From: H. Peter Anvin <hpa@linux.intel.com>
Date: Mon, 2 Aug 2010 22:34:44 +0000 (-0700)
Subject: x86, setup: Allow global variables and functions in the decompressor
X-Git-Tag: firefly_0821_release~9833^2~1259^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=22a57f5896df218356bae6203dfaf04bcfd6c88c;p=firefly-linux-kernel-4.4.55.git

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>
---

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)