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

1 files changed, 48 insertions, 26 deletions

diff --git a/include/linux/rslib.h b/include/linux/rslib.h
index 746580c1939c..5974cedd008c 100644
--- a/include/linux/rslib.h
+++ b/include/linux/rslib.h
@@ -1,28 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * include/linux/rslib.h
- *
- * Overview:
- *   Generic Reed Solomon encoder / decoder library
+ * Generic Reed Solomon encoder / decoder library
  *
  * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
  *
  * RS code lifted from reed solomon library written by Phil Karn
  * Copyright 2002 Phil Karn, KA9Q
- *
- * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 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.
  */
-
 #ifndef _RSLIB_H_
 #define _RSLIB_H_
 
 #include <linux/list.h>
+#include <linux/types.h>	/* for gfp_t */
+#include <linux/gfp.h>		/* for GFP_KERNEL */
 
 /**
- * struct rs_control - rs control structure
+ * struct rs_codec - rs codec data
  *
  * @mm:		Bits per symbol
  * @nn:		Symbols per block (= (1<<mm)-1)
@@ -36,24 +29,34 @@
  * @gfpoly:	The primitive generator polynominal
  * @gffunc:	Function to generate the field, if non-canonical representation
  * @users:	Users of this structure
- * @list:	List entry for the rs control list
+ * @list:	List entry for the rs codec list
 */
-struct rs_control {
-	int 		mm;
-	int 		nn;
+struct rs_codec {
+	int		mm;
+	int		nn;
 	uint16_t	*alpha_to;
 	uint16_t	*index_of;
 	uint16_t	*genpoly;
-	int 		nroots;
-	int 		fcr;
-	int 		prim;
-	int 		iprim;
+	int		nroots;
+	int		fcr;
+	int		prim;
+	int		iprim;
 	int		gfpoly;
 	int		(*gffunc)(int);
 	int		users;
 	struct list_head list;
 };
 
+/**
+ * struct rs_control - rs control structure per instance
+ * @codec:	The codec used for this instance
+ * @buffers:	Internal scratch buffers used in calls to decode_rs()
+ */
+struct rs_control {
+	struct rs_codec	*codec;
+	uint16_t	buffers[0];
+};
+
 /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit  */
 #ifdef CONFIG_REED_SOLOMON_ENC8
 int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
@@ -76,18 +79,37 @@ int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
 		uint16_t *corr);
 #endif
 
-/* Create or get a matching rs control structure */
-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);
+
+/**
+ * init_rs - 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
+ *		in index form
+ *  @prim:	primitive element to generate polynomial roots
+ *  @nroots:	RS code generator polynomial degree (number of roots)
+ *
+ * Allocations use GFP_KERNEL.
+ */
+static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr,
+					 int prim, int nroots)
+{
+	return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL);
+}
+
 struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int),
-                                         int fcr, int prim, int nroots);
+					 int fcr, int prim, int nroots);
 
 /* Release a rs control structure */
 void free_rs(struct rs_control *rs);
 
 /** modulo replacement for galois field arithmetics
  *
- *  @rs:	the rs control structure
+ *  @rs:	Pointer to the RS codec
  *  @x:		the value to reduce
  *
  *  where
@@ -97,7 +119,7 @@ void free_rs(struct rs_control *rs);
  *  Simple arithmetic modulo would return a wrong result for values
  *  >= 3 * rs->nn
 */
-static inline int rs_modnn(struct rs_control *rs, int x)
+static inline int rs_modnn(struct rs_codec *rs, int x)
 {
 	while (x >= rs->nn) {
 		x -= rs->nn;