl to make the used kcov device start collecting
|
|
* coverage for the code section identified by this handle.
|
|
*
|
|
* The usage of these annotations in the kernel code is different depending on
|
|
* the type of the kernel thread whose code is being annotated.
|
|
*
|
|
* For global kernel threads that are spawned in a limited number of instances
|
|
* (e.g. one USB hub_event() worker thread is spawned per USB HCD) and for
|
|
* softirqs, each instance must be assigned a unique 4-byte instance id. The
|
|
* instance id is then combined with a 1-byte subsystem id to get a handle via
|
|
* kcov_remote_handle(subsystem_id, instance_id).
|
|
*
|
|
* For local kernel threads that are spawned from system calls handler when a
|
|
* user interacts with some kernel interface (e.g. vhost workers), a handle is
|
|
* passed from a userspace process as the common_handle field of the
|
|
* kcov_remote_arg struct (note, that the user must generate a handle by using
|
|
* kcov_remote_handle() with KCOV_SUBSYSTEM_COMMON as the subsystem id and an
|
|
* arbitrary 4-byte non-zero number as the instance id). This common handle
|
|
* then gets saved into the task_struct of the process that issued the
|
|
* KCOV_REMOTE_ENABLE ioctl. When this process issues system calls that spawn
|
|
* kernel threads, the common handle must be retrieved via kcov_common_handle()
|
|
* and passed to the spawned threads via custom annotations. Those kernel
|
|
* threads must in turn be annotated with kcov_remote_start(common_handle) and
|
|
* kcov_remote_stop(). All of the threads that are spawned by the same process
|
|
* obtain the same handle, hence the name "common".
|
|
*
|
|
* See Documentation/dev-tools/kcov.rst for more details.
|
|
*
|
|
* Internally, kcov_remote_start() looks up the kcov device associated with the
|
|
* provided handle, allocates an area for coverage collection, and saves the
|
|
* pointers to kcov and area into the current task_struct to allow coverage to
|
|
* be collected via __sanitizer_cov_trace_pc().
|
|
* In turns kcov_remote_stop() clears those pointers from task_struct to stop
|
|
* collecting coverage and copies all collected coverage into the kcov area.
|
|
*/
|
|
|
|
static inline bool kcov_mode_enabled(unsigned int mode)
|
|
{
|
|
return (mode & ~KCOV_IN_CTXSW) != KCOV_MODE_DISABLED;
|
|
}
|
|
|
|
static void kcov_remote_softirq_start(struct task_struct *t)
|
|
{
|
|
struct kcov_percpu_data *data = this_cpu_ptr(&kcov_percpu_data);
|
|
unsigned int mode;
|
|
|
|
mode = READ_ONCE(t->kcov_mode);
|
|
barrier();
|
|
if (kcov_mode_enabled(mode)) {
|
|
data->saved_mode = mode;
|
|
data->saved_size = t->kcov_size;
|
|
data->saved_area = t->kcov_area;
|
|
data->saved_sequence = t->kcov_sequence;
|
|
data->saved_kcov = t->kcov;
|
|
kcov_stop(t);
|
|
}
|
|
}
|
|
|
|
static void kcov_remote_softirq_stop(struct task_struct *t)
|
|
{
|
|
struct kcov_percpu_data *data = this_cpu_ptr(&kcov_percpu_data);
|
|
|
|
if (data->saved_kcov) {
|
|
kcov_start(t, data->saved_kcov, data->saved_size,
|
|
data->saved_area, data->saved_mode,
|
|
data->saved_sequence);
|
|
data->saved_mode = 0;
|
|
data->saved_size = 0;
|
|
data->saved_area = NULL;
|
|
data->saved_sequence = 0;
|
|
data->saved_kcov = NULL;
|
|
}
|
|
}
|
|
|
|
void kcov_remote_start(u64 handle)
|
|
{
|
|
struct task_struct *t = current;
|
|
struct kcov_remote *remote;
|
|
struct kcov *kcov;
|
|
unsigned int mode;
|
|
void *area;
|
|
unsigned int size;
|
|
int sequence;
|
|
unsigned long flags;
|
|
|
|
if (WARN_ON(!kcov_check_handle(handle, true, true, true)))
|
|
return;
|
|
if (!in_task() && !in_serving_softirq())
|
|
return;
|
|
|
|
local_lock_irqsave(&kcov_percpu_data.lock, flags);
|
|
|
|
/*
|
|
* Check that kcov_remote_start() is not called twice in background
|
|
* threads nor called by user tasks (with enabled kcov).
|
|
*/
|
|
mode = READ_ONCE(t->kcov_mode);
|
|
if (WARN_ON(in_task() && kcov_mode_enabled(mode))) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
/*
|
|
* Check that kcov_remote_start() is not called twice in softirqs.
|
|
* Note, that kcov_remote_start() can be called from a softirq that
|
|
* happened while collecting coverage from a background thread.
|
|
*/
|
|
if (WARN_ON(in_serving_softirq() && t->kcov_softirq)) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
|
|
spin_lock(&kcov_remote_lock);
|
|
remote = kcov_remote_find(handle);
|
|
if (!remote) {
|
|
spin_unlock(&kcov_remote_lock);
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
kcov_debug("handle = %llx, context: %s\n", handle,
|
|
in_task() ? "task" : "softirq");
|
|
kcov = remote->kcov;
|
|
/* Put in kcov_remote_stop(). */
|
|
kcov_get(kcov);
|
|
/*
|
|
* Read kcov fields before unlock to prevent races with
|
|
* KCOV_DISABLE / kcov_remote_reset().
|
|
*/
|
|
mode = kcov->mode;
|
|
sequence = kcov->sequence;
|
|
if (in_task()) {
|
|
size = kcov->remote_size;
|
|
area = kcov_remote_area_get(size);
|
|
} else {
|
|
size = CONFIG_KCOV_IRQ_AREA_SIZE;
|
|
area = this_cpu_ptr(&kcov_percpu_data)->irq_area;
|
|
}
|
|
spin_unlock(&kcov_remote_lock);
|
|
|
|
/* Can only happen when in_task(). */
|
|
if (!area) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
area = vmalloc(size * sizeof(unsigned long));
|
|
if (!area) {
|
|
kcov_put(kcov);
|
|
return;
|
|
}
|
|
local_lock_irqsave(&kcov_percpu_data.lock, flags);
|
|
}
|
|
|
|
/* Reset coverage size. */
|
|
*(u64 *)area = 0;
|
|
|
|
if (in_serving_softirq()) {
|
|
kcov_remote_softirq_start(t);
|
|
t->kcov_softirq = 1;
|
|
}
|
|
kcov_start(t, kcov, size, area, mode, sequence);
|
|
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
|
|
}
|
|
EXPORT_SYMBOL(kcov_remote_start);
|
|
|
|
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_log;
|
|
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_log = __ilog2_u64(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);
|
|
BUILD_BUG_ON(!is_power_of_2(KCOV_WORDS_PER_CMP));
|
|
entry_size_log = __ilog2_u64(sizeof(u64) * KCOV_WORDS_PER_CMP);
|
|
break;
|
|
default:
|
|
WARN_ON(1);
|
|
return;
|
|
}
|
|
|
|
/* As arm can't divide u64 integers use log of entry size. */
|
|
if (dst_len > ((dst_area_size * word_size - count_size) >>
|
|
entry_size_log))
|
|
return;
|
|
dst_occupied = count_size + (dst_len << entry_size_log);
|
|
dst_free = dst_area_size * word_size - dst_occupied;
|
|
bytes_to_move = min(dst_free, src_len << entry_size_log);
|
|
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_log;
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
/* See the comment before kcov_remote_start() for usage details. */
|
|
void kcov_remote_stop(void)
|
|
{
|
|
struct task_struct *t = current;
|
|
struct kcov *kcov;
|
|
unsigned int mode;
|
|
void *area;
|
|
unsigned int size;
|
|
int sequence;
|
|
unsigned long flags;
|
|
|
|
if (!in_task() && !in_serving_softirq())
|
|
return;
|
|
|
|
local_lock_irqsave(&kcov_percpu_data.lock, flags);
|
|
|
|
mode = READ_ONCE(t->kcov_mode);
|
|
barrier();
|
|
if (!kcov_mode_enabled(mode)) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
/*
|
|
* When in softirq, check if the corresponding kcov_remote_start()
|
|
* actually found the remote handle and started collecting coverage.
|
|
*/
|
|
if (in_serving_softirq() && !t->kcov_softirq) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
/* Make sure that kcov_softirq is only set when in softirq. */
|
|
if (WARN_ON(!in_serving_softirq() && t->kcov_softirq)) {
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
return;
|
|
}
|
|
|
|
kcov = t->kcov;
|
|
area = t->kcov_area;
|
|
size = t->kcov_size;
|
|
sequence = t->kcov_sequence;
|
|
|
|
kcov_stop(t);
|
|
if (in_serving_softirq()) {
|
|
t->kcov_softirq = 0;
|
|
kcov_remote_softirq_stop(t);
|
|
}
|
|
|
|
spin_lock(&kcov->lock);
|
|
/*
|
|
* KCOV_DISABLE could have been called between kcov_remote_start()
|
|
* and kcov_remote_stop(), hence the sequence check.
|
|
*/
|
|
if (sequence == kcov->sequence && kcov->remote)
|
|
kcov_move_area(kcov->mode, kcov->area, kcov->size, area);
|
|
spin_unlock(&kcov->lock);
|
|
|
|
if (in_task()) {
|
|
spin_lock(&kcov_remote_lock);
|
|
kcov_remote_area_put(area, size);
|
|
spin_unlock(&kcov_remote_lock);
|
|
}
|
|
|
|
local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
|
|
|
|
/* Get in kcov_remote_start(). */
|
|
kcov_put(kcov);
|
|
}
|
|
EXPORT_SYMBOL(kcov_remote_stop);
|
|
|
|
/* See the comment before kcov_remote_start() for usage details. */
|
|
u64 kcov_common_handle(void)
|
|
{
|
|
if (!in_task())
|
|
return 0;
|
|
return current->kcov_handle;
|
|
}
|
|
EXPORT_SYMBOL(kcov_common_handle);
|
|
|
|
static int __init kcov_init(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
void *area = vmalloc_node(CONFIG_KCOV_IRQ_AREA_SIZE *
|
|
sizeof(unsigned long), cpu_to_node(cpu));
|
|
if (!area)
|
|
return -ENOMEM;
|
|
per_cpu_ptr(&kcov_percpu_data, cpu)->irq_area = area;
|
|
}
|
|
|
|
/*
|
|
* The kcov debugfs file won't ever get removed and thus,
|
|
* there is no need to protect it against removal races. The
|
|
* use of debugfs_create_file_unsafe() is actually safe here.
|
|
*/
|
|
debugfs_create_file_unsafe("kcov", 0600, NULL, NULL, &kcov_fops);
|
|
|
|
return 0;
|
|
}
|
|
|
|
device_initcall(kcov_init);
|