Subject: bug#41982: [PATCH v2] grub-core: Build fixes for i386

From: Jan Nieuwenhuizen <[email-masked]>
Date: Wed, 08 Jul 2020 19:29:31 +0200

Jan Nieuwenhuizen writes:

Hello!

> When cross-compiling Grub-2.04 from i386-linux-gnu to i586-pc-hurd on
> GNU Guix, I got this error

Today, we found* that my patch introduced a regression: a native, EFI
build on i686-linux-gnu failed with

    lib/i386/relocator64.S:97: Error: bad register name `%rsp'

The attached v2 fixes that.

Greetings,
Janneke

*) http://logs.guix.gnu.org/guix/2020-07-08.log#104852

>From 17b242e7b80108f1467037e15b605595e4823b2e Mon Sep 17 00:00:00 2001
From: "Jan (janneke) Nieuwenhuizen" <[email-masked]>
Date: Sun, 21 Jun 2020 15:10:40 +0200
Subject: [PATCH v2] grub-core: Build fixes for i386
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset=UTF-8

* grub-core/lib/i386/relocator64.S: Avoid x86_64 instructions on i386.
---
 grub-core/lib/i386/relocator64.S | 33 +++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/grub-core/lib/i386/relocator64.S b/grub-core/lib/i386/relocator64.S
index 148f38adb..ea39908c1 100644
--- a/grub-core/lib/i386/relocator64.S
+++ b/grub-core/lib/i386/relocator64.S
@@ -63,7 +63,9 @@ VARIABLE(grub_relocator64_cr3)
 	movq	%rax, %cr3
 #endif
 
+#ifdef __x86_64__
 	.code64
+#endif
 
 	/* mov imm64, %rax */
 	.byte 	0x48
@@ -71,7 +73,14 @@ VARIABLE(grub_relocator64_cr3)
 VARIABLE(grub_relocator64_rsp)
 	.quad	0
 
+#ifndef __x86_64__
+	/* movq	%rax, %rsp */
+	.byte 	0x48
+	.byte	0x89
+	.byte	0xc4
+#else
 	movq	%rax, %rsp
+#endif
 
 #ifdef GRUB_MACHINE_EFI
 	jmp	LOCAL(skip_efi_stack_align)
@@ -85,7 +94,14 @@ VARIABLE(grub_relocator64_rsp)
 	 */
 VARIABLE(grub_relocator64_efi_start)
 	/* Align the stack as UEFI spec requires. */
+#ifndef __x86_64__
+	.byte 0x48
+        .byte 0x83
+        .byte 0xe4
+        .byte 0xf0
+#else
 	andq	$~15, %rsp
+#endif
 
 LOCAL(skip_efi_stack_align):
 #endif
@@ -95,8 +111,15 @@ LOCAL(skip_efi_stack_align):
 VARIABLE(grub_relocator64_rsi)
 	.quad	0
 
+#ifndef	__x86_64__
+	/* movq	%rax, %rsi */
+	.byte 	0x48
+	.byte	0x89
+	.byte 	0xc6
+#else
 	movq	%rax, %rsi
-	
+#endif
+
 	/* mov imm64, %rax */
 	.byte 	0x48
 	.byte	0xb8
@@ -128,6 +151,14 @@ VARIABLE(grub_relocator64_rdx)
 #ifdef __APPLE__
 	.byte 0xff, 0x25
 	.quad 0
+#elif !defined (__x86_64__)
+	/* jmp *LOCAL(jump_addr) (%rip) */
+	.byte 0xff
+        .byte 0x25
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
 #else
 	jmp *LOCAL(jump_addr) (%rip)
 #endif
-- 
Jan Nieuwenhuizen <[email-masked]> | GNU LilyPond http://lilypond.org
Freelance IT http://JoyofSource.com | Avatar® http://AvatarAcademy.com

-- 
Jan Nieuwenhuizen <[email-masked]> | GNU LilyPond http://lilypond.org
Freelance IT http://JoyofSource.com | Avatar® http://AvatarAcademy.com