[PATCH] [POWERPC] Clean up some linker and symbol usage

[PATCH] [POWERPC] Clean up some linker and symbol usage

[Kumar Gala]

* use _stext and _end sybmols when reserving kernel text in the lmb.  Use
  of these symbols is a bit more robust way to determine the physical start
  and size of the kernel text.
* PAGE_OFFSET is not always the start of code, use _stext instead.
* grab PAGE_SIZE and KERNELBASE from asm/page.h like ppc64 does.  Makes the
  code a bit more common and provide a single place to manipulate the defines
  for things like kdump.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
---
 arch/powerpc/kernel/prom.c        |    2 +-
 arch/powerpc/kernel/setup_32.c    |    2 +-
 arch/powerpc/kernel/setup_64.c    |    2 +-
 arch/powerpc/kernel/vmlinux.lds.S |    4 +---
 4 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 9330920..60ef7d1 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -1124,7 +1124,7 @@ void __init early_init_devtree(void *params)
 	parse_early_param();

 	/* Reserve LMB regions used by kernel, initrd, dt, etc... */
-	lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
+	lmb_reserve(__pa(_stext), _end - _stext);
 	reserve_kdump_trampoline();
 	reserve_crashkernel();
 	early_reserve_mem();
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index cd870a8..b0989ca 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -277,7 +277,7 @@ void __init setup_arch(char **cmdline_p)
 	if (ppc_md.panic)
 		setup_panic();

-	init_mm.start_code = PAGE_OFFSET;
+	init_mm.start_code = (unsigned long)_stext;
 	init_mm.end_code = (unsigned long) _etext;
 	init_mm.end_data = (unsigned long) _edata;
 	init_mm.brk = klimit;
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 2c2d831..0205d40 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -510,7 +510,7 @@ void __init setup_arch(char **cmdline_p)
 	if (ppc_md.panic)
 		setup_panic();

-	init_mm.start_code = PAGE_OFFSET;
+	init_mm.start_code = (unsigned long)_stext;
 	init_mm.end_code = (unsigned long) _etext;
 	init_mm.end_data = (unsigned long) _edata;
 	init_mm.brk = klimit;
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 0afb9e3..b5a76bc 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -1,11 +1,9 @@
 #ifdef CONFIG_PPC64
-#include <asm/page.h>
 #define PROVIDE32(x)	PROVIDE(__unused__##x)
 #else
-#define PAGE_SIZE	4096
-#define KERNELBASE	CONFIG_KERNEL_START
 #define PROVIDE32(x)	PROVIDE(x)
 #endif
+#include <asm/page.h>
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/cache.h>

-- 
1.5.4.1

Re: [PATCH] [POWERPC] Clean up some linker and symbol usage

[Paul Mackerras]

Kumar Gala writes:

> @@ -1124,7 +1124,7 @@ void __init early_init_devtree(void *params)
>  	parse_early_param();
> 
>  	/* Reserve LMB regions used by kernel, initrd, dt, etc... */
> -	lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
> +	lmb_reserve(__pa(_stext), _end - _stext);

In the kdump case where the kernel starts at the 32MB point
(physical), wouldn't we want to reserve the first 32MB of RAM so that
it can't get allocated and used for random things?  Doesn't that first
32MB contain the old kernel that we want to write out?

Or do we only have the 32MB starting at the 32MB point in the lmb
system in that case?

Paul.

Re: [PATCH] [POWERPC] Clean up some linker and symbol usage

[Michael Ellerman]

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On Fri, 2008-03-28 at 10:14 +1100, Paul Mackerras wrote:
> Kumar Gala writes:
> 
> > @@ -1124,7 +1124,7 @@ void __init early_init_devtree(void *params)
> >  	parse_early_param();
> > 
> >  	/* Reserve LMB regions used by kernel, initrd, dt, etc... */
> > -	lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
> > +	lmb_reserve(__pa(_stext), _end - _stext);
> 
> In the kdump case where the kernel starts at the 32MB point
> (physical), wouldn't we want to reserve the first 32MB of RAM so that
> it can't get allocated and used for random things?  Doesn't that first
> 32MB contain the old kernel that we want to write out?

For kdump there is nMB of memory reserved at 32MB for the 2nd kernel,
and that's all it gets, all of the other memory is the old kernel text
or the old kernel's data.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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Re: [PATCH] [POWERPC] Clean up some linker and symbol usage

[Kumar Gala]

On Mar 27, 2008, at 7:45 PM, Michael Ellerman wrote:
>
> On Fri, 2008-03-28 at 10:14 +1100, Paul Mackerras wrote:
>> Kumar Gala writes:
>>
>>> @@ -1124,7 +1124,7 @@ void __init early_init_devtree(void *params)
>>> 	parse_early_param();
>>>
>>> 	/* Reserve LMB regions used by kernel, initrd, dt, etc... */
>>> -	lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
>>> +	lmb_reserve(__pa(_stext), _end - _stext);
>>
>> In the kdump case where the kernel starts at the 32MB point
>> (physical), wouldn't we want to reserve the first 32MB of RAM so that
>> it can't get allocated and used for random things?  Doesn't that  
>> first
>> 32MB contain the old kernel that we want to write out?
>
> For kdump there is nMB of memory reserved at 32MB for the 2nd kernel,
> and that's all it gets, all of the other memory is the old kernel text
> or the old kernel's data.

My understanding is those reservations are handled by the device tree  
that is passed to the 2nd kernel.

- k