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SubjectRe: [PATCH 5/8] arm64: kernel: replace early 64-bit literal loads with move-immediates
Date
On 04/18/2016 06:09 PM, Ard Biesheuvel wrote:
> When building a relocatable kernel, we currently rely on the fact that
> early 64-bit literal loads need to be deferred to after the relocation
> has been performed only if they involve symbol references, and not if
> they involve assemble time constants. While this is not an unreasonable
> assumption to make, it is better to switch to movk/movz sequences, since
> these are guaranteed to be resolved at link time, simply because there are
> no dynamic relocation types to describe them.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> arch/arm64/kernel/head.S | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 0d487d90d221..dae9cabaadf5 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -337,7 +337,7 @@ __create_page_tables:
> cmp x0, x6
> b.lo 1b
>
> - ldr x7, =SWAPPER_MM_MMUFLAGS
> + mov x7, SWAPPER_MM_MMUFLAGS

mov_q here too?

---
Best Regards, Laurentiu

>
> /*
> * Create the identity mapping.
> @@ -393,7 +393,7 @@ __create_page_tables:
> * Map the kernel image (starting with PHYS_OFFSET).
> */
> mov x0, x26 // swapper_pg_dir
> - ldr x5, =KIMAGE_VADDR
> + mov_q x5, KIMAGE_VADDR
> add x5, x5, x23 // add KASLR displacement
> create_pgd_entry x0, x5, x3, x6
> ldr w6, =kernel_img_size
> @@ -631,7 +631,7 @@ ENTRY(secondary_holding_pen)
> bl el2_setup // Drop to EL1, w20=cpu_boot_mode
> bl set_cpu_boot_mode_flag
> mrs x0, mpidr_el1
> - ldr x1, =MPIDR_HWID_BITMASK
> + mov_q x1, MPIDR_HWID_BITMASK
> and x0, x0, x1
> adr_l x3, secondary_holding_pen_release
> pen: ldr x4, [x3]
> @@ -773,7 +773,7 @@ __primary_switch:
> ldr w9, =__rela_offset // offset to reloc table
> ldr w10, =__rela_size // size of reloc table
>
> - ldr x11, =KIMAGE_VADDR // default virtual offset
> + mov_q x11, KIMAGE_VADDR // default virtual offset
> add x11, x11, x23 // actual virtual offset
> add x8, x8, x11 // __va(.dynsym)
> add x9, x9, x11 // __va(.rela)
>

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