From 135ccfc8a62b05ba6e2ac9192a404ab7e15b0fc7 Mon Sep 17 00:00:00 2001
From: dramforever <dramforever@live.com>
Date: Wed, 16 Apr 2025 22:33:51 +0800
Subject: [PATCH] Simplify exec_cpuid to use constraints

The existing implementation does not work when using the x32 ABI, which
has 32-bit addresses but otherwise can use 64-bit registers.

Use constraints to specify cpuid input and output instead, which is much
simpler anyway.
---
 libcpuid/asm-bits.c | 55 ++++-----------------------------------------
 1 file changed, 4 insertions(+), 51 deletions(-)

diff --git a/libcpuid/asm-bits.c b/libcpuid/asm-bits.c
index fb9be74..7c7cec7 100644
--- a/libcpuid/asm-bits.c
+++ b/libcpuid/asm-bits.c
@@ -84,57 +84,10 @@ int cpuid_exists_by_eflags(void)
 void exec_cpuid(uint32_t *regs)
 {
 #  if defined(COMPILER_GCC) || defined(COMPILER_CLANG)
-#	ifdef PLATFORM_X64
-	__asm __volatile(
-		"	mov	%0,	%%rdi\n"
-
-		"	push	%%rbx\n"
-		"	push	%%rcx\n"
-		"	push	%%rdx\n"
-
-		"	mov	(%%rdi),	%%eax\n"
-		"	mov	4(%%rdi),	%%ebx\n"
-		"	mov	8(%%rdi),	%%ecx\n"
-		"	mov	12(%%rdi),	%%edx\n"
-
-		"	cpuid\n"
-
-		"	movl	%%eax,	(%%rdi)\n"
-		"	movl	%%ebx,	4(%%rdi)\n"
-		"	movl	%%ecx,	8(%%rdi)\n"
-		"	movl	%%edx,	12(%%rdi)\n"
-		"	pop	%%rdx\n"
-		"	pop	%%rcx\n"
-		"	pop	%%rbx\n"
-		:
-		:"m"(regs)
-		:"memory", "eax", "rdi"
-	);
-#	elif defined(PLATFORM_X86)
-	__asm __volatile(
-		"	mov	%0,	%%edi\n"
-
-		"	push	%%ebx\n"
-		"	push	%%ecx\n"
-		"	push	%%edx\n"
-
-		"	mov	(%%edi),	%%eax\n"
-		"	mov	4(%%edi),	%%ebx\n"
-		"	mov	8(%%edi),	%%ecx\n"
-		"	mov	12(%%edi),	%%edx\n"
-
-		"	cpuid\n"
-
-		"	mov	%%eax,	(%%edi)\n"
-		"	mov	%%ebx,	4(%%edi)\n"
-		"	mov	%%ecx,	8(%%edi)\n"
-		"	mov	%%edx,	12(%%edi)\n"
-		"	pop	%%edx\n"
-		"	pop	%%ecx\n"
-		"	pop	%%ebx\n"
-		:
-		:"m"(regs)
-		:"memory", "eax", "edi"
+#	if defined(PLATFORM_X86) || defined(PLATFORM_X64)
+	__asm __volatile (
+		"cpuid"
+		: "+a"(regs[0]), "+b"(regs[1]), "+c"(regs[2]), "+d"(regs[3])::
 	);
 #	else
 	UNUSED(regs);