From: Arvind Sankar <nivedita@alum.mit.edu>
Date: Sun, 8 Mar 2020 09:08:44 +0100
Subject: x86/boot: Use unsigned comparison for addresses
Patch-mainline: v5.7-rc1
Git-commit: 81a34892c2c7c809f9c4e22c5ac936ae673fb9a2
References: jsc#SLE-16407

The load address is compared with LOAD_PHYSICAL_ADDR using a signed
comparison currently (using jge instruction).

When loading a 64-bit kernel using the new efi32_pe_entry() point added by:

  97aa276579b2 ("efi/x86: Add true mixed mode entry point into .compat section")

using Qemu with -m 3072, the firmware actually loads us above 2Gb,
resulting in a very early crash.

Use the JAE instruction to perform a unsigned comparison instead, as physical
addresses should be considered unsigned.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200301230436.2246909-6-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-14-ardb@kernel.org
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 arch/x86/boot/compressed/head_32.S |    2 +-
 arch/x86/boot/compressed/head_64.S |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -113,7 +113,7 @@ SYM_FUNC_START(startup_32)
 	notl	%eax
 	andl    %eax, %ebx
 	cmpl	$LOAD_PHYSICAL_ADDR, %ebx
-	jge	1f
+	jae	1f
 #endif
 	movl	$LOAD_PHYSICAL_ADDR, %ebx
 1:
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -112,7 +112,7 @@ SYM_FUNC_START(startup_32)
 	notl	%eax
 	andl	%eax, %ebx
 	cmpl	$LOAD_PHYSICAL_ADDR, %ebx
-	jge	1f
+	jae	1f
 #endif
 	movl	$LOAD_PHYSICAL_ADDR, %ebx
 1:
@@ -309,7 +309,7 @@ ENTRY(startup_64)
 	notq	%rax
 	andq	%rax, %rbp
 	cmpq	$LOAD_PHYSICAL_ADDR, %rbp
-	jge	1f
+	jae	1f
 #endif
 	movq	$LOAD_PHYSICAL_ADDR, %rbp
 1: