[PATCH v10 03/10] powerpc: Always define MODULES_{VADDR,END}

[Christophe Leroy]

Le 21/04/2021 à 04:46, Jordan Niethe a écrit :
> On Fri, Apr 2, 2021 at 12:36 AM Christophe Leroy
> <christophe.leroy at csgroup.eu> wrote:
>>
>>
>>
>> Le 30/03/2021 à 06:51, Jordan Niethe a écrit :
>>> If MODULES_{VADDR,END} are not defined set them to VMALLOC_START and
>>> VMALLOC_END respectively. This reduces the need for special cases. For
>>> example, powerpc's module_alloc() was previously predicated on
>>> MODULES_VADDR being defined but now is unconditionally defined.
>>>
>>> This will be useful reducing conditional code in other places that need
>>> to allocate from the module region (i.e., kprobes).
>>>
>>> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
>>> ---
>>> v10: New to series
>>> ---
>>>    arch/powerpc/include/asm/pgtable.h | 5 +++++
>>>    arch/powerpc/kernel/module.c       | 5 +----
>>
>> You probably also have changes to do in kernel/ptdump.c
>>
>> In mm/book3s32/mmu.c and mm/kasan/kasan_init_32.c as well allthough that's harmless here.
>>
>>>    2 files changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
>>> index 4eed82172e33..014c2921f26a 100644
>>> --- a/arch/powerpc/include/asm/pgtable.h
>>> +++ b/arch/powerpc/include/asm/pgtable.h
>>> @@ -167,6 +167,11 @@ struct seq_file;
>>>    void arch_report_meminfo(struct seq_file *m);
>>>    #endif /* CONFIG_PPC64 */
>>>
>>> +#ifndef MODULES_VADDR
>>> +#define MODULES_VADDR VMALLOC_START
>>> +#define MODULES_END VMALLOC_END
>>> +#endif
>>> +
>>>    #endif /* __ASSEMBLY__ */
>>>
>>>    #endif /* _ASM_POWERPC_PGTABLE_H */
>>> diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
>>> index a211b0253cdb..f1fb58389d58 100644
>>> --- a/arch/powerpc/kernel/module.c
>>> +++ b/arch/powerpc/kernel/module.c
>>> @@ -14,6 +14,7 @@
>>>    #include <asm/firmware.h>
>>>    #include <linux/sort.h>
>>>    #include <asm/setup.h>
>>> +#include <linux/mm.h>
>>>
>>>    static LIST_HEAD(module_bug_list);
>>>
>>> @@ -87,13 +88,9 @@ int module_finalize(const Elf_Ehdr *hdr,
>>>        return 0;
>>>    }
>>>
>>> -#ifdef MODULES_VADDR
>>>    void *module_alloc(unsigned long size)
>>>    {
>>> -     BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
>>> -
>>
>> The above check is needed somewhere, if you remove it from here you have to perform the check
>> somewhere else.
> 
> This also introduces this warning:
> fs/proc/kcore.c:626:52: warning: self-comparison always evaluates to
> false [-Wtautological-compare]
>    626 |  if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
> I might leave this patch out of this series and use an #ifdef for now
> and make this change separately as a follow up.

x86/32 at least does the same (see 
https://elixir.bootlin.com/linux/v5.12-rc8/source/arch/x86/include/asm/pgtable_32_areas.h#L47)

They probably also get the warning, so I think would shouldn't bother.
One day someone will fix fs/proc/kcore.c , that's not a powerpc problem.

> 
>>
>>>        return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, GFP_KERNEL,
>>>                                    PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
>>>                                    __builtin_return_address(0));
>>>    }
>>> -#endif
>>>