[PATCH 1/1] sandbox: ensure that state->ram_buf is in low memory

[Heinrich Schuchardt]

On 5/14/21 1:56 AM, Simon Glass wrote:
> Hi Heinrich,
>
> On Thu, 13 May 2021 at 08:53, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>
>> On 5/13/21 4:36 PM, Simon Glass wrote:
>>> Hi Heinrich,
>>>
>>> On Wed, 12 May 2021 at 15:28, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>>>
>>>> Am 12. Mai 2021 18:01:17 MESZ schrieb Simon Glass <sjg at chromium.org>:
>>>>> Hi Heinrich,
>>>>>
>>>>> On Tue, 11 May 2021 at 13:03, Heinrich Schuchardt <xypron.glpk at gmx.de>
>>>>> wrote:
>>>>>>
>>>>>> Addresses in state->ram_buf must be in the low 4 GiB of the address
>>>>> space.
>>>>>> Otherwise we cannot correctly fill SMBIOS tables. This shows up in
>>>>> warnings
>>>>>> like:
>>>>>>
>>>>>>       WARNING: SMBIOS table_address overflow 7f752735e020
>>>>>
>>>>> This sounds like a bug in the smbios-table code. For sandbox it should
>>>>> perhaps use addresses instead of pointers.
>>>>>
>>>>> I think that code (that I unfortunately wrote) was an expeditious way
>>>>> of getting it running, but is not correct.
>>>>
>>>> The field you are filling is only 32bit wide. I wonder how that table is meant to work on systems where the lowest memory address is above 4 GiB. Such ARMv8 systems exist.
>>>
>>> map_to_sysmem() will give you a 32-bit wide address. Yes SMBIOS is
>>> legacy and designed for 4GB.
>>
>> I know map_to_sysmem(). But you wrote in lib/smbios.c:487:
>>
>> /*
>>    * We must use a pointer here so things work correctly on sandbox. The
>>    * user of this table is not aware of the mapping of addresses to
>>    * sandbox's DRAM buffer.
>>    */
>>
>> For testing you could start a binary with command 'bootefi' or 'booti'
>> and that binary would analyze the table. So yes, your comment holds true
>> and you must not use map_to_sysmem() here.
>
> Yes, that is a good point. Perhaps I was not mad when I wrote that.
> What is using the tables on sandbox?

The UEFI shell has a command smbiosview to display the SMBIOS table.

With the current U-Boot sandbox it crashes. I do not know what the cause is:

FS0:\> smbiosview

Segmentation violation
pc = 0x7fb0df88d17e, pc_reloc = 0x7fb0cf88d17e

UEFI image [0x00007fb0df836000:0x00007fb0df920c5f] pc=0x5717e
'/Shell_x64.efi'

Here is some of the output for my laptop:

SMBIOS Entry Point Structure:
Anchor String:        _SM_
EPS Checksum:         0xEE
Entry Point Len:      31
Version:              3.1
Number of Structures: 62
Max Struct size:      145
Table Address:        0x986E9000
Table Length:         2316
Entry Point revision: 0x0
SMBIOS BCD Revision:  0x31
Inter Anchor:         _DMI_
Inter Checksum:       0x4E
Formatted Area:
   00000000: 00 00 00 00 00                                   *.....*

=========================================================
Query Structure, conditions are:
QueryType   = Random
QueryHandle = Random
ShowType    = SHOW_DETAIL


Enter to continue, :q to exit, :[0-3] to change mode, /? for help
$
=========================================================
Type=18, Handle=0x0
Dump Structure as:
Index=0,Length=0x19,Addr=0x986E9019
00000000: 12 17 00 00 03 02 02 00-00 00 00 00 00 00 80 00
*................*
00000010: 00 00 80 00 00 00 80 00-00                       *.........*

Enter to continue, :q to exit, :[0-3] to change mode, /? for help
$Structure Type: 32-bit Memory Error Information
Format part Len : 23
Structure Handle: 0
32-bit Memory Error Information - Type:   OK
Memory Error - Error granularity:   Unknown
Memory Error - Error Operation:   Unknown
VendorSyndrome: 0x0
MemoryArrayErrorAddress: 0x80000000
DeviceErrorAddress: 0x80000000
ErrorResolution: 0x80000000

Best regards

Heinrich