arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[Naresh Kamboju]

The arm64 build started failing from Linux next-20241203 tag with gcc-8
due to following build warnings / errors.

First seen on Linux next-20241203 tag
GOOD: Linux next-20241128 tag
BAD: Linux next-20241203 tag and next-20241205 tag

* arm64, build
  - gcc-8-defconfig
  - gcc-8-defconfig-40bc7ee5

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>

Build log:
===========
net/netfilter/ipvs/ip_vs_conn.c: In function 'ip_vs_conn_init':
include/linux/compiler_types.h:542:38: error: call to
'__compiletime_assert_1050' declared with attribute error: clamp() low
limit min greater than high limit max_avail
  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
                                      ^
include/linux/compiler_types.h:523:4: note: in definition of macro
'__compiletime_assert'
    prefix ## suffix();    \
    ^~~~~~
include/linux/compiler_types.h:542:2: note: in expansion of macro
'_compiletime_assert'
  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
  ^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:39:37: note: in expansion of macro
'compiletime_assert'
 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^~~~~~~~~~~~~~~~~~
include/linux/minmax.h:188:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
  BUILD_BUG_ON_MSG(statically_true(ulo > uhi),    \
  ^~~~~~~~~~~~~~~~
include/linux/minmax.h:195:2: note: in expansion of macro '__clamp_once'
  __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_),
__UNIQUE_ID(h_))
  ^~~~~~~~~~~~
include/linux/minmax.h:206:28: note: in expansion of macro '__careful_clamp'
 #define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
                            ^~~~~~~~~~~~~~~
net/netfilter/ipvs/ip_vs_conn.c:1498:8: note: in expansion of macro 'clamp'
  max = clamp(max, min, max_avail);
        ^~~~~

Links:
---
- https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/log
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/details/
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/history/

Steps to reproduce:
------------
# tuxmake --runtime podman --target-arch arm64 --toolchain gcc-8
--kconfig defconfig

metadata:
----
  git describe: next-20241203
  git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
  git sha: c245a7a79602ccbee780c004c1e4abcda66aec32
  kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/config
  build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
  toolchain: gcc-8
  config: gcc-8-defconfig
  arch: arm64

--
Linaro LKFT
https://lkft.linaro.org

Re: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[Dan Carpenter]

Add David to the CC list.

regards,
dan carpenter

On Thu, Dec 05, 2024 at 08:15:13PM +0530, Naresh Kamboju wrote:
> The arm64 build started failing from Linux next-20241203 tag with gcc-8
> due to following build warnings / errors.
> 
> First seen on Linux next-20241203 tag
> GOOD: Linux next-20241128 tag
> BAD: Linux next-20241203 tag and next-20241205 tag
> 
> * arm64, build
>   - gcc-8-defconfig
>   - gcc-8-defconfig-40bc7ee5
> 
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> 
> Build log:
> ===========
> net/netfilter/ipvs/ip_vs_conn.c: In function 'ip_vs_conn_init':
> include/linux/compiler_types.h:542:38: error: call to
> '__compiletime_assert_1050' declared with attribute error: clamp() low
> limit min greater than high limit max_avail
>   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>                                       ^
> include/linux/compiler_types.h:523:4: note: in definition of macro
> '__compiletime_assert'
>     prefix ## suffix();    \
>     ^~~~~~
> include/linux/compiler_types.h:542:2: note: in expansion of macro
> '_compiletime_assert'
>   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>   ^~~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:39:37: note: in expansion of macro
> 'compiletime_assert'
>  #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>                                      ^~~~~~~~~~~~~~~~~~
> include/linux/minmax.h:188:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
>   BUILD_BUG_ON_MSG(statically_true(ulo > uhi),    \
>   ^~~~~~~~~~~~~~~~
> include/linux/minmax.h:195:2: note: in expansion of macro '__clamp_once'
>   __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_),
> __UNIQUE_ID(h_))
>   ^~~~~~~~~~~~
> include/linux/minmax.h:206:28: note: in expansion of macro '__careful_clamp'
>  #define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
>                             ^~~~~~~~~~~~~~~
> net/netfilter/ipvs/ip_vs_conn.c:1498:8: note: in expansion of macro 'clamp'
>   max = clamp(max, min, max_avail);
>         ^~~~~
> 
> Links:
> ---
> - https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
> - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/log
> - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/details/
> - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/history/
> 
> Steps to reproduce:
> ------------
> # tuxmake --runtime podman --target-arch arm64 --toolchain gcc-8
> --kconfig defconfig
> 
> metadata:
> ----
>   git describe: next-20241203
>   git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>   git sha: c245a7a79602ccbee780c004c1e4abcda66aec32
>   kernel config:
> https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/config
>   build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
>   toolchain: gcc-8
>   config: gcc-8-defconfig
>   arch: arm64
> 
> --
> Linaro LKFT
> https://lkft.linaro.org

RE: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[David Laight]

From: Dan Carpenter <dan.carpenter@linaro.org>
> Sent: 05 December 2024 15:16
> 
> Add David to the CC list.

I've been forwarded this one before.
It is not unreasonable really.

Is all stems from order_base_2(totalram_pages()).
order_base_2(n) is 'n > 1 ? ilog2(n - 1) + 1 : 0'.
And the compiler is generating two copies of the code.
(Basically optimising for the zero case.)
And the one for totalram_pages() being zero hits the check in clamp().

Flipping to clamp(max_avail, min, max) will stop it bleating.

More interesting would be 'launder' the 0 in order_base_2().
By adding something like:
#define optimiser_hide_val(x) ({ \
	__auto_type(_x) = (x); \
	optimiser_hide_var(_x); \
	_x; \
})
and change order_base_2() to be:
	n > 1 ? ilog2(n - 1) + 1 : optimiser_hide_val(0);
(ISTR there is a split for constant v non-constant before then.)

	David

> 
> regards,
> dan carpenter
> 
> On Thu, Dec 05, 2024 at 08:15:13PM +0530, Naresh Kamboju wrote:
> > The arm64 build started failing from Linux next-20241203 tag with gcc-8
> > due to following build warnings / errors.
> >
> > First seen on Linux next-20241203 tag
> > GOOD: Linux next-20241128 tag
> > BAD: Linux next-20241203 tag and next-20241205 tag
> >
> > * arm64, build
> >   - gcc-8-defconfig
> >   - gcc-8-defconfig-40bc7ee5
> >
> > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> >
> > Build log:
> > ===========
> > net/netfilter/ipvs/ip_vs_conn.c: In function 'ip_vs_conn_init':
> > include/linux/compiler_types.h:542:38: error: call to
> > '__compiletime_assert_1050' declared with attribute error: clamp() low
> > limit min greater than high limit max_avail
> >   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >                                       ^
> > include/linux/compiler_types.h:523:4: note: in definition of macro
> > '__compiletime_assert'
> >     prefix ## suffix();    \
> >     ^~~~~~
> > include/linux/compiler_types.h:542:2: note: in expansion of macro
> > '_compiletime_assert'
> >   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >   ^~~~~~~~~~~~~~~~~~~
> > include/linux/build_bug.h:39:37: note: in expansion of macro
> > 'compiletime_assert'
> >  #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> >                                      ^~~~~~~~~~~~~~~~~~
> > include/linux/minmax.h:188:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
> >   BUILD_BUG_ON_MSG(statically_true(ulo > uhi),    \
> >   ^~~~~~~~~~~~~~~~
> > include/linux/minmax.h:195:2: note: in expansion of macro '__clamp_once'
> >   __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_),
> > __UNIQUE_ID(h_))
> >   ^~~~~~~~~~~~
> > include/linux/minmax.h:206:28: note: in expansion of macro '__careful_clamp'
> >  #define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
> >                             ^~~~~~~~~~~~~~~
> > net/netfilter/ipvs/ip_vs_conn.c:1498:8: note: in expansion of macro 'clamp'
> >   max = clamp(max, min, max_avail);
> >         ^~~~~
> >
> > Links:
> > ---
> > - https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
> > - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-
> 20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/log
> > - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-
> 20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/details/
> > - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-
> 20241203/testrun/26189105/suite/build/test/gcc-8-defconfig/history/
> >
> > Steps to reproduce:
> > ------------
> > # tuxmake --runtime podman --target-arch arm64 --toolchain gcc-8
> > --kconfig defconfig
> >
> > metadata:
> > ----
> >   git describe: next-20241203
> >   git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> >   git sha: c245a7a79602ccbee780c004c1e4abcda66aec32
> >   kernel config:
> > https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/config
> >   build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2pjAOE9K3Dz9gRywrldKTyaXQoT/
> >   toolchain: gcc-8
> >   config: gcc-8-defconfig
> >   arch: arm64
> >
> > --
> > Linaro LKFT
> > https://lkft.linaro.org

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[Naresh Kamboju]

On Thu, 5 Dec 2024 at 20:46, Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> Add David to the CC list.

Anders bisected this reported issue and found the first bad commit as,

# first bad commit:
  [ef32b92ac605ba1b7692827330b9c60259f0af49]
  minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()


 - Naresh

RE: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[David Laight]

From: Naresh Kamboju
> Sent: 05 December 2024 18:42
> 
> On Thu, 5 Dec 2024 at 20:46, Dan Carpenter <dan.carpenter@linaro.org> wrote:
> >
> > Add David to the CC list.
> 
> Anders bisected this reported issue and found the first bad commit as,
> 
> # first bad commit:
>   [ef32b92ac605ba1b7692827330b9c60259f0af49]
>   minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()

That 'just' changed the test to use __builtin_constant_p() and
thus gets checked after the optimiser has run.

I can paraphrase the code as:
unsigned int fn(unsigned int x)
{
	return clamp(10, 5, x == 0 ? 0 : x - 1);
}
which is never actually called with x <= 5.
The compiler converts it to:
	return x < 0 ? clamp(10, 5, 0) : clamp(10, 5, x);
(Probably because it can see that clamp(10, 5, 0) is constant.)
And then the compile-time sanity check in clamp() fires.

The order of the arguments to clamp is just wrong!

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[Bartosz Golaszewski]

On Fri, Dec 6, 2024 at 3:20 AM David Laight <David.Laight@aculab.com> wrote:
>
> From: Naresh Kamboju
> > Sent: 05 December 2024 18:42
> >
> > On Thu, 5 Dec 2024 at 20:46, Dan Carpenter <dan.carpenter@linaro.org> wrote:
> > >
> > > Add David to the CC list.
> >
> > Anders bisected this reported issue and found the first bad commit as,
> >
> > # first bad commit:
> >   [ef32b92ac605ba1b7692827330b9c60259f0af49]
> >   minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()
>
> That 'just' changed the test to use __builtin_constant_p() and
> thus gets checked after the optimiser has run.
>
> I can paraphrase the code as:
> unsigned int fn(unsigned int x)
> {
>         return clamp(10, 5, x == 0 ? 0 : x - 1);
> }
> which is never actually called with x <= 5.
> The compiler converts it to:
>         return x < 0 ? clamp(10, 5, 0) : clamp(10, 5, x);
> (Probably because it can see that clamp(10, 5, 0) is constant.)
> And then the compile-time sanity check in clamp() fires.
>
> The order of the arguments to clamp is just wrong!
>
>         David
>

The build is still failing with today's next, should the offending
commit be reverted?

Bartosz

Re: arm64: include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_1050' declared with attribute error: clamp() low limit min greater than high limit max_avail

[Dan Carpenter]

On Wed, Dec 11, 2024 at 01:46:11PM +0100, Bartosz Golaszewski wrote:
> On Fri, Dec 6, 2024 at 3:20 AM David Laight <David.Laight@aculab.com> wrote:
> >
> > From: Naresh Kamboju
> > > Sent: 05 December 2024 18:42
> > >
> > > On Thu, 5 Dec 2024 at 20:46, Dan Carpenter <dan.carpenter@linaro.org> wrote:
> > > >
> > > > Add David to the CC list.
> > >
> > > Anders bisected this reported issue and found the first bad commit as,
> > >
> > > # first bad commit:
> > >   [ef32b92ac605ba1b7692827330b9c60259f0af49]
> > >   minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()
> >
> > That 'just' changed the test to use __builtin_constant_p() and
> > thus gets checked after the optimiser has run.
> >
> > I can paraphrase the code as:
> > unsigned int fn(unsigned int x)
> > {
> >         return clamp(10, 5, x == 0 ? 0 : x - 1);
> > }
> > which is never actually called with x <= 5.
> > The compiler converts it to:
> >         return x < 0 ? clamp(10, 5, 0) : clamp(10, 5, x);
> > (Probably because it can see that clamp(10, 5, 0) is constant.)
> > And then the compile-time sanity check in clamp() fires.
> >
> > The order of the arguments to clamp is just wrong!
> >
> >         David
> >
> 
> The build is still failing with today's next, should the offending
> commit be reverted?
> 

It's a simple fix.  I've sent a patch.

regards,
dan carpenter