Merge branch 'core-rslib-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (568521d0) · Commits · EulixOS / Software / Kernel

lib/Kconfig.debug

+12 −0

Original line number	Diff line number	Diff line
		@@ -1754,6 +1754,18 @@ config RBTREE_TEST
		A benchmark measuring the performance of the rbtree library.
		Also includes rbtree invariant checks.

		config REED_SOLOMON_TEST
		tristate "Reed-Solomon library test"
		depends on DEBUG_KERNEL \|\| m
		select REED_SOLOMON
		select REED_SOLOMON_ENC16
		select REED_SOLOMON_DEC16
		help
		This option enables the self-test function of rslib at boot,
		or at module load time.

		If unsure, say N.

		config INTERVAL_TREE_TEST
		tristate "Interval tree test"
		depends on DEBUG_KERNEL

lib/reed_solomon/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -4,4 +4,4 @@
		#

		obj-$(CONFIG_REED_SOLOMON) += reed_solomon.o

		obj-$(CONFIG_REED_SOLOMON_TEST) += test_rslib.o

lib/reed_solomon/decode_rs.c

+85 −30

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@
		uint16_t *index_of = rs->index_of;
		uint16_t u, q, tmp, num1, num2, den, discr_r, syn_error;
		int count = 0;
		int num_corrected;
		uint16_t msk = (uint16_t) rs->nn;

		/*
		@@ -39,11 +40,21 @@

		/* Check length parameter for validity */
		pad = nn - nroots - len;
		BUG_ON(pad < 0 \|\| pad >= nn);
		BUG_ON(pad < 0 \|\| pad >= nn - nroots);

		/* Does the caller provide the syndrome ? */
		if (s != NULL)
		if (s != NULL) {
		for (i = 0; i < nroots; i++) {
		/* The syndrome is in index form,
		* so nn represents zero
		*/
		if (s[i] != nn)
		goto decode;
		}

		/* syndrome is zero, no errors to correct */
		return 0;
		}

		/* form the syndromes; i.e., evaluate data(x) at roots of
		* g(x) */
		@@ -88,8 +99,7 @@
		/* if syndrome is zero, data[] is a codeword and there are no
		* errors to correct. So return data[] unmodified
		*/
		count = 0;
		goto finish;
		return 0;
		}

		decode:
		@@ -99,9 +109,9 @@
		if (no_eras > 0) {
		/* Init lambda to be the erasure locator polynomial */
		lambda[1] = alpha_to[rs_modnn(rs,
		prim * (nn - 1 - eras_pos[0]))];
		prim * (nn - 1 - (eras_pos[0] + pad)))];
		for (i = 1; i < no_eras; i++) {
		u = rs_modnn(rs, prim * (nn - 1 - eras_pos[i]));
		u = rs_modnn(rs, prim * (nn - 1 - (eras_pos[i] + pad)));
		for (j = i + 1; j > 0; j--) {
		tmp = index_of[lambda[j - 1]];
		if (tmp != nn) {
		@@ -175,6 +185,15 @@
		if (lambda[i] != nn)
		deg_lambda = i;
		}

		if (deg_lambda == 0) {
		/*
		* deg(lambda) is zero even though the syndrome is non-zero
		* => uncorrectable error detected
		*/
		return -EBADMSG;
		}

		/* Find roots of error+erasure locator polynomial by Chien search */
		memcpy(&reg[1], &lambda[1], nroots * sizeof(reg[0]));
		count = 0; /* Number of roots of lambda(x) */
		@@ -188,6 +207,12 @@
		}
		if (q != 0)
		continue; /* Not a root */

		if (k < pad) {
		/* Impossible error location. Uncorrectable error. */
		return -EBADMSG;
		}

		/* store root (index-form) and error location number */
		root[count] = i;
		loc[count] = k;
		@@ -202,8 +227,7 @@
		* deg(lambda) unequal to number of roots => uncorrectable
		* error detected
		*/
		count = -EBADMSG;
		goto finish;
		return -EBADMSG;
		}
		/*
		* Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo
		@@ -223,7 +247,9 @@
		/*
		* Compute error values in poly-form. num1 = omega(inv(X(l))), num2 =
		* inv(X(l))**(fcr-1) and den = lambda_pr(inv(X(l))) all in poly-form
		* Note: we reuse the buffer for b to store the correction pattern
		*/
		num_corrected = 0;
		for (j = count - 1; j >= 0; j--) {
		num1 = 0;
		for (i = deg_omega; i >= 0; i--) {
		@@ -231,6 +257,13 @@
		num1 ^= alpha_to[rs_modnn(rs, omega[i] +
		i * root[j])];
		}

		if (num1 == 0) {
		/* Nothing to correct at this position */
		b[j] = 0;
		continue;
		}

		num2 = alpha_to[rs_modnn(rs, root[j] * (fcr - 1) + nn)];
		den = 0;

		@@ -242,30 +275,52 @@
		i * root[j])];
		}
		}
		/* Apply error to data */
		if (num1 != 0 && loc[j] >= pad) {
		uint16_t cor = alpha_to[rs_modnn(rs,index_of[num1] +

		b[j] = alpha_to[rs_modnn(rs, index_of[num1] +
		index_of[num2] +
		nn - index_of[den])];
		/* Store the error correction pattern, if a
		* correction buffer is available */
		if (corr) {
		corr[j] = cor;
		} else {
		/* If a data buffer is given and the
		* error is inside the message,
		* correct it */
		if (data && (loc[j] < (nn - nroots)))
		data[loc[j] - pad] ^= cor;
		num_corrected++;
		}

		/*
		* We compute the syndrome of the 'error' and check that it matches
		* the syndrome of the received word
		*/
		for (i = 0; i < nroots; i++) {
		tmp = 0;
		for (j = 0; j < count; j++) {
		if (b[j] == 0)
		continue;

		k = (fcr + i) * prim * (nn-loc[j]-1);
		tmp ^= alpha_to[rs_modnn(rs, index_of[b[j]] + k)];
		}

		if (tmp != alpha_to[s[i]])
		return -EBADMSG;
		}

		finish:
		if (eras_pos != NULL) {
		for (i = 0; i < count; i++)
		eras_pos[i] = loc[i] - pad;
		/*
		* Store the error correction pattern, if a
		* correction buffer is available
		*/
		if (corr && eras_pos) {
		j = 0;
		for (i = 0; i < count; i++) {
		if (b[i]) {
		corr[j] = b[i];
		eras_pos[j++] = loc[i] - pad;
		}
		}
		} else if (data && par) {
		/* Apply error to data and parity */
		for (i = 0; i < count; i++) {
		if (loc[i] < (nn - nroots))
		data[loc[i] - pad] ^= b[i];
		else
		par[loc[i] - pad - len] ^= b[i];
		}
		}
		return count;

		return num_corrected;
		}

lib/reed_solomon/reed_solomon.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -340,7 +340,8 @@ EXPORT_SYMBOL_GPL(encode_rs8);
		* @data: data field of a given type
		* @par: received parity data field
		* @len: data length
		* @s: syndrome data field (if NULL, syndrome is calculated)
		* @s: syndrome data field, must be in index form
		* (if NULL, syndrome is calculated)
		* @no_eras: number of erasures
		* @eras_pos: position of erasures, can be NULL
		* @invmsk: invert data mask (will be xored on data, not on parity!)
		@@ -354,7 +355,8 @@ EXPORT_SYMBOL_GPL(encode_rs8);
		* decoding, so the caller has to ensure that decoder invocations are
		* serialized.
		*
		* Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
		* Returns the number of corrected symbols or -EBADMSG for uncorrectable
		* errors. The count includes errors in the parity.
		*/
		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,
		@@ -391,7 +393,8 @@ EXPORT_SYMBOL_GPL(encode_rs16);
		* @data: data field of a given type
		* @par: received parity data field
		* @len: data length
		* @s: syndrome data field (if NULL, syndrome is calculated)
		* @s: syndrome data field, must be in index form
		* (if NULL, syndrome is calculated)
		* @no_eras: number of erasures
		* @eras_pos: position of erasures, can be NULL
		* @invmsk: invert data mask (will be xored on data, not on parity!)
		@@ -403,7 +406,8 @@ EXPORT_SYMBOL_GPL(encode_rs16);
		* decoding, so the caller has to ensure that decoder invocations are
		* serialized.
		*
		* Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
		* Returns the number of corrected symbols or -EBADMSG for uncorrectable
		* errors. The count includes errors in the parity.
		*/
		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,

lib/reed_solomon/test_rslib.c

0 → 100644

+518 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/*
		* Tests for Generic Reed Solomon encoder / decoder library
		*
		* Written by Ferdinand Blomqvist
		* Based on previous work by Phil Karn, KA9Q
		*/
		#include <linux/rslib.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/moduleparam.h>
		#include <linux/random.h>
		#include <linux/slab.h>

		enum verbosity {
		V_SILENT,
		V_PROGRESS,
		V_CSUMMARY
		};

		enum method {
		CORR_BUFFER,
		CALLER_SYNDROME,
		IN_PLACE
		};

		#define __param(type, name, init, msg) \
		static type name = init; \
		module_param(name, type, 0444); \
		MODULE_PARM_DESC(name, msg)

		__param(int, v, V_PROGRESS, "Verbosity level");
		__param(int, ewsc, 1, "Erasures without symbol corruption");
		__param(int, bc, 1, "Test for correct behaviour beyond error correction capacity");

		struct etab {
		int symsize;
		int genpoly;
		int fcs;
		int prim;
		int nroots;
		int ntrials;
		};

		/* List of codes to test */
		static struct etab Tab[] = {
		{2, 0x7, 1, 1, 1, 100000 },
		{3, 0xb, 1, 1, 2, 100000 },
		{3, 0xb, 1, 1, 3, 100000 },
		{3, 0xb, 2, 1, 4, 100000 },
		{4, 0x13, 1, 1, 4, 10000 },
		{5, 0x25, 1, 1, 6, 1000 },
		{6, 0x43, 3, 1, 8, 1000 },
		{7, 0x89, 1, 1, 14, 500 },
		{8, 0x11d, 1, 1, 30, 100 },
		{8, 0x187, 112, 11, 32, 100 },
		{9, 0x211, 1, 1, 33, 80 },
		{0, 0, 0, 0, 0, 0},
		};


		struct estat {
		int dwrong;
		int irv;
		int wepos;
		int nwords;
		};

		struct bcstat {
		int rfail;
		int rsuccess;
		int noncw;
		int nwords;
		};

		struct wspace {
		uint16_t c; / sent codeword */
		uint16_t r; / received word */
		uint16_t s; / syndrome */
		uint16_t corr; / correction buffer */
		int *errlocs;
		int *derrlocs;
		};

		struct pad {
		int mult;
		int shift;
		};

		static struct pad pad_coef[] = {
		{ 0, 0 },
		{ 1, 2 },
		{ 1, 1 },
		{ 3, 2 },
		{ 1, 0 },
		};

		static void free_ws(struct wspace *ws)
		{
		if (!ws)
		return;

		kfree(ws->errlocs);
		kfree(ws->c);
		kfree(ws);
		}

		static struct wspace alloc_ws(struct rs_codec rs)
		{
		int nroots = rs->nroots;
		struct wspace *ws;
		int nn = rs->nn;

		ws = kzalloc(sizeof(*ws), GFP_KERNEL);
		if (!ws)
		return NULL;

		ws->c = kmalloc_array(2 * (nn + nroots),
		sizeof(uint16_t), GFP_KERNEL);
		if (!ws->c)
		goto err;

		ws->r = ws->c + nn;
		ws->s = ws->r + nn;
		ws->corr = ws->s + nroots;

		ws->errlocs = kmalloc_array(nn + nroots, sizeof(int), GFP_KERNEL);
		if (!ws->errlocs)
		goto err;

		ws->derrlocs = ws->errlocs + nn;
		return ws;

		err:
		free_ws(ws);
		return NULL;
		}


		/*
		* Generates a random codeword and stores it in c. Generates random errors and
		* erasures, and stores the random word with errors in r. Erasure positions are
		* stored in derrlocs, while errlocs has one of three values in every position:
		*
		* 0 if there is no error in this position;
		* 1 if there is a symbol error in this position;
		* 2 if there is an erasure without symbol corruption.
		*
		* Returns the number of corrupted symbols.
		*/
		static int get_rcw_we(struct rs_control rs, struct wspace ws,
		int len, int errs, int eras)
		{
		int nroots = rs->codec->nroots;
		int *derrlocs = ws->derrlocs;
		int *errlocs = ws->errlocs;
		int dlen = len - nroots;
		int nn = rs->codec->nn;
		uint16_t *c = ws->c;
		uint16_t *r = ws->r;
		int errval;
		int errloc;
		int i;

		/* Load c with random data and encode */
		for (i = 0; i < dlen; i++)
		c[i] = prandom_u32() & nn;

		memset(c + dlen, 0, nroots * sizeof(*c));
		encode_rs16(rs, c, dlen, c + dlen, 0);

		/* Make copyand add errors and erasures */
		memcpy(r, c, len * sizeof(*r));
		memset(errlocs, 0, len * sizeof(*errlocs));
		memset(derrlocs, 0, nroots * sizeof(*derrlocs));

		/* Generating random errors */
		for (i = 0; i < errs; i++) {
		do {
		/* Error value must be nonzero */
		errval = prandom_u32() & nn;
		} while (errval == 0);

		do {
		/* Must not choose the same location twice */
		errloc = prandom_u32() % len;
		} while (errlocs[errloc] != 0);

		errlocs[errloc] = 1;
		r[errloc] ^= errval;
		}

		/* Generating random erasures */
		for (i = 0; i < eras; i++) {
		do {
		/* Must not choose the same location twice */
		errloc = prandom_u32() % len;
		} while (errlocs[errloc] != 0);

		derrlocs[i] = errloc;

		if (ewsc && (prandom_u32() & 1)) {
		/* Erasure with the symbol intact */
		errlocs[errloc] = 2;
		} else {
		/* Erasure with corrupted symbol */
		do {
		/* Error value must be nonzero */
		errval = prandom_u32() & nn;
		} while (errval == 0);

		errlocs[errloc] = 1;
		r[errloc] ^= errval;
		errs++;
		}
		}

		return errs;
		}

		static void fix_err(uint16_t data, int nerrs, uint16_t corr, int *errlocs)
		{
		int i;

		for (i = 0; i < nerrs; i++)
		data[errlocs[i]] ^= corr[i];
		}

		static void compute_syndrome(struct rs_control rsc, uint16_t data,
		int len, uint16_t *syn)
		{
		struct rs_codec *rs = rsc->codec;
		uint16_t *alpha_to = rs->alpha_to;
		uint16_t *index_of = rs->index_of;
		int nroots = rs->nroots;
		int prim = rs->prim;
		int fcr = rs->fcr;
		int i, j;

		/* Calculating syndrome */
		for (i = 0; i < nroots; i++) {
		syn[i] = data[0];
		for (j = 1; j < len; j++) {
		if (syn[i] == 0) {
		syn[i] = data[j];
		} else {
		syn[i] = data[j] ^
		alpha_to[rs_modnn(rs, index_of[syn[i]]
		+ (fcr + i) * prim)];
		}
		}
		}

		/* Convert to index form */
		for (i = 0; i < nroots; i++)
		syn[i] = rs->index_of[syn[i]];
		}

		/* Test up to error correction capacity */
		static void test_uc(struct rs_control *rs, int len, int errs,
		int eras, int trials, struct estat *stat,
		struct wspace *ws, int method)
		{
		int dlen = len - rs->codec->nroots;
		int *derrlocs = ws->derrlocs;
		int *errlocs = ws->errlocs;
		uint16_t *corr = ws->corr;
		uint16_t *c = ws->c;
		uint16_t *r = ws->r;
		uint16_t *s = ws->s;
		int derrs, nerrs;
		int i, j;

		for (j = 0; j < trials; j++) {
		nerrs = get_rcw_we(rs, ws, len, errs, eras);

		switch (method) {
		case CORR_BUFFER:
		derrs = decode_rs16(rs, r, r + dlen, dlen,
		NULL, eras, derrlocs, 0, corr);
		fix_err(r, derrs, corr, derrlocs);
		break;
		case CALLER_SYNDROME:
		compute_syndrome(rs, r, len, s);
		derrs = decode_rs16(rs, NULL, NULL, dlen,
		s, eras, derrlocs, 0, corr);
		fix_err(r, derrs, corr, derrlocs);
		break;
		case IN_PLACE:
		derrs = decode_rs16(rs, r, r + dlen, dlen,
		NULL, eras, derrlocs, 0, NULL);
		break;
		default:
		continue;
		}

		if (derrs != nerrs)
		stat->irv++;

		if (method != IN_PLACE) {
		for (i = 0; i < derrs; i++) {
		if (errlocs[derrlocs[i]] != 1)
		stat->wepos++;
		}
		}

		if (memcmp(r, c, len * sizeof(*r)))
		stat->dwrong++;
		}
		stat->nwords += trials;
		}

		static int ex_rs_helper(struct rs_control rs, struct wspace ws,
		int len, int trials, int method)
		{
		static const char * const desc[] = {
		"Testing correction buffer interface...",
		"Testing with caller provided syndrome...",
		"Testing in-place interface..."
		};

		struct estat stat = {0, 0, 0, 0};
		int nroots = rs->codec->nroots;
		int errs, eras, retval;

		if (v >= V_PROGRESS)
		pr_info(" %s\n", desc[method]);

		for (errs = 0; errs <= nroots / 2; errs++)
		for (eras = 0; eras <= nroots - 2 * errs; eras++)
		test_uc(rs, len, errs, eras, trials, &stat, ws, method);

		if (v >= V_CSUMMARY) {
		pr_info(" Decodes wrong: %d / %d\n",
		stat.dwrong, stat.nwords);
		pr_info(" Wrong return value: %d / %d\n",
		stat.irv, stat.nwords);
		if (method != IN_PLACE)
		pr_info(" Wrong error position: %d\n", stat.wepos);
		}

		retval = stat.dwrong + stat.wepos + stat.irv;
		if (retval && v >= V_PROGRESS)
		pr_warn(" FAIL: %d decoding failures!\n", retval);

		return retval;
		}

		static int exercise_rs(struct rs_control rs, struct wspace ws,
		int len, int trials)
		{

		int retval = 0;
		int i;

		if (v >= V_PROGRESS)
		pr_info("Testing up to error correction capacity...\n");

		for (i = 0; i <= IN_PLACE; i++)
		retval \|= ex_rs_helper(rs, ws, len, trials, i);

		return retval;
		}

		/* Tests for correct behaviour beyond error correction capacity */
		static void test_bc(struct rs_control *rs, int len, int errs,
		int eras, int trials, struct bcstat *stat,
		struct wspace *ws)
		{
		int nroots = rs->codec->nroots;
		int dlen = len - nroots;
		int *derrlocs = ws->derrlocs;
		uint16_t *corr = ws->corr;
		uint16_t *r = ws->r;
		int derrs, j;

		for (j = 0; j < trials; j++) {
		get_rcw_we(rs, ws, len, errs, eras);
		derrs = decode_rs16(rs, r, r + dlen, dlen,
		NULL, eras, derrlocs, 0, corr);
		fix_err(r, derrs, corr, derrlocs);

		if (derrs >= 0) {
		stat->rsuccess++;

		/*
		* We check that the returned word is actually a
		* codeword. The obious way to do this would be to
		* compute the syndrome, but we don't want to replicate
		* that code here. However, all the codes are in
		* systematic form, and therefore we can encode the
		* returned word, and see whether the parity changes or
		* not.
		*/
		memset(corr, 0, nroots * sizeof(*corr));
		encode_rs16(rs, r, dlen, corr, 0);

		if (memcmp(r + dlen, corr, nroots * sizeof(*corr)))
		stat->noncw++;
		} else {
		stat->rfail++;
		}
		}
		stat->nwords += trials;
		}

		static int exercise_rs_bc(struct rs_control rs, struct wspace ws,
		int len, int trials)
		{
		struct bcstat stat = {0, 0, 0, 0};
		int nroots = rs->codec->nroots;
		int errs, eras, cutoff;

		if (v >= V_PROGRESS)
		pr_info("Testing beyond error correction capacity...\n");

		for (errs = 1; errs <= nroots; errs++) {
		eras = nroots - 2 * errs + 1;
		if (eras < 0)
		eras = 0;

		cutoff = nroots <= len - errs ? nroots : len - errs;
		for (; eras <= cutoff; eras++)
		test_bc(rs, len, errs, eras, trials, &stat, ws);
		}

		if (v >= V_CSUMMARY) {
		pr_info(" decoder gives up: %d / %d\n",
		stat.rfail, stat.nwords);
		pr_info(" decoder returns success: %d / %d\n",
		stat.rsuccess, stat.nwords);
		pr_info(" not a codeword: %d / %d\n",
		stat.noncw, stat.rsuccess);
		}

		if (stat.noncw && v >= V_PROGRESS)
		pr_warn(" FAIL: %d silent failures!\n", stat.noncw);

		return stat.noncw;
		}

		static int run_exercise(struct etab *e)
		{
		int nn = (1 << e->symsize) - 1;
		int kk = nn - e->nroots;
		struct rs_control *rsc;
		int retval = -ENOMEM;
		int max_pad = kk - 1;
		int prev_pad = -1;
		struct wspace *ws;
		int i;

		rsc = init_rs(e->symsize, e->genpoly, e->fcs, e->prim, e->nroots);
		if (!rsc)
		return retval;

		ws = alloc_ws(rsc->codec);
		if (!ws)
		goto err;

		retval = 0;
		for (i = 0; i < ARRAY_SIZE(pad_coef); i++) {
		int pad = (pad_coef[i].mult * max_pad) >> pad_coef[i].shift;
		int len = nn - pad;

		if (pad == prev_pad)
		continue;

		prev_pad = pad;
		if (v >= V_PROGRESS) {
		pr_info("Testing (%d,%d)_%d code...\n",
		len, kk - pad, nn + 1);
		}

		retval \|= exercise_rs(rsc, ws, len, e->ntrials);
		if (bc)
		retval \|= exercise_rs_bc(rsc, ws, len, e->ntrials);
		}

		free_ws(ws);

		err:
		free_rs(rsc);
		return retval;
		}

		static int __init test_rslib_init(void)
		{
		int i, fail = 0;

		for (i = 0; Tab[i].symsize != 0 ; i++) {
		int retval;

		retval = run_exercise(Tab + i);
		if (retval < 0)
		return -ENOMEM;

		fail \|= retval;
		}

		if (fail)
		pr_warn("rslib: test failed\n");
		else
		pr_info("rslib: test ok\n");

		return -EAGAIN; /* Fail will directly unload the module */
		}

		static void __exit test_rslib_exit(void)
		{
		}

		module_init(test_rslib_init)
		module_exit(test_rslib_exit)

		MODULE_LICENSE("GPL");
		MODULE_AUTHOR("Ferdinand Blomqvist");
		MODULE_DESCRIPTION("Reed-Solomon library test");