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Commit f4dee0bb authored by Jiri Slaby's avatar Jiri Slaby Committed by Ingo Molnar
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x86/boot/32: Extract efi_pe_entry() from startup_32() 



The efi_pe_entry() body is somehow squashed into startup_32(). In the old days,
we forced startup_32() to start at offset 0x00 and efi_pe_entry() to start
at 0x10.

But this requirement was removed long time ago, in:

  99f857db ("x86, build: Dynamically find entry points in compressed startup code")

The way it is now makes the code less readable and illogical. Given
we can now safely extract the inlined efi_pe_entry() body from
startup_32() into a separate function, we do so and we separate it to two
functions as they are marked already: efi_pe_entry() + efi32_stub_entry().

We also annotate the functions appropriatelly by ENTRY+ENDPROC.

ABI offset is preserved:

  0000   128 FUNC    GLOBAL DEFAULT    6 startup_32
  0080    60 FUNC    GLOBAL DEFAULT    6 efi_pe_entry
  00bc    68 FUNC    GLOBAL DEFAULT    6 efi32_stub_entry

On the top-level, it looked like this:

	ENTRY(startup_32)
	#ifdef CONFIG_EFI_STUB		; start of inlined
		jmp     preferred_addr
	ENTRY(efi_pe_entry)
		... ; a lot of assembly (efi_pe_entry)
	ENTRY(efi32_stub_entry)
		... ; a lot of assembly (efi32_stub_entry)
		leal    preferred_addr(%eax), %eax
		jmp     *%eax
	preferred_addr:
	#endif				; end of inlined
		... ; a lot of assembly (startup_32)
	ENDPROC(startup_32)

And it is now converted into:

	ENTRY(startup_32)
		... ; a lot of assembly (startup_32)
	ENDPROC(startup_32)

	#ifdef CONFIG_EFI_STUB
	ENTRY(efi_pe_entry)
		... ; a lot of assembly (efi_pe_entry)
	ENDPROC(efi_pe_entry)

	ENTRY(efi32_stub_entry)
		... ; a lot of assembly (efi32_stub_entry)
		leal    startup_32(%eax), %eax
		jmp     *%eax
	ENDPROC(efi32_stub_entry)
	#endif

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: ard.biesheuvel@linaro.org
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170824073327.4129-1-jslaby@suse.cz


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ecda85e7

arch/x86/boot/compressed/head_32.S

+64 −65
Original line number Diff line number Diff line
@@ -61,71 +61,6 @@ 


	__HEAD

ENTRY(startup_32)

#ifdef CONFIG_EFI_STUB

	jmp	preferred_addr



	/*

	 * We don't need the return address, so set up the stack so

	 * efi_main() can find its arguments.

	 */

ENTRY(efi_pe_entry)

	add	$0x4, %esp



	call	1f

1:	popl	%esi

	subl	$1b, %esi



	popl	%ecx

	movl	%ecx, efi32_config(%esi)	/* Handle */

	popl	%ecx

	movl	%ecx, efi32_config+8(%esi)	/* EFI System table pointer */



	/* Relocate efi_config->call() */

	leal	efi32_config(%esi), %eax

	add	%esi, 40(%eax)

	pushl	%eax



	call	make_boot_params

	cmpl	$0, %eax

	je	fail

	movl	%esi, BP_code32_start(%eax)

	popl	%ecx

	pushl	%eax

	pushl	%ecx

	jmp	2f		/* Skip efi_config initialization */



ENTRY(efi32_stub_entry)

	add	$0x4, %esp

	popl	%ecx

	popl	%edx



	call	1f

1:	popl	%esi

	subl	$1b, %esi



	movl	%ecx, efi32_config(%esi)	/* Handle */

	movl	%edx, efi32_config+8(%esi)	/* EFI System table pointer */



	/* Relocate efi_config->call() */

	leal	efi32_config(%esi), %eax

	add	%esi, 40(%eax)

	pushl	%eax

2:

	call	efi_main

	cmpl	$0, %eax

	movl	%eax, %esi

	jne	2f

fail:

	/* EFI init failed, so hang. */

	hlt

	jmp	fail

2:

	movl	BP_code32_start(%esi), %eax

	leal	preferred_addr(%eax), %eax

	jmp	*%eax



preferred_addr:

#endif

	cld

	/*

	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
@@ -208,6 +143,70 @@ preferred_addr: 
	jmp	*%eax

ENDPROC(startup_32)



#ifdef CONFIG_EFI_STUB

/*

 * We don't need the return address, so set up the stack so efi_main() can find

 * its arguments.

 */

ENTRY(efi_pe_entry)

	add	$0x4, %esp



	call	1f

1:	popl	%esi

	subl	$1b, %esi



	popl	%ecx

	movl	%ecx, efi32_config(%esi)	/* Handle */

	popl	%ecx

	movl	%ecx, efi32_config+8(%esi)	/* EFI System table pointer */



	/* Relocate efi_config->call() */

	leal	efi32_config(%esi), %eax

	add	%esi, 40(%eax)

	pushl	%eax



	call	make_boot_params

	cmpl	$0, %eax

	je	fail

	movl	%esi, BP_code32_start(%eax)

	popl	%ecx

	pushl	%eax

	pushl	%ecx

	jmp	2f		/* Skip efi_config initialization */

ENDPROC(efi_pe_entry)



ENTRY(efi32_stub_entry)

	add	$0x4, %esp

	popl	%ecx

	popl	%edx



	call	1f

1:	popl	%esi

	subl	$1b, %esi



	movl	%ecx, efi32_config(%esi)	/* Handle */

	movl	%edx, efi32_config+8(%esi)	/* EFI System table pointer */



	/* Relocate efi_config->call() */

	leal	efi32_config(%esi), %eax

	add	%esi, 40(%eax)

	pushl	%eax

2:

	call	efi_main

	cmpl	$0, %eax

	movl	%eax, %esi

	jne	2f

fail:

	/* EFI init failed, so hang. */

	hlt

	jmp	fail

2:

	movl	BP_code32_start(%esi), %eax

	leal	startup_32(%eax), %eax

	jmp	*%eax

ENDPROC(efi32_stub_entry)

#endif



	.text

relocated: