1 files changed, 281 insertions, 0 deletions
diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
new file mode 100644
index 000000000..39b74221f
--- /dev/null
+++ b/lib/raid6/algos.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright 2002 H. Peter Anvin - All Rights Reserved
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * raid6/algos.c
+ *
+ * Algorithm list and algorithm selection for RAID-6
+ */
+
+#include <linux/raid/pq.h>
+#ifndef __KERNEL__
+#include <sys/mman.h>
+#include <stdio.h>
+#else
+#include <linux/module.h>
+#include <linux/gfp.h>
+#if !RAID6_USE_EMPTY_ZERO_PAGE
+/* In .bss so it's zeroed */
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
+EXPORT_SYMBOL(raid6_empty_zero_page);
+#endif
+#endif
+
+struct raid6_calls raid6_call;
+EXPORT_SYMBOL_GPL(raid6_call);
+
+const struct raid6_calls * const raid6_algos[] = {
+#if defined(__i386__) && !defined(__arch_um__)
+#ifdef CONFIG_AS_AVX512
+	&raid6_avx512x2,
+	&raid6_avx512x1,
+#endif
+	&raid6_avx2x2,
+	&raid6_avx2x1,
+	&raid6_sse2x2,
+	&raid6_sse2x1,
+	&raid6_sse1x2,
+	&raid6_sse1x1,
+	&raid6_mmxx2,
+	&raid6_mmxx1,
+#endif
+#if defined(__x86_64__) && !defined(__arch_um__)
+#ifdef CONFIG_AS_AVX512
+	&raid6_avx512x4,
+	&raid6_avx512x2,
+	&raid6_avx512x1,
+#endif
+	&raid6_avx2x4,
+	&raid6_avx2x2,
+	&raid6_avx2x1,
+	&raid6_sse2x4,
+	&raid6_sse2x2,
+	&raid6_sse2x1,
+#endif
+#ifdef CONFIG_ALTIVEC
+	&raid6_vpermxor8,
+	&raid6_vpermxor4,
+	&raid6_vpermxor2,
+	&raid6_vpermxor1,
+	&raid6_altivec8,
+	&raid6_altivec4,
+	&raid6_altivec2,
+	&raid6_altivec1,
+#endif
+#if defined(CONFIG_S390)
+	&raid6_s390vx8,
+#endif
+#ifdef CONFIG_KERNEL_MODE_NEON
+	&raid6_neonx8,
+	&raid6_neonx4,
+	&raid6_neonx2,
+	&raid6_neonx1,
+#endif
+#if defined(__ia64__)
+	&raid6_intx32,
+	&raid6_intx16,
+#endif
+	&raid6_intx8,
+	&raid6_intx4,
+	&raid6_intx2,
+	&raid6_intx1,
+	NULL
+};
+
+void (*raid6_2data_recov)(int, size_t, int, int, void **);
+EXPORT_SYMBOL_GPL(raid6_2data_recov);
+
+void (*raid6_datap_recov)(int, size_t, int, void **);
+EXPORT_SYMBOL_GPL(raid6_datap_recov);
+
+const struct raid6_recov_calls *const raid6_recov_algos[] = {
+#ifdef CONFIG_X86
+#ifdef CONFIG_AS_AVX512
+	&raid6_recov_avx512,
+#endif
+	&raid6_recov_avx2,
+	&raid6_recov_ssse3,
+#endif
+#ifdef CONFIG_S390
+	&raid6_recov_s390xc,
+#endif
+#if defined(CONFIG_KERNEL_MODE_NEON)
+	&raid6_recov_neon,
+#endif
+	&raid6_recov_intx1,
+	NULL
+};
+
+#ifdef __KERNEL__
+#define RAID6_TIME_JIFFIES_LG2	4
+#else
+/* Need more time to be stable in userspace */
+#define RAID6_TIME_JIFFIES_LG2	9
+#define time_before(x, y) ((x) < (y))
+#endif
+
+#define RAID6_TEST_DISKS	8
+#define RAID6_TEST_DISKS_ORDER	3
+
+static inline const struct raid6_recov_calls *raid6_choose_recov(void)
+{
+	const struct raid6_recov_calls *const *algo;
+	const struct raid6_recov_calls *best;
+
+	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
+		if (!best || (*algo)->priority > best->priority)
+			if (!(*algo)->valid || (*algo)->valid())
+				best = *algo;
+
+	if (best) {
+		raid6_2data_recov = best->data2;
+		raid6_datap_recov = best->datap;
+
+		pr_info("raid6: using %s recovery algorithm\n", best->name);
+	} else
+		pr_err("raid6: Yikes! No recovery algorithm found!\n");
+
+	return best;
+}
+
+static inline const struct raid6_calls *raid6_choose_gen(
+	void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
+{
+	unsigned long perf, bestgenperf, j0, j1;
+	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */
+	const struct raid6_calls *const *algo;
+	const struct raid6_calls *best;
+
+	for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
+		if (!best || (*algo)->priority >= best->priority) {
+			if ((*algo)->valid && !(*algo)->valid())
+				continue;
+
+			if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
+				best = *algo;
+				break;
+			}
+
+			perf = 0;
+
+			preempt_disable();
+			j0 = jiffies;
+			while ((j1 = jiffies) == j0)
+				cpu_relax();
+			while (time_before(jiffies,
+					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
+				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
+				perf++;
+			}
+			preempt_enable();
+
+			if (perf > bestgenperf) {
+				bestgenperf = perf;
+				best = *algo;
+			}
+			pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
+				(perf * HZ * (disks-2)) >>
+				(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
+		}
+	}
+
+	if (!best) {
+		pr_err("raid6: Yikes! No algorithm found!\n");
+		goto out;
+	}
+
+	raid6_call = *best;
+
+	if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
+		pr_info("raid6: skipped pq benchmark and selected %s\n",
+			best->name);
+		goto out;
+	}
+
+	pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
+		best->name,
+		(bestgenperf * HZ * (disks - 2)) >>
+		(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
+
+	if (best->xor_syndrome) {
+		perf = 0;
+
+		preempt_disable();
+		j0 = jiffies;
+		while ((j1 = jiffies) == j0)
+			cpu_relax();
+		while (time_before(jiffies,
+				   j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
+			best->xor_syndrome(disks, start, stop,
+					   PAGE_SIZE, *dptrs);
+			perf++;
+		}
+		preempt_enable();
+
+		pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
+			(perf * HZ * (disks - 2)) >>
+			(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
+	}
+
+out:
+	return best;
+}
+
+
+/* Try to pick the best algorithm */
+/* This code uses the gfmul table as convenient data set to abuse */
+
+int __init raid6_select_algo(void)
+{
+	const int disks = RAID6_TEST_DISKS;
+
+	const struct raid6_calls *gen_best;
+	const struct raid6_recov_calls *rec_best;
+	char *disk_ptr, *p;
+	void *dptrs[RAID6_TEST_DISKS];
+	int i, cycle;
+
+	/* prepare the buffer and fill it circularly with gfmul table */
+	disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
+	if (!disk_ptr) {
+		pr_err("raid6: Yikes!  No memory available.\n");
+		return -ENOMEM;
+	}
+
+	p = disk_ptr;
+	for (i = 0; i < disks; i++)
+		dptrs[i] = p + PAGE_SIZE * i;
+
+	cycle = ((disks - 2) * PAGE_SIZE) / 65536;
+	for (i = 0; i < cycle; i++) {
+		memcpy(p, raid6_gfmul, 65536);
+		p += 65536;
+	}
+
+	if ((disks - 2) * PAGE_SIZE % 65536)
+		memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
+
+	/* select raid gen_syndrome function */
+	gen_best = raid6_choose_gen(&dptrs, disks);
+
+	/* select raid recover functions */
+	rec_best = raid6_choose_recov();
+
+	free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
+
+	return gen_best && rec_best ? 0 : -EINVAL;
+}
+
+static void raid6_exit(void)
+{
+	do { } while (0);
+}
+
+subsys_initcall(raid6_select_algo);
+module_exit(raid6_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");