Re: [PATCH] ARM: xip: Use correct symbol for end of ROM marker

[Russell King - ARM Linux]

On Wed, Nov 11, 2015 at 09:17:35AM -0500, Chris Brandt wrote:
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index b58fd66..195554d 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -26,7 +26,7 @@
>   *   __ctors_start, __ctors_end
>   */
>  extern char _text[], _stext[], _etext[];
> -extern char _data[], _sdata[], _edata[];
> +extern char _data[], _sdata[], _edata[], _edata_loc[];

It's not good practice to put non-generic symbols in generic header files.
_edata_loc is an ARM specific symbol which no other architecture defines.
Please create an ARM private asm/sections.h header, which should include
the asm-generic version, and also declare the additional symbol.

Thanks.

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RE: [PATCH] ARM: xip: Use correct symbol for end of ROM marker

[Chris Brandt]

> I think below is required as well.
>
> --- a/arch/arm/kernel/module.c
> +++ b/arch/arm/kernel/module.c
> @@ -34,7 +36,7 @@
>   * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
>   */
>  #undef MODULES_VADDR
> -#define MODULES_VADDR(((unsigned long)_etext + ~PMD_MASK) & PMD_MASK)
> +#define MODULES_VADDR(((unsigned long)_edata_loc + ~PMD_MASK) & 
> PMD_MASK)
>  #endif


Thank you!
Somehow I missed that file when I was moving from one tree to another when 
preparing my commits.

I'll update and resubmit the patch.

Chris

Re: [PATCH] ARM: xip: Use correct symbol for end of ROM marker

[Peter Hurley]

On 11/11/2015 09:17 AM, Chris Brandt wrote:
> For an XIP build, _edata_loc, not _etext, represents the end of the
> binary image that will be programmed into ROM and mapped into the
> MODULES_VADDR area.
> With an XIP kernel, nothing is loaded into RAM before boot, meaning
> you have to take into account the size of the entire binary image
> that was programmed, including the init data values that will be copied
> to RAM during kernel boot.
> 
> This fixes the bug where you might lose the end of your kernel area
> after page table setup is complete.
> 
> 
> Signed-off-by: Chris Brandt 
> ---
>  arch/arm/mm/mmu.c  |4 ++--
>  include/asm-generic/sections.h |2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 4867f5d..dd5a56b 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1210,7 +1210,7 @@ static inline void prepare_page_table(void)
>  
>  #ifdef CONFIG_XIP_KERNEL
>   /* The XIP kernel is mapped in the module area -- skip over it */
> - addr = ((unsigned long)_etext + PMD_SIZE - 1) & PMD_MASK;
> + addr = ((unsigned long)_edata_loc + PMD_SIZE - 1) & PMD_MASK;
>  #endif
>   for ( ; addr < PAGE_OFFSET; addr += PMD_SIZE)
>   pmd_clear(pmd_off_k(addr));
> @@ -1292,7 +1292,7 @@ static void __init devicemaps_init(const struct 
> machine_desc *mdesc)
>  #ifdef CONFIG_XIP_KERNEL
>   map.pfn = __phys_to_pfn(CONFIG_XIP_PHYS_ADDR & SECTION_MASK);
>   map.virtual = MODULES_VADDR;
> - map.length = ((unsigned long)_etext - map.virtual + ~SECTION_MASK) & 
> SECTION_MASK;
> + map.length = ((unsigned long)_edata_loc - map.virtual + ~SECTION_MASK) 
> & SECTION_MASK;
>   map.type = MT_ROM;
>   create_mapping(&map);
>  #endif
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index b58fd66..195554d 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -26,7 +26,7 @@
>   *   __ctors_start, __ctors_end
>   */
>  extern char _text[], _stext[], _etext[];
> -extern char _data[], _sdata[], _edata[];
> +extern char _data[], _sdata[], _edata[], _edata_loc[];
>  extern char __bss_start[], __bss_stop[];
>  extern char __init_begin[], __init_end[];
>  extern char _sinittext[], _einittext[];
> 

I think below is required as well.

--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -34,7 +36,7 @@
  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
  */
 #undef MODULES_VADDR
-#define MODULES_VADDR  (((unsigned long)_etext + ~PMD_MASK) & PMD_MASK)
+#define MODULES_VADDR  (((unsigned long)_edata_loc + ~PMD_MASK) & PMD_MASK)
 #endif
 
Regards,
Peter Hurley

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