summaryrefslogtreecommitdiffstats
path: root/lib/reed_solomon/reed_solomon.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2018-06-05 10:48:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-05 10:48:05 -0700
commit25d80be86c5d7f53df41ec5ce96f6c6543cac245 (patch)
treea18fe8d5281d0ed44c049d5a59da499278bb6e3e /lib/reed_solomon/reed_solomon.c
parenta74e0c4c9cb02d44bc5ec1a70a6ba599366fb130 (diff)
parent45888b40d2a6221d46bb69959e2600ddba71cc1f (diff)
downloadlinux-0-day-25d80be86c5d7f53df41ec5ce96f6c6543cac245.tar.gz
linux-0-day-25d80be86c5d7f53df41ec5ce96f6c6543cac245.tar.xz
Merge tag 'rslib-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull reed-salomon library updates from Kees Cook: "Refactors rslib and callers to provide a per-instance allocation area instead of performing VLAs on the stack" * tag 'rslib-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: rslib: Allocate decoder buffers to avoid VLAs mtd: rawnand: diskonchip: Allocate rs control per instance rslib: Split rs control struct rslib: Simplify error path rslib: Remove GPL boilerplate rslib: Add SPDX identifiers rslib: Cleanup top level comments rslib: Cleanup whitespace damage dm/verity_fec: Use GFP aware reed solomon init rslib: Add GFP aware init function
Diffstat (limited to 'lib/reed_solomon/reed_solomon.c')
-rw-r--r--lib/reed_solomon/reed_solomon.c240
1 files changed, 138 insertions, 102 deletions
diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c
index 06d04cfa9339..dfcf54242fb9 100644
--- a/lib/reed_solomon/reed_solomon.c
+++ b/lib/reed_solomon/reed_solomon.c
@@ -1,43 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
/*
- * lib/reed_solomon/reed_solomon.c
- *
- * Overview:
- * Generic Reed Solomon encoder / decoder library
+ * Generic Reed Solomon encoder / decoder library
*
* Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
*
* Reed Solomon code lifted from reed solomon library written by Phil Karn
* Copyright 2002 Phil Karn, KA9Q
*
- * $Id: rslib.c,v 1.7 2005/11/07 11:14:59 gleixner Exp $
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
* Description:
*
* The generic Reed Solomon library provides runtime configurable
* encoding / decoding of RS codes.
- * Each user must call init_rs to get a pointer to a rs_control
- * structure for the given rs parameters. This structure is either
- * generated or a already available matching control structure is used.
- * If a structure is generated then the polynomial arrays for
- * fast encoding / decoding are built. This can take some time so
- * make sure not to call this function from a time critical path.
- * Usually a module / driver should initialize the necessary
- * rs_control structure on module / driver init and release it
- * on exit.
- * The encoding puts the calculated syndrome into a given syndrome
- * buffer.
- * The decoding is a two step process. The first step calculates
- * the syndrome over the received (data + syndrome) and calls the
- * second stage, which does the decoding / error correction itself.
- * Many hw encoders provide a syndrome calculation over the received
- * data + syndrome and can call the second stage directly.
*
+ * Each user must call init_rs to get a pointer to a rs_control structure
+ * for the given rs parameters. The control struct is unique per instance.
+ * It points to a codec which can be shared by multiple control structures.
+ * If a codec is newly allocated then the polynomial arrays for fast
+ * encoding / decoding are built. This can take some time so make sure not
+ * to call this function from a time critical path. Usually a module /
+ * driver should initialize the necessary rs_control structure on module /
+ * driver init and release it on exit.
+ *
+ * The encoding puts the calculated syndrome into a given syndrome buffer.
+ *
+ * The decoding is a two step process. The first step calculates the
+ * syndrome over the received (data + syndrome) and calls the second stage,
+ * which does the decoding / error correction itself. Many hw encoders
+ * provide a syndrome calculation over the received data + syndrome and can
+ * call the second stage directly.
*/
-
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -46,32 +37,44 @@
#include <linux/slab.h>
#include <linux/mutex.h>
-/* This list holds all currently allocated rs control structures */
-static LIST_HEAD (rslist);
+enum {
+ RS_DECODE_LAMBDA,
+ RS_DECODE_SYN,
+ RS_DECODE_B,
+ RS_DECODE_T,
+ RS_DECODE_OMEGA,
+ RS_DECODE_ROOT,
+ RS_DECODE_REG,
+ RS_DECODE_LOC,
+ RS_DECODE_NUM_BUFFERS
+};
+
+/* This list holds all currently allocated rs codec structures */
+static LIST_HEAD(codec_list);
/* Protection for the list */
static DEFINE_MUTEX(rslistlock);
/**
- * rs_init - Initialize a Reed-Solomon codec
+ * codec_init - Initialize a Reed-Solomon codec
* @symsize: symbol size, bits (1-8)
* @gfpoly: Field generator polynomial coefficients
* @gffunc: Field generator function
* @fcr: first root of RS code generator polynomial, index form
* @prim: primitive element to generate polynomial roots
* @nroots: RS code generator polynomial degree (number of roots)
+ * @gfp: GFP_ flags for allocations
*
- * Allocate a control structure and the polynom arrays for faster
+ * Allocate a codec structure and the polynom arrays for faster
* en/decoding. Fill the arrays according to the given parameters.
*/
-static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
- int fcr, int prim, int nroots)
+static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int),
+ int fcr, int prim, int nroots, gfp_t gfp)
{
- struct rs_control *rs;
int i, j, sr, root, iprim;
+ struct rs_codec *rs;
- /* Allocate the control structure */
- rs = kmalloc(sizeof (struct rs_control), GFP_KERNEL);
- if (rs == NULL)
+ rs = kzalloc(sizeof(*rs), gfp);
+ if (!rs)
return NULL;
INIT_LIST_HEAD(&rs->list);
@@ -85,17 +88,17 @@ static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
rs->gffunc = gffunc;
/* Allocate the arrays */
- rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
+ rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), gfp);
if (rs->alpha_to == NULL)
- goto errrs;
+ goto err;
- rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
+ rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), gfp);
if (rs->index_of == NULL)
- goto erralp;
+ goto err;
- rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), GFP_KERNEL);
+ rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), gfp);
if(rs->genpoly == NULL)
- goto erridx;
+ goto err;
/* Generate Galois field lookup tables */
rs->index_of[0] = rs->nn; /* log(zero) = -inf */
@@ -120,7 +123,7 @@ static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
}
/* If it's not primitive, exit */
if(sr != rs->alpha_to[0])
- goto errpol;
+ goto err;
/* Find prim-th root of 1, used in decoding */
for(iprim = 1; (iprim % prim) != 0; iprim += rs->nn);
@@ -148,42 +151,52 @@ static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
/* convert rs->genpoly[] to index form for quicker encoding */
for (i = 0; i <= nroots; i++)
rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
+
+ rs->users = 1;
+ list_add(&rs->list, &codec_list);
return rs;
- /* Error exit */
-errpol:
+err:
kfree(rs->genpoly);
-erridx:
kfree(rs->index_of);
-erralp:
kfree(rs->alpha_to);
-errrs:
kfree(rs);
return NULL;
}
/**
- * free_rs - Free the rs control structure, if it is no longer used
- * @rs: the control structure which is not longer used by the
+ * free_rs - Free the rs control structure
+ * @rs: The control structure which is not longer used by the
* caller
+ *
+ * Free the control structure. If @rs is the last user of the associated
+ * codec, free the codec as well.
*/
void free_rs(struct rs_control *rs)
{
+ struct rs_codec *cd;
+
+ if (!rs)
+ return;
+
+ cd = rs->codec;
mutex_lock(&rslistlock);
- rs->users--;
- if(!rs->users) {
- list_del(&rs->list);
- kfree(rs->alpha_to);
- kfree(rs->index_of);
- kfree(rs->genpoly);
- kfree(rs);
+ cd->users--;
+ if(!cd->users) {
+ list_del(&cd->list);
+ kfree(cd->alpha_to);
+ kfree(cd->index_of);
+ kfree(cd->genpoly);
+ kfree(cd);
}
mutex_unlock(&rslistlock);
+ kfree(rs);
}
+EXPORT_SYMBOL_GPL(free_rs);
/**
- * init_rs_internal - Find a matching or allocate a new rs control structure
+ * init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
* @symsize: the symbol size (number of bits)
* @gfpoly: the extended Galois field generator polynomial coefficients,
* with the 0th coefficient in the low order bit. The polynomial
@@ -191,55 +204,69 @@ void free_rs(struct rs_control *rs)
* @gffunc: pointer to function to generate the next field element,
* or the multiplicative identity element if given 0. Used
* instead of gfpoly if gfpoly is 0
- * @fcr: the first consecutive root of the rs code generator polynomial
+ * @fcr: the first consecutive root of the rs code generator polynomial
* in index form
* @prim: primitive element to generate polynomial roots
* @nroots: RS code generator polynomial degree (number of roots)
+ * @gfp: GFP_ flags for allocations
*/
static struct rs_control *init_rs_internal(int symsize, int gfpoly,
- int (*gffunc)(int), int fcr,
- int prim, int nroots)
+ int (*gffunc)(int), int fcr,
+ int prim, int nroots, gfp_t gfp)
{
- struct list_head *tmp;
- struct rs_control *rs;
+ struct list_head *tmp;
+ struct rs_control *rs;
+ unsigned int bsize;
/* Sanity checks */
if (symsize < 1)
return NULL;
if (fcr < 0 || fcr >= (1<<symsize))
- return NULL;
+ return NULL;
if (prim <= 0 || prim >= (1<<symsize))
- return NULL;
+ return NULL;
if (nroots < 0 || nroots >= (1<<symsize))
return NULL;
+ /*
+ * The decoder needs buffers in each control struct instance to
+ * avoid variable size or large fixed size allocations on
+ * stack. Size the buffers to arrays of [nroots + 1].
+ */
+ bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1);
+ rs = kzalloc(sizeof(*rs) + bsize, gfp);
+ if (!rs)
+ return NULL;
+
mutex_lock(&rslistlock);
/* Walk through the list and look for a matching entry */
- list_for_each(tmp, &rslist) {
- rs = list_entry(tmp, struct rs_control, list);
- if (symsize != rs->mm)
+ list_for_each(tmp, &codec_list) {
+ struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);
+
+ if (symsize != cd->mm)
continue;
- if (gfpoly != rs->gfpoly)
+ if (gfpoly != cd->gfpoly)
continue;
- if (gffunc != rs->gffunc)
+ if (gffunc != cd->gffunc)
continue;
- if (fcr != rs->fcr)
+ if (fcr != cd->fcr)
continue;
- if (prim != rs->prim)
+ if (prim != cd->prim)
continue;
- if (nroots != rs->nroots)
+ if (nroots != cd->nroots)
continue;
/* We have a matching one already */
- rs->users++;
+ cd->users++;
+ rs->codec = cd;
goto out;
}
/* Create a new one */
- rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
- if (rs) {
- rs->users = 1;
- list_add(&rs->list, &rslist);
+ rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
+ if (!rs->codec) {
+ kfree(rs);
+ rs = NULL;
}
out:
mutex_unlock(&rslistlock);
@@ -247,45 +274,48 @@ out:
}
/**
- * init_rs - Find a matching or allocate a new rs control structure
+ * init_rs_gfp - Create a RS control struct and initialize it
* @symsize: the symbol size (number of bits)
* @gfpoly: the extended Galois field generator polynomial coefficients,
* with the 0th coefficient in the low order bit. The polynomial
* must be primitive;
- * @fcr: the first consecutive root of the rs code generator polynomial
+ * @fcr: the first consecutive root of the rs code generator polynomial
* in index form
* @prim: primitive element to generate polynomial roots
* @nroots: RS code generator polynomial degree (number of roots)
+ * @gfp: GFP_ flags for allocations
*/
-struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
- int nroots)
+struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
+ int nroots, gfp_t gfp)
{
- return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots);
+ return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
}
+EXPORT_SYMBOL_GPL(init_rs_gfp);
/**
- * init_rs_non_canonical - Find a matching or allocate a new rs control
- * structure, for fields with non-canonical
- * representation
+ * init_rs_non_canonical - Allocate rs control struct for fields with
+ * non-canonical representation
* @symsize: the symbol size (number of bits)
* @gffunc: pointer to function to generate the next field element,
* or the multiplicative identity element if given 0. Used
* instead of gfpoly if gfpoly is 0
- * @fcr: the first consecutive root of the rs code generator polynomial
+ * @fcr: the first consecutive root of the rs code generator polynomial
* in index form
* @prim: primitive element to generate polynomial roots
* @nroots: RS code generator polynomial degree (number of roots)
*/
struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
- int fcr, int prim, int nroots)
+ int fcr, int prim, int nroots)
{
- return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots);
+ return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots,
+ GFP_KERNEL);
}
+EXPORT_SYMBOL_GPL(init_rs_non_canonical);
#ifdef CONFIG_REED_SOLOMON_ENC8
/**
* encode_rs8 - Calculate the parity for data values (8bit data width)
- * @rs: the rs control structure
+ * @rsc: the rs control structure
* @data: data field of a given type
* @len: data length
* @par: parity data, must be initialized by caller (usually all 0)
@@ -295,7 +325,7 @@ struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
* symbol size > 8. The calling code must take care of encoding of the
* syndrome result for storage itself.
*/
-int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
+int encode_rs8(struct rs_control *rsc, uint8_t *data, int len, uint16_t *par,
uint16_t invmsk)
{
#include "encode_rs.c"
@@ -306,7 +336,7 @@ EXPORT_SYMBOL_GPL(encode_rs8);
#ifdef CONFIG_REED_SOLOMON_DEC8
/**
* decode_rs8 - Decode codeword (8bit data width)
- * @rs: the rs control structure
+ * @rsc: the rs control structure
* @data: data field of a given type
* @par: received parity data field
* @len: data length
@@ -319,9 +349,14 @@ EXPORT_SYMBOL_GPL(encode_rs8);
* The syndrome and parity uses a uint16_t data type to enable
* symbol size > 8. The calling code must take care of decoding of the
* syndrome result and the received parity before calling this code.
+ *
+ * Note: The rs_control struct @rsc contains buffers which are used for
+ * decoding, so the caller has to ensure that decoder invocations are
+ * serialized.
+ *
* Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
*/
-int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
+int decode_rs8(struct rs_control *rsc, uint8_t *data, uint16_t *par, int len,
uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
uint16_t *corr)
{
@@ -333,7 +368,7 @@ EXPORT_SYMBOL_GPL(decode_rs8);
#ifdef CONFIG_REED_SOLOMON_ENC16
/**
* encode_rs16 - Calculate the parity for data values (16bit data width)
- * @rs: the rs control structure
+ * @rsc: the rs control structure
* @data: data field of a given type
* @len: data length
* @par: parity data, must be initialized by caller (usually all 0)
@@ -341,7 +376,7 @@ EXPORT_SYMBOL_GPL(decode_rs8);
*
* Each field in the data array contains up to symbol size bits of valid data.
*/
-int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
+int encode_rs16(struct rs_control *rsc, uint16_t *data, int len, uint16_t *par,
uint16_t invmsk)
{
#include "encode_rs.c"
@@ -352,7 +387,7 @@ EXPORT_SYMBOL_GPL(encode_rs16);
#ifdef CONFIG_REED_SOLOMON_DEC16
/**
* decode_rs16 - Decode codeword (16bit data width)
- * @rs: the rs control structure
+ * @rsc: the rs control structure
* @data: data field of a given type
* @par: received parity data field
* @len: data length
@@ -363,9 +398,14 @@ EXPORT_SYMBOL_GPL(encode_rs16);
* @corr: buffer to store correction bitmask on eras_pos
*
* Each field in the data array contains up to symbol size bits of valid data.
+ *
+ * Note: The rc_control struct @rsc contains buffers which are used for
+ * decoding, so the caller has to ensure that decoder invocations are
+ * serialized.
+ *
* Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
*/
-int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
+int decode_rs16(struct rs_control *rsc, uint16_t *data, uint16_t *par, int len,
uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
uint16_t *corr)
{
@@ -374,10 +414,6 @@ int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
EXPORT_SYMBOL_GPL(decode_rs16);
#endif
-EXPORT_SYMBOL_GPL(init_rs);
-EXPORT_SYMBOL_GPL(init_rs_non_canonical);
-EXPORT_SYMBOL_GPL(free_rs);
-
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
MODULE_AUTHOR("Phil Karn, Thomas Gleixner");