Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 06a4b6d0 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Russell King
Browse files

ARM: 8677/1: boot/compressed: fix decompressor header layout for v7-M 



As reported by Patrice, the header layout of the decompressor is
incorrect when building for v7-M. In this case, the __nop macro
resolves to 'mov r0, r0', which is emitted as a narrow encoding,
resulting in the header data fields to end up at lower offsets than
required.

Given the variety of targets we need to support with the same code,
the startup sequence is a bit of a jumble, and uses instructions
and macros whose encoding widths cannot be specified (badr), or only
exist in a narrow encoding (bx)

So force the use of a wide encoding in __nop, and replace the start
sequence with a simple jump to the label marking the start of code,
preceded by a Thumb2 mode switch if required (using explicit wide
encodings where appropriate). The label itself can be moved to the
start of code [where it belongs] due to the larger range of branch
instructions as compared to adr instructions.

Reported-by: default avatarPatrice CHOTARD <patrice.chotard@st.com>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 7ef4783e

arch/arm/boot/compressed/efi-header.S

+1 −3
Original line number Diff line number Diff line
@@ -17,14 +17,12 @@ 
		@ there.

		.inst	'M' | ('Z' << 8) | (0x1310 << 16)   @ tstne r0, #0x4d000

#else

		mov	r0, r0

		W(mov)	r0, r0

#endif

		.endm



		.macro	__EFI_HEADER

#ifdef CONFIG_EFI_STUB

		b	__efi_start



		.set	start_offset, __efi_start - start

		.org	start + 0x3c

		@

arch/arm/boot/compressed/head.S

+10 −7
Original line number Diff line number Diff line
@@ -130,19 +130,22 @@ start: 
		.rept	7

		__nop

		.endr

   ARM(		mov	r0, r0		)

   ARM(		b	1f		)

 THUMB(		badr	r12, 1f		)

 THUMB(		bx	r12		)

#ifndef CONFIG_THUMB2_KERNEL

		mov	r0, r0

#else

 AR_CLASS(	sub	pc, pc, #3	)	@ A/R: switch to Thumb2 mode

  M_CLASS(	nop.w			)	@ M: already in Thumb2 mode

		.thumb

#endif

		W(b)	1f



		.word	_magic_sig	@ Magic numbers to help the loader

		.word	_magic_start	@ absolute load/run zImage address

		.word	_magic_end	@ zImage end address

		.word	0x04030201	@ endianness flag



 THUMB(		.thumb			)

1:		__EFI_HEADER



		__EFI_HEADER

1:

 ARM_BE8(	setend	be		)	@ go BE8 if compiled for BE8

 AR_CLASS(	mrs	r9, cpsr	)

#ifdef CONFIG_ARM_VIRT_EXT