1 files changed, 83 insertions, 0 deletions
diff --git a/loader/wrapper.S b/loader/wrapper.S
new file mode 100644
index 0000000000..60028e670d
--- /dev/null
+++ b/loader/wrapper.S
@@ -0,0 +1,83 @@
+.section .data
+.globl caller_return
+caller_return:
+	.long 0
+.globl report_entry
+report_entry:
+	.long null_call
+.globl report_ret
+report_ret:	
+	.long null_call
+.global wrapper_target
+wrapper_target:	
+	.long null_call
+
+.section .text
+.globl null_call
+	.type null_call, @function
+	.align 16,0x90
+null_call:
+	ret
+.globl wrapper
+	.type wrapper, @function
+	.align 16,0x90
+wrapper:
+	pusha			# store registers (EAX, ECX, EDX, EBX, ESP, EBP, ESI, EDI) 
+	pushf			# store flags
+	
+	push %ebp		# set up a stack frame 
+	movl %esp, %ebp
+
+	leal 4(%ebp), %eax	# push flags addr
+	push %eax
+	leal 8(%ebp), %eax	# push registers addr
+	push %eax
+	
+	leal 40(%ebp), %edx	
+	movl (%ebp), %eax
+	subl %edx, %eax
+	push %eax
+	push %edx
+	
+	call *report_entry	# report entry
+	
+	test %eax, %eax
+	jnz .Ldone
+
+	leave			# restore %esp, %ebp
+	popf			# restore flags
+	popa			# restore registers
+	
+	popl caller_return	# switch return addresses
+	pushl $.Lwrapper_return 
+	
+	jmp *wrapper_target	# wrapper_target should return at .Lwrapper_return
+
+	.align 16, 0x90
+.Lwrapper_return:	
+	pushl caller_return	# restore the original return address
+	pusha			# more for reference sake here
+	pushf
+	
+	push %ebp		# set up a stack frame
+	movl %esp, %ebp
+
+	leal 4(%ebp), %eax	# push flags addr
+	push %eax
+	leal 8(%ebp), %eax	# push registers addr
+	push %eax
+
+	leal 40(%ebp), %edx	# push stack top address (relative to our entry)
+	movl (%ebp), %eax
+	subl %edx, %eax		# calculate difference between entry and previous frame
+	push %eax
+	push %edx
+
+	call *report_ret	# report the return information (same args)
+.Ldone:	
+
+	leave
+	popf
+	popa
+	ret
+	
+\ No newline at end of file