From 4b8bfe6ad3b26359fb8ee58776987ac0a1a3758c Mon Sep 17 00:00:00 2001
From: dex <marcel.busch@cs.fau.de>
Date: Tue, 19 Jan 2021 16:33:35 +0100
Subject: [PATCH] add arm syscall example
---
arm_asm/Makefile | 18 ++++++++++++++++++
arm_asm/README.md | 4 ++++
arm_asm/add.S | 7 +++++++
arm_asm/main.c | 26 ++++++++++++++++++++++++++
arm_asm/mywrite.S | 9 +++++++++
5 files changed, 64 insertions(+)
create mode 100644 arm_asm/Makefile
create mode 100644 arm_asm/README.md
create mode 100644 arm_asm/add.S
create mode 100644 arm_asm/main.c
create mode 100644 arm_asm/mywrite.S
diff --git a/arm_asm/Makefile b/arm_asm/Makefile
new file mode 100644
index 0000000..24c58ef
--- /dev/null
+++ b/arm_asm/Makefile
@@ -0,0 +1,18 @@
+
+.PHONY: run debug clean
+
+all: main.arm32
+
+main.arm32: main.c add.S mywrite.S
+ arm-linux-gnueabihf-gcc -marm -g -O0 -o $@ $^
+
+run: main.arm32
+ qemu-arm -L /usr/arm-linux-gnueabihf/ $<
+
+debug: main.arm32
+ @echo "attach using"
+ @echo "arm-none-eabi-gdb $<\n"
+ qemu-arm -g 1234 -L /usr/arm-linux-gnueabihf/ $<
+
+clean:
+ rm -f main.arm32
diff --git a/arm_asm/README.md b/arm_asm/README.md
new file mode 100644
index 0000000..671b868
--- /dev/null
+++ b/arm_asm/README.md
@@ -0,0 +1,4 @@
+Simple example for a C project integrating ARM assembly.
+You need an arm toolchain to build this.
+Change the compiler to your needs (`arm-linux-gnueabihf-gcc`).
+The `Makefile` uses `qemu-user` to run the example.
diff --git a/arm_asm/add.S b/arm_asm/add.S
new file mode 100644
index 0000000..3908067
--- /dev/null
+++ b/arm_asm/add.S
@@ -0,0 +1,7 @@
+.section .text.add, "x"
+
+.global add
+
+add:
+ add r0, r0, r1
+ mov pc, lr
diff --git a/arm_asm/main.c b/arm_asm/main.c
new file mode 100644
index 0000000..5edc824
--- /dev/null
+++ b/arm_asm/main.c
@@ -0,0 +1,26 @@
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+extern int add(int, int);
+extern int mywrite(int fd, void* buf, size_t count);
+
+int sub(int a, int b){
+ return a - b;
+}
+
+int main(int argc, char** argv){
+ int r = 0;
+ char* name = "Hello Reverser!\n";
+
+ write(STDOUT_FILENO, name, strlen(name));
+
+ r = sub(20, 10);
+ printf("sub(20, 10) = %d\n", r);
+ r = add(10, 20);
+ printf("add(10, 20) = %d\n", r);
+
+ mywrite(1, "Hello!\n", 8);
+ return EXIT_SUCCESS;
+}
diff --git a/arm_asm/mywrite.S b/arm_asm/mywrite.S
new file mode 100644
index 0000000..1a67dcc
--- /dev/null
+++ b/arm_asm/mywrite.S
@@ -0,0 +1,9 @@
+.section .text.mywrite, "x"
+
+.global mywrite
+
+mywrite:
+ push {r7, lr}
+ mov r7, #4
+ swi 0
+ pop {r7, pc}
--
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