Re: [PATCH v2] MIPS: fix incorrect mem=X@Y handling

[Marcin Nowakowski]

Hi Mathieu,

On 31.01.2018 08:47, Mathieu Malaterre wrote:

> Since it's been a week, could you confirm the patch is ok as-is or do
> you think some comment(s) from James should be incorporated ?

I'll prepare an updated patch that includes James' suggestions - I think 
they will lead to an overall cleaner (and probably slightly smaller) code.

Marcin


> On Tue, Jan 23, 2018 at 3:17 PM, James Hogan <jhogan@xxxxxxxxxx> wrote:
> > On Thu, Dec 21, 2017 at 10:00:59PM +0100, Mathieu Malaterre wrote:
> > > From: Marcin Nowakowski <marcin.nowakowski@xxxxxxxx>
> > >
> > > Change 73fbc1eba7ff added a fix to ensure that the memory range between
> >
> > Please refer to commits with e.g. commit 73fbc1eba7ff ("MIPS: fix
> > mem=X@Y commandline processing").
> >
> > > PHYS_OFFSET and low memory address specified by mem= cmdline argument is
> > > not later processed by free_all_bootmem.
> > > This change was incorrect for systems where the commandline specifies
> > > more than 1 mem argument, as it will cause all memory between
> > > PHYS_OFFSET and each of the memory offsets to be marked as reserved,
> > > which results in parts of the RAM marked as reserved (Creator CI20's
> > > u-boot has a default commandline argument 'mem=256M@0x0
> > > mem=768M@0x30000000').
> > >
> > > Change the behaviour to ensure that only the range between PHYS_OFFSET
> > > and the lowest start address of the memories is marked as protected.
> > >
> > > This change also ensures that the range is marked protected even if it's
> > > only defined through the devicetree and not only via commandline
> > > arguments.
> > >
> > > Reported-by: Mathieu Malaterre <mathieu.malaterre@xxxxxxxxx>
> > > Signed-off-by: Marcin Nowakowski <marcin.nowakowski@xxxxxxxx>
> > > Fixes: 73fbc1eba7ff ("MIPS: fix mem=X@Y commandline processing")
> > > Cc: <stable@xxxxxxxxxxxxxxx> # v4.11
> >
> > I'm guessing that should technically be v4.11+
>
> My fault, if this is the only change, I can re-submit.
>
> > > ---
> > > v2: Use updated email adress, add tag for stable.
> > >   arch/mips/kernel/setup.c | 19 ++++++++++++++++---
> > >   1 file changed, 16 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> > > index 702c678de116..f19d61224c71 100644
> > > --- a/arch/mips/kernel/setup.c
> > > +++ b/arch/mips/kernel/setup.c
> > > @@ -375,6 +375,7 @@ static void __init bootmem_init(void)
> > >        unsigned long reserved_end;
> > >        unsigned long mapstart = ~0UL;
> > >        unsigned long bootmap_size;
> > > +     phys_addr_t ramstart = ~0UL;
> >
> > Although practically it might not matter, technically phys_addr_t may be
> > 64-bits (CONFIG_PHYS_ADDR_T_64BIT) even on a 32-bit kernels, in which
> > case ~0UL may not be sufficiently large.
> >
> > Maybe that should be ~(phys_addr_t)0, or perhaps (phys_addr_t)ULLONG_MAX
> > to match add_memory_region().
> >
> > >        bool bootmap_valid = false;
> > >        int i;
> > >
> > > @@ -395,6 +396,21 @@ static void __init bootmem_init(void)
> > >        max_low_pfn = 0;
> > >
> > >        /*
> > > +      * Reserve any memory between the start of RAM and PHYS_OFFSET
> > > +      */
> > > +     for (i = 0; i < boot_mem_map.nr_map; i++) {
> > > +             if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
> > > +                     continue;
> > > +
> > > +             ramstart = min(ramstart, boot_mem_map.map[i].addr);
> >
> > Is it worth incorporating this into the existing loop below ...
> >
> > > +     }
> > > +
> > > +     if (ramstart > PHYS_OFFSET)
> > > +             add_memory_region(PHYS_OFFSET, ramstart - PHYS_OFFSET,
> > > +                               BOOT_MEM_RESERVED);
> >
> > ... and this then placed below that loop?
> >
> > Otherwise I can't find fault with this patch, though i'm not intimately
> > familiar with bootmem.
> >
> > Cheers
> > James
> >
> > > +
> > > +
> > > +     /*
> > >         * Find the highest page frame number we have available.
> > >         */
> > >        for (i = 0; i < boot_mem_map.nr_map; i++) {
> > > @@ -664,9 +680,6 @@ static int __init early_parse_mem(char *p)
> > >
> > >        add_memory_region(start, size, BOOT_MEM_RAM);
> > >
> > > -     if (start && start > PHYS_OFFSET)
> > > -             add_memory_region(PHYS_OFFSET, start - PHYS_OFFSET,
> > > -                             BOOT_MEM_RESERVED);
> > >        return 0;
> > >   }
> > >   early_param("mem", early_parse_mem);
> > > --
> > > 2.11.0