Commit 5d8beee2 authored by Dan Williams's avatar Dan Williams
Browse files

x86, nfit_test: Add unit test for memcpy_mcsafe() 



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: <x86@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: default avatarTony Luck <tony.luck@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 6dfdb2b6

arch/x86/Kconfig.debug

+3 −0
Original line number Diff line number Diff line
@@ -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_TEST

	def_bool n



config X86_PTDUMP_CORE

	def_bool n

arch/x86/include/asm/mcsafe_test.h

0 → 100644
+75 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _MCSAFE_TEST_H_

#define _MCSAFE_TEST_H_



#ifndef __ASSEMBLY__

#ifdef CONFIG_MCSAFE_TEST

extern unsigned long mcsafe_test_src;

extern unsigned long mcsafe_test_dst;



static inline void mcsafe_inject_src(void *addr)

{

	if (addr)

		mcsafe_test_src = (unsigned long) addr;

	else

		mcsafe_test_src = ~0UL;

}



static inline void mcsafe_inject_dst(void *addr)

{

	if (addr)

		mcsafe_test_dst = (unsigned long) addr;

	else

		mcsafe_test_dst = ~0UL;

}

#else /* CONFIG_MCSAFE_TEST */

static inline void mcsafe_inject_src(void *addr)

{

}



static inline void mcsafe_inject_dst(void *addr)

{

}

#endif /* CONFIG_MCSAFE_TEST */



#else /* __ASSEMBLY__ */

#include <asm/export.h>



#ifdef CONFIG_MCSAFE_TEST

.macro MCSAFE_TEST_CTL

	.pushsection .data

	.align 8

	.globl mcsafe_test_src

	mcsafe_test_src:

		.quad 0

	EXPORT_SYMBOL_GPL(mcsafe_test_src)

	.globl mcsafe_test_dst

	mcsafe_test_dst:

		.quad 0

	EXPORT_SYMBOL_GPL(mcsafe_test_dst)

	.popsection

.endm



.macro MCSAFE_TEST_SRC reg count target

	leaq \count(\reg), %r9

	cmp mcsafe_test_src, %r9

	ja \target

.endm



.macro MCSAFE_TEST_DST reg count target

	leaq \count(\reg), %r9

	cmp mcsafe_test_dst, %r9

	ja \target

.endm

#else

.macro MCSAFE_TEST_CTL

.endm



.macro MCSAFE_TEST_SRC reg count target

.endm



.macro MCSAFE_TEST_DST reg count target

.endm

#endif /* CONFIG_MCSAFE_TEST */

#endif /* __ASSEMBLY__ */

#endif /* _MCSAFE_TEST_H_ */

arch/x86/lib/memcpy_64.S

+10 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
#include <linux/linkage.h>

#include <asm/errno.h>

#include <asm/cpufeatures.h>

#include <asm/mcsafe_test.h>

#include <asm/alternative-asm.h>

#include <asm/export.h>
@@ -183,6 +184,9 @@ ENTRY(memcpy_orig) 
ENDPROC(memcpy_orig)



#ifndef CONFIG_UML



MCSAFE_TEST_CTL



/*

 * __memcpy_mcsafe - memory copy with machine check exception handling

 * Note that we only catch machine checks when reading the source addresses.
@@ -206,6 +210,8 @@ ENTRY(__memcpy_mcsafe) 
	subl %ecx, %edx

.L_read_leading_bytes:

	movb (%rsi), %al

	MCSAFE_TEST_SRC %rsi 1 .E_leading_bytes

	MCSAFE_TEST_DST %rdi 1 .E_leading_bytes

.L_write_leading_bytes:

	movb %al, (%rdi)

	incq %rsi
@@ -221,6 +227,8 @@ ENTRY(__memcpy_mcsafe) 


.L_read_words:

	movq (%rsi), %r8

	MCSAFE_TEST_SRC %rsi 8 .E_read_words

	MCSAFE_TEST_DST %rdi 8 .E_write_words

.L_write_words:

	movq %r8, (%rdi)

	addq $8, %rsi
@@ -237,6 +245,8 @@ ENTRY(__memcpy_mcsafe) 
	movl %edx, %ecx

.L_read_trailing_bytes:

	movb (%rsi), %al

	MCSAFE_TEST_SRC %rsi 1 .E_trailing_bytes

	MCSAFE_TEST_DST %rdi 1 .E_trailing_bytes

.L_write_trailing_bytes:

	movb %al, (%rdi)

	incq %rsi

tools/testing/nvdimm/test/nfit.c

+104 −0
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ 
#include "nfit_test.h"

#include "../watermark.h"



#include <asm/mcsafe_test.h>



/*

 * Generate an NFIT table to describe the following topology:

 *
@@ -2681,6 +2683,107 @@ static struct platform_driver nfit_test_driver = { 
	.id_table = nfit_test_id,

};



static char mcsafe_buf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));



enum INJECT {

	INJECT_NONE,

	INJECT_SRC,

	INJECT_DST,

};



static void mcsafe_test_init(char *dst, char *src, size_t size)

{

	size_t i;



	memset(dst, 0xff, size);

	for (i = 0; i < size; i++)

		src[i] = (char) i;

}



static bool mcsafe_test_validate(unsigned char *dst, unsigned char *src,

		size_t size, unsigned long rem)

{

	size_t i;



	for (i = 0; i < size - rem; i++)

		if (dst[i] != (unsigned char) i) {

			pr_info_once("%s:%d: offset: %zd got: %#x expect: %#x\n",

					__func__, __LINE__, i, dst[i],

					(unsigned char) i);

			return false;

		}

	for (i = size - rem; i < size; i++)

		if (dst[i] != 0xffU) {

			pr_info_once("%s:%d: offset: %zd got: %#x expect: 0xff\n",

					__func__, __LINE__, i, dst[i]);

			return false;

		}

	return true;

}



void mcsafe_test(void)

{

	char *inject_desc[] = { "none", "source", "destination" };

	enum INJECT inj;



	if (IS_ENABLED(CONFIG_MCSAFE_TEST)) {

		pr_info("%s: run...\n", __func__);

	} else {

		pr_info("%s: disabled, skip.\n", __func__);

		return;

	}



	for (inj = INJECT_NONE; inj <= INJECT_DST; inj++) {

		int i;



		pr_info("%s: inject: %s\n", __func__, inject_desc[inj]);

		for (i = 0; i < 512; i++) {

			unsigned long expect, rem;

			void *src, *dst;

			bool valid;



			switch (inj) {

			case INJECT_NONE:

				mcsafe_inject_src(NULL);

				mcsafe_inject_dst(NULL);

				dst = &mcsafe_buf[2048];

				src = &mcsafe_buf[1024 - i];

				expect = 0;

				break;

			case INJECT_SRC:

				mcsafe_inject_src(&mcsafe_buf[1024]);

				mcsafe_inject_dst(NULL);

				dst = &mcsafe_buf[2048];

				src = &mcsafe_buf[1024 - i];

				expect = 512 - i;

				break;

			case INJECT_DST:

				mcsafe_inject_src(NULL);

				mcsafe_inject_dst(&mcsafe_buf[2048]);

				dst = &mcsafe_buf[2048 - i];

				src = &mcsafe_buf[1024];

				expect = 512 - i;

				break;

			}



			mcsafe_test_init(dst, src, 512);

			rem = __memcpy_mcsafe(dst, src, 512);

			valid = mcsafe_test_validate(dst, src, 512, expect);

			if (rem == expect && valid)

				continue;

			pr_info("%s: copy(%#lx, %#lx, %d) off: %d rem: %ld %s expect: %ld\n",

					__func__,

					((unsigned long) dst) & ~PAGE_MASK,

					((unsigned long ) src) & ~PAGE_MASK,

					512, i, rem, valid ? "valid" : "bad",

					expect);

		}

	}



	mcsafe_inject_src(NULL);

	mcsafe_inject_dst(NULL);

}



static __init int nfit_test_init(void)

{

	int rc, i;
@@ -2689,6 +2792,7 @@ static __init int nfit_test_init(void) 
	libnvdimm_test();

	acpi_nfit_test();

	device_dax_test();

	mcsafe_test();



	nfit_test_setup(nfit_test_lookup, nfit_test_evaluate_dsm);

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