2023-10-30 10:30:41

by James Clark

[permalink] [raw]
Subject: [PATCH] coresight: etm4x: Fix width of CCITMIN field

CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
This probably wasn't an issue previously because values higher than 255
never occurred.

But since commit 0f55b43dedcd ("coresight: etm: Override TRCIDR3.CCITMIN
on errata affected cpus"), a comparison with 256 was done to enable the
errata, generating the following W=1 build error:

coresight-etm4x-core.c:1188:24: error: result of comparison of
constant 256 with expression of type 'u8' (aka 'unsigned char') is
always false [-Werror,-Wtautological-constant-out-of-range-compare]

if (drvdata->ccitmin == 256)

Cc: [email protected]
Fixes: 54ff892b76c6 ("coresight: etm4x: splitting struct etmv4_drvdata")
Signed-off-by: James Clark <[email protected]>
---
drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 20e2e4cb7614..da17b6c49b0f 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
u8 ctxid_size;
u8 vmid_size;
u8 ccsize;
- u8 ccitmin;
+ u16 ccitmin;
u8 s_ex_level;
u8 ns_ex_level;
u8 q_support;
--
2.34.1


2023-11-01 09:39:01

by Mike Leach

[permalink] [raw]
Subject: Re: [PATCH] coresight: etm4x: Fix width of CCITMIN field

On Mon, 30 Oct 2023 at 10:29, James Clark <[email protected]> wrote:
>
> CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
> This probably wasn't an issue previously because values higher than 255
> never occurred.
>
> But since commit 0f55b43dedcd ("coresight: etm: Override TRCIDR3.CCITMIN
> on errata affected cpus"), a comparison with 256 was done to enable the
> errata, generating the following W=1 build error:
>
> coresight-etm4x-core.c:1188:24: error: result of comparison of
> constant 256 with expression of type 'u8' (aka 'unsigned char') is
> always false [-Werror,-Wtautological-constant-out-of-range-compare]
>
> if (drvdata->ccitmin == 256)
>
> Cc: [email protected]
> Fixes: 54ff892b76c6 ("coresight: etm4x: splitting struct etmv4_drvdata")
> Signed-off-by: James Clark <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 20e2e4cb7614..da17b6c49b0f 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
> u8 ctxid_size;
> u8 vmid_size;
> u8 ccsize;
> - u8 ccitmin;
> + u16 ccitmin;
> u8 s_ex_level;
> u8 ns_ex_level;
> u8 q_support;
> --
> 2.34.1
>

Reviewed-by: Mike Leach <[email protected]>

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

2023-11-02 04:14:42

by Anshuman Khandual

[permalink] [raw]
Subject: Re: [PATCH] coresight: etm4x: Fix width of CCITMIN field



On 10/30/23 15:59, James Clark wrote:
> CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
> This probably wasn't an issue previously because values higher than 255
> never occurred.
>
> But since commit 0f55b43dedcd ("coresight: etm: Override TRCIDR3.CCITMIN
> on errata affected cpus"), a comparison with 256 was done to enable the
> errata, generating the following W=1 build error:
>
> coresight-etm4x-core.c:1188:24: error: result of comparison of
> constant 256 with expression of type 'u8' (aka 'unsigned char') is
> always false [-Werror,-Wtautological-constant-out-of-range-compare]
>
> if (drvdata->ccitmin == 256)
>
> Cc: [email protected]
> Fixes: 54ff892b76c6 ("coresight: etm4x: splitting struct etmv4_drvdata")
> Signed-off-by: James Clark <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 20e2e4cb7614..da17b6c49b0f 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
> u8 ctxid_size;
> u8 vmid_size;
> u8 ccsize;
> - u8 ccitmin;
> + u16 ccitmin;
> u8 s_ex_level;
> u8 ns_ex_level;
> u8 q_support;

Thanks James, so this takes care of the Smatch static checker
warning as reported by Dan Carpenter earlier.

Reviewed-by: Anshuman Khandual <[email protected]>

2023-11-02 09:35:56

by James Clark

[permalink] [raw]
Subject: Re: [PATCH] coresight: etm4x: Fix width of CCITMIN field



On 02/11/2023 04:14, Anshuman Khandual wrote:
>
>
> On 10/30/23 15:59, James Clark wrote:
>> CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
>> This probably wasn't an issue previously because values higher than 255
>> never occurred.
>>
>> But since commit 0f55b43dedcd ("coresight: etm: Override TRCIDR3.CCITMIN
>> on errata affected cpus"), a comparison with 256 was done to enable the
>> errata, generating the following W=1 build error:
>>
>> coresight-etm4x-core.c:1188:24: error: result of comparison of
>> constant 256 with expression of type 'u8' (aka 'unsigned char') is
>> always false [-Werror,-Wtautological-constant-out-of-range-compare]
>>
>> if (drvdata->ccitmin == 256)
>>
>> Cc: [email protected]
>> Fixes: 54ff892b76c6 ("coresight: etm4x: splitting struct etmv4_drvdata")
>> Signed-off-by: James Clark <[email protected]>
>> ---
>> drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index 20e2e4cb7614..da17b6c49b0f 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
>> u8 ctxid_size;
>> u8 vmid_size;
>> u8 ccsize;
>> - u8 ccitmin;
>> + u16 ccitmin;
>> u8 s_ex_level;
>> u8 ns_ex_level;
>> u8 q_support;
>
> Thanks James, so this takes care of the Smatch static checker
> warning as reported by Dan Carpenter earlier.
>

I didn't see that report, but it was in "[linux-next:master]
BUILD REGRESSION c503e3eec382ac708ee7adf874add37b77c5d312"

> Reviewed-by: Anshuman Khandual <[email protected]>