Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0-or-later
       2             : /*
       3             :  * A generic kernel FIFO implementation
       4             :  *
       5             :  * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
       6             :  */
       7             : 
       8             : #include <linux/kernel.h>
       9             : #include <linux/export.h>
      10             : #include <linux/slab.h>
      11             : #include <linux/err.h>
      12             : #include <linux/log2.h>
      13             : #include <linux/uaccess.h>
      14             : #include <linux/kfifo.h>
      15             : 
      16             : /*
      17             :  * internal helper to calculate the unused elements in a fifo
      18             :  */
      19             : static inline unsigned int kfifo_unused(struct __kfifo *fifo)
      20             : {
      21           0 :         return (fifo->mask + 1) - (fifo->in - fifo->out);
      22             : }
      23             : 
      24           0 : int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
      25             :                 size_t esize, gfp_t gfp_mask)
      26             : {
      27             :         /*
      28             :          * round up to the next power of 2, since our 'let the indices
      29             :          * wrap' technique works only in this case.
      30             :          */
      31           0 :         size = roundup_pow_of_two(size);
      32             : 
      33           0 :         fifo->in = 0;
      34           0 :         fifo->out = 0;
      35           0 :         fifo->esize = esize;
      36             : 
      37           0 :         if (size < 2) {
      38           0 :                 fifo->data = NULL;
      39           0 :                 fifo->mask = 0;
      40           0 :                 return -EINVAL;
      41             :         }
      42             : 
      43           0 :         fifo->data = kmalloc_array(esize, size, gfp_mask);
      44             : 
      45           0 :         if (!fifo->data) {
      46           0 :                 fifo->mask = 0;
      47           0 :                 return -ENOMEM;
      48             :         }
      49           0 :         fifo->mask = size - 1;
      50             : 
      51           0 :         return 0;
      52             : }
      53             : EXPORT_SYMBOL(__kfifo_alloc);
      54             : 
      55           0 : void __kfifo_free(struct __kfifo *fifo)
      56             : {
      57           0 :         kfree(fifo->data);
      58           0 :         fifo->in = 0;
      59           0 :         fifo->out = 0;
      60           0 :         fifo->esize = 0;
      61           0 :         fifo->data = NULL;
      62           0 :         fifo->mask = 0;
      63           0 : }
      64             : EXPORT_SYMBOL(__kfifo_free);
      65             : 
      66           0 : int __kfifo_init(struct __kfifo *fifo, void *buffer,
      67             :                 unsigned int size, size_t esize)
      68             : {
      69           0 :         size /= esize;
      70             : 
      71           0 :         if (!is_power_of_2(size))
      72           0 :                 size = rounddown_pow_of_two(size);
      73             : 
      74           0 :         fifo->in = 0;
      75           0 :         fifo->out = 0;
      76           0 :         fifo->esize = esize;
      77           0 :         fifo->data = buffer;
      78             : 
      79           0 :         if (size < 2) {
      80           0 :                 fifo->mask = 0;
      81           0 :                 return -EINVAL;
      82             :         }
      83           0 :         fifo->mask = size - 1;
      84             : 
      85           0 :         return 0;
      86             : }
      87             : EXPORT_SYMBOL(__kfifo_init);
      88             : 
      89           0 : static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
      90             :                 unsigned int len, unsigned int off)
      91             : {
      92           0 :         unsigned int size = fifo->mask + 1;
      93           0 :         unsigned int esize = fifo->esize;
      94             :         unsigned int l;
      95             : 
      96           0 :         off &= fifo->mask;
      97           0 :         if (esize != 1) {
      98           0 :                 off *= esize;
      99           0 :                 size *= esize;
     100           0 :                 len *= esize;
     101             :         }
     102           0 :         l = min(len, size - off);
     103             : 
     104           0 :         memcpy(fifo->data + off, src, l);
     105           0 :         memcpy(fifo->data, src + l, len - l);
     106             :         /*
     107             :          * make sure that the data in the fifo is up to date before
     108             :          * incrementing the fifo->in index counter
     109             :          */
     110           0 :         smp_wmb();
     111           0 : }
     112             : 
     113           0 : unsigned int __kfifo_in(struct __kfifo *fifo,
     114             :                 const void *buf, unsigned int len)
     115             : {
     116             :         unsigned int l;
     117             : 
     118           0 :         l = kfifo_unused(fifo);
     119           0 :         if (len > l)
     120           0 :                 len = l;
     121             : 
     122           0 :         kfifo_copy_in(fifo, buf, len, fifo->in);
     123           0 :         fifo->in += len;
     124           0 :         return len;
     125             : }
     126             : EXPORT_SYMBOL(__kfifo_in);
     127             : 
     128           0 : static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
     129             :                 unsigned int len, unsigned int off)
     130             : {
     131           0 :         unsigned int size = fifo->mask + 1;
     132           0 :         unsigned int esize = fifo->esize;
     133             :         unsigned int l;
     134             : 
     135           0 :         off &= fifo->mask;
     136           0 :         if (esize != 1) {
     137           0 :                 off *= esize;
     138           0 :                 size *= esize;
     139           0 :                 len *= esize;
     140             :         }
     141           0 :         l = min(len, size - off);
     142             : 
     143           0 :         memcpy(dst, fifo->data + off, l);
     144           0 :         memcpy(dst + l, fifo->data, len - l);
     145             :         /*
     146             :          * make sure that the data is copied before
     147             :          * incrementing the fifo->out index counter
     148             :          */
     149           0 :         smp_wmb();
     150           0 : }
     151             : 
     152           0 : unsigned int __kfifo_out_peek(struct __kfifo *fifo,
     153             :                 void *buf, unsigned int len)
     154             : {
     155             :         unsigned int l;
     156             : 
     157           0 :         l = fifo->in - fifo->out;
     158           0 :         if (len > l)
     159           0 :                 len = l;
     160             : 
     161           0 :         kfifo_copy_out(fifo, buf, len, fifo->out);
     162           0 :         return len;
     163             : }
     164             : EXPORT_SYMBOL(__kfifo_out_peek);
     165             : 
     166           0 : unsigned int __kfifo_out(struct __kfifo *fifo,
     167             :                 void *buf, unsigned int len)
     168             : {
     169           0 :         len = __kfifo_out_peek(fifo, buf, len);
     170           0 :         fifo->out += len;
     171           0 :         return len;
     172             : }
     173             : EXPORT_SYMBOL(__kfifo_out);
     174             : 
     175           0 : static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
     176             :         const void __user *from, unsigned int len, unsigned int off,
     177             :         unsigned int *copied)
     178             : {
     179           0 :         unsigned int size = fifo->mask + 1;
     180           0 :         unsigned int esize = fifo->esize;
     181             :         unsigned int l;
     182             :         unsigned long ret;
     183             : 
     184           0 :         off &= fifo->mask;
     185           0 :         if (esize != 1) {
     186           0 :                 off *= esize;
     187           0 :                 size *= esize;
     188           0 :                 len *= esize;
     189             :         }
     190           0 :         l = min(len, size - off);
     191             : 
     192           0 :         ret = copy_from_user(fifo->data + off, from, l);
     193           0 :         if (unlikely(ret))
     194           0 :                 ret = DIV_ROUND_UP(ret + len - l, esize);
     195             :         else {
     196           0 :                 ret = copy_from_user(fifo->data, from + l, len - l);
     197           0 :                 if (unlikely(ret))
     198           0 :                         ret = DIV_ROUND_UP(ret, esize);
     199             :         }
     200             :         /*
     201             :          * make sure that the data in the fifo is up to date before
     202             :          * incrementing the fifo->in index counter
     203             :          */
     204           0 :         smp_wmb();
     205           0 :         *copied = len - ret * esize;
     206             :         /* return the number of elements which are not copied */
     207           0 :         return ret;
     208             : }
     209             : 
     210           0 : int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
     211             :                 unsigned long len, unsigned int *copied)
     212             : {
     213             :         unsigned int l;
     214             :         unsigned long ret;
     215           0 :         unsigned int esize = fifo->esize;
     216             :         int err;
     217             : 
     218           0 :         if (esize != 1)
     219           0 :                 len /= esize;
     220             : 
     221           0 :         l = kfifo_unused(fifo);
     222           0 :         if (len > l)
     223           0 :                 len = l;
     224             : 
     225           0 :         ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
     226           0 :         if (unlikely(ret)) {
     227           0 :                 len -= ret;
     228           0 :                 err = -EFAULT;
     229             :         } else
     230             :                 err = 0;
     231           0 :         fifo->in += len;
     232           0 :         return err;
     233             : }
     234             : EXPORT_SYMBOL(__kfifo_from_user);
     235             : 
     236           0 : static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
     237             :                 unsigned int len, unsigned int off, unsigned int *copied)
     238             : {
     239             :         unsigned int l;
     240             :         unsigned long ret;
     241           0 :         unsigned int size = fifo->mask + 1;
     242           0 :         unsigned int esize = fifo->esize;
     243             : 
     244           0 :         off &= fifo->mask;
     245           0 :         if (esize != 1) {
     246           0 :                 off *= esize;
     247           0 :                 size *= esize;
     248           0 :                 len *= esize;
     249             :         }
     250           0 :         l = min(len, size - off);
     251             : 
     252           0 :         ret = copy_to_user(to, fifo->data + off, l);
     253           0 :         if (unlikely(ret))
     254           0 :                 ret = DIV_ROUND_UP(ret + len - l, esize);
     255             :         else {
     256           0 :                 ret = copy_to_user(to + l, fifo->data, len - l);
     257           0 :                 if (unlikely(ret))
     258           0 :                         ret = DIV_ROUND_UP(ret, esize);
     259             :         }
     260             :         /*
     261             :          * make sure that the data is copied before
     262             :          * incrementing the fifo->out index counter
     263             :          */
     264           0 :         smp_wmb();
     265           0 :         *copied = len - ret * esize;
     266             :         /* return the number of elements which are not copied */
     267           0 :         return ret;
     268             : }
     269             : 
     270           0 : int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
     271             :                 unsigned long len, unsigned int *copied)
     272             : {
     273             :         unsigned int l;
     274             :         unsigned long ret;
     275           0 :         unsigned int esize = fifo->esize;
     276             :         int err;
     277             : 
     278           0 :         if (esize != 1)
     279           0 :                 len /= esize;
     280             : 
     281           0 :         l = fifo->in - fifo->out;
     282           0 :         if (len > l)
     283           0 :                 len = l;
     284           0 :         ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
     285           0 :         if (unlikely(ret)) {
     286           0 :                 len -= ret;
     287           0 :                 err = -EFAULT;
     288             :         } else
     289             :                 err = 0;
     290           0 :         fifo->out += len;
     291           0 :         return err;
     292             : }
     293             : EXPORT_SYMBOL(__kfifo_to_user);
     294             : 
     295           0 : static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
     296             :                 int nents, unsigned int len)
     297             : {
     298             :         int n;
     299             :         unsigned int l;
     300             :         unsigned int off;
     301             :         struct page *page;
     302             : 
     303           0 :         if (!nents)
     304             :                 return 0;
     305             : 
     306           0 :         if (!len)
     307             :                 return 0;
     308             : 
     309           0 :         n = 0;
     310           0 :         page = virt_to_page(buf);
     311           0 :         off = offset_in_page(buf);
     312           0 :         l = 0;
     313             : 
     314           0 :         while (len >= l + PAGE_SIZE - off) {
     315             :                 struct page *npage;
     316             : 
     317           0 :                 l += PAGE_SIZE;
     318           0 :                 buf += PAGE_SIZE;
     319           0 :                 npage = virt_to_page(buf);
     320           0 :                 if (page_to_phys(page) != page_to_phys(npage) - l) {
     321           0 :                         sg_set_page(sgl, page, l - off, off);
     322           0 :                         sgl = sg_next(sgl);
     323           0 :                         if (++n == nents || sgl == NULL)
     324             :                                 return n;
     325           0 :                         page = npage;
     326           0 :                         len -= l - off;
     327           0 :                         l = off = 0;
     328             :                 }
     329             :         }
     330           0 :         sg_set_page(sgl, page, len, off);
     331           0 :         return n + 1;
     332             : }
     333             : 
     334           0 : static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
     335             :                 int nents, unsigned int len, unsigned int off)
     336             : {
     337           0 :         unsigned int size = fifo->mask + 1;
     338           0 :         unsigned int esize = fifo->esize;
     339             :         unsigned int l;
     340             :         unsigned int n;
     341             : 
     342           0 :         off &= fifo->mask;
     343           0 :         if (esize != 1) {
     344           0 :                 off *= esize;
     345           0 :                 size *= esize;
     346           0 :                 len *= esize;
     347             :         }
     348           0 :         l = min(len, size - off);
     349             : 
     350           0 :         n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
     351           0 :         n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
     352             : 
     353           0 :         return n;
     354             : }
     355             : 
     356           0 : unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
     357             :                 struct scatterlist *sgl, int nents, unsigned int len)
     358             : {
     359             :         unsigned int l;
     360             : 
     361           0 :         l = kfifo_unused(fifo);
     362           0 :         if (len > l)
     363           0 :                 len = l;
     364             : 
     365           0 :         return setup_sgl(fifo, sgl, nents, len, fifo->in);
     366             : }
     367             : EXPORT_SYMBOL(__kfifo_dma_in_prepare);
     368             : 
     369           0 : unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
     370             :                 struct scatterlist *sgl, int nents, unsigned int len)
     371             : {
     372             :         unsigned int l;
     373             : 
     374           0 :         l = fifo->in - fifo->out;
     375           0 :         if (len > l)
     376           0 :                 len = l;
     377             : 
     378           0 :         return setup_sgl(fifo, sgl, nents, len, fifo->out);
     379             : }
     380             : EXPORT_SYMBOL(__kfifo_dma_out_prepare);
     381             : 
     382           0 : unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
     383             : {
     384           0 :         unsigned int max = (1 << (recsize << 3)) - 1;
     385             : 
     386           0 :         if (len > max)
     387             :                 return max;
     388           0 :         return len;
     389             : }
     390             : EXPORT_SYMBOL(__kfifo_max_r);
     391             : 
     392             : #define __KFIFO_PEEK(data, out, mask) \
     393             :         ((data)[(out) & (mask)])
     394             : /*
     395             :  * __kfifo_peek_n internal helper function for determinate the length of
     396             :  * the next record in the fifo
     397             :  */
     398             : static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
     399             : {
     400             :         unsigned int l;
     401           0 :         unsigned int mask = fifo->mask;
     402           0 :         unsigned char *data = fifo->data;
     403             : 
     404           0 :         l = __KFIFO_PEEK(data, fifo->out, mask);
     405             : 
     406           0 :         if (--recsize)
     407           0 :                 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
     408             : 
     409             :         return l;
     410             : }
     411             : 
     412             : #define __KFIFO_POKE(data, in, mask, val) \
     413             :         ( \
     414             :         (data)[(in) & (mask)] = (unsigned char)(val) \
     415             :         )
     416             : 
     417             : /*
     418             :  * __kfifo_poke_n internal helper function for storing the length of
     419             :  * the record into the fifo
     420             :  */
     421             : static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
     422             : {
     423           0 :         unsigned int mask = fifo->mask;
     424           0 :         unsigned char *data = fifo->data;
     425             : 
     426           0 :         __KFIFO_POKE(data, fifo->in, mask, n);
     427             : 
     428           0 :         if (recsize > 1)
     429           0 :                 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
     430             : }
     431             : 
     432           0 : unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
     433             : {
     434           0 :         return __kfifo_peek_n(fifo, recsize);
     435             : }
     436             : EXPORT_SYMBOL(__kfifo_len_r);
     437             : 
     438           0 : unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
     439             :                 unsigned int len, size_t recsize)
     440             : {
     441           0 :         if (len + recsize > kfifo_unused(fifo))
     442             :                 return 0;
     443             : 
     444           0 :         __kfifo_poke_n(fifo, len, recsize);
     445             : 
     446           0 :         kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
     447           0 :         fifo->in += len + recsize;
     448           0 :         return len;
     449             : }
     450             : EXPORT_SYMBOL(__kfifo_in_r);
     451             : 
     452           0 : static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
     453             :         void *buf, unsigned int len, size_t recsize, unsigned int *n)
     454             : {
     455           0 :         *n = __kfifo_peek_n(fifo, recsize);
     456             : 
     457           0 :         if (len > *n)
     458           0 :                 len = *n;
     459             : 
     460           0 :         kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
     461           0 :         return len;
     462             : }
     463             : 
     464           0 : unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
     465             :                 unsigned int len, size_t recsize)
     466             : {
     467             :         unsigned int n;
     468             : 
     469           0 :         if (fifo->in == fifo->out)
     470             :                 return 0;
     471             : 
     472           0 :         return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
     473             : }
     474             : EXPORT_SYMBOL(__kfifo_out_peek_r);
     475             : 
     476           0 : unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
     477             :                 unsigned int len, size_t recsize)
     478             : {
     479             :         unsigned int n;
     480             : 
     481           0 :         if (fifo->in == fifo->out)
     482             :                 return 0;
     483             : 
     484           0 :         len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
     485           0 :         fifo->out += n + recsize;
     486           0 :         return len;
     487             : }
     488             : EXPORT_SYMBOL(__kfifo_out_r);
     489             : 
     490           0 : void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
     491             : {
     492             :         unsigned int n;
     493             : 
     494           0 :         n = __kfifo_peek_n(fifo, recsize);
     495           0 :         fifo->out += n + recsize;
     496           0 : }
     497             : EXPORT_SYMBOL(__kfifo_skip_r);
     498             : 
     499           0 : int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
     500             :         unsigned long len, unsigned int *copied, size_t recsize)
     501             : {
     502             :         unsigned long ret;
     503             : 
     504           0 :         len = __kfifo_max_r(len, recsize);
     505             : 
     506           0 :         if (len + recsize > kfifo_unused(fifo)) {
     507           0 :                 *copied = 0;
     508           0 :                 return 0;
     509             :         }
     510             : 
     511           0 :         __kfifo_poke_n(fifo, len, recsize);
     512             : 
     513           0 :         ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
     514           0 :         if (unlikely(ret)) {
     515           0 :                 *copied = 0;
     516           0 :                 return -EFAULT;
     517             :         }
     518           0 :         fifo->in += len + recsize;
     519           0 :         return 0;
     520             : }
     521             : EXPORT_SYMBOL(__kfifo_from_user_r);
     522             : 
     523           0 : int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
     524             :         unsigned long len, unsigned int *copied, size_t recsize)
     525             : {
     526             :         unsigned long ret;
     527             :         unsigned int n;
     528             : 
     529           0 :         if (fifo->in == fifo->out) {
     530           0 :                 *copied = 0;
     531           0 :                 return 0;
     532             :         }
     533             : 
     534           0 :         n = __kfifo_peek_n(fifo, recsize);
     535           0 :         if (len > n)
     536           0 :                 len = n;
     537             : 
     538           0 :         ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
     539           0 :         if (unlikely(ret)) {
     540           0 :                 *copied = 0;
     541           0 :                 return -EFAULT;
     542             :         }
     543           0 :         fifo->out += n + recsize;
     544           0 :         return 0;
     545             : }
     546             : EXPORT_SYMBOL(__kfifo_to_user_r);
     547             : 
     548           0 : unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
     549             :         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
     550             : {
     551           0 :         BUG_ON(!nents);
     552             : 
     553           0 :         len = __kfifo_max_r(len, recsize);
     554             : 
     555           0 :         if (len + recsize > kfifo_unused(fifo))
     556             :                 return 0;
     557             : 
     558           0 :         return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
     559             : }
     560             : EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
     561             : 
     562           0 : void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
     563             :         unsigned int len, size_t recsize)
     564             : {
     565           0 :         len = __kfifo_max_r(len, recsize);
     566           0 :         __kfifo_poke_n(fifo, len, recsize);
     567           0 :         fifo->in += len + recsize;
     568           0 : }
     569             : EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
     570             : 
     571           0 : unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
     572             :         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
     573             : {
     574           0 :         BUG_ON(!nents);
     575             : 
     576           0 :         len = __kfifo_max_r(len, recsize);
     577             : 
     578           0 :         if (len + recsize > fifo->in - fifo->out)
     579             :                 return 0;
     580             : 
     581           0 :         return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
     582             : }
     583             : EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
     584             : 
     585           0 : void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
     586             : {
     587             :         unsigned int len;
     588             : 
     589           0 :         len = __kfifo_peek_n(fifo, recsize);
     590           0 :         fifo->out += len + recsize;
     591           0 : }
     592             : EXPORT_SYMBOL(__kfifo_dma_out_finish_r);