x86/mmx_32: Remove X86_USE_3DNOW

This code puts an exception table entry on the PREFETCH instruction to
overwrite it with a JMP.d8 when it triggers an exception. Except of
course, our code is no longer writable, also SMP.

Instead of fixing this broken mess, simply take it out.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: Peter Zijlstra

arch/x86/Kconfig

@@ -1957,7 +1957,7 @@ config EFI
 
 config EFI_STUB
 	bool "EFI stub support"
-	depends on EFI && !X86_USE_3DNOW
+	depends on EFI
 	depends on $(cc-option,-mabi=ms) || X86_32
 	select RELOCATABLE
 	help

arch/x86/Kconfig.cpu

@@ -342,10 +342,6 @@ config X86_USE_PPRO_CHECKSUM
 	def_bool y
 	depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MVIAC7 || MEFFICEON || MGEODE_LX || MCORE2 || MATOM
 
-config X86_USE_3DNOW
-	def_bool y
-	depends on (MCYRIXIII || MK7 || MGEODE_LX) && !UML
-
 #
 # P6_NOPs are a relatively minor optimization that require a family >=
 # 6 processor, except that it is broken on certain VIA chips.

arch/x86/include/asm/mmx.h

@@ -1,15 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_X86_MMX_H
-#define _ASM_X86_MMX_H
-
-/*
- *	MMX 3Dnow! helper operations
- */
-
-#include <linux/types.h>
-
-extern void *_mmx_memcpy(void *to, const void *from, size_t size);
-extern void mmx_clear_page(void *page);
-extern void mmx_copy_page(void *to, void *from);
-
-#endif /* _ASM_X86_MMX_H */

arch/x86/include/asm/page_32.h

@@ -19,19 +19,6 @@ extern unsigned long __phys_addr(unsigned long);
 #define pfn_valid(pfn)		((pfn) < max_mapnr)
 #endif /* CONFIG_FLATMEM */
 
-#ifdef CONFIG_X86_USE_3DNOW
-#include <asm/mmx.h>
-
-static inline void clear_page(void *page)
-{
-	mmx_clear_page(page);
-}
-
-static inline void copy_page(void *to, void *from)
-{
-	mmx_copy_page(to, from);
-}
-#else  /* !CONFIG_X86_USE_3DNOW */
 #include <linux/string.h>
 
 static inline void clear_page(void *page)
@@ -43,7 +30,6 @@ static inline void copy_page(void *to, void *from)
 {
 	memcpy(to, from, PAGE_SIZE);
 }
-#endif	/* CONFIG_X86_USE_3DNOW */
 #endif	/* !__ASSEMBLY__ */
 
 #endif /* _ASM_X86_PAGE_32_H */

arch/x86/include/asm/required-features.h

@@ -35,11 +35,7 @@
 # define NEED_CMOV	0
 #endif
 
-#ifdef CONFIG_X86_USE_3DNOW
-# define NEED_3DNOW	(1<<(X86_FEATURE_3DNOW & 31))
-#else
 # define NEED_3DNOW	0
-#endif
 
 #if defined(CONFIG_X86_P6_NOP) || defined(CONFIG_X86_64)
 # define NEED_NOPL	(1<<(X86_FEATURE_NOPL & 31))

arch/x86/include/asm/string_32.h

@@ -146,42 +146,9 @@ static __always_inline void *__constant_memcpy(void *to, const void *from,
 extern void *memcpy(void *, const void *, size_t);
 
 #ifndef CONFIG_FORTIFY_SOURCE
-#ifdef CONFIG_X86_USE_3DNOW
-
-#include <asm/mmx.h>
-
-/*
- *	This CPU favours 3DNow strongly (eg AMD Athlon)
- */
-
-static inline void *__constant_memcpy3d(void *to, const void *from, size_t len)
-{
-	if (len < 512)
-		return __constant_memcpy(to, from, len);
-	return _mmx_memcpy(to, from, len);
-}
-
-static inline void *__memcpy3d(void *to, const void *from, size_t len)
-{
-	if (len < 512)
-		return __memcpy(to, from, len);
-	return _mmx_memcpy(to, from, len);
-}
-
-#define memcpy(t, f, n)				\
-	(__builtin_constant_p((n))		\
-	 ? __constant_memcpy3d((t), (f), (n))	\
-	 : __memcpy3d((t), (f), (n)))
-
-#else
-
-/*
- *	No 3D Now!
- */
 
 #define memcpy(t, f, n) __builtin_memcpy(t, f, n)
 
-#endif
 #endif /* !CONFIG_FORTIFY_SOURCE */
 
 #define __HAVE_ARCH_MEMMOVE

arch/x86/lib/Makefile

@@ -63,7 +63,6 @@ ifeq ($(CONFIG_X86_32),y)
 ifneq ($(CONFIG_X86_CMPXCHG64),y)
         lib-y += cmpxchg8b_emu.o atomic64_386_32.o
 endif
-        lib-$(CONFIG_X86_USE_3DNOW) += mmx_32.o
 else
         obj-y += iomap_copy_64.o
         lib-y += csum-partial_64.o csum-copy_64.o csum-wrappers_64.o

arch/x86/lib/memcpy_32.c

@@ -7,11 +7,7 @@
 
 __visible void *memcpy(void *to, const void *from, size_t n)
 {
-#if defined(CONFIG_X86_USE_3DNOW) && !defined(CONFIG_FORTIFY_SOURCE)
-	return __memcpy3d(to, from, n);
-#else
 	return __memcpy(to, from, n);
-#endif
 }
 EXPORT_SYMBOL(memcpy);