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-rw-r--r--lib/842/842_decompress.c417
1 files changed, 417 insertions, 0 deletions
diff --git a/lib/842/842_decompress.c b/lib/842/842_decompress.c
new file mode 100644
index 000000000..582085ef8
--- /dev/null
+++ b/lib/842/842_decompress.c
@@ -0,0 +1,417 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 842 Software Decompression
+ *
+ * Copyright (C) 2015 Dan Streetman, IBM Corp
+ *
+ * See 842.h for details of the 842 compressed format.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define MODULE_NAME "842_decompress"
+
+#include "842.h"
+#include "842_debugfs.h"
+
+/* rolling fifo sizes */
+#define I2_FIFO_SIZE (2 * (1 << I2_BITS))
+#define I4_FIFO_SIZE (4 * (1 << I4_BITS))
+#define I8_FIFO_SIZE (8 * (1 << I8_BITS))
+
+static u8 decomp_ops[OPS_MAX][4] = {
+ { D8, N0, N0, N0 },
+ { D4, D2, I2, N0 },
+ { D4, I2, D2, N0 },
+ { D4, I2, I2, N0 },
+ { D4, I4, N0, N0 },
+ { D2, I2, D4, N0 },
+ { D2, I2, D2, I2 },
+ { D2, I2, I2, D2 },
+ { D2, I2, I2, I2 },
+ { D2, I2, I4, N0 },
+ { I2, D2, D4, N0 },
+ { I2, D4, I2, N0 },
+ { I2, D2, I2, D2 },
+ { I2, D2, I2, I2 },
+ { I2, D2, I4, N0 },
+ { I2, I2, D4, N0 },
+ { I2, I2, D2, I2 },
+ { I2, I2, I2, D2 },
+ { I2, I2, I2, I2 },
+ { I2, I2, I4, N0 },
+ { I4, D4, N0, N0 },
+ { I4, D2, I2, N0 },
+ { I4, I2, D2, N0 },
+ { I4, I2, I2, N0 },
+ { I4, I4, N0, N0 },
+ { I8, N0, N0, N0 }
+};
+
+struct sw842_param {
+ u8 *in;
+ u8 bit;
+ u64 ilen;
+ u8 *out;
+ u8 *ostart;
+ u64 olen;
+};
+
+#define beN_to_cpu(d, s) \
+ ((s) == 2 ? be16_to_cpu(get_unaligned((__be16 *)d)) : \
+ (s) == 4 ? be32_to_cpu(get_unaligned((__be32 *)d)) : \
+ (s) == 8 ? be64_to_cpu(get_unaligned((__be64 *)d)) : \
+ 0)
+
+static int next_bits(struct sw842_param *p, u64 *d, u8 n);
+
+static int __split_next_bits(struct sw842_param *p, u64 *d, u8 n, u8 s)
+{
+ u64 tmp = 0;
+ int ret;
+
+ if (n <= s) {
+ pr_debug("split_next_bits invalid n %u s %u\n", n, s);
+ return -EINVAL;
+ }
+
+ ret = next_bits(p, &tmp, n - s);
+ if (ret)
+ return ret;
+ ret = next_bits(p, d, s);
+ if (ret)
+ return ret;
+ *d |= tmp << s;
+ return 0;
+}
+
+static int next_bits(struct sw842_param *p, u64 *d, u8 n)
+{
+ u8 *in = p->in, b = p->bit, bits = b + n;
+
+ if (n > 64) {
+ pr_debug("next_bits invalid n %u\n", n);
+ return -EINVAL;
+ }
+
+ /* split this up if reading > 8 bytes, or if we're at the end of
+ * the input buffer and would read past the end
+ */
+ if (bits > 64)
+ return __split_next_bits(p, d, n, 32);
+ else if (p->ilen < 8 && bits > 32 && bits <= 56)
+ return __split_next_bits(p, d, n, 16);
+ else if (p->ilen < 4 && bits > 16 && bits <= 24)
+ return __split_next_bits(p, d, n, 8);
+
+ if (DIV_ROUND_UP(bits, 8) > p->ilen)
+ return -EOVERFLOW;
+
+ if (bits <= 8)
+ *d = *in >> (8 - bits);
+ else if (bits <= 16)
+ *d = be16_to_cpu(get_unaligned((__be16 *)in)) >> (16 - bits);
+ else if (bits <= 32)
+ *d = be32_to_cpu(get_unaligned((__be32 *)in)) >> (32 - bits);
+ else
+ *d = be64_to_cpu(get_unaligned((__be64 *)in)) >> (64 - bits);
+
+ *d &= GENMASK_ULL(n - 1, 0);
+
+ p->bit += n;
+
+ if (p->bit > 7) {
+ p->in += p->bit / 8;
+ p->ilen -= p->bit / 8;
+ p->bit %= 8;
+ }
+
+ return 0;
+}
+
+static int do_data(struct sw842_param *p, u8 n)
+{
+ u64 v;
+ int ret;
+
+ if (n > p->olen)
+ return -ENOSPC;
+
+ ret = next_bits(p, &v, n * 8);
+ if (ret)
+ return ret;
+
+ switch (n) {
+ case 2:
+ put_unaligned(cpu_to_be16((u16)v), (__be16 *)p->out);
+ break;
+ case 4:
+ put_unaligned(cpu_to_be32((u32)v), (__be32 *)p->out);
+ break;
+ case 8:
+ put_unaligned(cpu_to_be64((u64)v), (__be64 *)p->out);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ p->out += n;
+ p->olen -= n;
+
+ return 0;
+}
+
+static int __do_index(struct sw842_param *p, u8 size, u8 bits, u64 fsize)
+{
+ u64 index, offset, total = round_down(p->out - p->ostart, 8);
+ int ret;
+
+ ret = next_bits(p, &index, bits);
+ if (ret)
+ return ret;
+
+ offset = index * size;
+
+ /* a ring buffer of fsize is used; correct the offset */
+ if (total > fsize) {
+ /* this is where the current fifo is */
+ u64 section = round_down(total, fsize);
+ /* the current pos in the fifo */
+ u64 pos = total - section;
+
+ /* if the offset is past/at the pos, we need to
+ * go back to the last fifo section
+ */
+ if (offset >= pos)
+ section -= fsize;
+
+ offset += section;
+ }
+
+ if (offset + size > total) {
+ pr_debug("index%x %lx points past end %lx\n", size,
+ (unsigned long)offset, (unsigned long)total);
+ return -EINVAL;
+ }
+
+ if (size != 2 && size != 4 && size != 8)
+ WARN(1, "__do_index invalid size %x\n", size);
+ else
+ pr_debug("index%x to %lx off %lx adjoff %lx tot %lx data %lx\n",
+ size, (unsigned long)index,
+ (unsigned long)(index * size), (unsigned long)offset,
+ (unsigned long)total,
+ (unsigned long)beN_to_cpu(&p->ostart[offset], size));
+
+ memcpy(p->out, &p->ostart[offset], size);
+ p->out += size;
+ p->olen -= size;
+
+ return 0;
+}
+
+static int do_index(struct sw842_param *p, u8 n)
+{
+ switch (n) {
+ case 2:
+ return __do_index(p, 2, I2_BITS, I2_FIFO_SIZE);
+ case 4:
+ return __do_index(p, 4, I4_BITS, I4_FIFO_SIZE);
+ case 8:
+ return __do_index(p, 8, I8_BITS, I8_FIFO_SIZE);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int do_op(struct sw842_param *p, u8 o)
+{
+ int i, ret = 0;
+
+ if (o >= OPS_MAX)
+ return -EINVAL;
+
+ for (i = 0; i < 4; i++) {
+ u8 op = decomp_ops[o][i];
+
+ pr_debug("op is %x\n", op);
+
+ switch (op & OP_ACTION) {
+ case OP_ACTION_DATA:
+ ret = do_data(p, op & OP_AMOUNT);
+ break;
+ case OP_ACTION_INDEX:
+ ret = do_index(p, op & OP_AMOUNT);
+ break;
+ case OP_ACTION_NOOP:
+ break;
+ default:
+ pr_err("Internal error, invalid op %x\n", op);
+ return -EINVAL;
+ }
+
+ if (ret)
+ return ret;
+ }
+
+ if (sw842_template_counts)
+ atomic_inc(&template_count[o]);
+
+ return 0;
+}
+
+/**
+ * sw842_decompress
+ *
+ * Decompress the 842-compressed buffer of length @ilen at @in
+ * to the output buffer @out, using no more than @olen bytes.
+ *
+ * The compressed buffer must be only a single 842-compressed buffer,
+ * with the standard format described in the comments in 842.h
+ * Processing will stop when the 842 "END" template is detected,
+ * not the end of the buffer.
+ *
+ * Returns: 0 on success, error on failure. The @olen parameter
+ * will contain the number of output bytes written on success, or
+ * 0 on error.
+ */
+int sw842_decompress(const u8 *in, unsigned int ilen,
+ u8 *out, unsigned int *olen)
+{
+ struct sw842_param p;
+ int ret;
+ u64 op, rep, tmp, bytes, total;
+ u64 crc;
+
+ p.in = (u8 *)in;
+ p.bit = 0;
+ p.ilen = ilen;
+ p.out = out;
+ p.ostart = out;
+ p.olen = *olen;
+
+ total = p.olen;
+
+ *olen = 0;
+
+ do {
+ ret = next_bits(&p, &op, OP_BITS);
+ if (ret)
+ return ret;
+
+ pr_debug("template is %lx\n", (unsigned long)op);
+
+ switch (op) {
+ case OP_REPEAT:
+ ret = next_bits(&p, &rep, REPEAT_BITS);
+ if (ret)
+ return ret;
+
+ if (p.out == out) /* no previous bytes */
+ return -EINVAL;
+
+ /* copy rep + 1 */
+ rep++;
+
+ if (rep * 8 > p.olen)
+ return -ENOSPC;
+
+ while (rep-- > 0) {
+ memcpy(p.out, p.out - 8, 8);
+ p.out += 8;
+ p.olen -= 8;
+ }
+
+ if (sw842_template_counts)
+ atomic_inc(&template_repeat_count);
+
+ break;
+ case OP_ZEROS:
+ if (8 > p.olen)
+ return -ENOSPC;
+
+ memset(p.out, 0, 8);
+ p.out += 8;
+ p.olen -= 8;
+
+ if (sw842_template_counts)
+ atomic_inc(&template_zeros_count);
+
+ break;
+ case OP_SHORT_DATA:
+ ret = next_bits(&p, &bytes, SHORT_DATA_BITS);
+ if (ret)
+ return ret;
+
+ if (!bytes || bytes > SHORT_DATA_BITS_MAX)
+ return -EINVAL;
+
+ while (bytes-- > 0) {
+ ret = next_bits(&p, &tmp, 8);
+ if (ret)
+ return ret;
+ *p.out = (u8)tmp;
+ p.out++;
+ p.olen--;
+ }
+
+ if (sw842_template_counts)
+ atomic_inc(&template_short_data_count);
+
+ break;
+ case OP_END:
+ if (sw842_template_counts)
+ atomic_inc(&template_end_count);
+
+ break;
+ default: /* use template */
+ ret = do_op(&p, op);
+ if (ret)
+ return ret;
+ break;
+ }
+ } while (op != OP_END);
+
+ /*
+ * crc(0:31) is saved in compressed data starting with the
+ * next bit after End of stream template.
+ */
+ ret = next_bits(&p, &crc, CRC_BITS);
+ if (ret)
+ return ret;
+
+ /*
+ * Validate CRC saved in compressed data.
+ */
+ if (crc != (u64)crc32_be(0, out, total - p.olen)) {
+ pr_debug("CRC mismatch for decompression\n");
+ return -EINVAL;
+ }
+
+ if (unlikely((total - p.olen) > UINT_MAX))
+ return -ENOSPC;
+
+ *olen = total - p.olen;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sw842_decompress);
+
+static int __init sw842_init(void)
+{
+ if (sw842_template_counts)
+ sw842_debugfs_create();
+
+ return 0;
+}
+module_init(sw842_init);
+
+static void __exit sw842_exit(void)
+{
+ if (sw842_template_counts)
+ sw842_debugfs_remove();
+}
+module_exit(sw842_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Software 842 Decompressor");
+MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 18:03:41 +0000