Re: [PATCH V2 2/2] riscv: Add modules to virtual kernel memory layout dump

[Xianting Tian]

在 2022/7/14 下午5:46, Heiko Stübner 写道:
> Am Donnerstag, 14. Juli 2022, 11:17:26 CEST schrieb Xianting Tian:
> > 在 2022/7/14 下午4:24, Arnd Bergmann 写道:
> > > On Thu, Jul 14, 2022 at 4:59 AM Xianting Tian
> > > <xianting.tian@xxxxxxxxxxxxxxxxx> wrote:
> > > > As MODULES is only defined for CONFIG_64BIT, so we dump it when
> > > > CONFIG_64BIT.
> > > Doesn't this cause a compile-time error on 32-bit?
> > I tested, rv32 compile is OK.
> > > >                   (unsigned long)VMEMMAP_END);
> > > >           print_ml("vmalloc", (unsigned long)VMALLOC_START,
> > > >                   (unsigned long)VMALLOC_END);
> > > > +       if (IS_ENABLED(CONFIG_64BIT))
> > > > +               print_ml("modules", (unsigned long)MODULES_VADDR,
> > > > +                       (unsigned long)MODULES_END);
> > > The IS_ENABLED() check prevents the line from getting executed, but
> > > unlike an #ifdef it still relies on it to be parsable.
> > Thanks, I will use #ifdef instead of IS_ENABLED
> Patch1 also has that issue with the
thanks, I will modify it in V3.
>        if (IS_ENABLED(CONFIG_64BIT)) {
>                vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
>                vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
>        ....
>
>
> module_alloc falls back to a weak variant [0] which is the same as the riscv variant
> only then using VMALLOC_START - VMALLOC_END as range, as the riscv-variant
> conditional to CONFIG_64BIT.

yes, I ever checked, actually before 5.13, it doesn't define MODULES 
area but use VMALLOC for modules,

crash> mod
     MODULE       NAME           BASE           SIZE  OBJECT FILE
ffffffdf8167f280  galcore  ffffffdf81646000  3075841  (not loaded)  
[CONFIG_KALLSYMS]

[    0.000000]      vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff   
(65535 MB)

> I'm wondering if it wouldn't be easier in the long run to just define
> MODULES_VADDR, MODULES_END for 32bit to use these values and get rid of
> the CONFIG_64BIT ifdef we already have for MODULES (and new ones we are
> introducing now).
>
>
> Heiko
>
>
> [0] https://elixir.bootlin.com/linux/latest/source/kernel/module.c#L2835