[PATCH v2 9/9] x86, nfit_test: unit test for memcpy_mcsafe()

[Dan Williams]

Given the fact that the ACPI "EINJ" (error injection) facility is not
universally available, implement software infrastructure to validate the
memcpy_mcsafe() exception handling implementation.

For each potential read exception point in memcpy_mcsafe(), inject a
emulated exception point at the address identified by 'mcsafe_inject'
variable. With this infrastructure implement a test to validate that the
'bytes remaining' calculation is correct for a range of various source
buffer alignments.

This code is compiled out by default. The CONFIG_MCSAFE_DEBUG
configuration symbol needs to be manually enabled by editing
Kconfig.debug. I.e. this functionality can not be accidentally enabled
by a user / distro, it's only for development.

Cc: 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Al Viro 
Cc: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Reported-by: Tony Luck 
Signed-off-by: Dan Williams 
---
 arch/x86/Kconfig.debug  |3 ++
 arch/x86/include/asm/mcsafe_debug.h |   50 +++
 arch/x86/lib/memcpy_64.S|7 +
 tools/testing/nvdimm/test/nfit.c|   48 ++
 4 files changed, 108 insertions(+)
 create mode 100644 arch/x86/include/asm/mcsafe_debug.h

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 192e4d2f9efc..8bdec78a405f 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -72,6 +72,9 @@ config EARLY_PRINTK_USB_XDBC
  You should normally say N here, unless you want to debug early
  crashes or need a very simple printk logging facility.
 
+config MCSAFE_DEBUG
+   def_bool n
+
 config X86_PTDUMP_CORE
def_bool n
 
diff --git a/arch/x86/include/asm/mcsafe_debug.h 
b/arch/x86/include/asm/mcsafe_debug.h
new file mode 100644
index ..0f85d24b46c5
--- /dev/null
+++ b/arch/x86/include/asm/mcsafe_debug.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MCSAFE_DEBUG_H_
+#define _MCSAFE_DEBUG_H_
+
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_MCSAFE_DEBUG
+extern unsigned long mcsafe_inject;
+
+static inline void set_mcsafe_inject(void *addr)
+{
+   if (addr)
+   mcsafe_inject = (unsigned long) addr;
+   else
+   mcsafe_inject = ~0UL;
+}
+#else /* CONFIG_MCSAFE_DEBUG */
+static inline void set_mcsafe_inject(void *addr)
+{
+}
+#endif /* CONFIG_MCSAFE_DEBUG */
+
+#else /* __ASSEMBLY__ */
+#include 
+
+#ifdef CONFIG_MCSAFE_DEBUG
+.macro MCSAFE_DEBUG_CTL
+   .pushsection .data
+   .align 8
+   .globl mcsafe_inject
+   mcsafe_inject:
+   .quad 0
+   EXPORT_SYMBOL_GPL(mcsafe_inject)
+   .popsection
+.endm
+
+.macro MCSAFE_DEBUG offset reg count target
+   leaq \offset(\reg), %r9
+   addq \count, %r9
+   cmp mcsafe_inject, %r9
+   jg \target
+.endm
+#else
+.macro MCSAFE_DEBUG_CTL
+.endm
+
+.macro MCSAFE_DEBUG offset reg count target
+.endm
+#endif /* CONFIG_MCSAFE_DEBUG */
+#endif /* __ASSEMBLY__ */
+#endif /* _MCSAFE_DEBUG_H_ */
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index c3b527a9f95d..e5f489b2c6ea 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -3,6 +3,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 
@@ -183,6 +184,9 @@ ENTRY(memcpy_orig)
 ENDPROC(memcpy_orig)
 
 #ifndef CONFIG_UML
+
+MCSAFE_DEBUG_CTL
+
 /*
  * __memcpy_mcsafe - memory copy with machine check exception handling
  * Note that we only catch machine checks when reading the source addresses.
@@ -205,6 +209,7 @@ ENTRY(__memcpy_mcsafe)
negl %ecx
subl %ecx, %edx
 .L_read_leading_bytes:
+   MCSAFE_DEBUG 0 %rsi $1 .E_leading_bytes
movb (%rsi), %al
 .L_write_leading_bytes:
movb %al, (%rdi)
@@ -220,6 +225,7 @@ ENTRY(__memcpy_mcsafe)
jz .L_no_whole_words
 
 .L_read_words:
+   MCSAFE_DEBUG 0 %rsi $8 .E_read_words
movq (%rsi), %r8
 .L_write_words:
movq %r8, (%rdi)
@@ -236,6 +242,7 @@ ENTRY(__memcpy_mcsafe)
/* Copy trailing bytes */
movl %edx, %ecx
 .L_read_trailing_bytes:
+   MCSAFE_DEBUG 0 %rsi $1 .E_trailing_bytes
movb (%rsi), %al
 .L_write_trailing_bytes:
movb %al, (%rdi)
diff --git a/tools/testing/nvdimm/test/nfit.c b/tools/testing/nvdimm/test/nfit.c
index 4ea385be528f..db04ff658971 100644
--- a/tools/testing/nvdimm/test/nfit.c
+++ b/tools/testing/nvdimm/test/nfit.c
@@ -29,6 +29,8 @@
 #include "nfit_test.h"
 #include "../watermark.h"
 
+#include 
+
 /*
  * Generate an NFIT table to describe the following topology:
  *
@@ -2681,6 +2683,51 @@ static struct platform_driver nfit_test_driver = {
.id_table = 

[PATCH v2 9/9] x86, nfit_test: unit test for memcpy_mcsafe()

[Dan Williams]

Given the fact that the ACPI "EINJ" (error injection) facility is not
universally available, implement software infrastructure to validate the
memcpy_mcsafe() exception handling implementation.

For each potential read exception point in memcpy_mcsafe(), inject a
emulated exception point at the address identified by 'mcsafe_inject'
variable. With this infrastructure implement a test to validate that the
'bytes remaining' calculation is correct for a range of various source
buffer alignments.

This code is compiled out by default. The CONFIG_MCSAFE_DEBUG
configuration symbol needs to be manually enabled by editing
Kconfig.debug. I.e. this functionality can not be accidentally enabled
by a user / distro, it's only for development.

Cc: 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Al Viro 
Cc: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Reported-by: Tony Luck 
Signed-off-by: Dan Williams 
---
 arch/x86/Kconfig.debug  |3 ++
 arch/x86/include/asm/mcsafe_debug.h |   50 +++
 arch/x86/lib/memcpy_64.S|7 +
 tools/testing/nvdimm/test/nfit.c|   48 ++
 4 files changed, 108 insertions(+)
 create mode 100644 arch/x86/include/asm/mcsafe_debug.h

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 192e4d2f9efc..8bdec78a405f 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -72,6 +72,9 @@ config EARLY_PRINTK_USB_XDBC
  You should normally say N here, unless you want to debug early
  crashes or need a very simple printk logging facility.
 
+config MCSAFE_DEBUG
+   def_bool n
+
 config X86_PTDUMP_CORE
def_bool n
 
diff --git a/arch/x86/include/asm/mcsafe_debug.h 
b/arch/x86/include/asm/mcsafe_debug.h
new file mode 100644
index ..0f85d24b46c5
--- /dev/null
+++ b/arch/x86/include/asm/mcsafe_debug.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MCSAFE_DEBUG_H_
+#define _MCSAFE_DEBUG_H_
+
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_MCSAFE_DEBUG
+extern unsigned long mcsafe_inject;
+
+static inline void set_mcsafe_inject(void *addr)
+{
+   if (addr)
+   mcsafe_inject = (unsigned long) addr;
+   else
+   mcsafe_inject = ~0UL;
+}
+#else /* CONFIG_MCSAFE_DEBUG */
+static inline void set_mcsafe_inject(void *addr)
+{
+}
+#endif /* CONFIG_MCSAFE_DEBUG */
+
+#else /* __ASSEMBLY__ */
+#include 
+
+#ifdef CONFIG_MCSAFE_DEBUG
+.macro MCSAFE_DEBUG_CTL
+   .pushsection .data
+   .align 8
+   .globl mcsafe_inject
+   mcsafe_inject:
+   .quad 0
+   EXPORT_SYMBOL_GPL(mcsafe_inject)
+   .popsection
+.endm
+
+.macro MCSAFE_DEBUG offset reg count target
+   leaq \offset(\reg), %r9
+   addq \count, %r9
+   cmp mcsafe_inject, %r9
+   jg \target
+.endm
+#else
+.macro MCSAFE_DEBUG_CTL
+.endm
+
+.macro MCSAFE_DEBUG offset reg count target
+.endm
+#endif /* CONFIG_MCSAFE_DEBUG */
+#endif /* __ASSEMBLY__ */
+#endif /* _MCSAFE_DEBUG_H_ */
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index c3b527a9f95d..e5f489b2c6ea 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -3,6 +3,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 
@@ -183,6 +184,9 @@ ENTRY(memcpy_orig)
 ENDPROC(memcpy_orig)
 
 #ifndef CONFIG_UML
+
+MCSAFE_DEBUG_CTL
+
 /*
  * __memcpy_mcsafe - memory copy with machine check exception handling
  * Note that we only catch machine checks when reading the source addresses.
@@ -205,6 +209,7 @@ ENTRY(__memcpy_mcsafe)
negl %ecx
subl %ecx, %edx
 .L_read_leading_bytes:
+   MCSAFE_DEBUG 0 %rsi $1 .E_leading_bytes
movb (%rsi), %al
 .L_write_leading_bytes:
movb %al, (%rdi)
@@ -220,6 +225,7 @@ ENTRY(__memcpy_mcsafe)
jz .L_no_whole_words
 
 .L_read_words:
+   MCSAFE_DEBUG 0 %rsi $8 .E_read_words
movq (%rsi), %r8
 .L_write_words:
movq %r8, (%rdi)
@@ -236,6 +242,7 @@ ENTRY(__memcpy_mcsafe)
/* Copy trailing bytes */
movl %edx, %ecx
 .L_read_trailing_bytes:
+   MCSAFE_DEBUG 0 %rsi $1 .E_trailing_bytes
movb (%rsi), %al
 .L_write_trailing_bytes:
movb %al, (%rdi)
diff --git a/tools/testing/nvdimm/test/nfit.c b/tools/testing/nvdimm/test/nfit.c
index 4ea385be528f..db04ff658971 100644
--- a/tools/testing/nvdimm/test/nfit.c
+++ b/tools/testing/nvdimm/test/nfit.c
@@ -29,6 +29,8 @@
 #include "nfit_test.h"
 #include "../watermark.h"
 
+#include 
+
 /*
  * Generate an NFIT table to describe the following topology:
  *
@@ -2681,6 +2683,51 @@ static struct platform_driver nfit_test_driver = {
.id_table = nfit_test_id,
 };
 
+static char mcsafe_buf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
+
+void mcsafe_test(void)
+{
+   bool do_inject = false;
+   int i;
+
+   if (IS_ENABLED(CONFIG_MCSAFE_DEBUG)) {
+   pr_info("%s: run...\n", __func__);
+