linux-kernel - [PATCH v2 05/16] x86/compressed: efi-mixed: move efi32_entry out of head

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Date:   Wed, 21 Sep 2022 16:54:11 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Michael Roth <michael.roth@....com>
Subject: [PATCH v2 05/16] x86/compressed: efi-mixed: move efi32_entry out of head_64.S

Move the efi32_entry() routine out of head_64.S and into efi-mixed.S,
which reduces clutter in the complicated startup routines. It also
permits linkage of some symbols used by code to be made local.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/boot/compressed/efi_mixed.S | 44 +++++++++++++++-----
 arch/x86/boot/compressed/head_64.S   | 32 --------------
 2 files changed, 34 insertions(+), 42 deletions(-)

diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S
index 77e77c3ea393..5007a44cd966 100644
--- a/arch/x86/boot/compressed/efi_mixed.S
+++ b/arch/x86/boot/compressed/efi_mixed.S
@@ -105,7 +105,7 @@ SYM_FUNC_START(__efi64_thunk)
 	/*
 	 * Switch to IDT and GDT with 32-bit segments. This is the firmware GDT
 	 * and IDT that was installed when the kernel started executing. The
-	 * pointers were saved at the EFI stub entry point in head_64.S.
+	 * pointers were saved by the efi32_entry() routine below.
 	 *
 	 * Pass the saved DS selector to the 32-bit code, and use far return to
 	 * restore the saved CS selector.
@@ -217,22 +217,46 @@ SYM_FUNC_START_LOCAL(efi_enter32)
 	lret
 SYM_FUNC_END(efi_enter32)
 
+SYM_FUNC_START(efi32_entry)
+	call	1f
+1:	pop	%ebx
+
+	/* Save firmware GDTR and code/data selectors */
+	sgdtl	(efi32_boot_gdt - 1b)(%ebx)
+	movw	%cs, (efi32_boot_cs - 1b)(%ebx)
+	movw	%ds, (efi32_boot_ds - 1b)(%ebx)
+
+	/* Store firmware IDT descriptor */
+	sidtl	(efi32_boot_idt - 1b)(%ebx)
+
+	/* Store boot arguments */
+	leal	(efi32_boot_args - 1b)(%ebx), %ebx
+	movl	%ecx, 0(%ebx)
+	movl	%edx, 4(%ebx)
+	movl	%esi, 8(%ebx)
+	movb	$0x0, 12(%ebx)          // efi_is64
+
+	/* Disable paging */
+	movl	%cr0, %eax
+	btrl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
+	jmp	startup_32
+SYM_FUNC_END(efi32_entry)
+
 	.data
 	.balign	8
-SYM_DATA_START(efi32_boot_gdt)
+SYM_DATA_START_LOCAL(efi32_boot_gdt)
 	.word	0
 	.quad	0
 SYM_DATA_END(efi32_boot_gdt)
 
-SYM_DATA_START(efi32_boot_idt)
+SYM_DATA_START_LOCAL(efi32_boot_idt)
 	.word	0
 	.quad	0
 SYM_DATA_END(efi32_boot_idt)
 
-SYM_DATA_START(efi32_boot_cs)
-	.word	0
-SYM_DATA_END(efi32_boot_cs)
-
-SYM_DATA_START(efi32_boot_ds)
-	.word	0
-SYM_DATA_END(efi32_boot_ds)
+SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
+SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
+SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
+SYM_DATA(efi_is64, .byte 1)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 9ae6ddccd3ef..be95d5685717 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -289,35 +289,6 @@ SYM_FUNC_START(efi32_stub_entry)
 	popl	%esi
 	jmp	efi32_entry
 SYM_FUNC_END(efi32_stub_entry)
-
-	.text
-SYM_FUNC_START_LOCAL(efi32_entry)
-	call	1f
-1:	pop	%ebx
-
-	/* Save firmware GDTR and code/data selectors */
-	sgdtl	(efi32_boot_gdt - 1b)(%ebx)
-	movw	%cs, (efi32_boot_cs - 1b)(%ebx)
-	movw	%ds, (efi32_boot_ds - 1b)(%ebx)
-
-	/* Store firmware IDT descriptor */
-	sidtl	(efi32_boot_idt - 1b)(%ebx)
-
-	/* Store boot arguments */
-	leal	(efi32_boot_args - 1b)(%ebx), %ebx
-	movl	%ecx, 0(%ebx)
-	movl	%edx, 4(%ebx)
-	movl	%esi, 8(%ebx)
-	movb	$0x0, 12(%ebx)          // efi_is64
-
-	/* Disable paging */
-	movl	%cr0, %eax
-	btrl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-
-	jmp	startup_32
-SYM_FUNC_END(efi32_entry)
-	__HEAD
 #endif
 
 	.code64
@@ -750,9 +721,6 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
 SYM_DATA(image_offset, .long 0)
 #endif
 #ifdef CONFIG_EFI_MIXED
-SYM_DATA(efi32_boot_args, .long 0, 0, 0)
-SYM_DATA(efi_is64, .byte 1)
-
 #define ST32_boottime		60 // offsetof(efi_system_table_32_t, boottime)
 #define BS32_handle_protocol	88 // offsetof(efi_boot_services_32_t, handle_protocol)
 #define LI32_image_base		32 // offsetof(efi_loaded_image_32_t, image_base)
-- 
2.35.1