crypto: 842 - Add CRC and validation support

This patch adds CRC generation and validation support for nx-842.
Add CRC flag so that nx842 coprocessor includes CRC during compression
and validates during decompression.

Also changes in 842 SW compression to append CRC value at the end
of template and checks during decompression.

Signed-off-by: Haren Myneni <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/nx/nx-842-powernv.c

···
 				  void *wmem)
 {
 	return nx842_powernv_function(in, inlen, out, outlenp,
-				      wmem, CCW_FC_842_COMP_NOCRC);
+				      wmem, CCW_FC_842_COMP_CRC);
 }
 
 /**
···
 				    void *wmem)
 {
 	return nx842_powernv_function(in, inlen, out, outlenp,
-				      wmem, CCW_FC_842_DECOMP_NOCRC);
+				      wmem, CCW_FC_842_DECOMP_CRC);
 }
 
 static int __init nx842_powernv_probe(struct device_node *dn)

drivers/crypto/nx/nx-842-pseries.c

···
 		dev_dbg(dev, "%s: Out of space in output buffer\n",
 					__func__);
 		return -ENOSPC;
+	case 65: /* Calculated CRC doesn't match the passed value */
+		dev_dbg(dev, "%s: CRC mismatch for decompression\n",
+					__func__);
+		return -EINVAL;
 	case 66: /* Input data contains an illegal template field */
 	case 67: /* Template indicates data past the end of the input stream */
 		dev_dbg(dev, "%s: Bad data for decompression (code:%d)\n",
···
 	slout.entries = (struct nx842_slentry *)workmem->slout;
 
 	/* Init operation */
-	op.flags = NX842_OP_COMPRESS;
+	op.flags = NX842_OP_COMPRESS_CRC;
 	csbcpb = &workmem->csbcpb;
 	memset(csbcpb, 0, sizeof(*csbcpb));
 	op.csbcpb = nx842_get_pa(csbcpb);
···
 	slout.entries = (struct nx842_slentry *)workmem->slout;
 
 	/* Init operation */
-	op.flags = NX842_OP_DECOMPRESS;
+	op.flags = NX842_OP_DECOMPRESS_CRC;
 	csbcpb = &workmem->csbcpb;
 	memset(csbcpb, 0, sizeof(*csbcpb));
 	op.csbcpb = nx842_get_pa(csbcpb);

lib/842/842.h

···
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/bitops.h>
+#include <linux/crc32.h>
 #include <asm/unaligned.h>
 
 #include <linux/sw842.h>
···
 #define I2_BITS		(8)
 #define I4_BITS		(9)
 #define I8_BITS		(8)
+#define CRC_BITS	(32)
 
 #define REPEAT_BITS_MAX		(0x3f)
 #define SHORT_DATA_BITS_MAX	(0x7)

lib/842/842_compress.c

···
 	int ret;
 	u64 last, next, pad, total;
 	u8 repeat_count = 0;
+	u32 crc;
 
 	BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS);
 
···
 	}
 
 	ret = add_end_template(p);
+	if (ret)
+		return ret;
+
+	/*
+	 * crc(0:31) is appended to target data starting with the next
+	 * bit after End of stream template.
+	 * nx842 calculates CRC for data in big-endian format. So doing
+	 * same here so that sw842 decompression can be used for both
+	 * compressed data.
+	 */
+	crc = crc32_be(0, in, ilen);
+	ret = add_bits(p, crc, CRC_BITS);
 	if (ret)
 		return ret;
 

lib/842/842_decompress.c

···
 	struct sw842_param p;
 	int ret;
 	u64 op, rep, tmp, bytes, total;
+	u64 crc;
 
 	p.in = (u8 *)in;
 	p.bit = 0;
···
 			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;