Re: [PATCH 1/2] powerpc/vdso: Remove unused ENTRY in linker scripts

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 5/10/22 06:46, Nathan Chancellor wrote:
> When linking vdso{32,64}.so.dbg with ld.lld, there is a warning about
> not finding _start for the starting address:
> 
>    ld.lld: warning: cannot find entry symbol _start; not setting start address
>    ld.lld: warning: cannot find entry symbol _start; not setting start address
> 
> Looking at GCC + GNU ld, the entry point address is 0x0:
> 
>    $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
>    File: vdso32.so.dbg
>      Entry point address:               0x0
>    File: vdso64.so.dbg
>      Entry point address:               0x0
> 
> This matches what ld.lld emits:
> 
>    $ powerpc64le-linux-gnu-readelf -p .comment vdso{32,64}.so.dbg
> 
>    File: vdso32.so.dbg
> 
>    String dump of section '.comment':
>      [     0]  Linker: LLD 14.0.0
>      [    14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)
> 
>    File: vdso64.so.dbg
> 
>    String dump of section '.comment':
>      [     0]  Linker: LLD 14.0.0
>      [    14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)
> 
>    $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
>    File: vdso32.so.dbg
>      Entry point address:               0x0
>    File: vdso64.so.dbg
>      Entry point address:               0x0
> 
> Remove ENTRY to remove the warning, as it is unnecessary for the vDSO to
> function correctly.


Sounds more like a bugfix to me - _start is simply not defined, I wonder 
why ld is not complaining.


Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>


> 
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>   arch/powerpc/kernel/vdso/vdso32.lds.S | 1 -
>   arch/powerpc/kernel/vdso/vdso64.lds.S | 1 -
>   2 files changed, 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
> index 58e0099f70f4..e0d19d74455f 100644
> --- a/arch/powerpc/kernel/vdso/vdso32.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
> @@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf32-powerpcle", "elf32-powerpcle", "elf32-powerpcle")
>   OUTPUT_FORMAT("elf32-powerpc", "elf32-powerpc", "elf32-powerpc")
>   #endif
>   OUTPUT_ARCH(powerpc:common)
> -ENTRY(_start)
>   
>   SECTIONS
>   {
> diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S b/arch/powerpc/kernel/vdso/vdso64.lds.S
> index 0288cad428b0..1a4a7bc4c815 100644
> --- a/arch/powerpc/kernel/vdso/vdso64.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
> @@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", "elf64-powerpcle")
>   OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc")
>   #endif
>   OUTPUT_ARCH(powerpc:common64)
> -ENTRY(_start)
>   
>   SECTIONS
>   {