On 2021/6/7 13:48, Christophe Leroy wrote:

Hi Kefeng,

Le 07/06/2021 à 02:55, Kefeng Wang a écrit :

quoted

On 2021/6/7 5:29, Mike Rapoport wrote:

quoted

Hello Kefeng,

On Fri, Jun 04, 2021 at 03:06:18PM +0800, Kefeng Wang wrote:

quoted

Add setup_initial_init_mm() helper, then use it
to cleanup the text, data and brk setup code.

v2:
- change argument from "char *" to "void *" setup_initial_init_mm()
   suggested by Geert Uytterhoeven
- use NULL instead of (void *)0 on h8300 and m68k
- collect ACKs

Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-csky@vger.kernel.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-m68k@lists.linux-m68k.org
Cc: openrisc@lists.librecores.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-sh@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Kefeng Wang (15):
   mm: add setup_initial_init_mm() helper
   arc: convert to setup_initial_init_mm()
   arm: convert to setup_initial_init_mm()
   arm64: convert to setup_initial_init_mm()
   csky: convert to setup_initial_init_mm()
   h8300: convert to setup_initial_init_mm()
   m68k: convert to setup_initial_init_mm()
   nds32: convert to setup_initial_init_mm()
   nios2: convert to setup_initial_init_mm()
   openrisc: convert to setup_initial_init_mm()
   powerpc: convert to setup_initial_init_mm()
   riscv: convert to setup_initial_init_mm()
   s390: convert to setup_initial_init_mm()
   sh: convert to setup_initial_init_mm()
   x86: convert to setup_initial_init_mm()

I might be missing something, but AFAIU the init_mm.start_code and 
other
fields are not used really early so the new setup_initial_init_mm()
function can be called in the generic code outside setup_arch(), e.g in
mm_init().

Hi Mike， each architecture has their own value, not the same, eg m68K 
and

h8300, also the name of the text/code/brk is different in some arch, 
so I keep

unchanged.

What you could do is to define a __weak function that architectures 
can override and call that function from mm_init() as suggested by Mike,

Something like:

void __weak setup_initial_init_mm(void)
{
    init_mm.start_code = (unsigned long)_stext;
    init_mm.end_code = (unsigned long)_etext;
    init_mm.end_data = (unsigned long)_edata;
    init_mm.brk = (unsigned long)_end;
}

Then only the few architecture that are different would override it.

I see a few archictectures are usigne PAGE_OFFSET to set .start_code, 
but it is likely that this is equivalent to _stext.

Yes,  the __weak function is option, but the change is only covered 14 
archs, there are 7 other archs（alpha  hexagon  ia64

microblaze  mips sparc  um xtensa）without related setup code. Also like 
x86, it has own brk , maybe there are some

other different in some arch, so I think let's keep unchanged for now,  
thanks.

Christophe
.