File 0001-crc-fix-x86-CRC-dispatcher.patch of Package isa-l

From 4b8a74db220266ac37fba70b5fb55d3c95fab7b4 Mon Sep 17 00:00:00 2001
From: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Date: Fri, 20 Mar 2026 09:11:11 +0000
Subject: [PATCH] crc: fix x86 CRC dispatcher

rbx register was being clobbered by a function pointer
before being used to decide on the AVX512+VPCLMUL implementation
to be used, based on its content from CPUID instruction.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Reported-by: Maodi Ma <mamaodi@hygon.cn>
---
 Release_notes.txt       |  5 +++++
 include/multibinary.asm | 27 ++++++++++++++-------------
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/Release_notes.txt b/Release_notes.txt
index 96032dd..b7ca581 100644
--- a/Release_notes.txt
+++ b/Release_notes.txt
@@ -11,6 +11,11 @@ RELEASE NOTE CONTENTS
 
 2. FIXED ISSUES
 ---------------
+Unreleased
+
+* Fixed x86 CRC dispatcher (AVX512+VPLCMUL implementation could not be always reached
+  when the ISA was available).
+
 v2.32
 
 * Fixed RAID performance application for MacOS.
diff --git a/include/multibinary.asm b/include/multibinary.asm
index 6de280b..f6630a1 100644
--- a/include/multibinary.asm
+++ b/include/multibinary.asm
@@ -131,7 +131,6 @@
 	section .text
 	%1_dispatch_init:
 		push	rsi
-		push	rax
 		push	rbx
 		push	rcx
 		push	rdx
@@ -164,33 +163,35 @@
 		;; Test for AVX2
 		xor	ecx, ecx
 		mov	eax, 7
-		cpuid
+		cpuid ; ebx, ecx returned to be checked
 		test	ebx, FLAG_CPUID7_EBX_AVX2
 		je	_%1_init_done		; No AVX2 possible
-		and	ecx, FLAGS_CPUID7_ECX_AVX2_G2
-		cmp	ecx, FLAGS_CPUID7_ECX_AVX2_G2
-		lea	rbx, [%5 WRT_OPT]
-		cmove	rsi, rbx
+		mov     eax, ecx
+		and	eax, FLAGS_CPUID7_ECX_AVX2_G2
+		cmp	eax, FLAGS_CPUID7_ECX_AVX2_G2
+		lea	rax, [%5 WRT_OPT]
+		cmove	rsi, rax
 
 		;; Test for AVX512
 		and	edi, FLAG_XGETBV_EAX_ZMM_OPM
 		cmp	edi, FLAG_XGETBV_EAX_ZMM_OPM
 		jne	_%1_init_done	  ; No AVX512 possible
-		and	ebx, FLAGS_CPUID7_EBX_AVX512_G1
-		cmp	ebx, FLAGS_CPUID7_EBX_AVX512_G1
+		mov     eax, ebx
+		and	eax, FLAGS_CPUID7_EBX_AVX512_G1
+		cmp	eax, FLAGS_CPUID7_EBX_AVX512_G1
 		jne	_%1_init_done
 
-		and	ecx, FLAGS_CPUID7_ECX_AVX512_G2
-		cmp	ecx, FLAGS_CPUID7_ECX_AVX512_G2
-		lea	rbx, [%6 WRT_OPT] ; AVX512/10 opt
-		cmove	rsi, rbx
+		mov     eax, ecx
+		and	eax, FLAGS_CPUID7_ECX_AVX512_G2
+		cmp	eax, FLAGS_CPUID7_ECX_AVX512_G2
+		lea	rax, [%6 WRT_OPT] ; AVX512/10 opt
+		cmove	rsi, rax
 
 	_%1_init_done:
 		pop	rdi
 		pop	rdx
 		pop	rcx
 		pop	rbx
-		pop	rax
 		mov	[%1_dispatched], rsi
 		pop	rsi
 		ret
-- 
2.43.0