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

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  [PATCH] ARM: xip: Use correct symbol for end of ROM marker Chris Brandt <chris.brandt@renesas.com> - 2015-11-11 15:20 +0100
    Re: [PATCH] ARM: xip: Use correct symbol for end of ROM marker Peter Hurley <peter@hurleysoftware.com> - 2015-11-12 13:20 +0100
      RE: [PATCH] ARM: xip: Use correct symbol for end of ROM marker Chris Brandt <Chris.Brandt@renesas.com> - 2015-11-12 14:20 +0100
    Re: [PATCH] ARM: xip: Use correct symbol for end of ROM marker Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-12 17:40 +0100

#1267214 — [PATCH] ARM: xip: Use correct symbol for end of ROM marker

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 <chris.brandt@renesas.com>
---
 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[];
-- 
1.7.9.5


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#1267872

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 <chris.brandt@renesas.com>
> ---
>  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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#1267902

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aXRzLg0KDQpJJ2xsIHVwZGF0ZSBhbmQgcmVzdWJtaXQgdGhlIHBhdGNoLg0KDQpDaHJpcw0KDQo=
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#1268098

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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