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

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Date:   Wed, 12 Jun 2019 17:35:59 +0200
From:   Sam Caccavale <samcacc@...zon.de>
To:     unlisted-recipients:; (no To-header on input)
CC:     <samcaccavale@...il.com>, <nmanthey@...zon.de>,
        <wipawel@...zon.de>, <dwmw@...zon.co.uk>, <mpohlack@...zon.de>,
        <graf@...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>, Sam Caccavale <samcacc@...zon.de>
Subject: [v2, 3/4] Demonstrating unit testing via simple-harness

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
+		     ".byte 0x0f, 0x6f, 0xde;" // same instruction...
+		     ".byte 0x90;"
+		     "__end:");
+}
+
+int main(int argc, char **argv)
+{
+	extern unsigned char __start;
+	extern unsigned char __end;
+	struct state *state = create_emulator();
+	int rc;
+
+	/* Ensures the emulator is in a valid state. */
+	initialize_emulator(state);
+
+	/* Provide the emulator with instructions to emulate. */
+	state->data = &__start;
+	state->data_available = &__end - &__start;
+
+	/* rip addressed instruction */
+	rc = emulate_until_complete(state);
+
+	/* Free the emulator. */
+	free_emulator(state);
+
+	return 0;
+}
--
2.17.1




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