linux-kernel - Re: [PATCH] x86_64: Some vmlinux.lds.S cleanups

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Date:	Thu, 26 Oct 2006 09:44:42 -0400
From:	Vivek Goyal <vgoyal@...ibm.com>
To:	Jan Beulich <jbeulich@...ell.com>
Cc:	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@....de>,
	Ian Campbell <Ian.Campbell@...source.com>
Subject: Re: [PATCH] x86_64: Some vmlinux.lds.S cleanups

On Thu, Oct 26, 2006 at 08:08:21AM +0100, Jan Beulich wrote:
> I was about to ack it when I saw that you left .bss in init - that doesn't seem
> too good an idea... Jan
> 

Should I create a separate program header say "bss" for .bss section? Last
time when I suggested it you said there is no need to create a separate
program header for bss.

More program headers we create, we need to make sure that they are on page
size boundaries so that kexec on vmlinux does not break.

Thanks
Vivek

> >>> Vivek Goyal <vgoyal@...ibm.com> 24.10.06 23:01 >>>
> 
> 
> o Some cleanups based on Jan Beulich's suggestions. It boots on my box. Hope
>   does not break anything else.
> 
> o Renamed program header name data.init to init. "init" is now supposed
>   to contain init text/data.
> 
> o Moved sections ".data.init_task" and ".data.page_aligned" into program
>   header "data" as they don't fit logically into "init".
> 
> o Got rid of "R" permission for "note" phdr as only boot loaer is supposed
>   to look at note phdr.
> 
> o Got rid of "E" permission for "data" phdr.  
> 
> Signed-off-by: Vivek Goyal <vgoyal@...ibm.com>
> ---
> 
>  arch/x86_64/kernel/vmlinux.lds.S |   32 ++++++++++++++++----------------
>  1 file changed, 16 insertions(+), 16 deletions(-)
> 
> diff -puN arch/x86_64/kernel/vmlinux.lds.S~x86_64-vmlinux-lds-S-cleanup arch/x86_64/kernel/vmlinux.lds.S
> --- linux-2.6.19-rc3/arch/x86_64/kernel/vmlinux.lds.S~x86_64-vmlinux-lds-S-cleanup	2006-10-24 15:58:23.000000000
> -0400
> +++ linux-2.6.19-rc3-root/arch/x86_64/kernel/vmlinux.lds.S	2006-10-24 16:35:56.000000000 -0400
> @@ -15,10 +15,10 @@ ENTRY(phys_startup_64)
>  jiffies_64 = jiffies;
>  PHDRS {
>  	text PT_LOAD FLAGS(5);	/* R_E */
> -	data PT_LOAD FLAGS(7);	/* RWE */
> +	data PT_LOAD FLAGS(6);	/* RW_ */
>  	user PT_LOAD FLAGS(7);	/* RWE */
> -	data.init PT_LOAD FLAGS(7);	/* RWE */
> -	note PT_NOTE FLAGS(4);	/* R__ */
> +	init PT_LOAD FLAGS(7);	/* RWE */
> +	note PT_NOTE FLAGS(0);	/* None */
>  }
>  SECTIONS
>  {
> @@ -78,9 +78,19 @@ SECTIONS
>    	*(.data.read_mostly)
>    }
>  
> +  . = ALIGN(8192);		/* init_task */
> +  .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
> +	*(.data.init_task)
> +  }
> +
> +  . = ALIGN(4096);
> +  .data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
> +	*(.data.page_aligned)
> +  }
> +
>  #define VSYSCALL_ADDR (-10*1024*1024)
> -#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data.read_mostly) + SIZEOF(.data.read_mostly) + 4095) & ~(4095))
> -#define VSYSCALL_VIRT_ADDR ((ADDR(.data.read_mostly) + SIZEOF(.data.read_mostly) + 4095) & ~(4095))
> +#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data.page_aligned) + SIZEOF(.data.page_aligned) + 4095) & ~(4095))
> +#define VSYSCALL_VIRT_ADDR ((ADDR(.data.page_aligned) + SIZEOF(.data.page_aligned) + 4095) & ~(4095))
>  
>  #define VLOAD_OFFSET (VSYSCALL_ADDR - VSYSCALL_PHYS_ADDR)
>  #define VLOAD(x) (ADDR(x) - VLOAD_OFFSET)
> @@ -129,23 +139,13 @@ SECTIONS
>  #undef VVIRT_OFFSET
>  #undef VVIRT
>  
> -  . = ALIGN(8192);		/* init_task */
> -  .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
> -	*(.data.init_task)
> -  }:data.init
> -
> -  . = ALIGN(4096);
> -  .data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
> -	*(.data.page_aligned)
> -  }
> -
>    /* might get freed after init */
>    . = ALIGN(4096);
>    __smp_alt_begin = .;
>    __smp_alt_instructions = .;
>    .smp_altinstructions : AT(ADDR(.smp_altinstructions) - LOAD_OFFSET) {
>  	*(.smp_altinstructions)
> -  }
> +  }:init
>    __smp_alt_instructions_end = .;
>    . = ALIGN(8);
>    __smp_locks = .;
> _
-
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