[linux-block.git] / mm / kmsan / hooks.c

// SPDX-License-Identifier: GPL-2.0
/*
 * KMSAN hooks for kernel subsystems.
 *
 * These functions handle creation of KMSAN metadata for memory allocations.
 *
 * Copyright (C) 2018-2022 Google LLC
 * Author: Alexander Potapenko <glider@google.com>
 *
 */

#include <linux/cacheflush.h>
#include <linux/dma-direction.h>
#include <linux/gfp.h>
#include <linux/kmsan.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/usb.h>

#include "../internal.h"
#include "../slab.h"
#include "kmsan.h"

/*
 * Instrumented functions shouldn't be called under
 * kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to
 * skipping effects of functions like memset() inside instrumented code.
 */

void kmsan_task_create(struct task_struct *task)
{
	kmsan_enter_runtime();
	kmsan_internal_task_create(task);
	kmsan_leave_runtime();
}

void kmsan_task_exit(struct task_struct *task)
{
	struct kmsan_ctx *ctx = &task->kmsan_ctx;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;

	ctx->allow_reporting = false;
}

void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
{
	if (unlikely(object == NULL))
		return;
	if (!kmsan_enabled || kmsan_in_runtime())
		return;
	/*
	 * There's a ctor or this is an RCU cache - do nothing. The memory
	 * status hasn't changed since last use.
	 */
	if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU))
		return;

	kmsan_enter_runtime();
	if (flags & __GFP_ZERO)
		kmsan_internal_unpoison_memory(object, s->object_size,
					       KMSAN_POISON_CHECK);
	else
		kmsan_internal_poison_memory(object, s->object_size, flags,
					     KMSAN_POISON_CHECK);
	kmsan_leave_runtime();
}

void kmsan_slab_free(struct kmem_cache *s, void *object)
{
	if (!kmsan_enabled || kmsan_in_runtime())
		return;

	/* RCU slabs could be legally used after free within the RCU period */
	if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)))
		return;
	/*
	 * If there's a constructor, freed memory must remain in the same state
	 * until the next allocation. We cannot save its state to detect
	 * use-after-free bugs, instead we just keep it unpoisoned.
	 */
	if (s->ctor)
		return;
	kmsan_enter_runtime();
	kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
				     KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
	kmsan_leave_runtime();
}

void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
{
	if (unlikely(ptr == NULL))
		return;
	if (!kmsan_enabled || kmsan_in_runtime())
		return;
	kmsan_enter_runtime();
	if (flags & __GFP_ZERO)
		kmsan_internal_unpoison_memory((void *)ptr, size,
					       /*checked*/ true);
	else
		kmsan_internal_poison_memory((void *)ptr, size, flags,
					     KMSAN_POISON_CHECK);
	kmsan_leave_runtime();
}

void kmsan_kfree_large(const void *ptr)
{
	struct page *page;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;
	kmsan_enter_runtime();
	page = virt_to_head_page((void *)ptr);
	KMSAN_WARN_ON(ptr != page_address(page));
	kmsan_internal_poison_memory((void *)ptr,
				     PAGE_SIZE << compound_order(page),
				     GFP_KERNEL,
				     KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
	kmsan_leave_runtime();
}

static unsigned long vmalloc_shadow(unsigned long addr)
{
	return (unsigned long)kmsan_get_metadata((void *)addr,
						 KMSAN_META_SHADOW);
}

static unsigned long vmalloc_origin(unsigned long addr)
{
	return (unsigned long)kmsan_get_metadata((void *)addr,
						 KMSAN_META_ORIGIN);
}

void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
{
	__vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
	__vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
}

/*
 * This function creates new shadow/origin pages for the physical pages mapped
 * into the virtual memory. If those physical pages already had shadow/origin,
 * those are ignored.
 */
void kmsan_ioremap_page_range(unsigned long start, unsigned long end,
			      phys_addr_t phys_addr, pgprot_t prot,
			      unsigned int page_shift)
{
	gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;
	struct page *shadow, *origin;
	unsigned long off = 0;
	int nr;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;

	nr = (end - start) / PAGE_SIZE;
	kmsan_enter_runtime();
	for (int i = 0; i < nr; i++, off += PAGE_SIZE) {
		shadow = alloc_pages(gfp_mask, 1);
		origin = alloc_pages(gfp_mask, 1);
		__vmap_pages_range_noflush(
			vmalloc_shadow(start + off),
			vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
			PAGE_SHIFT);
		__vmap_pages_range_noflush(
			vmalloc_origin(start + off),
			vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
			PAGE_SHIFT);
	}
	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
	kmsan_leave_runtime();
}

void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
{
	unsigned long v_shadow, v_origin;
	struct page *shadow, *origin;
	int nr;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;

	nr = (end - start) / PAGE_SIZE;
	kmsan_enter_runtime();
	v_shadow = (unsigned long)vmalloc_shadow(start);
	v_origin = (unsigned long)vmalloc_origin(start);
	for (int i = 0; i < nr;
	     i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
		shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
		origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
		__vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
		__vunmap_range_noflush(v_origin, vmalloc_origin(end));
		if (shadow)
			__free_pages(shadow, 1);
		if (origin)
			__free_pages(origin, 1);
	}
	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
	kmsan_leave_runtime();
}

void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
			size_t left)
{
	unsigned long ua_flags;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;
	/*
	 * At this point we've copied the memory already. It's hard to check it
	 * before copying, as the size of actually copied buffer is unknown.
	 */

	/* copy_to_user() may copy zero bytes. No need to check. */
	if (!to_copy)
		return;
	/* Or maybe copy_to_user() failed to copy anything. */
	if (to_copy <= left)
		return;

	ua_flags = user_access_save();
	if ((u64)to < TASK_SIZE) {
		/* This is a user memory access, check it. */
		kmsan_internal_check_memory((void *)from, to_copy - left, to,
					    REASON_COPY_TO_USER);
	} else {
		/* Otherwise this is a kernel memory access. This happens when a
		 * compat syscall passes an argument allocated on the kernel
		 * stack to a real syscall.
		 * Don't check anything, just copy the shadow of the copied
		 * bytes.
		 */
		kmsan_internal_memmove_metadata((void *)to, (void *)from,
						to_copy - left);
	}
	user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_copy_to_user);

/* Helper function to check an URB. */
void kmsan_handle_urb(const struct urb *urb, bool is_out)
{
	if (!urb)
		return;
	if (is_out)
		kmsan_internal_check_memory(urb->transfer_buffer,
					    urb->transfer_buffer_length,
					    /*user_addr*/ 0, REASON_SUBMIT_URB);
	else
		kmsan_internal_unpoison_memory(urb->transfer_buffer,
					       urb->transfer_buffer_length,
					       /*checked*/ false);
}
EXPORT_SYMBOL_GPL(kmsan_handle_urb);

static void kmsan_handle_dma_page(const void *addr, size_t size,
				  enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_BIDIRECTIONAL:
		kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
					    REASON_ANY);
		kmsan_internal_unpoison_memory((void *)addr, size,
					       /*checked*/ false);
		break;
	case DMA_TO_DEVICE:
		kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
					    REASON_ANY);
		break;
	case DMA_FROM_DEVICE:
		kmsan_internal_unpoison_memory((void *)addr, size,
					       /*checked*/ false);
		break;
	case DMA_NONE:
		break;
	}
}

/* Helper function to handle DMA data transfers. */
void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
		      enum dma_data_direction dir)
{
	u64 page_offset, to_go, addr;

	if (PageHighMem(page))
		return;
	addr = (u64)page_address(page) + offset;
	/*
	 * The kernel may occasionally give us adjacent DMA pages not belonging
	 * to the same allocation. Process them separately to avoid triggering
	 * internal KMSAN checks.
	 */
	while (size > 0) {
		page_offset = addr % PAGE_SIZE;
		to_go = min(PAGE_SIZE - page_offset, (u64)size);
		kmsan_handle_dma_page((void *)addr, to_go, dir);
		addr += to_go;
		size -= to_go;
	}
}

void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
			 enum dma_data_direction dir)
{
	struct scatterlist *item;
	int i;

	for_each_sg(sg, item, nents, i)
		kmsan_handle_dma(sg_page(item), item->offset, item->length,
				 dir);
}

/* Functions from kmsan-checks.h follow. */
void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
{
	if (!kmsan_enabled || kmsan_in_runtime())
		return;
	kmsan_enter_runtime();
	/* The users may want to poison/unpoison random memory. */
	kmsan_internal_poison_memory((void *)address, size, flags,
				     KMSAN_POISON_NOCHECK);
	kmsan_leave_runtime();
}
EXPORT_SYMBOL(kmsan_poison_memory);

void kmsan_unpoison_memory(const void *address, size_t size)
{
	unsigned long ua_flags;

	if (!kmsan_enabled || kmsan_in_runtime())
		return;

	ua_flags = user_access_save();
	kmsan_enter_runtime();
	/* The users may want to poison/unpoison random memory. */
	kmsan_internal_unpoison_memory((void *)address, size,
				       KMSAN_POISON_NOCHECK);
	kmsan_leave_runtime();
	user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_unpoison_memory);

/*
 * Version of kmsan_unpoison_memory() that can be called from within the KMSAN
 * runtime.
 *
 * Non-instrumented IRQ entry functions receive struct pt_regs from assembly
 * code. Those regs need to be unpoisoned, otherwise using them will result in
 * false positives.
 * Using kmsan_unpoison_memory() is not an option in entry code, because the
 * return value of in_task() is inconsistent - as a result, certain calls to
 * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
 * the registers are unpoisoned even if kmsan_in_runtime() is true in the early
 * entry code.
 */
void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
{
	unsigned long ua_flags;

	if (!kmsan_enabled)
		return;

	ua_flags = user_access_save();
	kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
				       KMSAN_POISON_NOCHECK);
	user_access_restore(ua_flags);
}

void kmsan_check_memory(const void *addr, size_t size)
{
	if (!kmsan_enabled)
		return;
	return kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
					   REASON_ANY);
}
EXPORT_SYMBOL(kmsan_check_memory);
Commit	Line	Data
f80be457 AP	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* KMSAN hooks for kernel subsystems.
	4	*
	5	* These functions handle creation of KMSAN metadata for memory allocations.
	6	*
	7	* Copyright (C) 2018-2022 Google LLC
	8	* Author: Alexander Potapenko <glider@google.com>
	9	*
	10	*/
	11
	12	#include <linux/cacheflush.h>
7ade4f10	13	#include <linux/dma-direction.h>
f80be457	14	#include <linux/gfp.h>
b073d7f8	15	#include <linux/kmsan.h>
f80be457 AP	16	#include <linux/mm.h>
f80be457 AP	17	#include <linux/mm_types.h>
7ade4f10	18	#include <linux/scatterlist.h>
f80be457 AP	19	#include <linux/slab.h>
f80be457 AP	20	#include <linux/uaccess.h>
553a8018	21	#include <linux/usb.h>
f80be457 AP	22
	23	#include "../internal.h"
	24	#include "../slab.h"
	25	#include "kmsan.h"
	26
	27	/*
	28	* Instrumented functions shouldn't be called under
	29	* kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to
	30	* skipping effects of functions like memset() inside instrumented code.
	31	*/
	32
50b5e49c AP	33	void kmsan_task_create(struct task_struct *task)
	34	{
	35	kmsan_enter_runtime();
	36	kmsan_internal_task_create(task);
	37	kmsan_leave_runtime();
	38	}
	39
	40	void kmsan_task_exit(struct task_struct *task)
	41	{
	42	struct kmsan_ctx *ctx = &task->kmsan_ctx;
	43
	44	if (!kmsan_enabled \|\| kmsan_in_runtime())
	45	return;
	46
	47	ctx->allow_reporting = false;
	48	}
	49
68ef169a AP	50	void kmsan_slab_alloc(struct kmem_cache s, void object, gfp_t flags)
	51	{
	52	if (unlikely(object == NULL))
	53	return;
	54	if (!kmsan_enabled \|\| kmsan_in_runtime())
	55	return;
	56	/*
	57	* There's a ctor or this is an RCU cache - do nothing. The memory
	58	* status hasn't changed since last use.
	59	*/
	60	if (s->ctor \|\| (s->flags & SLAB_TYPESAFE_BY_RCU))
	61	return;
	62
	63	kmsan_enter_runtime();
	64	if (flags & __GFP_ZERO)
	65	kmsan_internal_unpoison_memory(object, s->object_size,
	66	KMSAN_POISON_CHECK);
	67	else
	68	kmsan_internal_poison_memory(object, s->object_size, flags,
	69	KMSAN_POISON_CHECK);
	70	kmsan_leave_runtime();
	71	}
	72
	73	void kmsan_slab_free(struct kmem_cache s, void object)
	74	{
	75	if (!kmsan_enabled \|\| kmsan_in_runtime())
	76	return;
	77
	78	/* RCU slabs could be legally used after free within the RCU period */
	79	if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU \| SLAB_POISON)))
	80	return;
	81	/*
	82	* If there's a constructor, freed memory must remain in the same state
	83	* until the next allocation. We cannot save its state to detect
	84	* use-after-free bugs, instead we just keep it unpoisoned.
	85	*/
	86	if (s->ctor)
	87	return;
	88	kmsan_enter_runtime();
	89	kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
	90	KMSAN_POISON_CHECK \| KMSAN_POISON_FREE);
	91	kmsan_leave_runtime();
	92	}
	93
	94	void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
	95	{
	96	if (unlikely(ptr == NULL))
	97	return;
	98	if (!kmsan_enabled \|\| kmsan_in_runtime())
	99	return;
	100	kmsan_enter_runtime();
	101	if (flags & __GFP_ZERO)
	102	kmsan_internal_unpoison_memory((void *)ptr, size,
	103	/checked/ true);
	104	else
	105	kmsan_internal_poison_memory((void *)ptr, size, flags,
	106	KMSAN_POISON_CHECK);
	107	kmsan_leave_runtime();
	108	}
	109
	110	void kmsan_kfree_large(const void *ptr)
	111	{
	112	struct page *page;
	113
114	if (!kmsan_enabled \|\| kmsan_in_runtime())
115	return;
116	kmsan_enter_runtime();
117	page = virt_to_head_page((void *)ptr);
118	KMSAN_WARN_ON(ptr != page_address(page));
119	kmsan_internal_poison_memory((void *)ptr,
120	PAGE_SIZE << compound_order(page),
121	GFP_KERNEL,
122	KMSAN_POISON_CHECK \| KMSAN_POISON_FREE);
123	kmsan_leave_runtime();
124	}
125
b073d7f8 AP	126	static unsigned long vmalloc_shadow(unsigned long addr)
	127	{
	128	return (unsigned long)kmsan_get_metadata((void *)addr,
	129	KMSAN_META_SHADOW);
	130	}
	131
	132	static unsigned long vmalloc_origin(unsigned long addr)
	133	{
	134	return (unsigned long)kmsan_get_metadata((void *)addr,
	135	KMSAN_META_ORIGIN);
	136	}
	137
	138	void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
	139	{
	140	__vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
	141	__vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
	142	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
	143	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
	144	}
	145
	146	/*
	147	* This function creates new shadow/origin pages for the physical pages mapped
	148	* into the virtual memory. If those physical pages already had shadow/origin,
	149	* those are ignored.
	150	*/
	151	void kmsan_ioremap_page_range(unsigned long start, unsigned long end,
	152	phys_addr_t phys_addr, pgprot_t prot,
	153	unsigned int page_shift)
	154	{
	155	gfp_t gfp_mask = GFP_KERNEL \| __GFP_ZERO;
	156	struct page shadow, origin;
	157	unsigned long off = 0;
	158	int nr;
	159
	160	if (!kmsan_enabled \|\| kmsan_in_runtime())
	161	return;
	162
	163	nr = (end - start) / PAGE_SIZE;
	164	kmsan_enter_runtime();
	165	for (int i = 0; i < nr; i++, off += PAGE_SIZE) {
	166	shadow = alloc_pages(gfp_mask, 1);
	167	origin = alloc_pages(gfp_mask, 1);
	168	__vmap_pages_range_noflush(
	169	vmalloc_shadow(start + off),
	170	vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
	171	PAGE_SHIFT);
	172	__vmap_pages_range_noflush(
	173	vmalloc_origin(start + off),
	174	vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
	175	PAGE_SHIFT);
	176	}
	177	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
	178	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
	179	kmsan_leave_runtime();
	180	}
	181
	182	void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
	183	{
	184	unsigned long v_shadow, v_origin;
	185	struct page shadow, origin;
	186	int nr;
	187
	188	if (!kmsan_enabled \|\| kmsan_in_runtime())
	189	return;
190
191	nr = (end - start) / PAGE_SIZE;
192	kmsan_enter_runtime();
193	v_shadow = (unsigned long)vmalloc_shadow(start);
194	v_origin = (unsigned long)vmalloc_origin(start);
195	for (int i = 0; i < nr;
196	i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
197	shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
198	origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
199	__vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
200	__vunmap_range_noflush(v_origin, vmalloc_origin(end));
201	if (shadow)
202	__free_pages(shadow, 1);
203	if (origin)
204	__free_pages(origin, 1);
205	}
206	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
207	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
208	kmsan_leave_runtime();
209	}
210
75cf0290 AP	211	void kmsan_copy_to_user(void __user to, const void from, size_t to_copy,
	212	size_t left)
	213	{
	214	unsigned long ua_flags;
	215
	216	if (!kmsan_enabled \|\| kmsan_in_runtime())
	217	return;
	218	/*
	219	* At this point we've copied the memory already. It's hard to check it
	220	* before copying, as the size of actually copied buffer is unknown.
	221	*/
	222
	223	/* copy_to_user() may copy zero bytes. No need to check. */
	224	if (!to_copy)
	225	return;
	226	/* Or maybe copy_to_user() failed to copy anything. */
	227	if (to_copy <= left)
	228	return;
	229
	230	ua_flags = user_access_save();
	231	if ((u64)to < TASK_SIZE) {
	232	/* This is a user memory access, check it. */
	233	kmsan_internal_check_memory((void *)from, to_copy - left, to,
	234	REASON_COPY_TO_USER);
	235	} else {
	236	/* Otherwise this is a kernel memory access. This happens when a
	237	* compat syscall passes an argument allocated on the kernel
	238	* stack to a real syscall.
	239	* Don't check anything, just copy the shadow of the copied
	240	* bytes.
	241	*/
	242	kmsan_internal_memmove_metadata((void )to, (void )from,
	243	to_copy - left);
	244	}
	245	user_access_restore(ua_flags);
	246	}
	247	EXPORT_SYMBOL(kmsan_copy_to_user);
	248
553a8018 AP	249	/* Helper function to check an URB. */
	250	void kmsan_handle_urb(const struct urb *urb, bool is_out)
	251	{
	252	if (!urb)
	253	return;
	254	if (is_out)
	255	kmsan_internal_check_memory(urb->transfer_buffer,
	256	urb->transfer_buffer_length,
	257	/user_addr/ 0, REASON_SUBMIT_URB);
	258	else
	259	kmsan_internal_unpoison_memory(urb->transfer_buffer,
	260	urb->transfer_buffer_length,
	261	/checked/ false);
	262	}
7ba594d7	263	EXPORT_SYMBOL_GPL(kmsan_handle_urb);
553a8018	264
7ade4f10 AP	265	static void kmsan_handle_dma_page(const void *addr, size_t size,
	266	enum dma_data_direction dir)
	267	{
	268	switch (dir) {
	269	case DMA_BIDIRECTIONAL:
	270	kmsan_internal_check_memory((void )addr, size, /user_addr*/ 0,
	271	REASON_ANY);
	272	kmsan_internal_unpoison_memory((void *)addr, size,
	273	/checked/ false);
	274	break;
	275	case DMA_TO_DEVICE:
	276	kmsan_internal_check_memory((void )addr, size, /user_addr*/ 0,
	277	REASON_ANY);
	278	break;
	279	case DMA_FROM_DEVICE:
	280	kmsan_internal_unpoison_memory((void *)addr, size,
	281	/checked/ false);
	282	break;
	283	case DMA_NONE:
	284	break;
	285	}
	286	}
	287
	288	/* Helper function to handle DMA data transfers. */
	289	void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
	290	enum dma_data_direction dir)
	291	{
	292	u64 page_offset, to_go, addr;
	293
	294	if (PageHighMem(page))
	295	return;
	296	addr = (u64)page_address(page) + offset;
	297	/*
	298	* The kernel may occasionally give us adjacent DMA pages not belonging
	299	* to the same allocation. Process them separately to avoid triggering
	300	* internal KMSAN checks.
	301	*/
	302	while (size > 0) {
	303	page_offset = addr % PAGE_SIZE;
	304	to_go = min(PAGE_SIZE - page_offset, (u64)size);
	305	kmsan_handle_dma_page((void *)addr, to_go, dir);
	306	addr += to_go;
	307	size -= to_go;
	308	}
	309	}
	310
	311	void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
	312	enum dma_data_direction dir)
	313	{
	314	struct scatterlist *item;
	315	int i;
	316
	317	for_each_sg(sg, item, nents, i)
	318	kmsan_handle_dma(sg_page(item), item->offset, item->length,
	319	dir);
	320	}
	321
f80be457 AP	322	/* Functions from kmsan-checks.h follow. */
	323	void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
	324	{
	325	if (!kmsan_enabled \|\| kmsan_in_runtime())
	326	return;
	327	kmsan_enter_runtime();
	328	/* The users may want to poison/unpoison random memory. */
	329	kmsan_internal_poison_memory((void *)address, size, flags,
	330	KMSAN_POISON_NOCHECK);
	331	kmsan_leave_runtime();
	332	}
	333	EXPORT_SYMBOL(kmsan_poison_memory);
	334
	335	void kmsan_unpoison_memory(const void *address, size_t size)
	336	{
	337	unsigned long ua_flags;
	338
	339	if (!kmsan_enabled \|\| kmsan_in_runtime())
	340	return;
	341
	342	ua_flags = user_access_save();
	343	kmsan_enter_runtime();
	344	/* The users may want to poison/unpoison random memory. */
	345	kmsan_internal_unpoison_memory((void *)address, size,
	346	KMSAN_POISON_NOCHECK);
	347	kmsan_leave_runtime();
	348	user_access_restore(ua_flags);
	349	}
	350	EXPORT_SYMBOL(kmsan_unpoison_memory);
	351
6cae637f AP	352	/*
	353	* Version of kmsan_unpoison_memory() that can be called from within the KMSAN
	354	* runtime.
	355	*
	356	* Non-instrumented IRQ entry functions receive struct pt_regs from assembly
	357	* code. Those regs need to be unpoisoned, otherwise using them will result in
	358	* false positives.
	359	* Using kmsan_unpoison_memory() is not an option in entry code, because the
	360	* return value of in_task() is inconsistent - as a result, certain calls to
	361	* kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
	362	* the registers are unpoisoned even if kmsan_in_runtime() is true in the early
	363	* entry code.
	364	*/
	365	void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
	366	{
	367	unsigned long ua_flags;
	368
	369	if (!kmsan_enabled)
	370	return;
	371
	372	ua_flags = user_access_save();
	373	kmsan_internal_unpoison_memory((void )regs, sizeof(regs),
	374	KMSAN_POISON_NOCHECK);
	375	user_access_restore(ua_flags);
	376	}
	377
f80be457 AP	378	void kmsan_check_memory(const void *addr, size_t size)
	379	{
	380	if (!kmsan_enabled)
	381	return;
	382	return kmsan_internal_check_memory((void )addr, size, /user_addr*/ 0,
	383	REASON_ANY);
	384	}
	385	EXPORT_SYMBOL(kmsan_check_memory);