[RFC PATCH -next V3 6/6] arm64: add cow to machine check safe
From: Tong Tiangen
Date: Tue Apr 12 2022 - 04:11:26 EST
In the cow(copy on write) processing, the data of the user process is
copied, when hardware memory error is encountered during copy, only the
relevant processes are affected, so killing the user process and isolate
the user page with hardware memory errors is a more reasonable choice than
kernel panic.
Add new helper copy_page_mc() which provide a page copy implementation with
machine check safe. At present, only used in cow. In future, we can expand
more scenes. As long as the consequences of page copy failure are not
fatal(eg: only affect user process), we can use this helper.
The copy_page_mc() in copy_page_mc.S is largely borrows from copy_page()
in copy_page.S and the main difference is copy_page_mc() add some extable
entry to support machine check safe. largely to keep the patch simple. If
needed those optimizations can be folded in.
Add new extable type EX_TYPE_COPY_PAGE_MC which used in copy_page_mc().
This type only be processed in fixup_exception_mc(), The reason is that
copy_page_mc() is consistent with copy_page() except machine check safe is
considered, and copy_page() do not need to consider exception fixup.
Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
---
arch/arm64/include/asm/asm-extable.h | 5 ++
arch/arm64/include/asm/page.h | 10 +++
arch/arm64/lib/Makefile | 2 +
arch/arm64/lib/copy_page_mc.S | 99 ++++++++++++++++++++++++++++
arch/arm64/mm/copypage.c | 36 ++++++++--
arch/arm64/mm/extable.c | 1 +
include/linux/highmem.h | 8 +++
mm/memory.c | 2 +-
8 files changed, 156 insertions(+), 7 deletions(-)
create mode 100644 arch/arm64/lib/copy_page_mc.S
diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h
index 62eafb651773..274bd7edcff6 100644
--- a/arch/arm64/include/asm/asm-extable.h
+++ b/arch/arm64/include/asm/asm-extable.h
@@ -11,6 +11,7 @@
/* _MC indicates that can fixup from machine check errors */
#define EX_TYPE_UACCESS_MC 5
#define EX_TYPE_UACCESS_MC_ERR_ZERO 6
+#define EX_TYPE_COPY_PAGE_MC 7
#ifdef __ASSEMBLY__
@@ -39,6 +40,10 @@
__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_UACCESS_MC, 0)
.endm
+ .macro _asm_extable_copy_page_mc, insn, fixup
+ __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_COPY_PAGE_MC, 0)
+ .endm
+
/*
* Create an exception table entry for `insn` if `fixup` is provided. Otherwise
* do nothing.
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 993a27ea6f54..832571a7dddb 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -29,6 +29,16 @@ void copy_user_highpage(struct page *to, struct page *from,
void copy_highpage(struct page *to, struct page *from);
#define __HAVE_ARCH_COPY_HIGHPAGE
+#ifdef CONFIG_ARCH_HAS_COPY_MC
+extern void copy_page_mc(void *to, const void *from);
+void copy_highpage_mc(struct page *to, struct page *from);
+#define __HAVE_ARCH_COPY_HIGHPAGE_MC
+
+void copy_user_highpage_mc(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma);
+#define __HAVE_ARCH_COPY_USER_HIGHPAGE_MC
+#endif
+
struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
unsigned long vaddr);
#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
index 29490be2546b..0d9f292ef68a 100644
--- a/arch/arm64/lib/Makefile
+++ b/arch/arm64/lib/Makefile
@@ -15,6 +15,8 @@ endif
lib-$(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) += uaccess_flushcache.o
+lib-$(CONFIG_ARCH_HAS_COPY_MC) += copy_page_mc.o
+
obj-$(CONFIG_CRC32) += crc32.o
obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
diff --git a/arch/arm64/lib/copy_page_mc.S b/arch/arm64/lib/copy_page_mc.S
new file mode 100644
index 000000000000..93b4203bdf45
--- /dev/null
+++ b/arch/arm64/lib/copy_page_mc.S
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#include <linux/linkage.h>
+#include <linux/const.h>
+#include <asm/assembler.h>
+#include <asm/page.h>
+#include <asm/cpufeature.h>
+#include <asm/alternative.h>
+#include <asm/asm-extable.h>
+
+/*
+ * Copy a page from src to dest (both are page aligned) with machine check
+ *
+ * Parameters:
+ * x0 - dest
+ * x1 - src
+ */
+SYM_FUNC_START(__pi_copy_page_mc)
+alternative_if ARM64_HAS_NO_HW_PREFETCH
+ // Prefetch three cache lines ahead.
+ prfm pldl1strm, [x1, #128]
+ prfm pldl1strm, [x1, #256]
+ prfm pldl1strm, [x1, #384]
+alternative_else_nop_endif
+
+100: ldp x2, x3, [x1]
+101: ldp x4, x5, [x1, #16]
+102: ldp x6, x7, [x1, #32]
+103: ldp x8, x9, [x1, #48]
+104: ldp x10, x11, [x1, #64]
+105: ldp x12, x13, [x1, #80]
+106: ldp x14, x15, [x1, #96]
+107: ldp x16, x17, [x1, #112]
+
+ add x0, x0, #256
+ add x1, x1, #128
+1:
+ tst x0, #(PAGE_SIZE - 1)
+
+alternative_if ARM64_HAS_NO_HW_PREFETCH
+ prfm pldl1strm, [x1, #384]
+alternative_else_nop_endif
+
+ stnp x2, x3, [x0, #-256]
+200: ldp x2, x3, [x1]
+ stnp x4, x5, [x0, #16 - 256]
+201: ldp x4, x5, [x1, #16]
+ stnp x6, x7, [x0, #32 - 256]
+202: ldp x6, x7, [x1, #32]
+ stnp x8, x9, [x0, #48 - 256]
+203: ldp x8, x9, [x1, #48]
+ stnp x10, x11, [x0, #64 - 256]
+204: ldp x10, x11, [x1, #64]
+ stnp x12, x13, [x0, #80 - 256]
+205: ldp x12, x13, [x1, #80]
+ stnp x14, x15, [x0, #96 - 256]
+206: ldp x14, x15, [x1, #96]
+ stnp x16, x17, [x0, #112 - 256]
+207: ldp x16, x17, [x1, #112]
+
+ add x0, x0, #128
+ add x1, x1, #128
+
+ b.ne 1b
+
+ stnp x2, x3, [x0, #-256]
+ stnp x4, x5, [x0, #16 - 256]
+ stnp x6, x7, [x0, #32 - 256]
+ stnp x8, x9, [x0, #48 - 256]
+ stnp x10, x11, [x0, #64 - 256]
+ stnp x12, x13, [x0, #80 - 256]
+ stnp x14, x15, [x0, #96 - 256]
+ stnp x16, x17, [x0, #112 - 256]
+
+300: ret
+
+_asm_extable_copy_page_mc 100b, 300b
+_asm_extable_copy_page_mc 101b, 300b
+_asm_extable_copy_page_mc 102b, 300b
+_asm_extable_copy_page_mc 103b, 300b
+_asm_extable_copy_page_mc 104b, 300b
+_asm_extable_copy_page_mc 105b, 300b
+_asm_extable_copy_page_mc 106b, 300b
+_asm_extable_copy_page_mc 107b, 300b
+_asm_extable_copy_page_mc 200b, 300b
+_asm_extable_copy_page_mc 201b, 300b
+_asm_extable_copy_page_mc 202b, 300b
+_asm_extable_copy_page_mc 203b, 300b
+_asm_extable_copy_page_mc 204b, 300b
+_asm_extable_copy_page_mc 205b, 300b
+_asm_extable_copy_page_mc 206b, 300b
+_asm_extable_copy_page_mc 207b, 300b
+
+SYM_FUNC_END(__pi_copy_page_mc)
+SYM_FUNC_ALIAS(copy_page_mc, __pi_copy_page_mc)
+EXPORT_SYMBOL(copy_page_mc)
diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
index 0dea80bf6de4..0f28edfcb234 100644
--- a/arch/arm64/mm/copypage.c
+++ b/arch/arm64/mm/copypage.c
@@ -14,13 +14,8 @@
#include <asm/cpufeature.h>
#include <asm/mte.h>
-void copy_highpage(struct page *to, struct page *from)
+static void do_mte(struct page *to, struct page *from, void *kto, void *kfrom)
{
- void *kto = page_address(to);
- void *kfrom = page_address(from);
-
- copy_page(kto, kfrom);
-
if (system_supports_mte() && test_bit(PG_mte_tagged, &from->flags)) {
set_bit(PG_mte_tagged, &to->flags);
page_kasan_tag_reset(to);
@@ -35,6 +30,15 @@ void copy_highpage(struct page *to, struct page *from)
mte_copy_page_tags(kto, kfrom);
}
}
+
+void copy_highpage(struct page *to, struct page *from)
+{
+ void *kto = page_address(to);
+ void *kfrom = page_address(from);
+
+ copy_page(kto, kfrom);
+ do_mte(to, from, kto, kfrom);
+}
EXPORT_SYMBOL(copy_highpage);
void copy_user_highpage(struct page *to, struct page *from,
@@ -44,3 +48,23 @@ void copy_user_highpage(struct page *to, struct page *from,
flush_dcache_page(to);
}
EXPORT_SYMBOL_GPL(copy_user_highpage);
+
+#ifdef CONFIG_ARCH_HAS_COPY_MC
+void copy_highpage_mc(struct page *to, struct page *from)
+{
+ void *kto = page_address(to);
+ void *kfrom = page_address(from);
+
+ copy_page_mc(kto, kfrom);
+ do_mte(to, from, kto, kfrom);
+}
+EXPORT_SYMBOL(copy_highpage_mc);
+
+void copy_user_highpage_mc(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma)
+{
+ copy_highpage_mc(to, from);
+ flush_dcache_page(to);
+}
+EXPORT_SYMBOL_GPL(copy_user_highpage_mc);
+#endif
diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
index ca7388f3923b..7ee67fcf9e81 100644
--- a/arch/arm64/mm/extable.c
+++ b/arch/arm64/mm/extable.c
@@ -98,6 +98,7 @@ bool fixup_exception_mc(struct pt_regs *regs)
switch (ex->type) {
case EX_TYPE_UACCESS_MC:
+ case EX_TYPE_COPY_PAGE_MC:
return ex_handler_fixup(ex, regs);
case EX_TYPE_UACCESS_MC_ERR_ZERO:
return ex_handler_uaccess_err_zero(ex, regs);
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 39bb9b47fa9c..a9dbf331b038 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -283,6 +283,10 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
#endif
+#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE_MC
+#define copy_user_highpage_mc copy_user_highpage
+#endif
+
#ifndef __HAVE_ARCH_COPY_HIGHPAGE
static inline void copy_highpage(struct page *to, struct page *from)
@@ -298,6 +302,10 @@ static inline void copy_highpage(struct page *to, struct page *from)
#endif
+#ifndef __HAVE_ARCH_COPY_HIGHPAGE_MC
+#define cop_highpage_mc copy_highpage
+#endif
+
static inline void memcpy_page(struct page *dst_page, size_t dst_off,
struct page *src_page, size_t src_off,
size_t len)
diff --git a/mm/memory.c b/mm/memory.c
index 76e3af9639d9..d5f62234152d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2767,7 +2767,7 @@ static inline bool cow_user_page(struct page *dst, struct page *src,
unsigned long addr = vmf->address;
if (likely(src)) {
- copy_user_highpage(dst, src, addr, vma);
+ copy_user_highpage_mc(dst, src, addr, vma);
return true;
}
--
2.18.0.huawei.25