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From:   Robert Elliott <elliott@hpe.com>
To:     herbert@gondor.apana.org.au, davem@davemloft.net, corbet@lwn.net,
        linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Robert Elliott <elliott@hpe.com>
Subject: [PATCH 4/8] crypto: x86/crc - add kernel-doc comments to assembly
Date:   Thu, 15 Dec 2022 00:38:53 -0600
Message-Id: <20221215063857.161665-5-elliott@hpe.com>
In-Reply-To: <20221215063857.161665-1-elliott@hpe.com>
References: <20221215063857.161665-1-elliott@hpe.com>
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Add kernel-doc comments for assembly language functions exported to
C glue code.

Signed-off-by: Robert Elliott <elliott@hpe.com>
---
 arch/x86/crypto/crc32-pclmul_asm.S        | 24 ++++++++++---------
 arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 29 ++++++++++++++---------
 arch/x86/crypto/crct10dif-pcl-asm_64.S    | 24 +++++++++++++------
 3 files changed, 48 insertions(+), 29 deletions(-)

diff --git a/arch/x86/crypto/crc32-pclmul_asm.S b/arch/x86/crypto/crc32-pclmul_asm.S
index ca53e96996ac..f704b2067a80 100644
--- a/arch/x86/crypto/crc32-pclmul_asm.S
+++ b/arch/x86/crypto/crc32-pclmul_asm.S
@@ -17,7 +17,6 @@
 
 #include <linux/linkage.h>
 
-
 .section .rodata
 .align 16
 /*
@@ -67,19 +66,22 @@
 #define CRC     %ecx
 #endif
 
-
-
 .text
 /**
- *      Calculate crc32
- *      BUF - buffer (16 bytes aligned)
- *      LEN - sizeof buffer (16 bytes aligned), LEN should be grater than 63
- *      CRC - initial crc32
- *      return %eax crc32
- *      uint crc32_pclmul_le_16(unsigned char const *buffer,
- *	                     size_t len, uint crc32)
+ * crc32_pclmul_le_16 - Calculate CRC32 using x86 PCLMULQDQ instructions
+ * @buffer:	address of data (32-bit %eax/64-bit %rdi, BUF macro);
+ *		must be aligned to a multiple of 16
+ * @len:	data size (32-bit %edx/64 bit %rsi, LEN macro);
+ *		must be a multiple of 16 and greater than 63
+ * @crc32:	initial CRC32 value (32-bit %ecx/64-bit $edx, CRC macro)
+ *		only uses lower 32 bits
+ *
+ * This function supports both 32-bit and 64-bit CPUs.
+ * It requires data to be aligned and a minimum size.
+ *
+ * Return:	(32-bit %eax/64-bit %rax) CRC32 value (in lower 32 bits)
+ * Prototype:	asmlinkage u32 crc32_pclmul_le_16(const u8 *buffer, size_t len, u32 crc32);
  */
-
 SYM_FUNC_START(crc32_pclmul_le_16) /* buffer and buffer size are 16 bytes aligned */
 	movdqa  (BUF), %xmm1
 	movdqa  0x10(BUF), %xmm2
diff --git a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
index ec35915f0901..3d646011d84b 100644
--- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
+++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
@@ -70,22 +70,30 @@
 .error "SMALL_ SIZE must be < 256"
 .endif
 
-# unsigned int crc_pcl(u8 *buffer, int len, unsigned int crc_init);
-
 .text
+/**
+ * crc_pcl - Calculate CRC32C using x86 CRC32 and PCLMULQDQ instructions
+ * @buffer:	address of data (%rdi, bufp macro)
+ * @len:	data size (%rsi, len macro)
+ * @crc_init:	initial CRC32C value (%rdx, crc_init_arg macro);
+ *		only using lower 32 bits
+ *
+ * This function supports 64-bit CPUs.
+ * It loops on 8-byte aligned QWORDs, but also supports unaligned
+ * addresses and all length values.
+ *
+ * Return:	CRC32C value (upper 32 bits zero)(%rax)
+ * Prototype:	asmlinkage unsigned int crc_pcl(const u8 *buffer, unsigned int len,
+						unsigned int crc_init);
+ */
 SYM_FUNC_START(crc_pcl)
 #define    bufp		rdi
-#define    bufp_dw	%edi
-#define    bufp_w	%di
-#define    bufp_b	%dil
 #define    bufptmp	%rcx
 #define    block_0	%rcx
 #define    block_1	%rdx
 #define    block_2	%r11
 #define    len		%rsi
 #define    len_dw	%esi
-#define    len_w	%si
-#define    len_b	%sil
 #define    crc_init_arg %rdx
 #define    tmp		%rbx
 #define    crc_init	%r8
@@ -97,7 +105,7 @@ SYM_FUNC_START(crc_pcl)
 	pushq   %rdi
 	pushq   %rsi
 
-	## Move crc_init for Linux to a different
+	## Move crc_init for Linux to a different register
 	mov     crc_init_arg, crc_init
 
 	################################################################
@@ -216,7 +224,7 @@ LABEL crc_ %i
 	## 4) Combine three results:
 	################################################################
 
-	lea	(K_table-8)(%rip), %bufp		# first entry is for idx 1
+	lea	(K_table-8)(%rip), %bufp	# first entry is for idx 1
 	shlq    $3, %rax			# rax *= 8
 	pmovzxdq (%bufp,%rax), %xmm0		# 2 consts: K1:K2
 	leal	(%eax,%eax,2), %eax		# rax *= 3 (total *24)
@@ -326,10 +334,9 @@ JMPTBL_ENTRY %i
 	i=i+1
 .endr
 
-
 	################################################################
 	## PCLMULQDQ tables
-	## Table is 128 entries x 2 words (8 bytes) each
+	## Table is 128 entries x 8 bytes each
 	################################################################
 .align 8
 K_table:
diff --git a/arch/x86/crypto/crct10dif-pcl-asm_64.S b/arch/x86/crypto/crct10dif-pcl-asm_64.S
index 721474abfb71..88af572703b2 100644
--- a/arch/x86/crypto/crct10dif-pcl-asm_64.S
+++ b/arch/x86/crypto/crct10dif-pcl-asm_64.S
@@ -52,8 +52,6 @@
 
 #include <linux/linkage.h>
 
-.text
-
 #define		init_crc	%edi
 #define		buf		%rsi
 #define		len		%rdx
@@ -89,11 +87,23 @@
 	xorps	\src_reg, \dst_reg
 .endm
 
-#
-# u16 crc_t10dif_pcl(u16 init_crc, const *u8 buf, size_t len);
-#
-# Assumes len >= 16.
-#
+.text
+/**
+ * crc_t10dif_pcl - Calculate CRC16 per T10 DIF (data integrity format)
+ *		    using x86 PCLMULQDQ instructions
+ * @init_crc:	initial CRC16 value (%rdi, init_crc macro);
+ *		only uses lower 16 bits
+ * @buf:	address of data (%rsi, buf macro);
+ *		data buffer must be at least 16 bytes
+ * @len:	data size (%rdx, len macro);
+ *		must be >= 16
+ *
+ * This function supports 64-bit CPUs.
+ * It allows data to be at any offset.
+ *
+ * Return:	(%rax) CRC16 value (upper 48 bits zero)
+ * Prototype:	asmlinkage u16 crc_t10dif_pcl(u16 init_crc, const *u8 buf, size_t len);
+ */
 .align 16
 SYM_FUNC_START(crc_t10dif_pcl)
 
-- 
2.38.1