[PATCH v2 2/4] arm64: move early boot code to the .init segment
will.deacon at arm.com
Thu Apr 14 09:32:36 PDT 2016
On Wed, Mar 30, 2016 at 05:43:07PM +0200, Ard Biesheuvel wrote:
> Apart from the arm64/linux and EFI header data structures, there is nothing
> in the .head.text section that must reside at the beginning of the Image.
> So let's move it to the .init section where it belongs.
> Note that this involves some minor tweaking of the EFI header, primarily
> because the address of 'stext' no longer coincides with the start of the
> .text section. It also requires a couple of relocated symbol references
> to be slightly rewritten or their definition moved to the linker script.
> bl preserve_boot_args
> bl el2_setup // Drop to EL1, w20=cpu_boot_mode
> @@ -223,12 +224,12 @@ ENTRY(stext)
> * the TCR will have been set.
> ldr x27, 0f // address to jump to after
> - // MMU has been enabled
> + neg x27, x27 // MMU has been enabled
> adr_l lr, __enable_mmu // return (PIC) address
> b __cpu_setup // initialise processor
> .align 3
> -0: .quad __mmap_switched - (_head - TEXT_OFFSET) + KIMAGE_VADDR
> +0: .quad (_text - TEXT_OFFSET) - __mmap_switched - KIMAGE_VADDR
I'm struggling to understand why you need to change this. Furthermore,
it looks like the gas docs for expressions require that addition/subtraction
can only be performed on arguments that are in the same section, so
this feels pretty rickety.
What's the problem you're solving here?
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