From 22a57f5896df218356bae6203dfaf04bcfd6c88c Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Mon, 2 Aug 2010 15:34:44 -0700
Subject: [PATCH] x86, setup: Allow global variables and functions in the
 decompressor

In order for global variables and functions to work in the
decompressor, we need to fix up the GOT in assembly code.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4C57382E.8050501@zytor.com>
---
 arch/x86/boot/compressed/head_32.S     | 13 +++++++++++++
 arch/x86/boot/compressed/head_64.S     | 13 +++++++++++++
 arch/x86/boot/compressed/vmlinux.lds.S |  6 ++++++
 3 files changed, 32 insertions(+)

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index f543b70ffae2..67a655a39ce4 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -123,6 +123,19 @@ relocated:
 	shrl	$2, %ecx
 	rep	stosl
 
+/*
+ * Adjust our own GOT
+ */
+	leal	_got(%ebx), %edx
+	leal	_egot(%ebx), %ecx
+1:
+	cmpl	%ecx, %edx
+	jae	2f
+	addl	%ebx, (%edx)
+	addl	$4, %edx
+	jmp	1b
+2:
+
 /*
  * Do the decompression, and jump to the new kernel..
  */
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index faff0dc9c06a..52f85a196fa0 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -279,6 +279,19 @@ relocated:
 	shrq	$3, %rcx
 	rep	stosq
 
+/*
+ * Adjust our own GOT
+ */
+	leaq	_got(%rip), %rdx
+	leaq	_egot(%rip), %rcx
+1:
+	cmpq	%rcx, %rdx
+	jae	2f
+	addq	%rbx, (%rdx)
+	addq	$8, %rdx
+	jmp	1b
+2:
+	
 /*
  * Do the decompression, and jump to the new kernel..
  */
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 5ddabceee124..34d047c98284 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -41,6 +41,12 @@ SECTIONS
 		*(.rodata.*)
 		_erodata = . ;
 	}
+	.got : {
+		_got = .;
+		KEEP(*(.got.plt))
+		KEEP(*(.got))
+		_egot = .;
+	}
 	.data :	{
 		_data = . ;
 		*(.data)