From: Liwei Song <[email protected]>
This is a follow up to commit f712c71f7b2b ("ACPI, APEI: Fixup common
access width firmware bug") fix the following firmware bug:
[Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
This is due to an 8-bit access width is specified for a 16-bit register,
Do bit_width check just like what the original commit have done.
Signed-off-by: Liwei Song <[email protected]>
---
drivers/acpi/apei/apei-base.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
index da370e1..7e47bc6 100644
--- a/drivers/acpi/apei/apei-base.c
+++ b/drivers/acpi/apei/apei-base.c
@@ -610,6 +610,9 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr,
else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
*access_bit_width < 64)
*access_bit_width = 64;
+ else if (bit_width == 16 && bit_offset == 0 && (*paddr & 0x01) == 0 &&
+ *access_bit_width < 16)
+ *access_bit_width = 16;
if ((bit_width + bit_offset) > *access_bit_width) {
pr_warning(FW_BUG APEI_PFX
--
2.7.4
On Fri, Jul 21, 2017 at 12:41 PM, Song liwei <[email protected]> wrote:
> [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
>
> This is due to an 8-bit access width is specified for a 16-bit register,
> Do bit_width check just like what the original commit have done.
> else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
> *access_bit_width < 64)
> *access_bit_width = 64;
> + else if (bit_width == 16 && bit_offset == 0 && (*paddr & 0x01) == 0 &&
> + *access_bit_width < 16)
> + *access_bit_width = 16;
Wouldn't be better to rearrange that it will go in a sequence
(16,32,64 or 64,32,16) ?
or move bit_offset == 0 into external condion
/* Fixup common BIOS bug */
if (bit_offset == 0) {
if (bit_width == 16 && (*paddr & 0x01) == 0 && *access_bit_width < 16)
*access_bit_width = 16;
else if (bit_width == 32 && (*paddr & 0x03) == 0 &&
*access_bit_width < 32)
*access_bit_width = 32;
else if (bit_width == 64 && (*paddr & 0x07) == 0 &&
*access_bit_width < 64)
*access_bit_width = 64;
}
It might be (I'm not sure it will make it better, just a side note)
considered to convert each internal conditional to
...if (bit_width == XX && (*paddr & YY) == 0)
*access_bit_width = max(*access_bit_width, bit_width);
--
With Best Regards,
Andy Shevchenko
On 07/21/2017 05:56 PM, Andy Shevchenko wrote:
> On Fri, Jul 21, 2017 at 12:41 PM, Song liwei <[email protected]> wrote:
>
>> [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
>>
>> This is due to an 8-bit access width is specified for a 16-bit register,
>> Do bit_width check just like what the original commit have done.
>
>> else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
>> *access_bit_width < 64)
>> *access_bit_width = 64;
>> + else if (bit_width == 16 && bit_offset == 0 && (*paddr & 0x01) == 0 &&
>> + *access_bit_width < 16)
>> + *access_bit_width = 16;
>
> Wouldn't be better to rearrange that it will go in a sequence
> (16,32,64 or 64,32,16) ?
>
> or move bit_offset == 0 into external condion
>
> /* Fixup common BIOS bug */
> if (bit_offset == 0) {
> if (bit_width == 16 && (*paddr & 0x01) == 0 && *access_bit_width < 16)
> *access_bit_width = 16;
> else if (bit_width == 32 && (*paddr & 0x03) == 0 &&
> *access_bit_width < 32)
> *access_bit_width = 32;
> else if (bit_width == 64 && (*paddr & 0x07) == 0 &&
> *access_bit_width < 64)
> *access_bit_width = 64;
> }
>
>
> It might be (I'm not sure it will make it better, just a side note)
> considered to convert each internal conditional to
>
> ...if (bit_width == XX && (*paddr & YY) == 0)
> *access_bit_width = max(*access_bit_width, bit_width);
Hi Andy,
Thanks for your suggestion, what about the condition like the following?
The main bug in bios is bit_width is not comfortable with access_bit_width
So check it first.
if (*access_bit_width < bit_width && bit_offset == 0) {
if ((bit_width == 16 && (*paddr & 0x01) == 0) ||
(bit_width == 32 && (*paddr & 0x03) == 0) ||
(bit_width == 64 && (*paddr & 0x07) == 0))
*access_bit_width = bit_width;
}
Thanks,
Liwei.
>
On Wed, Jul 26, 2017 at 9:16 AM, Liwei Song <[email protected]> wrote:
> On 07/21/2017 05:56 PM, Andy Shevchenko wrote:
>> On Fri, Jul 21, 2017 at 12:41 PM, Song liwei <[email protected]> wrote:
>> /* Fixup common BIOS bug */
>> if (bit_offset == 0) {
>> if (bit_width == 16 && (*paddr & 0x01) == 0 && *access_bit_width < 16)
>> *access_bit_width = 16;
>> else if (bit_width == 32 && (*paddr & 0x03) == 0 &&
>> *access_bit_width < 32)
>> *access_bit_width = 32;
>> else if (bit_width == 64 && (*paddr & 0x07) == 0 &&
>> *access_bit_width < 64)
>> *access_bit_width = 64;
>> }
> Thanks for your suggestion, what about the condition like the following?
> The main bug in bios is bit_width is not comfortable with access_bit_width
> So check it first.
>
> if (*access_bit_width < bit_width && bit_offset == 0) {
> if ((bit_width == 16 && (*paddr & 0x01) == 0) ||
> (bit_width == 32 && (*paddr & 0x03) == 0) ||
> (bit_width == 64 && (*paddr & 0x07) == 0))
> *access_bit_width = bit_width;
> }
Either works to me.
P.S. Less explicit case is to use bit operations to check those, i.e.
is_power_of_2(), fls().
--
With Best Regards,
Andy Shevchenko