cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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misc.c (10215B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  linux/fs/fat/misc.c
      4 *
      5 *  Written 1992,1993 by Werner Almesberger
      6 *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
      7 *		 and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
      8 */
      9
     10#include "fat.h"
     11#include <linux/iversion.h>
     12
     13/*
     14 * fat_fs_error reports a file system problem that might indicate fa data
     15 * corruption/inconsistency. Depending on 'errors' mount option the
     16 * panic() is called, or error message is printed FAT and nothing is done,
     17 * or filesystem is remounted read-only (default behavior).
     18 * In case the file system is remounted read-only, it can be made writable
     19 * again by remounting it.
     20 */
     21void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
     22{
     23	struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
     24	va_list args;
     25	struct va_format vaf;
     26
     27	if (report) {
     28		va_start(args, fmt);
     29		vaf.fmt = fmt;
     30		vaf.va = &args;
     31		fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
     32		va_end(args);
     33	}
     34
     35	if (opts->errors == FAT_ERRORS_PANIC)
     36		panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
     37	else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {
     38		sb->s_flags |= SB_RDONLY;
     39		fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
     40	}
     41}
     42EXPORT_SYMBOL_GPL(__fat_fs_error);
     43
     44/**
     45 * _fat_msg() - Print a preformatted FAT message based on a superblock.
     46 * @sb: A pointer to a &struct super_block
     47 * @level: A Kernel printk level constant
     48 * @fmt: The printf-style format string to print.
     49 *
     50 * Everything that is not fat_fs_error() should be fat_msg().
     51 *
     52 * fat_msg() wraps _fat_msg() for printk indexing.
     53 */
     54void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
     55{
     56	struct va_format vaf;
     57	va_list args;
     58
     59	va_start(args, fmt);
     60	vaf.fmt = fmt;
     61	vaf.va = &args;
     62	_printk(FAT_PRINTK_PREFIX "%pV\n", level, sb->s_id, &vaf);
     63	va_end(args);
     64}
     65
     66/* Flushes the number of free clusters on FAT32 */
     67/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
     68int fat_clusters_flush(struct super_block *sb)
     69{
     70	struct msdos_sb_info *sbi = MSDOS_SB(sb);
     71	struct buffer_head *bh;
     72	struct fat_boot_fsinfo *fsinfo;
     73
     74	if (!is_fat32(sbi))
     75		return 0;
     76
     77	bh = sb_bread(sb, sbi->fsinfo_sector);
     78	if (bh == NULL) {
     79		fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
     80		return -EIO;
     81	}
     82
     83	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
     84	/* Sanity check */
     85	if (!IS_FSINFO(fsinfo)) {
     86		fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
     87		       "0x%08x, 0x%08x (sector = %lu)",
     88		       le32_to_cpu(fsinfo->signature1),
     89		       le32_to_cpu(fsinfo->signature2),
     90		       sbi->fsinfo_sector);
     91	} else {
     92		if (sbi->free_clusters != -1)
     93			fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
     94		if (sbi->prev_free != -1)
     95			fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
     96		mark_buffer_dirty(bh);
     97	}
     98	brelse(bh);
     99
    100	return 0;
    101}
    102
    103/*
    104 * fat_chain_add() adds a new cluster to the chain of clusters represented
    105 * by inode.
    106 */
    107int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
    108{
    109	struct super_block *sb = inode->i_sb;
    110	struct msdos_sb_info *sbi = MSDOS_SB(sb);
    111	int ret, new_fclus, last;
    112
    113	/*
    114	 * We must locate the last cluster of the file to add this new
    115	 * one (new_dclus) to the end of the link list (the FAT).
    116	 */
    117	last = new_fclus = 0;
    118	if (MSDOS_I(inode)->i_start) {
    119		int fclus, dclus;
    120
    121		ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
    122		if (ret < 0)
    123			return ret;
    124		new_fclus = fclus + 1;
    125		last = dclus;
    126	}
    127
    128	/* add new one to the last of the cluster chain */
    129	if (last) {
    130		struct fat_entry fatent;
    131
    132		fatent_init(&fatent);
    133		ret = fat_ent_read(inode, &fatent, last);
    134		if (ret >= 0) {
    135			int wait = inode_needs_sync(inode);
    136			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
    137			fatent_brelse(&fatent);
    138		}
    139		if (ret < 0)
    140			return ret;
    141		/*
    142		 * FIXME:Although we can add this cache, fat_cache_add() is
    143		 * assuming to be called after linear search with fat_cache_id.
    144		 */
    145//		fat_cache_add(inode, new_fclus, new_dclus);
    146	} else {
    147		MSDOS_I(inode)->i_start = new_dclus;
    148		MSDOS_I(inode)->i_logstart = new_dclus;
    149		/*
    150		 * Since generic_write_sync() synchronizes regular files later,
    151		 * we sync here only directories.
    152		 */
    153		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
    154			ret = fat_sync_inode(inode);
    155			if (ret)
    156				return ret;
    157		} else
    158			mark_inode_dirty(inode);
    159	}
    160	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
    161		fat_fs_error(sb, "clusters badly computed (%d != %llu)",
    162			     new_fclus,
    163			     (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
    164		fat_cache_inval_inode(inode);
    165	}
    166	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
    167
    168	return 0;
    169}
    170
    171/*
    172 * The epoch of FAT timestamp is 1980.
    173 *     :  bits :     value
    174 * date:  0 -  4: day	(1 -  31)
    175 * date:  5 -  8: month	(1 -  12)
    176 * date:  9 - 15: year	(0 - 127) from 1980
    177 * time:  0 -  4: sec	(0 -  29) 2sec counts
    178 * time:  5 - 10: min	(0 -  59)
    179 * time: 11 - 15: hour	(0 -  23)
    180 */
    181#define SECS_PER_MIN	60
    182#define SECS_PER_HOUR	(60 * 60)
    183#define SECS_PER_DAY	(SECS_PER_HOUR * 24)
    184/* days between 1.1.70 and 1.1.80 (2 leap days) */
    185#define DAYS_DELTA	(365 * 10 + 2)
    186/* 120 (2100 - 1980) isn't leap year */
    187#define YEAR_2100	120
    188#define IS_LEAP_YEAR(y)	(!((y) & 3) && (y) != YEAR_2100)
    189
    190/* Linear day numbers of the respective 1sts in non-leap years. */
    191static long days_in_year[] = {
    192	/* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
    193	0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
    194};
    195
    196static inline int fat_tz_offset(const struct msdos_sb_info *sbi)
    197{
    198	return (sbi->options.tz_set ?
    199	       -sbi->options.time_offset :
    200	       sys_tz.tz_minuteswest) * SECS_PER_MIN;
    201}
    202
    203/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
    204void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
    205		       __le16 __time, __le16 __date, u8 time_cs)
    206{
    207	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
    208	time64_t second;
    209	long day, leap_day, month, year;
    210
    211	year  = date >> 9;
    212	month = max(1, (date >> 5) & 0xf);
    213	day   = max(1, date & 0x1f) - 1;
    214
    215	leap_day = (year + 3) / 4;
    216	if (year > YEAR_2100)		/* 2100 isn't leap year */
    217		leap_day--;
    218	if (IS_LEAP_YEAR(year) && month > 2)
    219		leap_day++;
    220
    221	second =  (time & 0x1f) << 1;
    222	second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
    223	second += (time >> 11) * SECS_PER_HOUR;
    224	second += (time64_t)(year * 365 + leap_day
    225		   + days_in_year[month] + day
    226		   + DAYS_DELTA) * SECS_PER_DAY;
    227
    228	second += fat_tz_offset(sbi);
    229
    230	if (time_cs) {
    231		ts->tv_sec = second + (time_cs / 100);
    232		ts->tv_nsec = (time_cs % 100) * 10000000;
    233	} else {
    234		ts->tv_sec = second;
    235		ts->tv_nsec = 0;
    236	}
    237}
    238
    239/* Export fat_time_fat2unix() for the fat_test KUnit tests. */
    240EXPORT_SYMBOL_GPL(fat_time_fat2unix);
    241
    242/* Convert linear UNIX date to a FAT time/date pair. */
    243void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
    244		       __le16 *time, __le16 *date, u8 *time_cs)
    245{
    246	struct tm tm;
    247	time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
    248
    249	/*  FAT can only support year between 1980 to 2107 */
    250	if (tm.tm_year < 1980 - 1900) {
    251		*time = 0;
    252		*date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
    253		if (time_cs)
    254			*time_cs = 0;
    255		return;
    256	}
    257	if (tm.tm_year > 2107 - 1900) {
    258		*time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
    259		*date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
    260		if (time_cs)
    261			*time_cs = 199;
    262		return;
    263	}
    264
    265	/* from 1900 -> from 1980 */
    266	tm.tm_year -= 80;
    267	/* 0~11 -> 1~12 */
    268	tm.tm_mon++;
    269	/* 0~59 -> 0~29(2sec counts) */
    270	tm.tm_sec >>= 1;
    271
    272	*time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
    273	*date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
    274	if (time_cs)
    275		*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
    276}
    277EXPORT_SYMBOL_GPL(fat_time_unix2fat);
    278
    279static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
    280{
    281	return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
    282}
    283
    284/*
    285 * truncate atime to 24 hour granularity (00:00:00 in local timezone)
    286 */
    287struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
    288				     const struct timespec64 *ts)
    289{
    290	/* to localtime */
    291	time64_t seconds = ts->tv_sec - fat_tz_offset(sbi);
    292	s32 remainder;
    293
    294	div_s64_rem(seconds, SECS_PER_DAY, &remainder);
    295	/* to day boundary, and back to unix time */
    296	seconds = seconds + fat_tz_offset(sbi) - remainder;
    297
    298	return (struct timespec64){ seconds, 0 };
    299}
    300
    301/*
    302 * truncate mtime to 2 second granularity
    303 */
    304struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
    305				     const struct timespec64 *ts)
    306{
    307	return fat_timespec64_trunc_2secs(*ts);
    308}
    309
    310/*
    311 * truncate the various times with appropriate granularity:
    312 *   all times in root node are always 0
    313 */
    314int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
    315{
    316	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
    317	struct timespec64 ts;
    318
    319	if (inode->i_ino == MSDOS_ROOT_INO)
    320		return 0;
    321
    322	if (now == NULL) {
    323		now = &ts;
    324		ts = current_time(inode);
    325	}
    326
    327	if (flags & S_ATIME)
    328		inode->i_atime = fat_truncate_atime(sbi, now);
    329	/*
    330	 * ctime and mtime share the same on-disk field, and should be
    331	 * identical in memory. all mtime updates will be applied to ctime,
    332	 * but ctime updates are ignored.
    333	 */
    334	if (flags & S_MTIME)
    335		inode->i_mtime = inode->i_ctime = fat_truncate_mtime(sbi, now);
    336
    337	return 0;
    338}
    339EXPORT_SYMBOL_GPL(fat_truncate_time);
    340
    341int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
    342{
    343	int dirty_flags = 0;
    344
    345	if (inode->i_ino == MSDOS_ROOT_INO)
    346		return 0;
    347
    348	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
    349		fat_truncate_time(inode, now, flags);
    350		if (inode->i_sb->s_flags & SB_LAZYTIME)
    351			dirty_flags |= I_DIRTY_TIME;
    352		else
    353			dirty_flags |= I_DIRTY_SYNC;
    354	}
    355
    356	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
    357		dirty_flags |= I_DIRTY_SYNC;
    358
    359	__mark_inode_dirty(inode, dirty_flags);
    360	return 0;
    361}
    362EXPORT_SYMBOL_GPL(fat_update_time);
    363
    364int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
    365{
    366	int i, err = 0;
    367
    368	for (i = 0; i < nr_bhs; i++)
    369		write_dirty_buffer(bhs[i], 0);
    370
    371	for (i = 0; i < nr_bhs; i++) {
    372		wait_on_buffer(bhs[i]);
    373		if (!err && !buffer_uptodate(bhs[i]))
    374			err = -EIO;
    375	}
    376	return err;
    377}