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Message-ID: <YZKQzUmeNuwyvZpk@hirez.programming.kicks-ass.net>
Date: Mon, 15 Nov 2021 17:54:37 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.orgg
Cc: linux-kernel@...r.kernel.org, jpoimboe@...hat.com,
mark.rutland@....com, dvyukov@...gle.com, seanjc@...gle.com,
pbonzini@...hat.com, mbenes@...e.cz
Subject: [PATCH v2.1 02/23] x86/mmx_32: Remove X86_USE_3DNOW
The alternative (har har) for this patch is the below, which seems
favoured by Boris.
---
Subject: x86/mmx_32: Remove X86_USE_3DNOW
From: Peter Zijlstra <peterz@...radead.org>
Date: Mon Nov 15 17:46:39 CET 2021
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) <peterz@...radead.org>
---
arch/x86/Kconfig | 2
arch/x86/Kconfig.cpu | 4
arch/x86/include/asm/mmx.h | 15
arch/x86/include/asm/page_32.h | 14
arch/x86/include/asm/required-features.h | 4
arch/x86/include/asm/string_32.h | 33 --
arch/x86/lib/Makefile | 1
arch/x86/lib/memcpy_32.c | 4
arch/x86/lib/mmx_32.c | 388 -------------------------
arch/x86/lib/usercopy_32.c | 1
tools/arch/x86/include/asm/required-features.h | 4
11 files changed, 1 insertion(+), 469 deletions(-)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1945,7 +1945,7 @@ 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
--- a/arch/x86/Kconfig.cpu
+++ b/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.
--- a/arch/x86/include/asm/mmx.h
+++ b/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 */
--- a/arch/x86/include/asm/page_32.h
+++ b/arch/x86/include/asm/page_32.h
@@ -19,19 +19,6 @@ extern unsigned long __phys_addr(unsigne
#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, v
{
memcpy(to, from, PAGE_SIZE);
}
-#endif /* CONFIG_X86_USE_3DNOW */
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_PAGE_32_H */
--- a/arch/x86/include/asm/required-features.h
+++ b/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))
--- a/arch/x86/include/asm/string_32.h
+++ b/arch/x86/include/asm/string_32.h
@@ -146,42 +146,9 @@ static __always_inline void *__constant_
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
--- a/arch/x86/lib/Makefile
+++ b/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
--- a/arch/x86/lib/memcpy_32.c
+++ b/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);
--- a/arch/x86/lib/mmx_32.c
+++ b/arch/x86/lib/mmx_32.c
@@ -1,388 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * MMX 3DNow! library helper functions
- *
- * To do:
- * We can use MMX just for prefetch in IRQ's. This may be a win.
- * (reported so on K6-III)
- * We should use a better code neutral filler for the short jump
- * leal ebx. [ebx] is apparently best for K6-2, but Cyrix ??
- * We also want to clobber the filler register so we don't get any
- * register forwarding stalls on the filler.
- *
- * Add *user handling. Checksums are not a win with MMX on any CPU
- * tested so far for any MMX solution figured.
- *
- * 22/09/2000 - Arjan van de Ven
- * Improved for non-engineering-sample Athlons
- *
- */
-#include <linux/hardirq.h>
-#include <linux/string.h>
-#include <linux/export.h>
-#include <linux/sched.h>
-#include <linux/types.h>
-
-#include <asm/fpu/api.h>
-#include <asm/asm.h>
-
-/*
- * Use KFPU_387. MMX instructions are not affected by MXCSR,
- * but both AMD and Intel documentation states that even integer MMX
- * operations will result in #MF if an exception is pending in FCW.
- *
- * EMMS is not needed afterwards because, after calling kernel_fpu_end(),
- * any subsequent user of the 387 stack will reinitialize it using
- * KFPU_387.
- */
-
-void *_mmx_memcpy(void *to, const void *from, size_t len)
-{
- void *p;
- int i;
-
- if (unlikely(in_interrupt()))
- return __memcpy(to, from, len);
-
- p = to;
- i = len >> 6; /* len/64 */
-
- kernel_fpu_begin_mask(KFPU_387);
-
- __asm__ __volatile__ (
- "1: prefetch (%0)\n" /* This set is 28 bytes */
- " prefetch 64(%0)\n"
- " prefetch 128(%0)\n"
- " prefetch 192(%0)\n"
- " prefetch 256(%0)\n"
- "2: \n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x1AEB, 1b\n" /* jmp on 26 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- : : "r" (from));
-
- for ( ; i > 5; i--) {
- __asm__ __volatile__ (
- "1: prefetch 320(%0)\n"
- "2: movq (%0), %%mm0\n"
- " movq 8(%0), %%mm1\n"
- " movq 16(%0), %%mm2\n"
- " movq 24(%0), %%mm3\n"
- " movq %%mm0, (%1)\n"
- " movq %%mm1, 8(%1)\n"
- " movq %%mm2, 16(%1)\n"
- " movq %%mm3, 24(%1)\n"
- " movq 32(%0), %%mm0\n"
- " movq 40(%0), %%mm1\n"
- " movq 48(%0), %%mm2\n"
- " movq 56(%0), %%mm3\n"
- " movq %%mm0, 32(%1)\n"
- " movq %%mm1, 40(%1)\n"
- " movq %%mm2, 48(%1)\n"
- " movq %%mm3, 56(%1)\n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x05EB, 1b\n" /* jmp on 5 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- : : "r" (from), "r" (to) : "memory");
-
- from += 64;
- to += 64;
- }
-
- for ( ; i > 0; i--) {
- __asm__ __volatile__ (
- " movq (%0), %%mm0\n"
- " movq 8(%0), %%mm1\n"
- " movq 16(%0), %%mm2\n"
- " movq 24(%0), %%mm3\n"
- " movq %%mm0, (%1)\n"
- " movq %%mm1, 8(%1)\n"
- " movq %%mm2, 16(%1)\n"
- " movq %%mm3, 24(%1)\n"
- " movq 32(%0), %%mm0\n"
- " movq 40(%0), %%mm1\n"
- " movq 48(%0), %%mm2\n"
- " movq 56(%0), %%mm3\n"
- " movq %%mm0, 32(%1)\n"
- " movq %%mm1, 40(%1)\n"
- " movq %%mm2, 48(%1)\n"
- " movq %%mm3, 56(%1)\n"
- : : "r" (from), "r" (to) : "memory");
-
- from += 64;
- to += 64;
- }
- /*
- * Now do the tail of the block:
- */
- __memcpy(to, from, len & 63);
- kernel_fpu_end();
-
- return p;
-}
-EXPORT_SYMBOL(_mmx_memcpy);
-
-#ifdef CONFIG_MK7
-
-/*
- * The K7 has streaming cache bypass load/store. The Cyrix III, K6 and
- * other MMX using processors do not.
- */
-
-static void fast_clear_page(void *page)
-{
- int i;
-
- kernel_fpu_begin_mask(KFPU_387);
-
- __asm__ __volatile__ (
- " pxor %%mm0, %%mm0\n" : :
- );
-
- for (i = 0; i < 4096/64; i++) {
- __asm__ __volatile__ (
- " movntq %%mm0, (%0)\n"
- " movntq %%mm0, 8(%0)\n"
- " movntq %%mm0, 16(%0)\n"
- " movntq %%mm0, 24(%0)\n"
- " movntq %%mm0, 32(%0)\n"
- " movntq %%mm0, 40(%0)\n"
- " movntq %%mm0, 48(%0)\n"
- " movntq %%mm0, 56(%0)\n"
- : : "r" (page) : "memory");
- page += 64;
- }
-
- /*
- * Since movntq is weakly-ordered, a "sfence" is needed to become
- * ordered again:
- */
- __asm__ __volatile__("sfence\n"::);
-
- kernel_fpu_end();
-}
-
-static void fast_copy_page(void *to, void *from)
-{
- int i;
-
- kernel_fpu_begin_mask(KFPU_387);
-
- /*
- * maybe the prefetch stuff can go before the expensive fnsave...
- * but that is for later. -AV
- */
- __asm__ __volatile__(
- "1: prefetch (%0)\n"
- " prefetch 64(%0)\n"
- " prefetch 128(%0)\n"
- " prefetch 192(%0)\n"
- " prefetch 256(%0)\n"
- "2: \n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x1AEB, 1b\n" /* jmp on 26 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b) : : "r" (from));
-
- for (i = 0; i < (4096-320)/64; i++) {
- __asm__ __volatile__ (
- "1: prefetch 320(%0)\n"
- "2: movq (%0), %%mm0\n"
- " movntq %%mm0, (%1)\n"
- " movq 8(%0), %%mm1\n"
- " movntq %%mm1, 8(%1)\n"
- " movq 16(%0), %%mm2\n"
- " movntq %%mm2, 16(%1)\n"
- " movq 24(%0), %%mm3\n"
- " movntq %%mm3, 24(%1)\n"
- " movq 32(%0), %%mm4\n"
- " movntq %%mm4, 32(%1)\n"
- " movq 40(%0), %%mm5\n"
- " movntq %%mm5, 40(%1)\n"
- " movq 48(%0), %%mm6\n"
- " movntq %%mm6, 48(%1)\n"
- " movq 56(%0), %%mm7\n"
- " movntq %%mm7, 56(%1)\n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x05EB, 1b\n" /* jmp on 5 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b) : : "r" (from), "r" (to) : "memory");
-
- from += 64;
- to += 64;
- }
-
- for (i = (4096-320)/64; i < 4096/64; i++) {
- __asm__ __volatile__ (
- "2: movq (%0), %%mm0\n"
- " movntq %%mm0, (%1)\n"
- " movq 8(%0), %%mm1\n"
- " movntq %%mm1, 8(%1)\n"
- " movq 16(%0), %%mm2\n"
- " movntq %%mm2, 16(%1)\n"
- " movq 24(%0), %%mm3\n"
- " movntq %%mm3, 24(%1)\n"
- " movq 32(%0), %%mm4\n"
- " movntq %%mm4, 32(%1)\n"
- " movq 40(%0), %%mm5\n"
- " movntq %%mm5, 40(%1)\n"
- " movq 48(%0), %%mm6\n"
- " movntq %%mm6, 48(%1)\n"
- " movq 56(%0), %%mm7\n"
- " movntq %%mm7, 56(%1)\n"
- : : "r" (from), "r" (to) : "memory");
- from += 64;
- to += 64;
- }
- /*
- * Since movntq is weakly-ordered, a "sfence" is needed to become
- * ordered again:
- */
- __asm__ __volatile__("sfence \n"::);
- kernel_fpu_end();
-}
-
-#else /* CONFIG_MK7 */
-
-/*
- * Generic MMX implementation without K7 specific streaming
- */
-static void fast_clear_page(void *page)
-{
- int i;
-
- kernel_fpu_begin_mask(KFPU_387);
-
- __asm__ __volatile__ (
- " pxor %%mm0, %%mm0\n" : :
- );
-
- for (i = 0; i < 4096/128; i++) {
- __asm__ __volatile__ (
- " movq %%mm0, (%0)\n"
- " movq %%mm0, 8(%0)\n"
- " movq %%mm0, 16(%0)\n"
- " movq %%mm0, 24(%0)\n"
- " movq %%mm0, 32(%0)\n"
- " movq %%mm0, 40(%0)\n"
- " movq %%mm0, 48(%0)\n"
- " movq %%mm0, 56(%0)\n"
- " movq %%mm0, 64(%0)\n"
- " movq %%mm0, 72(%0)\n"
- " movq %%mm0, 80(%0)\n"
- " movq %%mm0, 88(%0)\n"
- " movq %%mm0, 96(%0)\n"
- " movq %%mm0, 104(%0)\n"
- " movq %%mm0, 112(%0)\n"
- " movq %%mm0, 120(%0)\n"
- : : "r" (page) : "memory");
- page += 128;
- }
-
- kernel_fpu_end();
-}
-
-static void fast_copy_page(void *to, void *from)
-{
- int i;
-
- kernel_fpu_begin_mask(KFPU_387);
-
- __asm__ __volatile__ (
- "1: prefetch (%0)\n"
- " prefetch 64(%0)\n"
- " prefetch 128(%0)\n"
- " prefetch 192(%0)\n"
- " prefetch 256(%0)\n"
- "2: \n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x1AEB, 1b\n" /* jmp on 26 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b) : : "r" (from));
-
- for (i = 0; i < 4096/64; i++) {
- __asm__ __volatile__ (
- "1: prefetch 320(%0)\n"
- "2: movq (%0), %%mm0\n"
- " movq 8(%0), %%mm1\n"
- " movq 16(%0), %%mm2\n"
- " movq 24(%0), %%mm3\n"
- " movq %%mm0, (%1)\n"
- " movq %%mm1, 8(%1)\n"
- " movq %%mm2, 16(%1)\n"
- " movq %%mm3, 24(%1)\n"
- " movq 32(%0), %%mm0\n"
- " movq 40(%0), %%mm1\n"
- " movq 48(%0), %%mm2\n"
- " movq 56(%0), %%mm3\n"
- " movq %%mm0, 32(%1)\n"
- " movq %%mm1, 40(%1)\n"
- " movq %%mm2, 48(%1)\n"
- " movq %%mm3, 56(%1)\n"
- ".section .fixup, \"ax\"\n"
- "3: movw $0x05EB, 1b\n" /* jmp on 5 bytes */
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- : : "r" (from), "r" (to) : "memory");
-
- from += 64;
- to += 64;
- }
- kernel_fpu_end();
-}
-
-#endif /* !CONFIG_MK7 */
-
-/*
- * Favour MMX for page clear and copy:
- */
-static void slow_zero_page(void *page)
-{
- int d0, d1;
-
- __asm__ __volatile__(
- "cld\n\t"
- "rep ; stosl"
-
- : "=&c" (d0), "=&D" (d1)
- :"a" (0), "1" (page), "0" (1024)
- :"memory");
-}
-
-void mmx_clear_page(void *page)
-{
- if (unlikely(in_interrupt()))
- slow_zero_page(page);
- else
- fast_clear_page(page);
-}
-EXPORT_SYMBOL(mmx_clear_page);
-
-static void slow_copy_page(void *to, void *from)
-{
- int d0, d1, d2;
-
- __asm__ __volatile__(
- "cld\n\t"
- "rep ; movsl"
- : "=&c" (d0), "=&D" (d1), "=&S" (d2)
- : "0" (1024), "1" ((long) to), "2" ((long) from)
- : "memory");
-}
-
-void mmx_copy_page(void *to, void *from)
-{
- if (unlikely(in_interrupt()))
- slow_copy_page(to, from);
- else
- fast_copy_page(to, from);
-}
-EXPORT_SYMBOL(mmx_copy_page);
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -8,7 +8,6 @@
*/
#include <linux/export.h>
#include <linux/uaccess.h>
-#include <asm/mmx.h>
#include <asm/asm.h>
#ifdef CONFIG_X86_INTEL_USERCOPY
--- a/tools/arch/x86/include/asm/required-features.h
+++ b/tools/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))
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