1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2007 Oracle.  All rights reserved.
  4 */
  5
  6#include <asm/unaligned.h>
  7
  8#include "ctree.h"
  9
 10static inline u8 get_unaligned_le8(const void *p)
 11{
 12       return *(u8 *)p;
 13}
 14
 15static inline void put_unaligned_le8(u8 val, void *p)
 16{
 17       *(u8 *)p = val;
 18}
 19
 20static bool check_setget_bounds(const struct extent_buffer *eb,
 21				const void *ptr, unsigned off, int size)
 22{
 23	const unsigned long member_offset = (unsigned long)ptr + off;
 24
 25	if (member_offset > eb->len) {
 26		btrfs_warn(eb->fs_info,
 27	"bad eb member start: ptr 0x%lx start %llu member offset %lu size %d",
 28			(unsigned long)ptr, eb->start, member_offset, size);
 29		return false;
 30	}
 31	if (member_offset + size > eb->len) {
 32		btrfs_warn(eb->fs_info,
 33	"bad eb member end: ptr 0x%lx start %llu member offset %lu size %d",
 34			(unsigned long)ptr, eb->start, member_offset, size);
 35		return false;
 36	}
 37
 38	return true;
 39}
 40
 41/*
 42 * Macro templates that define helpers to read/write extent buffer data of a
 43 * given size, that are also used via ctree.h for access to item members by
 44 * specialized helpers.
 45 *
 46 * Generic helpers:
 47 * - btrfs_set_8 (for 8/16/32/64)
 48 * - btrfs_get_8 (for 8/16/32/64)
 49 *
 50 * Generic helpers with a token (cached address of the most recently accessed
 51 * page):
 52 * - btrfs_set_token_8 (for 8/16/32/64)
 53 * - btrfs_get_token_8 (for 8/16/32/64)
 54 *
 55 * The set/get functions handle data spanning two pages transparently, in case
 56 * metadata block size is larger than page.  Every pointer to metadata items is
 57 * an offset into the extent buffer page array, cast to a specific type.  This
 58 * gives us all the type checking.
 59 *
 60 * The extent buffer pages stored in the array pages do not form a contiguous
 61 * phyusical range, but the API functions assume the linear offset to the range
 62 * from 0 to metadata node size.
 63 */
 64
 65#define DEFINE_BTRFS_SETGET_BITS(bits)					\
 66u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,		\
 67			       const void *ptr, unsigned long off)	\
 68{									\
 69	const unsigned long member_offset = (unsigned long)ptr + off;	\
 70	const unsigned long idx = member_offset >> PAGE_SHIFT;		\
 71	const unsigned long oip = offset_in_page(member_offset);	\
 72	const int size = sizeof(u##bits);				\
 73	u8 lebytes[sizeof(u##bits)];					\
 74	const int part = PAGE_SIZE - oip;				\
 75									\
 76	ASSERT(token);							\
 77	ASSERT(token->kaddr);						\
 78	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
 79	if (token->offset <= member_offset &&				\
 80	    member_offset + size <= token->offset + PAGE_SIZE) {	\
 81		return get_unaligned_le##bits(token->kaddr + oip);	\
 82	}								\
 83	token->kaddr = page_address(token->eb->pages[idx]);		\
 84	token->offset = idx << PAGE_SHIFT;				\
 85	if (oip + size <= PAGE_SIZE)					\
 86		return get_unaligned_le##bits(token->kaddr + oip);	\
 87									\
 88	memcpy(lebytes, token->kaddr + oip, part);			\
 89	token->kaddr = page_address(token->eb->pages[idx + 1]);		\
 90	token->offset = (idx + 1) << PAGE_SHIFT;			\
 91	memcpy(lebytes + part, token->kaddr, size - part);		\
 92	return get_unaligned_le##bits(lebytes);				\
 93}									\
 94u##bits btrfs_get_##bits(const struct extent_buffer *eb,		\
 95			 const void *ptr, unsigned long off)		\
 96{									\
 97	const unsigned long member_offset = (unsigned long)ptr + off;	\
 98	const unsigned long oip = offset_in_page(member_offset);	\
 99	const unsigned long idx = member_offset >> PAGE_SHIFT;		\
100	char *kaddr = page_address(eb->pages[idx]);			\
101	const int size = sizeof(u##bits);				\
102	const int part = PAGE_SIZE - oip;				\
103	u8 lebytes[sizeof(u##bits)];					\
104									\
105	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
106	if (oip + size <= PAGE_SIZE)					\
107		return get_unaligned_le##bits(kaddr + oip);		\
108									\
109	memcpy(lebytes, kaddr + oip, part);				\
110	kaddr = page_address(eb->pages[idx + 1]);			\
111	memcpy(lebytes + part, kaddr, size - part);			\
112	return get_unaligned_le##bits(lebytes);				\
113}									\
114void btrfs_set_token_##bits(struct btrfs_map_token *token,		\
115			    const void *ptr, unsigned long off,		\
116			    u##bits val)				\
117{									\
118	const unsigned long member_offset = (unsigned long)ptr + off;	\
119	const unsigned long idx = member_offset >> PAGE_SHIFT;		\
120	const unsigned long oip = offset_in_page(member_offset);	\
121	const int size = sizeof(u##bits);				\
122	u8 lebytes[sizeof(u##bits)];					\
123	const int part = PAGE_SIZE - oip;				\
124									\
125	ASSERT(token);							\
126	ASSERT(token->kaddr);						\
127	ASSERT(check_setget_bounds(token->eb, ptr, off, size));		\
128	if (token->offset <= member_offset &&				\
129	    member_offset + size <= token->offset + PAGE_SIZE) {	\
130		put_unaligned_le##bits(val, token->kaddr + oip);	\
131		return;							\
132	}								\
133	token->kaddr = page_address(token->eb->pages[idx]);		\
134	token->offset = idx << PAGE_SHIFT;				\
135	if (oip + size <= PAGE_SIZE) {					\
136		put_unaligned_le##bits(val, token->kaddr + oip);	\
137		return;							\
138	}								\
139	put_unaligned_le##bits(val, lebytes);				\
140	memcpy(token->kaddr + oip, lebytes, part);			\
141	token->kaddr = page_address(token->eb->pages[idx + 1]);		\
142	token->offset = (idx + 1) << PAGE_SHIFT;			\
143	memcpy(token->kaddr, lebytes + part, size - part);		\
144}									\
145void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,	\
146		      unsigned long off, u##bits val)			\
147{									\
148	const unsigned long member_offset = (unsigned long)ptr + off;	\
149	const unsigned long oip = offset_in_page(member_offset);	\
150	const unsigned long idx = member_offset >> PAGE_SHIFT;		\
151	char *kaddr = page_address(eb->pages[idx]);			\
152	const int size = sizeof(u##bits);				\
153	const int part = PAGE_SIZE - oip;				\
154	u8 lebytes[sizeof(u##bits)];					\
155									\
156	ASSERT(check_setget_bounds(eb, ptr, off, size));		\
157	if (oip + size <= PAGE_SIZE) {					\
158		put_unaligned_le##bits(val, kaddr + oip);		\
159		return;							\
160	}								\
161									\
162	put_unaligned_le##bits(val, lebytes);				\
163	memcpy(kaddr + oip, lebytes, part);				\
164	kaddr = page_address(eb->pages[idx + 1]);			\
165	memcpy(kaddr, lebytes + part, size - part);			\
166}
167
168DEFINE_BTRFS_SETGET_BITS(8)
169DEFINE_BTRFS_SETGET_BITS(16)
170DEFINE_BTRFS_SETGET_BITS(32)
171DEFINE_BTRFS_SETGET_BITS(64)
172
173void btrfs_node_key(const struct extent_buffer *eb,
174		    struct btrfs_disk_key *disk_key, int nr)
175{
176	unsigned long ptr = btrfs_node_key_ptr_offset(nr);
177	read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
178		       struct btrfs_key_ptr, key, disk_key);
179}