[PATCH] of: Fix memory block alignment in early_init_dt_add_memory_arch()

[PATCH] of: Fix memory block alignment in early_init_dt_add_memory_arch()

[Geert Uytterhoeven]

If a memory block is not aligned to PAGE_SIZE, its base address must be
rounded up, not down, and its size must be reduced.

Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>
---
 drivers/of/fdt.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index f46a24ffa3fe..95fa81b8ca19 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 {
 	const u64 phys_offset = __pa(PAGE_OFFSET);
-	base &= PAGE_MASK;
+
+	if (!PAGE_ALIGNED(base)) {
+		size -= PAGE_SIZE - (base & ~PAGE_MASK);
+		base = PAGE_ALIGN(base);
+	}
 	size &= PAGE_MASK;
 
 	if (base > MAX_PHYS_ADDR) {
-- 
1.9.1

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Re: [PATCH] of: Fix memory block alignment in early_init_dt_add_memory_arch()

[Grant Likely]

On Wed, 20 Aug 2014 17:10:31 +0200, Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org> wrote:
> If a memory block is not aligned to PAGE_SIZE, its base address must be
> rounded up, not down, and its size must be reduced.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>

Looks reasonable. What is the situation that exposed this problem?
Should size be checked for page alignment also?

g.

> ---
>  drivers/of/fdt.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index f46a24ffa3fe..95fa81b8ca19 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>  {
>  	const u64 phys_offset = __pa(PAGE_OFFSET);
> -	base &= PAGE_MASK;
> +
> +	if (!PAGE_ALIGNED(base)) {
> +		size -= PAGE_SIZE - (base & ~PAGE_MASK);
> +		base = PAGE_ALIGN(base);
> +	}
>  	size &= PAGE_MASK;
>  
>  	if (base > MAX_PHYS_ADDR) {
> -- 
> 1.9.1
> 

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Re: [PATCH] of: Fix memory block alignment in early_init_dt_add_memory_arch()

[Geert Uytterhoeven]

Hi Grant,

On Wed, Aug 27, 2014 at 12:30 PM, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> On Wed, 20 Aug 2014 17:10:31 +0200, Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org> wrote:
>> If a memory block is not aligned to PAGE_SIZE, its base address must be
>> rounded up, not down, and its size must be reduced.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>
>
> Looks reasonable. What is the situation that exposed this problem?

When ARM switched from arm_add_memory() to early_init_dt_add_memory_arch()
for DT-based platforms, I just noticed this when comparing the two
implementations.

I don't know if it triggers in the wild.

> Should size be checked for page alignment also?

Size is already rounded down if it's not page aligned, cfr. the context below.

>> ---
>>  drivers/of/fdt.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index f46a24ffa3fe..95fa81b8ca19 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>>  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>>  {
>>       const u64 phys_offset = __pa(PAGE_OFFSET);
>> -     base &= PAGE_MASK;
>> +
>> +     if (!PAGE_ALIGNED(base)) {
>> +             size -= PAGE_SIZE - (base & ~PAGE_MASK);
>> +             base = PAGE_ALIGN(base);
>> +     }
>>       size &= PAGE_MASK;
>>
>>       if (base > MAX_PHYS_ADDR) {
>> --
>> 1.9.1

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Re: [PATCH] of: Fix memory block alignment in early_init_dt_add_memory_arch()

[Grant Likely]

On Wed, 27 Aug 2014 13:08:51 +0200, Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
> Hi Grant,
> 
> On Wed, Aug 27, 2014 at 12:30 PM, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> > On Wed, 20 Aug 2014 17:10:31 +0200, Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org> wrote:
> >> If a memory block is not aligned to PAGE_SIZE, its base address must be
> >> rounded up, not down, and its size must be reduced.
> >>
> >> Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>
> >
> > Looks reasonable. What is the situation that exposed this problem?
> 
> When ARM switched from arm_add_memory() to early_init_dt_add_memory_arch()
> for DT-based platforms, I just noticed this when comparing the two
> implementations.
> 
> I don't know if it triggers in the wild.
> 
> > Should size be checked for page alignment also?
> 
> Size is already rounded down if it's not page aligned, cfr. the context below.

Indeed it is. Silly me. Applied, thanks.

g.

> 
> >> ---
> >>  drivers/of/fdt.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> >> index f46a24ffa3fe..95fa81b8ca19 100644
> >> --- a/drivers/of/fdt.c
> >> +++ b/drivers/of/fdt.c
> >> @@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
> >>  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
> >>  {
> >>       const u64 phys_offset = __pa(PAGE_OFFSET);
> >> -     base &= PAGE_MASK;
> >> +
> >> +     if (!PAGE_ALIGNED(base)) {
> >> +             size -= PAGE_SIZE - (base & ~PAGE_MASK);
> >> +             base = PAGE_ALIGN(base);
> >> +     }
> >>       size &= PAGE_MASK;
> >>
> >>       if (base > MAX_PHYS_ADDR) {
> >> --
> >> 1.9.1
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

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