linux-kernel - Re: [v2, 3/4] Demonstrating unit testing via simple-harness

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Message-ID: <54e7eb69-3700-2e54-77b9-79b61ca69a1b@amazon.com>
Date:   Fri, 21 Jun 2019 15:43:51 +0200
From:   Alexander Graf <graf@...zon.com>
To:     Sam Caccavale <samcacc@...zon.de>
CC:     <samcaccavale@...il.com>, <nmanthey@...zon.de>,
        <wipawel@...zon.de>, <dwmw@...zon.co.uk>, <mpohlack@...zon.de>,
        <karahmed@...zon.de>, <andrew.cooper3@...rix.com>,
        <JBeulich@...e.com>, <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <hpa@...or.com>, <paullangton4@...il.com>,
        <anirudhkaushik@...gle.com>, <x86@...nel.org>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [v2, 3/4] Demonstrating unit testing via simple-harness



On 12.06.19 17:35, Sam Caccavale wrote:
> Simple-harness.c uses inline asm support to generate asm and then has the
> emulator emulate this code.  This may be useful as a form of testing for
> the emulator.
> 
> CR: https://code.amazon.com/reviews/CR-8591638
> ---
>   tools/fuzz/x86ie/Makefile         |  7 ++++--
>   tools/fuzz/x86ie/simple-harness.c | 42 +++++++++++++++++++++++++++++++
>   2 files changed, 47 insertions(+), 2 deletions(-)
>   create mode 100644 tools/fuzz/x86ie/simple-harness.c
> 
> diff --git a/tools/fuzz/x86ie/Makefile b/tools/fuzz/x86ie/Makefile
> index d45fe6d266b9..e79d275e1040 100644
> --- a/tools/fuzz/x86ie/Makefile
> +++ b/tools/fuzz/x86ie/Makefile
> @@ -44,8 +44,11 @@ LOCAL_OBJS := emulator_ops.o stubs.o
>   afl-harness: afl-harness.o $(LOCAL_OBJS) $(KERNEL_OBJS)
>   	@$(CC) -v $(KBUILD_CFLAGS) $(LOCAL_OBJS) $(KERNEL_OBJS) $< $(INCLUDES) -Istubs.h -o $@ -no-pie
> 
> -all: afl-harness
> +simple-harness: simple-harness.o $(LOCAL_OBJS) $(KERNEL_OBJS)
> +	@$(CC) -v $(KBUILD_CFLAGS) $(LOCAL_OBJS) $(KERNEL_OBJS) $< $(INCLUDES) -Istubs.h -o $@ -no-pie
> +
> +all: afl-harness simple-harness
> 
>   .PHONY: clean
>   clean:
> -	$(RM) -r *.o afl-harness
> +	$(RM) -r *.o afl-harness simple-harness
> diff --git a/tools/fuzz/x86ie/simple-harness.c b/tools/fuzz/x86ie/simple-harness.c
> new file mode 100644
> index 000000000000..f21fdafe1dd1
> --- /dev/null
> +++ b/tools/fuzz/x86ie/simple-harness.c
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <assert.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include "emulator_ops.h"
> +#include <asm/kvm_emulate.h>
> +
> +extern void foo(void)
> +{
> +	asm volatile("__start:"
> +		     ".byte 0x32, 0x05, 0x00, 0x00, 0x00, 0x00;" // xor eax,DWORD PTR [rip+0x0]
> +		     ".byte 0x90;"
> +		     //".byte 0x0f, 0x7f, 0xde;" // movq mm6,mm3

Why?

Alex