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Note that now the spinlock in struct kcov applies to every member of struct kcov_state, including the sequence number. This prepares us for the upcoming change that will introduce more kcov state. Also update the MAINTAINERS entry: add include/linux/kcov_types..h, add myself as kcov reviewer. Signed-off-by: Alexander Potapenko --- Change-Id: If225682ea2f6e91245381b3270de16e7ea40df39 v2: - add myself to kcov MAINTAINERS - rename kcov-state.h to kcov_types.h - update the description - do not move mode into struct kcov_state - use '{ }' instead of '{ 0 }' --- MAINTAINERS | 2 + include/linux/kcov.h | 2 +- include/linux/kcov_types.h | 22 +++++++ include/linux/sched.h | 13 +---- kernel/kcov.c | 115 ++++++++++++++++--------------------- 5 files changed, 78 insertions(+), 76 deletions(-) create mode 100644 include/linux/kcov_types.h diff --git a/MAINTAINERS b/MAINTAINERS index dd844ac8d9107..5bbc78b0fa6ed 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12823,11 +12823,13 @@ F: include/linux/kcore.h KCOV R: Dmitry Vyukov R: Andrey Konovalov +R: Alexander Potapenko L: kasan-dev@googlegroups.com S: Maintained B: https://bugzilla.kernel.org/buglist.cgi?component=3DSanitizers&product= =3DMemory%20Management F: Documentation/dev-tools/kcov.rst F: include/linux/kcov.h +F: include/linux/kcov_types.h F: include/uapi/linux/kcov.h F: kernel/kcov.c F: scripts/Makefile.kcov diff --git a/include/linux/kcov.h b/include/linux/kcov.h index 932b4face1005..0e425c3524b86 100644 --- a/include/linux/kcov.h +++ b/include/linux/kcov.h @@ -2,7 +2,7 @@ #ifndef _LINUX_KCOV_H #define _LINUX_KCOV_H =20 -#include +#include #include =20 struct task_struct; diff --git a/include/linux/kcov_types.h b/include/linux/kcov_types.h new file mode 100644 index 0000000000000..53b25b6f0addd --- /dev/null +++ b/include/linux/kcov_types.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_KCOV_STATE_H +#define _LINUX_KCOV_STATE_H + +#ifdef CONFIG_KCOV +/* See kernel/kcov.c for more details. */ +struct kcov_state { + /* Size of the area (in long's). */ + unsigned int size; + + /* Buffer for coverage collection, shared with the userspace. */ + void *area; + + /* + * KCOV sequence number: incremented each time kcov is reenabled, used + * by kcov_remote_stop(), see the comment there. + */ + int sequence; +}; +#endif /* CONFIG_KCOV */ + +#endif /* _LINUX_KCOV_STATE_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index f96ac19828934..68af8d6eaee3a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -42,6 +42,7 @@ #include #include #include +#include #include #include #include @@ -1512,16 +1513,11 @@ struct task_struct { #endif /* CONFIG_TRACING */ =20 #ifdef CONFIG_KCOV - /* See kernel/kcov.c for more details. */ - /* Coverage collection mode enabled for this task (0 if disabled): */ unsigned int kcov_mode; =20 - /* Size of the kcov_area: */ - unsigned int kcov_size; - - /* Buffer for coverage collection: */ - void *kcov_area; + /* kcov buffer state for this task. */ + struct kcov_state kcov_state; =20 /* KCOV descriptor wired with this task or NULL: */ struct kcov *kcov; @@ -1529,9 +1525,6 @@ struct task_struct { /* KCOV common handle for remote coverage collection: */ u64 kcov_handle; =20 - /* KCOV sequence number: */ - int kcov_sequence; - /* Collect coverage from softirq context: */ unsigned int kcov_softirq; #endif diff --git a/kernel/kcov.c b/kernel/kcov.c index 0dd42b78694c9..ff7f118644f49 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -54,24 +55,17 @@ struct kcov { * - each code section for remote coverage collection */ refcount_t refcount; - /* The lock protects mode, size, area and t. */ + /* The lock protects state 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; + struct kcov_state state; + /* 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; }; =20 struct kcov_remote_area { @@ -92,12 +86,9 @@ static struct list_head kcov_remote_areas =3D LIST_HEAD_= INIT(kcov_remote_areas); struct kcov_percpu_data { void *irq_area; local_lock_t lock; - - unsigned int saved_mode; - unsigned int saved_size; - void *saved_area; + enum kcov_mode saved_mode; struct kcov *saved_kcov; - int saved_sequence; + struct kcov_state saved_state; }; =20 static DEFINE_PER_CPU(struct kcov_percpu_data, kcov_percpu_data) =3D { @@ -219,10 +210,10 @@ void notrace __sanitizer_cov_trace_pc(void) if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t)) return; =20 - area =3D t->kcov_area; + area =3D t->kcov_state.area; /* The first 64-bit word is the number of subsequent PCs. */ pos =3D READ_ONCE(area[0]) + 1; - if (likely(pos < t->kcov_size)) { + if (likely(pos < t->kcov_state.size)) { /* Previously we write pc before updating pos. However, some * early interrupt code could bypass check_kcov_mode() check * and invoke __sanitizer_cov_trace_pc(). If such interrupt is @@ -252,10 +243,10 @@ static void notrace write_comp_data(u64 type, u64 arg= 1, u64 arg2, u64 ip) =20 /* * We write all comparison arguments and types as u64. - * The buffer was allocated for t->kcov_size unsigned longs. + * The buffer was allocated for t->kcov_state.size unsigned longs. */ - area =3D (u64 *)t->kcov_area; - max_pos =3D t->kcov_size * sizeof(unsigned long); + area =3D (u64 *)t->kcov_state.area; + max_pos =3D t->kcov_state.size * sizeof(unsigned long); =20 count =3D READ_ONCE(area[0]); =20 @@ -356,17 +347,15 @@ EXPORT_SYMBOL(__sanitizer_cov_trace_switch); #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ =20 static void kcov_start(struct task_struct *t, struct kcov *kcov, - unsigned int size, void *area, enum kcov_mode mode, - int sequence) + enum kcov_mode mode, struct kcov_state *state) { - kcov_debug("t =3D %px, size =3D %u, area =3D %px\n", t, size, area); + kcov_debug("t =3D %px, size =3D %u, area =3D %px\n", t, state->size, + state->area); t->kcov =3D kcov; /* Cache in task struct for performance. */ - t->kcov_size =3D size; - t->kcov_area =3D area; - t->kcov_sequence =3D sequence; - /* See comment in check_kcov_mode(). */ + t->kcov_state =3D *state; barrier(); + /* See comment in check_kcov_mode(). */ WRITE_ONCE(t->kcov_mode, mode); } =20 @@ -375,14 +364,14 @@ static void kcov_stop(struct task_struct *t) WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); barrier(); t->kcov =3D NULL; - t->kcov_size =3D 0; - t->kcov_area =3D NULL; + t->kcov_state.size =3D 0; + t->kcov_state.area =3D NULL; } =20 static void kcov_task_reset(struct task_struct *t) { kcov_stop(t); - t->kcov_sequence =3D 0; + t->kcov_state.sequence =3D 0; t->kcov_handle =3D 0; } =20 @@ -398,7 +387,7 @@ static void kcov_reset(struct kcov *kcov) kcov->mode =3D KCOV_MODE_INIT; kcov->remote =3D false; kcov->remote_size =3D 0; - kcov->sequence++; + kcov->state.sequence++; } =20 static void kcov_remote_reset(struct kcov *kcov) @@ -438,7 +427,7 @@ static void kcov_put(struct kcov *kcov) { if (refcount_dec_and_test(&kcov->refcount)) { kcov_remote_reset(kcov); - vfree(kcov->area); + vfree(kcov->state.area); kfree(kcov); } } @@ -495,8 +484,8 @@ static int kcov_mmap(struct file *filep, struct vm_area= _struct *vma) unsigned long flags; =20 spin_lock_irqsave(&kcov->lock, flags); - size =3D kcov->size * sizeof(unsigned long); - if (kcov->area =3D=3D NULL || vma->vm_pgoff !=3D 0 || + size =3D kcov->state.size * sizeof(unsigned long); + if (kcov->state.area =3D=3D NULL || vma->vm_pgoff !=3D 0 || vma->vm_end - vma->vm_start !=3D size) { res =3D -EINVAL; goto exit; @@ -504,7 +493,7 @@ static int kcov_mmap(struct file *filep, struct vm_area= _struct *vma) spin_unlock_irqrestore(&kcov->lock, flags); vm_flags_set(vma, VM_DONTEXPAND); for (off =3D 0; off < size; off +=3D PAGE_SIZE) { - page =3D vmalloc_to_page(kcov->area + off); + page =3D vmalloc_to_page(kcov->state.area + off); res =3D vm_insert_page(vma, vma->vm_start + off, page); if (res) { pr_warn_once("kcov: vm_insert_page() failed\n"); @@ -525,7 +514,7 @@ static int kcov_open(struct inode *inode, struct file *= filep) if (!kcov) return -ENOMEM; kcov->mode =3D KCOV_MODE_DISABLED; - kcov->sequence =3D 1; + kcov->state.sequence =3D 1; refcount_set(&kcov->refcount, 1); spin_lock_init(&kcov->lock); filep->private_data =3D kcov; @@ -560,10 +549,10 @@ static int kcov_get_mode(unsigned long arg) static void kcov_fault_in_area(struct kcov *kcov) { unsigned long stride =3D PAGE_SIZE / sizeof(unsigned long); - unsigned long *area =3D kcov->area; + unsigned long *area =3D kcov->state.area; unsigned long offset; =20 - for (offset =3D 0; offset < kcov->size; offset +=3D stride) + for (offset =3D 0; offset < kcov->state.size; offset +=3D stride) READ_ONCE(area[offset]); } =20 @@ -602,7 +591,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigne= d int cmd, * at task exit or voluntary by KCOV_DISABLE. After that it can * be enabled for another task. */ - if (kcov->mode !=3D KCOV_MODE_INIT || !kcov->area) + if (kcov->mode !=3D KCOV_MODE_INIT || !kcov->state.area) return -EINVAL; t =3D current; if (kcov->t !=3D NULL || t->kcov !=3D NULL) @@ -612,8 +601,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigne= d int cmd, return mode; kcov_fault_in_area(kcov); kcov->mode =3D mode; - kcov_start(t, kcov, kcov->size, kcov->area, kcov->mode, - kcov->sequence); + kcov_start(t, kcov, mode, &kcov->state); kcov->t =3D t; /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ kcov_get(kcov); @@ -630,7 +618,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigne= d int cmd, kcov_put(kcov); return 0; case KCOV_REMOTE_ENABLE: - if (kcov->mode !=3D KCOV_MODE_INIT || !kcov->area) + if (kcov->mode !=3D KCOV_MODE_INIT || !kcov->state.area) return -EINVAL; t =3D current; if (kcov->t !=3D NULL || t->kcov !=3D NULL) @@ -725,8 +713,8 @@ static long kcov_ioctl(struct file *filep, unsigned int= cmd, unsigned long arg) vfree(area); return -EBUSY; } - kcov->area =3D area; - kcov->size =3D size; + kcov->state.area =3D area; + kcov->state.size =3D size; kcov->mode =3D KCOV_MODE_INIT; spin_unlock_irqrestore(&kcov->lock, flags); return 0; @@ -825,10 +813,8 @@ static void kcov_remote_softirq_start(struct task_stru= ct *t) mode =3D READ_ONCE(t->kcov_mode); barrier(); if (kcov_mode_enabled(mode)) { + data->saved_state =3D t->kcov_state; data->saved_mode =3D mode; - data->saved_size =3D t->kcov_size; - data->saved_area =3D t->kcov_area; - data->saved_sequence =3D t->kcov_sequence; data->saved_kcov =3D t->kcov; kcov_stop(t); } @@ -839,13 +825,9 @@ static void kcov_remote_softirq_stop(struct task_struc= t *t) struct kcov_percpu_data *data =3D this_cpu_ptr(&kcov_percpu_data); =20 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 =3D 0; - data->saved_size =3D 0; - data->saved_area =3D NULL; - data->saved_sequence =3D 0; + kcov_start(t, data->saved_kcov, t->kcov_mode, + &data->saved_state); + data->saved_state =3D (struct kcov_state){}; data->saved_kcov =3D NULL; } } @@ -854,12 +836,12 @@ void kcov_remote_start(u64 handle) { struct task_struct *t =3D current; struct kcov_remote *remote; + struct kcov_state state; + enum kcov_mode mode; + unsigned long flags; + unsigned int size; struct kcov *kcov; - unsigned int mode; void *area; - unsigned int size; - int sequence; - unsigned long flags; =20 if (WARN_ON(!kcov_check_handle(handle, true, true, true))) return; @@ -904,7 +886,7 @@ void kcov_remote_start(u64 handle) * KCOV_DISABLE / kcov_remote_reset(). */ mode =3D kcov->mode; - sequence =3D kcov->sequence; + state.sequence =3D kcov->state.sequence; if (in_task()) { size =3D kcov->remote_size; area =3D kcov_remote_area_get(size); @@ -927,12 +909,14 @@ void kcov_remote_start(u64 handle) =20 /* Reset coverage size. */ *(u64 *)area =3D 0; + state.area =3D area; + state.size =3D size; =20 if (in_serving_softirq()) { kcov_remote_softirq_start(t); t->kcov_softirq =3D 1; } - kcov_start(t, kcov, size, area, mode, sequence); + kcov_start(t, kcov, t->kcov_mode, &state); =20 local_unlock_irqrestore(&kcov_percpu_data.lock, flags); } @@ -1030,9 +1014,9 @@ void kcov_remote_stop(void) } =20 kcov =3D t->kcov; - area =3D t->kcov_area; - size =3D t->kcov_size; - sequence =3D t->kcov_sequence; + area =3D t->kcov_state.area; + size =3D t->kcov_state.size; + sequence =3D t->kcov_state.sequence; =20 kcov_stop(t); if (in_serving_softirq()) { @@ -1045,8 +1029,9 @@ void kcov_remote_stop(void) * KCOV_DISABLE could have been called between kcov_remote_start() * and kcov_remote_stop(), hence the sequence check. */ - if (sequence =3D=3D kcov->sequence && kcov->remote) - kcov_move_area(kcov->mode, kcov->area, kcov->size, area); + if (sequence =3D=3D kcov->state.sequence && kcov->remote) + kcov_move_area(kcov->mode, kcov->state.area, kcov->state.size, + area); spin_unlock(&kcov->lock); =20 if (in_task()) { --=20 2.50.0.727.gbf7dc18ff4-goog