Messages in this thread Patch in this message | | | From | Uros Bizjak <> | Date | Tue, 2 Apr 2024 22:40:06 +0200 | Subject | Re: warning: cast removes address space '__percpu' of expression |
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On Tue, Apr 2, 2024 at 10:10 PM Charlemagne Lasse <charlemagnelasse@gmail.com> wrote: > > Am Di., 2. Apr. 2024 um 11:53 Uhr schrieb Charlemagne Lasse > <charlemagnelasse@gmail.com>: > > > > Am Di., 2. Apr. 2024 um 11:43 Uhr schrieb Uros Bizjak <ubizjak@gmail.com>: > > [snip] > > > Please try the attached patch that informs sparse about this action. > > > > I've tested it using > > > > ``` > > git reset --hard v6.9-rc2 > > patch -p1 -i ~/p.diff.txt > > git clean -dfx > > make allnoconfig -j$(nproc) > > make kvm_guest.config > > make prepare -j$(nproc) > > touch include/linux/netdevice.h > > make C=1 net/core/dev.o CHECK="sparse -Wcast-from-as" > > ``` > > > > And it seems to work. Thanks > > But I found another problem which seem to have been introduced by > commit ed2f752e0e0a ("x86/percpu: Introduce const-qualified > const_pcpu_hot to micro-optimize code generation") > > > ``` > git reset --hard ed2f752e0e0a21d941ca0ee539ef3d4cd576bc5e > git cherry-pick 3a1d3829e193c091475ceab481c5f8deab385023 > patch -p1 -i ~/p.diff.txt > git clean -dfx > make allnoconfig -j$(nproc) > make kvm_guest.config > echo CONFIG_MODULES=y >> .config > echo CONFIG_NET_9P_VIRTIO=m >> .config > make olddefconfig > make prepare -j$(nproc) > touch net/9p/trans_virtio.o > make C=1 M=net/9p/ trans_virtio.o CHECK="sparse -Wconstexpr-not-const" > ``` > > This now shows the warning: > > ``` > net/9p/trans_virtio.c:831:1: warning: non-constant initializer for static object > net/9p/trans_virtio.c:832:1: warning: non-constant initializer for static object > ``` > > Which is from > > ``` > module_init(p9_virtio_init); > module_exit(p9_virtio_cleanup); > ``` > > The same happens when directly switching to the mentioned commit: > > ``` > git reset --hard ed2f752e0e0a21d941ca0ee539ef3d4cd576bc5e > git cherry-pick 3a1d3829e193c091475ceab481c5f8deab385023 > patch -p1 -i ~/p.diff.txt > git clean -dfx > make allnoconfig -j$(nproc) > make kvm_guest.config > echo CONFIG_MODULES=y >> .config > echo CONFIG_NET_9P_VIRTIO=m >> .config > make olddefconfig > make prepare -j$(nproc) > touch net/9p/trans_virtio.o > make C=1 M=net/9p/ trans_virtio.o CHECK="sparse -Wconstexpr-not-const" > ``` > > > So something for module_init and module_exit changed with this commit. > I can't see this when switching to a version before this commit: > > ``` > git reset --hard ed2f752e0e0a21d941ca0ee539ef3d4cd576bc5e~1 > git cherry-pick 3a1d3829e193c091475ceab481c5f8deab385023 > git clean -dfx > make allnoconfig -j$(nproc) > make kvm_guest.config > echo CONFIG_MODULES=y >> .config > echo CONFIG_NET_9P_VIRTIO=m >> .config > make olddefconfig > make prepare -j$(nproc) > touch net/9p/trans_virtio.o > make C=1 M=net/9p/ trans_virtio.o CHECK="sparse -Wconstexpr-not-const" > ```
It's this part:
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index d7779a18b24fc3..bf9815eaf4aabf 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -212,7 +212,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, */ #define ___ADDRESSABLE(sym, __attrs) \ static void * __used __attrs \ - __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; + __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)(uintptr_t)&sym; #define __ADDRESSABLE(sym) \ ___ADDRESSABLE(sym, __section(".discard.addressable"))
But ... how is this not const?
Uros.
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