diff mbox series

[PULL,03/20] nubus-device: expose separate super slot memory region

Message ID 20210929092843.2686234-4-laurent@vivier.eu
State New
Headers show
Series [PULL,01/20] nubus: add comment indicating reference documents | expand

Commit Message

Laurent Vivier Sept. 29, 2021, 9:28 a.m. UTC 
From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

According to "Designing Cards and Drivers for the Macintosh Family" each physical
nubus slot can access 2 separate address ranges: a super slot memory region which
is 256MB and a standard slot memory region which is 16MB.

Currently a Nubus device uses the physical slot number to determine whether it is
using a standard slot memory region or a super slot memory region rather than
exposing both memory regions for use as required.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210924073808.1041-4-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 include/hw/nubus/nubus.h |  1 +
 hw/nubus/nubus-device.c  | 36 ++++++++++++++++++------------------
 2 files changed, 19 insertions(+), 18 deletions(-)

Comments

Peter Maydell Oct. 2, 2021, 10:33 a.m. UTC | #1 
On Wed, 29 Sept 2021 at 10:49, Laurent Vivier <laurent@vivier.eu> wrote:
>
> From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>
> According to "Designing Cards and Drivers for the Macintosh Family" each physical
> nubus slot can access 2 separate address ranges: a super slot memory region which
> is 256MB and a standard slot memory region which is 16MB.
>
> Currently a Nubus device uses the physical slot number to determine whether it is
> using a standard slot memory region or a super slot memory region rather than
> exposing both memory regions for use as required.


> +    /* Super */
> +    slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;

Hi; Coverity thinks this multiply might overflow, because
we're calculating a hw_addr (64-bits) but the multiply is only
done at 32-bits. Adding an explicit cast or using 'ULL' in the
constant #define rather than just 'U' would fix this.
This is CID 1464070.

> +
> +    name = g_strdup_printf("nubus-super-slot-%x", nd->slot);
> +    memory_region_init(&nd->super_slot_mem, OBJECT(dev), name,
> +                       NUBUS_SUPER_SLOT_SIZE);
> +    memory_region_add_subregion(&nubus->super_slot_io, slot_offset,
> +                                &nd->super_slot_mem);
> +    g_free(name);
> +
> +    /* Normal */
> +    slot_offset = nd->slot * NUBUS_SLOT_SIZE;

Same with this one.

thanks
-- PMM
Laurent Vivier Oct. 4, 2021, 7:01 a.m. UTC | #2 
Le 02/10/2021 à 12:33, Peter Maydell a écrit :
> On Wed, 29 Sept 2021 at 10:49, Laurent Vivier <laurent@vivier.eu> wrote:
>>
>> From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>
>> According to "Designing Cards and Drivers for the Macintosh Family" each physical
>> nubus slot can access 2 separate address ranges: a super slot memory region which
>> is 256MB and a standard slot memory region which is 16MB.
>>
>> Currently a Nubus device uses the physical slot number to determine whether it is
>> using a standard slot memory region or a super slot memory region rather than
>> exposing both memory regions for use as required.
> 
> 
>> +    /* Super */
>> +    slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;
> 
> Hi; Coverity thinks this multiply might overflow, because
> we're calculating a hw_addr (64-bits) but the multiply is only
> done at 32-bits. Adding an explicit cast or using 'ULL' in the
> constant #define rather than just 'U' would fix this.
> This is CID 1464070.
> 

I'm wondering if adding "assert(nd->slot < NUBUS_SUPER_SLOT_NB)" would help coverity to avoid the
error without using 64bit arithmetic?


>> +
>> +    name = g_strdup_printf("nubus-super-slot-%x", nd->slot);
>> +    memory_region_init(&nd->super_slot_mem, OBJECT(dev), name,
>> +                       NUBUS_SUPER_SLOT_SIZE);
>> +    memory_region_add_subregion(&nubus->super_slot_io, slot_offset,
>> +                                &nd->super_slot_mem);
>> +    g_free(name);
>> +
>> +    /* Normal */
>> +    slot_offset = nd->slot * NUBUS_SLOT_SIZE;
> 
> Same with this one.

assert(nb->slot < NUBUS_SLOT_NB)

> thanks
> -- PMM
> 

Laurent
BALATON Zoltan Oct. 4, 2021, 10:16 a.m. UTC | #3 
On Mon, 4 Oct 2021, Laurent Vivier wrote:
> Le 02/10/2021 à 12:33, Peter Maydell a écrit :
>> On Wed, 29 Sept 2021 at 10:49, Laurent Vivier <laurent@vivier.eu> wrote:
>>>
>>> From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>>
>>> According to "Designing Cards and Drivers for the Macintosh Family" each physical
>>> nubus slot can access 2 separate address ranges: a super slot memory region which
>>> is 256MB and a standard slot memory region which is 16MB.
>>>
>>> Currently a Nubus device uses the physical slot number to determine whether it is
>>> using a standard slot memory region or a super slot memory region rather than
>>> exposing both memory regions for use as required.
>>
>>
>>> +    /* Super */
>>> +    slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;
>>
>> Hi; Coverity thinks this multiply might overflow, because
>> we're calculating a hw_addr (64-bits) but the multiply is only
>> done at 32-bits. Adding an explicit cast or using 'ULL' in the
>> constant #define rather than just 'U' would fix this.
>> This is CID 1464070.
>>
>
> I'm wondering if adding "assert(nd->slot < NUBUS_SUPER_SLOT_NB)" would help coverity to avoid the
> error without using 64bit arithmetic?

Using ULL in constant is simpler and better, assert is an unnecessary 
condition evaluation in cases where it can't happen (that's not a 
performance problem here but could be in some frequently called code).

Regards,
BALATON Zoltan

>
>>> +
>>> +    name = g_strdup_printf("nubus-super-slot-%x", nd->slot);
>>> +    memory_region_init(&nd->super_slot_mem, OBJECT(dev), name,
>>> +                       NUBUS_SUPER_SLOT_SIZE);
>>> +    memory_region_add_subregion(&nubus->super_slot_io, slot_offset,
>>> +                                &nd->super_slot_mem);
>>> +    g_free(name);
>>> +
>>> +    /* Normal */
>>> +    slot_offset = nd->slot * NUBUS_SLOT_SIZE;
>>
>> Same with this one.
>
> assert(nb->slot < NUBUS_SLOT_NB)
>
>> thanks
>> -- PMM
>>
>
> Laurent
>
>
>
diff mbox series

Patch

diff --git a/include/hw/nubus/nubus.h b/include/hw/nubus/nubus.h
index 424309dd730d..89b0976aaa3d 100644
--- a/include/hw/nubus/nubus.h
+++ b/include/hw/nubus/nubus.h
@@ -43,6 +43,7 @@  struct NubusDevice {
     DeviceState qdev;
 
     int slot;
+    MemoryRegion super_slot_mem;
     MemoryRegion slot_mem;
 
     /* Format Block */
diff --git a/hw/nubus/nubus-device.c b/hw/nubus/nubus-device.c
index be0126956391..4e23df1280f9 100644
--- a/hw/nubus/nubus-device.c
+++ b/hw/nubus/nubus-device.c
@@ -168,26 +168,26 @@  static void nubus_device_realize(DeviceState *dev, Error **errp)
     }
 
     nd->slot = nubus->current_slot++;
-    name = g_strdup_printf("nubus-slot-%d", nd->slot);
-
-    if (nd->slot < NUBUS_FIRST_SLOT) {
-        /* Super */
-        slot_offset = (nd->slot - 6) * NUBUS_SUPER_SLOT_SIZE;
-
-        memory_region_init(&nd->slot_mem, OBJECT(dev), name,
-                           NUBUS_SUPER_SLOT_SIZE);
-        memory_region_add_subregion(&nubus->super_slot_io, slot_offset,
-                                    &nd->slot_mem);
-    } else {
-        /* Normal */
-        slot_offset = nd->slot * NUBUS_SLOT_SIZE;
-
-        memory_region_init(&nd->slot_mem, OBJECT(dev), name, NUBUS_SLOT_SIZE);
-        memory_region_add_subregion(&nubus->slot_io, slot_offset,
-                                    &nd->slot_mem);
-    }
 
+    /* Super */
+    slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;
+
+    name = g_strdup_printf("nubus-super-slot-%x", nd->slot);
+    memory_region_init(&nd->super_slot_mem, OBJECT(dev), name,
+                       NUBUS_SUPER_SLOT_SIZE);
+    memory_region_add_subregion(&nubus->super_slot_io, slot_offset,
+                                &nd->super_slot_mem);
+    g_free(name);
+
+    /* Normal */
+    slot_offset = nd->slot * NUBUS_SLOT_SIZE;
+
+    name = g_strdup_printf("nubus-slot-%x", nd->slot);
+    memory_region_init(&nd->slot_mem, OBJECT(dev), name, NUBUS_SLOT_SIZE);
+    memory_region_add_subregion(&nubus->slot_io, slot_offset,
+                                &nd->slot_mem);
     g_free(name);
+
     nubus_register_format_block(nd);
 }