Re: [Minios-devel] [UNIKRAFT PATCH v3 4/7] plat/xen: Add preinit_array and init_array sections (x86, ARM)

[Yuri Volchkov <yuri.volchkov@xxxxxxxxx>]

Reviewed-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>

Simon Kuenzer <simon.kuenzer@xxxxxxxxx> writes:

> Adds preinit_array and init_array sections with the linker script.
> Those sections are populated by the compiler/linker with function
> pointer arrays. Such functions are typically part of initializing
> the language runtime (e.g., C++) and have to be called early during
> bootstrapping. However, they can also be used by Unikraft libraries
> for early initializations (functions with constructor attribute).
>
> Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> ---
>  plat/xen/arm/link32.ld | 43 +++++++++++++++++++------------------------
>  plat/xen/memory.c      | 10 +++++-----
>  plat/xen/x86/link64.ld | 17 +++++++++++++++++
>  3 files changed, 41 insertions(+), 29 deletions(-)
>
> diff --git a/plat/xen/arm/link32.ld b/plat/xen/arm/link32.ld
> index 77184c0..4508e05 100644
> --- a/plat/xen/arm/link32.ld
> +++ b/plat/xen/arm/link32.ld
> @@ -47,37 +47,32 @@ SECTIONS
>  
>       _etext = .;                     /* End of text section */
>  
> +     /* Read-only data */
>       _rodata = .;
> -     .rodata : { *(.rodata) *(.rodata.*) }
> +     .rodata :
> +     {
> +             *(.rodata)
> +             *(.rodata.*)
> +     }
>       . = ALIGN(4096);
>       _erodata = .;
>  
> -     /* newlib initialization functions */
> -     . = ALIGN(32 / 8);
> -     PROVIDE (__preinit_array_start = .);
> -     .preinit_array : { *(.preinit_array) }
> -     PROVIDE (__preinit_array_end = .);
> -     PROVIDE (__init_array_start = .);
> -     .init_array : { *(.init_array) }
> -     PROVIDE (__init_array_end = .);
> -     PROVIDE (__fini_array_start = .);
> -     .fini_array : { *(.fini_array) }
> -     PROVIDE (__fini_array_end = .);
> -
> -     .ctors : {
> -             __CTOR_LIST__ = .;
> -             *(.ctors)
> -             CONSTRUCTORS
> -             LONG(0)
> -             __CTOR_END__ = .;
> +     _ctors = .;
> +     .preinit_array : {
> +             . = ALIGN(0x8);
> +             PROVIDE_HIDDEN (__preinit_array_start = .);
> +             KEEP (*(.preinit_array))
> +             PROVIDE_HIDDEN (__preinit_array_end = .);
>       }
>  
> -     .dtors : {
> -             __DTOR_LIST__ = .;
> -             *(.dtors)
> -             LONG(0)
> -             __DTOR_END__ = .;
> +     .init_array : {
> +             . = ALIGN(0x8);
> +             PROVIDE_HIDDEN (__init_array_start = .);
> +             KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) 
> SORT_BY_INIT_PRIORITY(.ctors.*)))
> +             KEEP (*(.init_array .ctors))
> +             PROVIDE_HIDDEN (__init_array_end = .);
>       }
> +     _ectors = .;
>  
>       .data : {                       /* Data */
>               _data = .;
> diff --git a/plat/xen/memory.c b/plat/xen/memory.c
> index c40ea3d..df56616 100644
> --- a/plat/xen/memory.c
> +++ b/plat/xen/memory.c
> @@ -50,7 +50,7 @@ int ukplat_memregion_count(void)
>  
>  int ukplat_memregion_get(int i, struct ukplat_memregion_desc *m)
>  {
> -     extern char _text, _etext, _data, _edata, _rodata, _erodata, _end, 
> __bss_start;
> +     extern char _text, _etext, _data, _edata, _rodata, _erodata, _ctors, 
> _ectors, _end, __bss_start;
>  
>       UK_ASSERT(m);
>  
> @@ -73,13 +73,13 @@ int ukplat_memregion_get(int i, struct 
> ukplat_memregion_desc *m)
>               m->name  = "rodata";
>  #endif
>               break;
> -     case 2: /* ctors, dtors */
> -             m->base  = &_erodata;
> -             m->len   = (size_t) &_data - (size_t) &_erodata;
> +     case 2: /* ctors */
> +             m->base  = &_ctors;
> +             m->len   = (size_t) &_ectors - (size_t) &_ctors;
>               m->flags = (UKPLAT_MEMRF_RESERVED
>                           | UKPLAT_MEMRF_READABLE);
>  #if UKPLAT_MEMRNAME
> -             m->name  = "ctors+dtors";
> +             m->name  = "ctors";
>  #endif
>               break;
>       case 3: /* data */
> diff --git a/plat/xen/x86/link64.ld b/plat/xen/x86/link64.ld
> index dd092aa..5391dbd 100644
> --- a/plat/xen/x86/link64.ld
> +++ b/plat/xen/x86/link64.ld
> @@ -47,6 +47,23 @@ SECTIONS
>       . = ALIGN(4096);
>       _erodata = .;
>  
> +     _ctors = .;
> +     .preinit_array : {
> +             . = ALIGN(0x8);
> +             PROVIDE_HIDDEN (__preinit_array_start = .);
> +             KEEP (*(.preinit_array))
> +             PROVIDE_HIDDEN (__preinit_array_end = .);
> +     }
> +
> +     .init_array : {
> +             . = ALIGN(0x8);
> +             PROVIDE_HIDDEN (__init_array_start = .);
> +             KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) 
> SORT_BY_INIT_PRIORITY(.ctors.*)))
> +             KEEP (*(.init_array .ctors))
> +             PROVIDE_HIDDEN (__init_array_end = .);
> +     }
> +     _ectors = .;
> +
>       _data = .;
>       .data : {                       /* Data */
>               *(.data)
> -- 
> 2.7.4
>
>
> _______________________________________________
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> Minios-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/minios-devel

-- 
Yuri Volchkov
Software Specialist

NEC Europe Ltd
Kurfürsten-Anlage 36
D-69115 Heidelberg

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