// SPDX-License-Identifier: GPL-2.0#define pr_fmt(fmt) "kcov: " fmt #define DISABLE_BRANCH_PROFILING#include <linux/atomic.h>#include <linux/compiler.h>#include <linux/errno.h>#include <linux/export.h>#include <linux/types.h>#include <linux/file.h>#include <linux/fs.h>#include <linux/hashtable.h>#include <linux/init.h>#include <linux/mm.h>#include <linux/preempt.h>#include <linux/printk.h>#include <linux/sched.h>#include <linux/slab.h>#include <linux/spinlock.h>#include <linux/vmalloc.h>#include <linux/debugfs.h>#include <linux/uaccess.h>#include <linux/kcov.h>#include <linux/refcount.h>#include <linux/log2.h>#include <asm/setup.h> #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 /* * kcov descriptor (one per opened debugfs file). * State transitions of the descriptor: * - initial state after open() * - then there must be a single ioctl(KCOV_INIT_TRACE) call * - then, mmap() call (several calls are allowed but not useful) * - then, ioctl(KCOV_ENABLE, arg), where arg is * KCOV_TRACE_PC - to trace only the PCs * or * KCOV_TRACE_CMP - to trace only the comparison operands * - then, ioctl(KCOV_DISABLE) to disable the task. * Enabling/disabling ioctls can be repeated (only one task a time allowed). */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). */ 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 (background) threads. */ bool remote; /* Size of remote area (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); struct kcov_percpu_data { void *irq_area; unsigned int saved_mode; unsigned int saved_size; void *saved_area; struct kcov *saved_kcov; int saved_sequence;}; static DEFINE_PER_CPU(struct kcov_percpu_data, kcov_percpu_data); /* Must be called with kcov_remote_lock locked. */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;} /* Must be called with kcov_remote_lock locked. */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;} /* Must be called with kcov_remote_lock locked. */static struct kcov_remote_area *kcov_remote_area_get(unsigned int size){ struct kcov_remote_area *area; struct list_head *pos; list_for_each(pos, &kcov_remote_areas) { area = list_entry(pos, struct kcov_remote_area, list); if (area->size == size) { list_del(&area->list); return area; } } return NULL;} /* Must be called with kcov_remote_lock locked. */static void kcov_remote_area_put(struct kcov_remote_area *area, unsigned int 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; /* * We are interested in code coverage as a function of a syscall inputs, * so we ignore code executed in interrupts, unless we are in a remote * coverage collection section in a softirq. */ if (!in_task() && !(in_serving_softirq() && t->kcov_softirq)) return false; mode = READ_ONCE(t->kcov_mode); /* * There is some code that runs in interrupts but for which * 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_start(). */ barrier(); return mode == needed_mode;} static notrace unsigned long canonicalize_ip(unsigned long ip){#ifdef CONFIG_RANDOMIZE_BASE ip -= kaslr_offset();#endif return ip;} /* * Entry point from instrumented code. * This is called once per basic-block/edge. */void notrace __sanitizer_cov_trace_pc(void){ struct task_struct *t; unsigned long *area; unsigned long ip = canonicalize_ip(_RET_IP_); unsigned long pos; t = current; if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t)) return; area = t->kcov_area; /* The first 64-bit word is the number of subsequent PCs. */ pos = READ_ONCE(area[0]) + 1; if (likely(pos < t->kcov_size)) { area[pos] = ip; WRITE_ONCE(area[0], pos); }}EXPORT_SYMBOL(__sanitizer_cov_trace_pc); #ifdef CONFIG_KCOV_ENABLE_COMPARISONSstatic void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip){ struct task_struct *t; u64 *area; u64 count, start_index, end_pos, max_pos; t = current; if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t)) return; ip = canonicalize_ip(ip); /* * We write all comparison arguments and types as u64. * The buffer was allocated for t->kcov_size unsigned longs. */ area = (u64 *)t->kcov_area; max_pos = t->kcov_size * sizeof(unsigned long); count = READ_ONCE(area[0]); /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */ start_index = 1 + count * KCOV_WORDS_PER_CMP; end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64); if (likely(end_pos <= max_pos)) { area[start_index] = type; area[start_index + 1] = arg1; area[start_index + 2] = arg2; area[start_index + 3] = ip; WRITE_ONCE(area[0], count + 1); }} void notrace __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2){ write_comp_data(KCOV_CMP_SIZE(0), arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1); void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2){ write_comp_data(KCOV_CMP_SIZE(1), arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2); void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2){ write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4); void notrace __sanitizer_cov_trace_cmp8(u64 arg1, u64 arg2){ write_comp_data(KCOV_CMP_SIZE(3), arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8); void notrace __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2){ write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1); void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2){ write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2); void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2){ write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4); void notrace __sanitizer_cov_trace_const_cmp8(u64 arg1, u64 arg2){ write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8); void notrace __sanitizer_cov_trace_switch(u64 val, u64 *cases){ u64 i; u64 count = cases[0]; u64 size = cases[1]; u64 type = KCOV_CMP_CONST; switch (size) { case 8: type |= KCOV_CMP_SIZE(0); break; case 16: type |= KCOV_CMP_SIZE(1); break; case 32: type |= KCOV_CMP_SIZE(2); break; case 64: type |= KCOV_CMP_SIZE(3); break; default: return; } for (i = 0; i < count; i++) write_comp_data(type, cases[i + 2], val, _RET_IP_);}EXPORT_SYMBOL(__sanitizer_cov_trace_switch);#endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ static void kcov_start(struct task_struct *t, struct kcov *kcov, unsigned int size, void *area, enum kcov_mode mode, int sequence){ kcov_debug("t = %px, size = %u, area = %px\n", t, size, area); t->kcov = kcov; /* Cache in task struct for performance. */ t->kcov_size = size; t->kcov_area = area; t->kcov_sequence = sequence; /* See comment in check_kcov_mode(). */ barrier(); WRITE_ONCE(t->kcov_mode, mode);} static void kcov_stop(struct task_struct *t){ WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); barrier(); t->kcov = NULL; t->kcov_size = 0; t->kcov_area = NULL;} static void kcov_task_reset(struct task_struct *t){ kcov_stop(t); 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; unsigned long flags; spin_lock_irqsave(&kcov_remote_lock, flags); hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { if (remote->kcov != kcov) continue; hash_del(&remote->hnode); kfree(remote); } /* Do reset before unlock to prevent races with kcov_remote_start(). */ kcov_reset(kcov); spin_unlock_irqrestore(&kcov_remote_lock, flags);} 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);} 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_exit(struct task_struct *t){ struct kcov *kcov; unsigned long flags; kcov = t->kcov; if (kcov == NULL) return; spin_lock_irqsave(&kcov->lock, flags); kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t); /* * For KCOV_ENABLE devices we want to make sure that t->kcov->t == t, * which comes down to: * WARN_ON(!kcov->remote && kcov->t != t); * * For KCOV_REMOTE_ENABLE devices, the exiting task is either: * * 1. A remote task between kcov_remote_start() and kcov_remote_stop(). * In this case we should print a warning right away, since a task * shouldn't be exiting when it's in a kcov coverage collection * 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; void *area; struct kcov *kcov = vma->vm_file->private_data; unsigned long size, off; struct page *page; unsigned long flags; area = vmalloc_user(vma->vm_end - vma->vm_start); if (!area) return -ENOMEM; spin_lock_irqsave(&kcov->lock, flags); size = kcov->size * sizeof(unsigned long); if (kcov->mode != KCOV_MODE_INIT || vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != size) { res = -EINVAL; goto exit; } if (!kcov->area) { kcov->area = area; vma->vm_flags |= VM_DONTEXPAND; spin_unlock_irqrestore(&kcov->lock, flags); for (off = 0; off < size; off += PAGE_SIZE) { page = vmalloc_to_page(kcov->area + off); if (vm_insert_page(vma, vma->vm_start + off, page)) WARN_ONCE(1, "vm_insert_page() failed"); } return 0; }exit: spin_unlock_irqrestore(&kcov->lock, flags); vfree(area); 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;Lines 1–500 of 1054. 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// SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) "kcov: " fmt #define DISABLE_BRANCH_PROFILING #include <linux/atomic.h> #include <linux/compiler.h> #include <linux/errno.h> #include <linux/export.h> #include <linux/types.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/hashtable.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/preempt.h> #include <linux/printk.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/vmalloc.h> #include <linux/debugfs.h> #include <linux/uaccess.h> #include <linux/kcov.h> #include <linux/refcount.h> #include <linux/log2.h> #include <asm/setup.h> #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 /* * kcov descriptor (one per opened debugfs file). * State transitions of the descriptor: * - initial state after open() * - then there must be a single ioctl(KCOV_INIT_TRACE) call * - then, mmap() call (several calls are allowed but not useful) * - then, ioctl(KCOV_ENABLE, arg), where arg is * KCOV_TRACE_PC - to trace only the PCs * or * KCOV_TRACE_CMP - to trace only the comparison operands * - then, ioctl(KCOV_DISABLE) to disable the task. * Enabling/disabling ioctls can be repeated (only one task a time allowed). */ 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). */ 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 (background) threads. */ bool remote; /* Size of remote area (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); struct kcov_percpu_data { void *irq_area; unsigned int saved_mode; unsigned int saved_size; void *saved_area; struct kcov *saved_kcov; int saved_sequence; }; static DEFINE_PER_CPU(struct kcov_percpu_data, kcov_percpu_data); /* Must be called with kcov_remote_lock locked. */ 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; } /* Must be called with kcov_remote_lock locked. */ 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; } /* Must be called with kcov_remote_lock locked. */ static struct kcov_remote_area *kcov_remote_area_get(unsigned int size) { struct kcov_remote_area *area; struct list_head *pos; list_for_each(pos, &kcov_remote_areas) { area = list_entry(pos, struct kcov_remote_area, list); if (area->size == size) { list_del(&area->list); return area; } } return NULL; } /* Must be called with kcov_remote_lock locked. */ static void kcov_remote_area_put(struct kcov_remote_area *area, unsigned int 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; /* * We are interested in code coverage as a function of a syscall inputs, * so we ignore code executed in interrupts, unless we are in a remote * coverage collection section in a softirq. */ if (!in_task() && !(in_serving_softirq() && t->kcov_softirq)) return false; mode = READ_ONCE(t->kcov_mode); /* * There is some code that runs in interrupts but for which * 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_start(). */ barrier(); return mode == needed_mode; } static notrace unsigned long canonicalize_ip(unsigned long ip) { #ifdef CONFIG_RANDOMIZE_BASE ip -= kaslr_offset(); #endif return ip; } /* * Entry point from instrumented code. * This is called once per basic-block/edge. */ void notrace __sanitizer_cov_trace_pc(void) { struct task_struct *t; unsigned long *area; unsigned long ip = canonicalize_ip(_RET_IP_); unsigned long pos; t = current; if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t)) return; area = t->kcov_area; /* The first 64-bit word is the number of subsequent PCs. */ pos = READ_ONCE(area[0]) + 1; if (likely(pos < t->kcov_size)) { area[pos] = ip; WRITE_ONCE(area[0], pos); } } EXPORT_SYMBOL(__sanitizer_cov_trace_pc); #ifdef CONFIG_KCOV_ENABLE_COMPARISONS static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) { struct task_struct *t; u64 *area; u64 count, start_index, end_pos, max_pos; t = current; if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t)) return; ip = canonicalize_ip(ip); /* * We write all comparison arguments and types as u64. * The buffer was allocated for t->kcov_size unsigned longs. */ area = (u64 *)t->kcov_area; max_pos = t->kcov_size * sizeof(unsigned long); count = READ_ONCE(area[0]); /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */ start_index = 1 + count * KCOV_WORDS_PER_CMP; end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64); if (likely(end_pos <= max_pos)) { area[start_index] = type; area[start_index + 1] = arg1; area[start_index + 2] = arg2; area[start_index + 3] = ip; WRITE_ONCE(area[0], count + 1); } } void notrace __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2) { write_comp_data(KCOV_CMP_SIZE(0), arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1); void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2) { write_comp_data(KCOV_CMP_SIZE(1), arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2); void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2) { write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4); void notrace __sanitizer_cov_trace_cmp8(u64 arg1, u64 arg2) { write_comp_data(KCOV_CMP_SIZE(3), arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8); void notrace __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2) { write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1); void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2) { write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2); void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2) { write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4); void notrace __sanitizer_cov_trace_const_cmp8(u64 arg1, u64 arg2) { write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST, arg1, arg2, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8); void notrace __sanitizer_cov_trace_switch(u64 val, u64 *cases) { u64 i; u64 count = cases[0]; u64 size = cases[1]; u64 type = KCOV_CMP_CONST; switch (size) { case 8: type |= KCOV_CMP_SIZE(0); break; case 16: type |= KCOV_CMP_SIZE(1); break; case 32: type |= KCOV_CMP_SIZE(2); break; case 64: type |= KCOV_CMP_SIZE(3); break; default: return; } for (i = 0; i < count; i++) write_comp_data(type, cases[i + 2], val, _RET_IP_); } EXPORT_SYMBOL(__sanitizer_cov_trace_switch); #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ static void kcov_start(struct task_struct *t, struct kcov *kcov, unsigned int size, void *area, enum kcov_mode mode, int sequence) { kcov_debug("t = %px, size = %u, area = %px\n", t, size, area); t->kcov = kcov; /* Cache in task struct for performance. */ t->kcov_size = size; t->kcov_area = area; t->kcov_sequence = sequence; /* See comment in check_kcov_mode(). */ barrier(); WRITE_ONCE(t->kcov_mode, mode); } static void kcov_stop(struct task_struct *t) { WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); barrier(); t->kcov = NULL; t->kcov_size = 0; t->kcov_area = NULL; } static void kcov_task_reset(struct task_struct *t) { kcov_stop(t); 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; unsigned long flags; spin_lock_irqsave(&kcov_remote_lock, flags); hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { if (remote->kcov != kcov) continue; hash_del(&remote->hnode); kfree(remote); } /* Do reset before unlock to prevent races with kcov_remote_start(). */ kcov_reset(kcov); spin_unlock_irqrestore(&kcov_remote_lock, flags); } 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); } 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_exit(struct task_struct *t) { struct kcov *kcov; unsigned long flags; kcov = t->kcov; if (kcov == NULL) return; spin_lock_irqsave(&kcov->lock, flags); kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t); /* * For KCOV_ENABLE devices we want to make sure that t->kcov->t == t, * which comes down to: * WARN_ON(!kcov->remote && kcov->t != t); * * For KCOV_REMOTE_ENABLE devices, the exiting task is either: * * 1. A remote task between kcov_remote_start() and kcov_remote_stop(). * In this case we should print a warning right away, since a task * shouldn't be exiting when it's in a kcov coverage collection * 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; void *area; struct kcov *kcov = vma->vm_file->private_data; unsigned long size, off; struct page *page; unsigned long flags; area = vmalloc_user(vma->vm_end - vma->vm_start); if (!area) return -ENOMEM; spin_lock_irqsave(&kcov->lock, flags); size = kcov->size * sizeof(unsigned long); if (kcov->mode != KCOV_MODE_INIT || vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != size) { res = -EINVAL; goto exit; } if (!kcov->area) { kcov->area = area; vma->vm_flags |= VM_DONTEXPAND; spin_unlock_irqrestore(&kcov->lock, flags); for (off = 0; off < size; off += PAGE_SIZE) { page = vmalloc_to_page(kcov->area + off); if (vm_insert_page(vma, vma->vm_start + off, page)) WARN_ONCE(1, "vm_insert_page() failed"); } return 0; } exit: spin_unlock_irqrestore(&kcov->lock, flags); vfree(area); 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;