Re: [Xen-devel] [PATCH MM-PART2 RESEND v2 08/19] xen/arm64: head: Move earlyprintk messages in .rodata.str

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 14 May 2019, Julien Grall wrote:
> At the moment, the earlyprintk messages are interleaved with the
> instructions. This makes more difficult to read the objdump output.
> 
> Introduce a new macro to add a string in .rodata.str and use it for all
> the earlyprintk messages.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> 
> I haven't done a similar change in arm32 yet because the compiler will
> throw an error when using 'adr' when load an address from a different
> section (see A5-200 in ARM DDI 0406C.a for the technical reason).
> The change is likely to be more elaborate.
> 
>     Changes in v2:
>         - Add Andrii's reviewed-by
> ---
>  xen/arch/arm/arm64/head.S       | 14 +++++---------
>  xen/include/asm-arm/asm_defns.h |  5 +++++
>  2 files changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index ad446e7345..b957eb90fb 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -81,13 +81,10 @@
>  /* Macro to print a string to the UART, if there is one.
>   * Clobbers x0-x3. */
>  #ifdef CONFIG_EARLY_PRINTK
> -#define PRINT(_s)       \
> -        adr   x0, 98f ; \
> -        bl    puts    ; \
> -        b     99f     ; \
> -98:     .asciz _s     ; \
> -        .align 2      ; \
> -99:
> +#define PRINT(_s)           \
> +        adr   x0, 98f ;     \
> +        bl    puts    ;     \
> +        RODATA_STR(98, _s)
>  #else /* CONFIG_EARLY_PRINTK */
>  #define PRINT(s)
>  #endif /* !CONFIG_EARLY_PRINTK */
> @@ -633,8 +630,7 @@ init_uart:
>  #endif
>          adr   x0, 1f
>          b     puts
> -1:      .asciz "- UART enabled -\r\n"
> -        .align 4
> +RODATA_STR(1, "- UART enabled -\r\n")
>  
>  /* Print early debug messages.
>   * x0: Nul-terminated string to print.
> diff --git a/xen/include/asm-arm/asm_defns.h b/xen/include/asm-arm/asm_defns.h
> index 02be83e2b3..3f21def0ab 100644
> --- a/xen/include/asm-arm/asm_defns.h
> +++ b/xen/include/asm-arm/asm_defns.h
> @@ -16,6 +16,11 @@
>  # error "unknown ARM variant"
>  #endif
>  
> +#define RODATA_STR(label, msg)                  \
> +.pushsection .rodata.str, "aMS", %progbits, 1 ; \
> +label:  .asciz msg;                             \
> +.popsection
> +
>  #endif /* __ARM_ASM_DEFNS_H__ */
>  /*
>   * Local variables:
> -- 
> 2.11.0
> 

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