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

3 files changed, 159 insertions, 130 deletions

diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
index 0ec3f257ffdf..1db74eb098d0 100644
--- a/lib/reed_solomon/decode_rs.c
+++ b/lib/reed_solomon/decode_rs.c
@@ -1,22 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * lib/reed_solomon/decode_rs.c
- *
- * Overview:
- *   Generic Reed Solomon encoder / decoder library
+ * Generic Reed Solomon encoder / decoder library
  *
  * Copyright 2002, Phil Karn, KA9Q
  * May be used under the terms of the GNU General Public License (GPL)
  *
  * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
  *
- * $Id: decode_rs.c,v 1.7 2005/11/07 11:14:59 gleixner Exp $
- *
- */
-
-/* Generic data width independent code which is included by the
- * wrappers.
+ * Generic data width independent code which is included by the wrappers.
  */
 {
+        struct rs_codec *rs = rsc->codec;
         int deg_lambda, el, deg_omega;
         int i, j, r, k, pad;
         int nn = rs->nn;
@@ -27,16 +21,22 @@
         uint16_t *alpha_to = rs->alpha_to;
         uint16_t *index_of = rs->index_of;
         uint16_t u, q, tmp, num1, num2, den, discr_r, syn_error;
-        /* Err+Eras Locator poly and syndrome poly The maximum value
-         * of nroots is 8. So the necessary stack size will be about
-         * 220 bytes max.
-         */
-        uint16_t lambda[nroots + 1], syn[nroots];
-        uint16_t b[nroots + 1], t[nroots + 1], omega[nroots + 1];
-        uint16_t root[nroots], reg[nroots + 1], loc[nroots];
         int count = 0;
         uint16_t msk = (uint16_t) rs->nn;
 
+        /*
+         * The decoder buffers are in the rs control struct. They are
+         * arrays sized [nroots + 1]
+         */
+        uint16_t *lambda = rsc->buffers + RS_DECODE_LAMBDA * (nroots + 1);
+        uint16_t *syn = rsc->buffers + RS_DECODE_SYN * (nroots + 1);
+        uint16_t *b = rsc->buffers + RS_DECODE_B * (nroots + 1);
+        uint16_t *t = rsc->buffers + RS_DECODE_T * (nroots + 1);
+        uint16_t *omega = rsc->buffers + RS_DECODE_OMEGA * (nroots + 1);
+        uint16_t *root = rsc->buffers + RS_DECODE_ROOT * (nroots + 1);
+        uint16_t *reg = rsc->buffers + RS_DECODE_REG * (nroots + 1);
+        uint16_t *loc = rsc->buffers + RS_DECODE_LOC * (nroots + 1);
+
         /* Check length parameter for validity */
         pad = nn - nroots - len;
         BUG_ON(pad < 0 || pad >= nn);
diff --git a/lib/reed_solomon/encode_rs.c b/lib/reed_solomon/encode_rs.c
index 0b5b1a6728ec..9112d46e869e 100644
--- a/lib/reed_solomon/encode_rs.c
+++ b/lib/reed_solomon/encode_rs.c
@@ -1,23 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * lib/reed_solomon/encode_rs.c
- *
- * Overview:
- *   Generic Reed Solomon encoder / decoder library
+ * Generic Reed Solomon encoder / decoder library
  *
  * Copyright 2002, Phil Karn, KA9Q
  * May be used under the terms of the GNU General Public License (GPL)
  *
  * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
  *
- * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $
- *
- */
-
-/* Generic data width independent code which is included by the
- * wrappers.
- * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
+ * Generic data width independent code which is included by the wrappers.
  */
 {
+        struct rs_codec *rs = rsc->codec;
         int i, j, pad;
         int nn = rs->nn;
         int nroots = rs->nroots;
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");