[PATCH] mm, kasan: don't poison boot memory

[George Kennedy]

On 2/28/2021 1:08 PM, Mike Rapoport wrote:
> On Fri, Feb 26, 2021 at 11:16:06AM -0500, George Kennedy wrote:
>> On 2/26/2021 6:17 AM, Mike Rapoport wrote:
>>> Hi George,
>>>
>>> On Thu, Feb 25, 2021 at 08:19:18PM -0500, George Kennedy wrote:
>>>> Not sure if it's the right thing to do, but added
>>>> "acpi_tb_find_table_address()" to return the physical address of a table to
>>>> use with memblock_reserve().
>>>>
>>>> virt_to_phys(table) does not seem to return the physical address for the
>>>> iBFT table (it would be nice if struct acpi_table_header also had a
>>>> "address" element for the physical address of the table).
>>> virt_to_phys() does not work that early because then it is mapped with
>>> early_memremap()  which uses different virtual to physical scheme.
>>>
>>> I'd say that acpi_tb_find_table_address() makes sense if we'd like to
>>> reserve ACPI tables outside of drivers/acpi.
>>>
>>> But probably we should simply reserve all the tables during
>>> acpi_table_init() so that any table that firmware put in the normal memory
>>> will be surely reserved.
>>>> Ran 10 successful boots with the above without failure.
>>> That's good news indeed :)
>> Wondering if we could do something like this instead (trying to keep changes
>> minimal). Just do the memblock_reserve() for all the standard tables.
> I think something like this should work, but I'm not an ACPI expert to say
> if this the best way to reserve the tables.
Adding ACPI maintainers to the CC list.
>   
>> diff --git a/drivers/acpi/acpica/tbinstal.c b/drivers/acpi/acpica/tbinstal.c
>> index 0bb15ad..830f82c 100644
>> --- a/drivers/acpi/acpica/tbinstal.c
>> +++ b/drivers/acpi/acpica/tbinstal.c
>> @@ -7,6 +7,7 @@
>>    *
>> *****************************************************************************/
>>
>> +#include <linux/memblock.h>
>>   #include <acpi/acpi.h>
>>   #include "accommon.h"
>>   #include "actables.h"
>> @@ -14,6 +15,23 @@
>>   #define _COMPONENT          ACPI_TABLES
>>   ACPI_MODULE_NAME("tbinstal")
>>
>> +void
>> +acpi_tb_reserve_standard_table(acpi_physical_address address,
>> +               struct acpi_table_header *header)
>> +{
>> +    struct acpi_table_header local_header;
>> +
>> +    if ((ACPI_COMPARE_NAMESEG(header->signature, ACPI_SIG_FACS)) ||
>> +        (ACPI_VALIDATE_RSDP_SIG(header->signature))) {
>> +        return;
>> +    }
>> +    /* Standard ACPI table with full common header */
>> +
>> +    memcpy(&local_header, header, sizeof(struct acpi_table_header));
>> +
>> +    memblock_reserve(address, PAGE_ALIGN(local_header.length));
>> +}
>> +
>>   /*******************************************************************************
>>    *
>>    * FUNCTION:    acpi_tb_install_table_with_override
>> @@ -58,6 +76,9 @@
>>                         new_table_desc->flags,
>>                         new_table_desc->pointer);
>>
>> +    acpi_tb_reserve_standard_table(new_table_desc->address,
>> +                   new_table_desc->pointer);
>> +
>>       acpi_tb_print_table_header(new_table_desc->address,
>>                      new_table_desc->pointer);
>>
>> There should be no harm in doing the memblock_reserve() for all the standard
>> tables, right?
> It should be ok to memblock_reserve() all the tables very early as long as
> we don't run out of static entries in memblock.reserved.
>
> We just need to make sure the tables are reserved before memblock
> allocations are possible, so we'd still need to move acpi_table_init() in
> x86::setup_arch() before e820__memblock_setup().
> Not sure how early ACPI is initialized on arm64.

Thanks Mike. Will try to move the memblock_reserves() before 
e820__memblock_setup().

George
>   
>> Ran 10 boots with the above without failure.
>>
>> George