Re: [PATCH v3] MIPS: fix incorrect mem=X@Y handling

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James,

On Thu, Feb 1, 2018 at 1:12 PM, Mathieu Malaterre <malat@xxxxxxxxxx> wrote:
> On Thu, Feb 1, 2018 at 12:37 PM, Marcin Nowakowski
> <marcin.nowakowski@xxxxxxxx> wrote:
>> Commit 73fbc1eba7ff ("MIPS: fix mem=X@Y commandline processing") added a
>> fix to ensure that the memory range between 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+
>> ---
>> v3: Update stable version, code cleanup as suggested by James Hogan
>> v2: Use updated email adress, add tag for stable.
>> ---
>>  arch/mips/kernel/setup.c | 16 ++++++++++++----
>>  1 file changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
>> index 702c678de116..e4a1581ce822 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 = (phys_addr_t)ULLONG_MAX;
>>         bool bootmap_valid = false;
>>         int i;
>>
>> @@ -395,7 +396,8 @@ static void __init bootmem_init(void)
>>         max_low_pfn = 0;
>>
>>         /*
>> -        * Find the highest page frame number we have available.
>> +        * Find the highest page frame number we have available
>> +        * and the lowest used RAM address
>>          */
>>         for (i = 0; i < boot_mem_map.nr_map; i++) {
>>                 unsigned long start, end;
>> @@ -407,6 +409,8 @@ static void __init bootmem_init(void)
>>                 end = PFN_DOWN(boot_mem_map.map[i].addr
>>                                 + boot_mem_map.map[i].size);
>>
>> +               ramstart = min(ramstart, boot_mem_map.map[i].addr);
>> +
>>  #ifndef CONFIG_HIGHMEM
>>                 /*
>>                  * Skip highmem here so we get an accurate max_low_pfn if low
>> @@ -436,6 +440,13 @@ static void __init bootmem_init(void)
>>                 mapstart = max(reserved_end, start);
>>         }
>>
>> +       /*
>> +        * Reserve any memory between the start of RAM and PHYS_OFFSET
>> +        */
>> +       if (ramstart > PHYS_OFFSET)
>> +               add_memory_region(PHYS_OFFSET, ramstart - PHYS_OFFSET,
>> +                                 BOOT_MEM_RESERVED);
>> +
>>         if (min_low_pfn >= max_low_pfn)
>>                 panic("Incorrect memory mapping !!!");
>>         if (min_low_pfn > ARCH_PFN_OFFSET) {
>> @@ -664,9 +675,6 @@ 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);
>> --
>> 2.14.1
>>
>
> Looks good to me:
>
> $ cat /proc/cpuinfo
> system type : JZ4780
> machine : Creator CI20
> processor : 0
> cpu model : Ingenic JZRISC V4.15  FPU V0.0
> BogoMIPS : 956.00
> wait instruction : yes
> microsecond timers : no
> tlb_entries : 32
> extra interrupt vector : yes
> hardware watchpoint : yes, count: 1, address/irw mask: [0x0fff]
> isa : mips1 mips2 mips32r1 mips32r2
> ASEs implemented :
> shadow register sets : 1
> kscratch registers : 0
> package : 0
> core : 0
> VCED exceptions : not available
> VCEI exceptions : not available
> $ uname -a
> Linux ci20 4.15.0+ #323 PREEMPT Thu Feb 1 13:08:11 CET 2018 mips GNU/Linux
>
> Tested-by: Mathieu Malaterre <malat@xxxxxxxxxx>
>
> Thanks

Could you please review the patch v3 ?

Thanks,


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