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Message-ID: <20191104094748.GB23288@rapoport-lnx>
Date:   Mon, 4 Nov 2019 11:47:49 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        Greentime Hu <green.hu@...il.com>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Helge Deller <deller@....de>,
        "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        Jeff Dike <jdike@...toit.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mark Salter <msalter@...hat.com>,
        Matt Turner <mattst88@...il.com>,
        Michal Simek <monstr@...str.eu>, Peter Rosin <peda@...ntia.se>,
        Richard Weinberger <richard@....at>,
        Rolf Eike Beer <eike-kernel@...tec.de>,
        Russell King <linux@...linux.org.uk>,
        Sam Creasey <sammy@...my.net>,
        Vincent Chen <deanbo422@...il.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        alpha <linux-alpha@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-c6x-dev@...ux-c6x.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Parisc List <linux-parisc@...r.kernel.org>,
        linux-um@...ts.infradead.org,
        sparclinux <sparclinux@...r.kernel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH v3 05/13] m68k: mm: use pgtable-nopXd instead of
 4level-fixup

On Mon, Nov 04, 2019 at 09:53:34AM +0100, Geert Uytterhoeven wrote:
> Hi Mike,
> 
> On Mon, Nov 4, 2019 at 7:57 AM Mike Rapoport <rppt@...nel.org> wrote:
> > From: Mike Rapoport <rppt@...ux.ibm.com>
> > m68k has two or three levels of page tables and can use appropriate
> > pgtable-nopXd and folding of the upper layers.
> >
> > Replace usage of include/asm-generic/4level-fixup.h and explicit
> > definitions of __PAGETABLE_PxD_FOLDED in m68k with
> > include/asm-generic/pgtable-nopmd.h for two-level configurations and with
> > include/asm-generic/pgtable-nopud.h for three-lelve configurations and
> > adjust page table manipulation macros and functions accordingly.
> >
> > Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> > Acked-by: Greg Ungerer <gerg@...ux-m68k.org>
> 
> Thanks for your patch!
> 
> The build error reported for v1 by kbuild test robot when building for
> sun3x is still there (m68k defconfig or sun3x_defconfig):
> 
>     arch/m68k/sun3x/dvma.c: In function ‘dvma_map_cpu’:
>     arch/m68k/sun3x/dvma.c:98:33: error: passing argument 2 of
> ‘pmd_alloc’ from incompatible pointer type
> [-Werror=incompatible-pointer-types]
>        if((pmd = pmd_alloc(&init_mm, pgd, vaddr)) == NULL) {
>                                      ^~~
>     In file included from arch/m68k/sun3x/dvma.c:17:
>     include/linux/mm.h:1875:61: note: expected ‘pud_t *’ {aka ‘struct
> <anonymous> *’} but argument is of type ‘pgd_t *’ {aka ‘struct
> <anonymous> *’}
>      static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud,
> unsigned long address)
>                                                           ~~~~~~~^~~

The initial report was against older mmotm (base:
git://git.cmpxchg.org/linux-mmotm.git master) and I presumed this was the
cause of the error. Will fix in v4.
 
> This indeed boots fine on ARAnyM, which emulates on 68040.
> It would be good to have some boot testing on '020/030, too.
 
To be honest, I have no idea how to to that :)

> > --- a/arch/m68k/mm/kmap.c
> > +++ b/arch/m68k/mm/kmap.c
> 
> > @@ -196,17 +198,21 @@ void __iomem *__ioremap(unsigned long physaddr, unsigned long size, int cachefla
> >                         printk ("\npa=%#lx va=%#lx ", physaddr, virtaddr);
> >  #endif
> >                 pgd_dir = pgd_offset_k(virtaddr);
> > -               pmd_dir = pmd_alloc(&init_mm, pgd_dir, virtaddr);
> > +               p4d_dir = p4d_offset(pgd_dir, virtaddr);
> > +               pud_dir = pud_offset(p4d_dir, virtaddr);
> > +               pmd_dir = pmd_alloc(&init_mm, pud_dir, virtaddr);
> >                 if (!pmd_dir) {
> >                         printk("ioremap: no mem for pmd_dir\n");
> >                         return NULL;
> >                 }
> >
> >                 if (CPU_IS_020_OR_030) {
> > +#if CONFIG_PGTABLE_LEVELS == 3
> 
> This check puzzled me a bit: when we get here, CONFIG_PGTABLE_LEVELS is
> always true.
> However, the check cannot be removed, as the code it protects fails to compile
> when building for Coldfire.
> 
> Perhaps this can be made more clear by reverting the order?
> I.e.
> 
>     #if CONFIG_PGTABLE_LEVELS == 3
>             if (CPU_IS_020_OR_030) {
>                     ...
>             } else
>     #endif
>             {
> 
> Or is there some better way?

I think reverting the order is fine. Here it's a bit ugly because of
'} else {', but for the other cases below it will fine.
 
> >                         pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
> >                         physaddr += PTRTREESIZE;
> >                         virtaddr += PTRTREESIZE;
> >                         size -= PTRTREESIZE;
> > +#endif
> >                 } else {
> >                         pte_dir = pte_alloc_kernel(pmd_dir, virtaddr);
> >                         if (!pte_dir) {
> > @@ -258,19 +264,24 @@ void __iounmap(void *addr, unsigned long size)
> >  {
> >         unsigned long virtaddr = (unsigned long)addr;
> >         pgd_t *pgd_dir;
> > +       p4d_t *p4d_dir;
> > +       pud_t *pud_dir;
> >         pmd_t *pmd_dir;
> >         pte_t *pte_dir;
> >
> >         while ((long)size > 0) {
> >                 pgd_dir = pgd_offset_k(virtaddr);
> > -               if (pgd_bad(*pgd_dir)) {
> > -                       printk("iounmap: bad pgd(%08lx)\n", pgd_val(*pgd_dir));
> > -                       pgd_clear(pgd_dir);
> > +               p4d_dir = p4d_offset(pgd_dir, virtaddr);
> > +               pud_dir = pud_offset(p4d_dir, virtaddr);
> > +               if (pud_bad(*pud_dir)) {
> > +                       printk("iounmap: bad pgd(%08lx)\n", pud_val(*pud_dir));
> > +                       pud_clear(pud_dir);
> >                         return;
> >                 }
> > -               pmd_dir = pmd_offset(pgd_dir, virtaddr);
> > +               pmd_dir = pmd_offset(pud_dir, virtaddr);
> >
> >                 if (CPU_IS_020_OR_030) {
> > +#if CONFIG_PGTABLE_LEVELS == 3
> 
> Likewise.
> 
> >                         int pmd_off = (virtaddr/PTRTREESIZE) & 15;
> >                         int pmd_type = pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK;
> >
> 
> > @@ -341,14 +355,17 @@ void kernel_set_cachemode(void *addr, unsigned long size, int cmode)
> >
> >         while ((long)size > 0) {
> >                 pgd_dir = pgd_offset_k(virtaddr);
> > -               if (pgd_bad(*pgd_dir)) {
> > -                       printk("iocachemode: bad pgd(%08lx)\n", pgd_val(*pgd_dir));
> > -                       pgd_clear(pgd_dir);
> > +               p4d_dir = p4d_offset(pgd_dir, virtaddr);
> > +               pud_dir = pud_offset(p4d_dir, virtaddr);
> > +               if (pud_bad(*pud_dir)) {
> > +                       printk("iocachemode: bad pud(%08lx)\n", pud_val(*pud_dir));
> > +                       pud_clear(pud_dir);
> >                         return;
> >                 }
> > -               pmd_dir = pmd_offset(pgd_dir, virtaddr);
> > +               pmd_dir = pmd_offset(pud_dir, virtaddr);
> >
> >                 if (CPU_IS_020_OR_030) {
> > +#if CONFIG_PGTABLE_LEVELS == 3
> 
> Likewise
> 
> >                         int pmd_off = (virtaddr/PTRTREESIZE) & 15;
> >
> >                         if ((pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK) == _PAGE_PRESENT) {
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

-- 
Sincerely yours,
Mike.

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