* [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
@ 2025-03-08 20:56 kernel test robot
2025-03-09 8:37 ` Andrea Righi
0 siblings, 1 reply; 4+ messages in thread
From: kernel test robot @ 2025-03-08 20:56 UTC (permalink / raw)
To: Andrea Righi; +Cc: oe-kbuild-all, Tejun Heo, Yury Norov
tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head: 0a2f889128969dab41861b6e40111aa03dc57014
commit: 48849271e66114cb980a3bc44218b04d0f8cdcdd [3203/9634] sched_ext: idle: Per-node idle cpumasks
config: powerpc-randconfig-r112-20250308 (https://download.01.org/0day-ci/archive/20250309/202503090435.wITkzD2e-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce: (https://download.01.org/0day-ci/archive/20250309/202503090435.wITkzD2e-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/oe-kbuild-all/202503090435.wITkzD2e-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from kernel/sched/build_policy.c:16:
In file included from include/linux/sched/clock.h:5:
In file included from include/linux/smp.h:13:
In file included from include/linux/cpumask.h:11:
In file included from include/linux/kernel.h:23:
In file included from include/linux/bitops.h:68:
>> arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
126 | DEFINE_CLROP(clear_bits, "")
| ^
1 error generated.
vim +/n +126 arch/powerpc/include/asm/bitops.h
fb350784d8d179 Christophe Leroy 2021-09-21 125
fb350784d8d179 Christophe Leroy 2021-09-21 @126 DEFINE_CLROP(clear_bits, "")
fb350784d8d179 Christophe Leroy 2021-09-21 127 DEFINE_CLROP(clear_bits_unlock, PPC_RELEASE_BARRIER)
fb350784d8d179 Christophe Leroy 2021-09-21 128
:::::: The code at line 126 was first introduced by commit
:::::: fb350784d8d17952afa93383bb47aaa6b715c459 powerpc/bitops: Use immediate operand when possible
:::::: TO: Christophe Leroy <christophe.leroy@csgroup.eu>
:::::: CC: Michael Ellerman <mpe@ellerman.id.au>
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
2025-03-08 20:56 [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression kernel test robot
@ 2025-03-09 8:37 ` Andrea Righi
2025-03-09 18:48 ` Christophe Leroy
0 siblings, 1 reply; 4+ messages in thread
From: Andrea Righi @ 2025-03-09 8:37 UTC (permalink / raw)
To: kernel test robot; +Cc: oe-kbuild-all, Tejun Heo, Yury Norov, Christophe Leroy
On Sun, Mar 09, 2025 at 04:56:45AM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head: 0a2f889128969dab41861b6e40111aa03dc57014
> commit: 48849271e66114cb980a3bc44218b04d0f8cdcdd [3203/9634] sched_ext: idle: Per-node idle cpumasks
> config: powerpc-randconfig-r112-20250308 (https://download.01.org/0day-ci/archive/20250309/202503090435.wITkzD2e-lkp@intel.com/config)
> compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
> reproduce: (https://download.01.org/0day-ci/archive/20250309/202503090435.wITkzD2e-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/oe-kbuild-all/202503090435.wITkzD2e-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
> In file included from kernel/sched/build_policy.c:16:
> In file included from include/linux/sched/clock.h:5:
> In file included from include/linux/smp.h:13:
> In file included from include/linux/cpumask.h:11:
> In file included from include/linux/kernel.h:23:
> In file included from include/linux/bitops.h:68:
> >> arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
> 126 | DEFINE_CLROP(clear_bits, "")
> | ^
> 1 error generated.
I've expanded the for_each_node_numadist() macro to better understand
what's going on, it seems that clang isn't happy with a node_clear() inside
the for loop, and it's not complaining about a similar node_clear() outside
the for loop.
Also, it seems to happen only with clang (gcc is always happy).
Here's the relevant code (with the macro expanded and comments removed):
===
static DEFINE_PER_CPU(nodemask_t, per_cpu_unvisited);
static s32 pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, int node, u64 flags)
{
nodemask_t *unvisited;
s32 cpu = -EBUSY;
preempt_disable();
unvisited = this_cpu_ptr(&per_cpu_unvisited);
nodes_copy(*unvisited, node_states[N_ONLINE]);
node_clear(node, *unvisited);
for (int __start = node,
node = nearest_node_nodemask(__start, unvisited);
node < MAX_NUMNODES;
// node_clear(node, *unvisited), <- clang is happy with this one commented!
node = nearest_node_nodemask(__start, unvisited)) {
cpu = pick_idle_cpu_in_node(cpus_allowed, node, flags);
if (cpu >= 0)
break;
}
preempt_enable();
return cpu;
}
===
The code looks correct to me, but I don't know much about powerpc assembly.
Christophe, maybe you have a better idea of what's happening here?
Thanks,
-Andrea
>
>
> vim +/n +126 arch/powerpc/include/asm/bitops.h
>
> fb350784d8d179 Christophe Leroy 2021-09-21 125
> fb350784d8d179 Christophe Leroy 2021-09-21 @126 DEFINE_CLROP(clear_bits, "")
> fb350784d8d179 Christophe Leroy 2021-09-21 127 DEFINE_CLROP(clear_bits_unlock, PPC_RELEASE_BARRIER)
> fb350784d8d179 Christophe Leroy 2021-09-21 128
>
> :::::: The code at line 126 was first introduced by commit
> :::::: fb350784d8d17952afa93383bb47aaa6b715c459 powerpc/bitops: Use immediate operand when possible
>
> :::::: TO: Christophe Leroy <christophe.leroy@csgroup.eu>
> :::::: CC: Michael Ellerman <mpe@ellerman.id.au>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
2025-03-09 8:37 ` Andrea Righi
@ 2025-03-09 18:48 ` Christophe Leroy
2025-03-09 20:47 ` Andrea Righi
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2025-03-09 18:48 UTC (permalink / raw)
To: Andrea Righi, kernel test robot
Cc: oe-kbuild-all, Tejun Heo, Yury Norov, clang-built-linux,
llvm@lists.linux.dev
Le 09/03/2025 à 09:37, Andrea Righi a écrit :
> [Vous ne recevez pas souvent de courriers de arighi@nvidia.com. D?couvrez pourquoi ceci est important ? https://aka.ms/LearnAboutSenderIdentification ]
>
> On Sun, Mar 09, 2025 at 04:56:45AM +0800, kernel test robot wrote:
>> tree: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062684017698%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=lK0Vy%2F4o95CtQF5szPezehhmcdFjDEGgf6JWYRIG%2FcY%3D&reserved=0 master
>> head: 0a2f889128969dab41861b6e40111aa03dc57014
>> commit: 48849271e66114cb980a3bc44218b04d0f8cdcdd [3203/9634] sched_ext: idle: Per-node idle cpumasks
>> config: powerpc-randconfig-r112-20250308 (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdownload.01.org%2F0day-ci%2Farchive%2F20250309%2F202503090435.wITkzD2e-lkp%40intel.com%2Fconfig&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062687408543%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=dNaCIS1An989v%2BhSzWt0F1M33pxzf0WO6G09wU3%2F90s%3D&reserved=0)
>> compiler: clang version 18.1.8 (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fllvm%2Fllvm-project&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062687416861%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=bBHENBhnCpqHz2ErtwY4iMTakfvmq5kumF0BVqN6hKQ%3D&reserved=0 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
>> reproduce: (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdownload.01.org%2F0day-ci%2Farchive%2F20250309%2F202503090435.wITkzD2e-lkp%40intel.com%2Freproduce&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062687424999%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Wm6O%2BaoClsBaKLXtVLOi4uDpPVx6z%2FoXnE6LF%2BMnBH8%3D&reserved=0)
>>
>> 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Foe-kbuild-all%2F202503090435.wITkzD2e-lkp%40intel.com%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062687433012%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=vh%2BADDGxZZJblkU6V0NlC9VPlK2ZgQQWfTCdRMtfXNY%3D&reserved=0
>>
>> All errors (new ones prefixed by >>):
>>
>> In file included from kernel/sched/build_policy.c:16:
>> In file included from include/linux/sched/clock.h:5:
>> In file included from include/linux/smp.h:13:
>> In file included from include/linux/cpumask.h:11:
>> In file included from include/linux/kernel.h:23:
>> In file included from include/linux/bitops.h:68:
>>>> arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
>> 126 | DEFINE_CLROP(clear_bits, "")
>> | ^
>> 1 error generated.
>
> I've expanded the for_each_node_numadist() macro to better understand
> what's going on, it seems that clang isn't happy with a node_clear() inside
> the for loop, and it's not complaining about a similar node_clear() outside
> the for loop.
>
> Also, it seems to happen only with clang (gcc is always happy).
>
> Here's the relevant code (with the macro expanded and comments removed):
>
> ===
> static DEFINE_PER_CPU(nodemask_t, per_cpu_unvisited);
>
> static s32 pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, int node, u64 flags)
> {
> nodemask_t *unvisited;
> s32 cpu = -EBUSY;
>
> preempt_disable();
> unvisited = this_cpu_ptr(&per_cpu_unvisited);
>
> nodes_copy(*unvisited, node_states[N_ONLINE]);
> node_clear(node, *unvisited);
>
> for (int __start = node,
> node = nearest_node_nodemask(__start, unvisited);
> node < MAX_NUMNODES;
> // node_clear(node, *unvisited), <- clang is happy with this one commented!
> node = nearest_node_nodemask(__start, unvisited)) {
> cpu = pick_idle_cpu_in_node(cpus_allowed, node, flags);
> if (cpu >= 0)
> break;
> }
> preempt_enable();
>
> return cpu;
> }
> ===
>
> The code looks correct to me, but I don't know much about powerpc assembly.
> Christophe, maybe you have a better idea of what's happening here?
#define DEFINE_CLROP(fn, prefix) \
static inline void fn(unsigned long mask, volatile unsigned long *_p) \
{ \
unsigned long old; \
unsigned long *p = (unsigned long *)_p; \
\
if (IS_ENABLED(CONFIG_PPC32) && \
__builtin_constant_p(mask) && is_rlwinm_mask_valid(~mask)) {\
asm volatile ( \
prefix \
"1:" "lwarx %0,0,%3\n" \
"rlwinm %0,%0,0,%2\n" \
"stwcx. %0,0,%3\n" \
"bne- 1b\n" \
: "=&r" (old), "+m" (*p) \
: "n" (~mask), "r" (p) \
: "cc", "memory"); \
} else { \
asm volatile ( \
prefix \
"1:" PPC_LLARX "%0,0,%3,0\n" \
"andc %0,%0,%2\n" \
PPC_STLCX "%0,0,%3\n" \
"bne- 1b\n" \
: "=&r" (old), "+m" (*p) \
: "r" (mask), "r" (p) \
: "cc", "memory"); \
} \
}
clang says "constraint 'n' expects an integer constant expression" ?
The only place I see 'n' constraint in that macro is the '"n" (~mask)'
in the if __builtin_constant_p(mask) branch. As far as I know if mask is
a constant (~mask) is also a constant ?
Must be a clang bug ?
Maybe try with __builtin_constant_p(~mask) instead of
__builtin_constant_p(mask)
Christophe
>
> Thanks,
> -Andrea
>
>>
>>
>> vim +/n +126 arch/powerpc/include/asm/bitops.h
>>
>> fb350784d8d179 Christophe Leroy 2021-09-21 125
>> fb350784d8d179 Christophe Leroy 2021-09-21 @126 DEFINE_CLROP(clear_bits, "")
>> fb350784d8d179 Christophe Leroy 2021-09-21 127 DEFINE_CLROP(clear_bits_unlock, PPC_RELEASE_BARRIER)
>> fb350784d8d179 Christophe Leroy 2021-09-21 128
>>
>> :::::: The code at line 126 was first introduced by commit
>> :::::: fb350784d8d17952afa93383bb47aaa6b715c459 powerpc/bitops: Use immediate operand when possible
>>
>> :::::: TO: Christophe Leroy <christophe.leroy@csgroup.eu>
>> :::::: CC: Michael Ellerman <mpe@ellerman.id.au>
>>
>> --
>> 0-DAY CI Kernel Test Service
>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fintel%2Flkp-tests%2Fwiki&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C01ad01407fee4a03676d08dd5ee5a99d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638771062687441670%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=y4xmCm57X1U8WeYk2lPntirA60ajGxiW6u2xjp3t580%3D&reserved=0
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression
2025-03-09 18:48 ` Christophe Leroy
@ 2025-03-09 20:47 ` Andrea Righi
0 siblings, 0 replies; 4+ messages in thread
From: Andrea Righi @ 2025-03-09 20:47 UTC (permalink / raw)
To: Christophe Leroy
Cc: kernel test robot, oe-kbuild-all, Tejun Heo, Yury Norov,
clang-built-linux, llvm@lists.linux.dev
Hi Christophe,
On Sun, Mar 09, 2025 at 07:48:56PM +0100, Christophe Leroy wrote:
...
> #define DEFINE_CLROP(fn, prefix) \
> static inline void fn(unsigned long mask, volatile unsigned long *_p) \
> { \
> unsigned long old; \
> unsigned long *p = (unsigned long *)_p; \
> \
> if (IS_ENABLED(CONFIG_PPC32) && \
> __builtin_constant_p(mask) && is_rlwinm_mask_valid(~mask)) {\
> asm volatile ( \
> prefix \
> "1:" "lwarx %0,0,%3\n" \
> "rlwinm %0,%0,0,%2\n" \
> "stwcx. %0,0,%3\n" \
> "bne- 1b\n" \
> : "=&r" (old), "+m" (*p) \
> : "n" (~mask), "r" (p) \
> : "cc", "memory"); \
> } else { \
> asm volatile ( \
> prefix \
> "1:" PPC_LLARX "%0,0,%3,0\n" \
> "andc %0,%0,%2\n" \
> PPC_STLCX "%0,0,%3\n" \
> "bne- 1b\n" \
> : "=&r" (old), "+m" (*p) \
> : "r" (mask), "r" (p) \
> : "cc", "memory"); \
> } \
> }
>
>
> clang says "constraint 'n' expects an integer constant expression" ?
>
> The only place I see 'n' constraint in that macro is the '"n" (~mask)' in
> the if __builtin_constant_p(mask) branch. As far as I know if mask is a
> constant (~mask) is also a constant ?
Right, that's my understanding as well.
>
> Must be a clang bug ?
Possibly...
>
> Maybe try with __builtin_constant_p(~mask) instead of
> __builtin_constant_p(mask)
I tried using ~mask, and even tried to use just mask throughout the
entire macro (although the code would be incorrect), but I still get the
same build error.
The only way that I found to fix this is by adding
!IS_ENABLED(CONFIG_CC_IS_CLANG) to the if, which isn't really elegant, but
maybe it's a reasonable workaround? I'll also open a clang issue in the
meantime.
Thanks,
-Andrea
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-03-09 20:47 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-03-08 20:56 [linux-next:master 3203/9634] arch/powerpc/include/asm/bitops.h:126:26: error: constraint 'n' expects an integer constant expression kernel test robot
2025-03-09 8:37 ` Andrea Righi
2025-03-09 18:48 ` Christophe Leroy
2025-03-09 20:47 ` Andrea Righi
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