From 8e3411139b27a3421e9ac75c13f14f99f6dd3137 Mon Sep 17 00:00:00 2001
From: Miguel <m.i@gmx.at>
Date: Sun, 2 Sep 2018 00:08:42 +0200
Subject: syscalls

---
 newlib/syscall.h | 11 +++++++++++
 newlib/syscall.s | 16 ++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 newlib/syscall.h
 create mode 100644 newlib/syscall.s

(limited to 'newlib')

diff --git a/newlib/syscall.h b/newlib/syscall.h
new file mode 100644
index 0000000..2cadce4
--- /dev/null
+++ b/newlib/syscall.h
@@ -0,0 +1,11 @@
+/* 
+ * Issue a System Call from Ring 3 / User Space 
+ *
+ * Accepts up to 3 parameters.
+ * Check syscalls.h for details.
+ */
+
+uint32_t syscall(uint32_t code,
+                 uint32_t param_1, 
+                 uint32_t param_2, 
+                 uint32_t param_3);
diff --git a/newlib/syscall.s b/newlib/syscall.s
new file mode 100644
index 0000000..abce63a
--- /dev/null
+++ b/newlib/syscall.s
@@ -0,0 +1,16 @@
+.global syscall
+
+syscall:
+
+	push %ebx // preserve (sysV abi convnetion)
+
+	mov 0x8(%esp),%eax    //syscall number
+	mov 0xC(%esp),%edx    //p1
+	mov 0x10(%esp),%ecx   //p2
+	mov 0x14(%esp),%ebx   //p3
+	
+	int $0x80
+	mov %ebx, %eax // set as return value
+
+	pop %ebx // preserve
+	ret
-- 
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