Re: drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection

Re: drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection

[Nathan Chancellor]

On Fri, Nov 21, 2025 at 09:51:33PM -0800, Josh Poimboeuf wrote:
> On Fri, Nov 21, 2025 at 06:34:14PM -0700, Nathan Chancellor wrote:
> > On Sat, Nov 22, 2025 at 08:41:37AM +0800, kernel test robot wrote:
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head:   2eba5e05d9bcf4cdea995ed51b0f07ba0275794a
> > > commit: 188d90f817e13b66e03e110eb6f82e8f5f0d654b objtool: Append "()" to function name in "unexpected end of section" warning
> > > date:   8 months ago
> > > :::::: branch date: 4 hours ago
> > > :::::: commit date: 8 months ago
> > > config: x86_64-randconfig-101-20251122 (https://download.01.org/0day-ci/archive/20251122/202511220717.5HHMLUHG-lkp@intel.com/config)
> > > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251122/202511220717.5HHMLUHG-lkp@intel.com/reproduce)
> > > 
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Closes: https://lore.kernel.org/r/202511220717.5HHMLUHG-lkp@intel.com/
> > > 
> > > All errors (new ones prefixed by >>):
> > > 
> > > >> drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection
> > 
> > That change obviously does not result in this warning/error. This
> > appears to be another divide by zero issue but based on my analysis so
> > far, I do not understand how...
> > 
> > https://github.com/ClangBuiltLinux/linux/issues/2129
> 
> Here ya go :-)  After looking at a gazillion of these I can often spot
> these pretty easily.  I'm not sure what the correct fix is here but this
> made the error go away.
> 
> diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> index 1c889c878abd..2429c05bffb3 100644
> --- a/drivers/media/i2c/ccs/ccs-core.c
> +++ b/drivers/media/i2c/ccs/ccs-core.c
> @@ -2346,7 +2346,7 @@ static void ccs_set_compose_scaler(struct v4l2_subdev *subdev,
>  		* CCS_LIM(sensor, SCALER_N_MIN) / sel->r.height;
>  	max_m = crops[CCS_PAD_SINK]->width
>  		* CCS_LIM(sensor, SCALER_N_MIN)
> -		/ CCS_LIM(sensor, MIN_X_OUTPUT_SIZE);
> +		/ (CCS_LIM(sensor, MIN_X_OUTPUT_SIZE) ? : 1);
>  
>  	a = clamp(a, CCS_LIM(sensor, SCALER_M_MIN),
>  		  CCS_LIM(sensor, SCALER_M_MAX));

Aha! Thanks a lot :) I had thought it might be something with CCS_LIM()
since ccs_get_limit() returns zero if ccs_limit_ptr() errors and in the
default case of the switch statement. There are a lot of unchecked
divides with the result of CCS_LIM() throughout this driver so I figured
if that was it, there would be other instances of this warning... oh
well.

Something like the following diff also fixes it since LLVM no longer
sees 0 as a possible divisor, which seems a little better to me since it
seems like one of the other uses could turn problematic with other
optimizations.  Given these cases are both errors and have visible WARNs
in case they are hit, it seems like it is better to use a valid divisor
instead of 0.

Just one more warning to tackle in my personal configuration then I can
enable CONFIG_OBJTOOL_WERROR to make new warnings from LLVM uprevs more
obvious :)

  https://github.com/ClangBuiltLinux/linux/issues/2130

diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
index 1c889c878abd..05c3da29f14c 100644
--- a/drivers/media/i2c/ccs/ccs-core.c
+++ b/drivers/media/i2c/ccs/ccs-core.c
@@ -137,7 +137,7 @@ u32 ccs_get_limit(struct ccs_sensor *sensor, unsigned int limit,

        ret = ccs_limit_ptr(sensor, limit, offset, &ptr);
        if (ret)
-               return 0;
+               return 1;

        switch (CCI_REG_WIDTH_BYTES(ccs_limits[ccs_limit_offsets[limit].info].reg)) {
        case sizeof(u8):
@@ -151,7 +151,7 @@ u32 ccs_get_limit(struct ccs_sensor *sensor, unsigned int limit,
                break;
        default:
                WARN_ON(1);
-               return 0;
+               return 1;
        }

        return ccs_reg_conv(sensor, ccs_limits[limit].reg, val);

Re: drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection

[Sakari Ailus]

Hi folks,

On Fri, Nov 21, 2025 at 11:29:46PM -0700, Nathan Chancellor wrote:
> On Fri, Nov 21, 2025 at 09:51:33PM -0800, Josh Poimboeuf wrote:
> > On Fri, Nov 21, 2025 at 06:34:14PM -0700, Nathan Chancellor wrote:
> > > On Sat, Nov 22, 2025 at 08:41:37AM +0800, kernel test robot wrote:
> > > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > > head:   2eba5e05d9bcf4cdea995ed51b0f07ba0275794a
> > > > commit: 188d90f817e13b66e03e110eb6f82e8f5f0d654b objtool: Append "()" to function name in "unexpected end of section" warning
> > > > date:   8 months ago
> > > > :::::: branch date: 4 hours ago
> > > > :::::: commit date: 8 months ago
> > > > config: x86_64-randconfig-101-20251122 (https://download.01.org/0day-ci/archive/20251122/202511220717.5HHMLUHG-lkp@intel.com/config)
> > > > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> > > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251122/202511220717.5HHMLUHG-lkp@intel.com/reproduce)
> > > > 
> > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > > the same patch/commit), kindly add following tags
> > > > | Reported-by: kernel test robot <lkp@intel.com>
> > > > | Closes: https://lore.kernel.org/r/202511220717.5HHMLUHG-lkp@intel.com/
> > > > 
> > > > All errors (new ones prefixed by >>):
> > > > 
> > > > >> drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection
> > > 
> > > That change obviously does not result in this warning/error. This
> > > appears to be another divide by zero issue but based on my analysis so
> > > far, I do not understand how...
> > > 
> > > https://github.com/ClangBuiltLinux/linux/issues/2129
> > 
> > Here ya go :-)  After looking at a gazillion of these I can often spot
> > these pretty easily.  I'm not sure what the correct fix is here but this
> > made the error go away.
> > 
> > diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> > index 1c889c878abd..2429c05bffb3 100644
> > --- a/drivers/media/i2c/ccs/ccs-core.c
> > +++ b/drivers/media/i2c/ccs/ccs-core.c
> > @@ -2346,7 +2346,7 @@ static void ccs_set_compose_scaler(struct v4l2_subdev *subdev,
> >  		* CCS_LIM(sensor, SCALER_N_MIN) / sel->r.height;
> >  	max_m = crops[CCS_PAD_SINK]->width
> >  		* CCS_LIM(sensor, SCALER_N_MIN)
> > -		/ CCS_LIM(sensor, MIN_X_OUTPUT_SIZE);
> > +		/ (CCS_LIM(sensor, MIN_X_OUTPUT_SIZE) ? : 1);

Thanks for cc'ing me.

I prefer this as there's no guarantee the value read via ccs_get_limit()
would be non-zero. Presumably it is (and has been so far as no-one has hit
this to my knowledge), but we shouldn't rely on that.

I can post a patch as well.

> >  
> >  	a = clamp(a, CCS_LIM(sensor, SCALER_M_MIN),
> >  		  CCS_LIM(sensor, SCALER_M_MAX));
> 
> Aha! Thanks a lot :) I had thought it might be something with CCS_LIM()
> since ccs_get_limit() returns zero if ccs_limit_ptr() errors and in the
> default case of the switch statement. There are a lot of unchecked
> divides with the result of CCS_LIM() throughout this driver so I figured
> if that was it, there would be other instances of this warning... oh
> well.
> 
> Something like the following diff also fixes it since LLVM no longer
> sees 0 as a possible divisor, which seems a little better to me since it
> seems like one of the other uses could turn problematic with other
> optimizations.  Given these cases are both errors and have visible WARNs
> in case they are hit, it seems like it is better to use a valid divisor
> instead of 0.
> 
> Just one more warning to tackle in my personal configuration then I can
> enable CONFIG_OBJTOOL_WERROR to make new warnings from LLVM uprevs more
> obvious :)
> 
>   https://github.com/ClangBuiltLinux/linux/issues/2130
> 
> diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> index 1c889c878abd..05c3da29f14c 100644
> --- a/drivers/media/i2c/ccs/ccs-core.c
> +++ b/drivers/media/i2c/ccs/ccs-core.c
> @@ -137,7 +137,7 @@ u32 ccs_get_limit(struct ccs_sensor *sensor, unsigned int limit,
> 
>         ret = ccs_limit_ptr(sensor, limit, offset, &ptr);
>         if (ret)
> -               return 0;
> +               return 1;
> 
>         switch (CCI_REG_WIDTH_BYTES(ccs_limits[ccs_limit_offsets[limit].info].reg)) {
>         case sizeof(u8):
> @@ -151,7 +151,7 @@ u32 ccs_get_limit(struct ccs_sensor *sensor, unsigned int limit,
>                 break;
>         default:
>                 WARN_ON(1);
> -               return 0;
> +               return 1;
>         }
> 
>         return ccs_reg_conv(sensor, ccs_limits[limit].reg, val);

-- 
Kind regards,

Sakari Ailus

Re: drivers/media/i2c/ccs/ccs.o: error: objtool: ccs_set_selection(): unexpected end of section .text.ccs_set_selection

[Nathan Chancellor]

Hi Sakari,

On Mon, Nov 24, 2025 at 12:29:06AM +0200, Sakari Ailus wrote:
> Thanks for cc'ing me.
> 
> I prefer this as there's no guarantee the value read via ccs_get_limit()
> would be non-zero. Presumably it is (and has been so far as no-one has hit
> this to my knowledge), but we shouldn't rely on that.

Ah, that makes sense. I misread some of the other places I thought were
using the value of CCS_LIM() as a divisor, guess I forgot my elementary
order of operations :) This appears to be the only overt one that I can
see.

> I can post a patch as well.

If you have time, that would be great (I am happy to build test and
review it). Otherwise, I can get to it soon.

Cheers,
Nathan

[PATCH 1/1] media: ccs: Avoid possible division by zero

[Sakari Ailus]

Calculating maximum M for scaler configuration involves dividing by
MIN_X_OUTPUT_SIZE limit register's value. Albeit the value is presumably
non-zero, the driver was missing the check it in fact was. Fix this.

Reported-by: Josh Poimboeuf <jpoimboe@kernel.org>
Closes: https://lore.kernel.org/all/ahukd6b3wonye3zgtptvwzvrxldcruazs2exfvll6etjhmcxyj@vq3eh6pd375b/
Fixes: ccfc97bdb5ae ("[media] smiapp: Add driver")
Cc: stable@vger.kernel.org # for 5.15 and later
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
Not tested but what could go wrong here? :-)

 drivers/media/i2c/ccs/ccs-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
index f8523140784c..dadff8c50679 100644
--- a/drivers/media/i2c/ccs/ccs-core.c
+++ b/drivers/media/i2c/ccs/ccs-core.c
@@ -2346,7 +2346,7 @@ static void ccs_set_compose_scaler(struct v4l2_subdev *subdev,
 		* CCS_LIM(sensor, SCALER_N_MIN) / sel->r.height;
 	max_m = crops[CCS_PAD_SINK]->width
 		* CCS_LIM(sensor, SCALER_N_MIN)
-		/ CCS_LIM(sensor, MIN_X_OUTPUT_SIZE);
+		/ (CCS_LIM(sensor, MIN_X_OUTPUT_SIZE) ?: 1);
 
 	a = clamp(a, CCS_LIM(sensor, SCALER_M_MIN),
 		  CCS_LIM(sensor, SCALER_M_MAX));
-- 
2.47.3

Re: [PATCH 1/1] media: ccs: Avoid possible division by zero

[Nathan Chancellor]

On Tue, Nov 25, 2025 at 01:00:45AM +0200, Sakari Ailus wrote:
> Calculating maximum M for scaler configuration involves dividing by
> MIN_X_OUTPUT_SIZE limit register's value. Albeit the value is presumably
> non-zero, the driver was missing the check it in fact was. Fix this.
> 
> Reported-by: Josh Poimboeuf <jpoimboe@kernel.org>
> Closes: https://lore.kernel.org/all/ahukd6b3wonye3zgtptvwzvrxldcruazs2exfvll6etjhmcxyj@vq3eh6pd375b/
> Fixes: ccfc97bdb5ae ("[media] smiapp: Add driver")
> Cc: stable@vger.kernel.org # for 5.15 and later
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---

This clears up the objtool warning for me.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build

>  drivers/media/i2c/ccs/ccs-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> index f8523140784c..dadff8c50679 100644
> --- a/drivers/media/i2c/ccs/ccs-core.c
> +++ b/drivers/media/i2c/ccs/ccs-core.c
> @@ -2346,7 +2346,7 @@ static void ccs_set_compose_scaler(struct v4l2_subdev *subdev,
>  		* CCS_LIM(sensor, SCALER_N_MIN) / sel->r.height;
>  	max_m = crops[CCS_PAD_SINK]->width
>  		* CCS_LIM(sensor, SCALER_N_MIN)
> -		/ CCS_LIM(sensor, MIN_X_OUTPUT_SIZE);
> +		/ (CCS_LIM(sensor, MIN_X_OUTPUT_SIZE) ?: 1);
>  
>  	a = clamp(a, CCS_LIM(sensor, SCALER_M_MIN),
>  		  CCS_LIM(sensor, SCALER_M_MAX));
> -- 
> 2.47.3
>