linux-kernel - Re: [PATCH v2 07/11] openrisc: mm: Convert to GENERIC

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Message-ID: <YwxfxKrTUtAuejKQ@oscomms1>
Date:   Mon, 29 Aug 2022 06:42:12 +0000
From:   Stafford Horne <shorne@...il.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, agordeev@...ux.ibm.com,
        wangkefeng.wang@...wei.com, linux-arm-kernel@...ts.infradead.org,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        openrisc@...ts.librecores.org
Subject: Re: [PATCH v2 07/11] openrisc: mm: Convert to GENERIC_IOREMAP

On Mon, Aug 29, 2022 at 09:40:24AM +0800, Baoquan He wrote:
> On 08/21/22 at 12:03am, Christoph Hellwig wrote:
> > > +	if (unlikely(!mem_init_done)) {
> > >  		if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
> > > +			return IOMEM_ERR_PTR(ret);
> > >  		v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
> > >  		fixmaps_used += (size >> PAGE_SHIFT);
> > >  
> > > +		if (ioremap_page_range(v, v + size, p, __pgprot(*prot_val))) {
> > >  			fixmaps_used -= (size >> PAGE_SHIFT);
> > > +			return IOMEM_ERR_PTR(ret);
> > > +		}
> > > +
> > > +		return (void __iomem *)(offset + (char *)v);
> > >  	}
> > 
> > This code needs to go away, and all very early boot uses of ioremap
> > need to switch to use early_ioremap insted.
> 
> Makes sense. On openrisc, the thing is I didn't find one place where
> ioremap() is called in arch code. I can cut the early ioremap out and
> wrap into a separate early_ioremap() function, however I don't know
> where to put it. Not sure if I miss anything or openrisc doesn't really
> need early ioremap.

Hi,

I don't know of any early_ioremap usage either in openrisc, maybe some drivers
use it?  However, we do not initialize any early_ioremap infrastructure in
openrisc so that may cause issues if it is used.

We can try to remove it all.  I tested these below additional changes and they
work, if you want to add them we can see if kbuild robots pick anything up.

-Stafford

diff --git a/arch/openrisc/mm/ioremap.c b/arch/openrisc/mm/ioremap.c
index bc41660e1fb0..ffe6d5e2b5fe 100644
--- a/arch/openrisc/mm/ioremap.c
+++ b/arch/openrisc/mm/ioremap.c
@@ -22,14 +22,10 @@
 
 extern int mem_init_done;
 
-static unsigned int fixmaps_used __initdata;
-
 void __iomem *
 arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
 {
-       phys_addr_t p;
-       unsigned long v;
-       unsigned long offset, last_addr, addr = *paddr;
+       unsigned long last_addr, addr = *paddr;
        int ret = -EINVAL;
 
        /* Don't allow wraparound or zero size */
@@ -37,27 +33,6 @@ arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
        if (!size || last_addr < addr)
                return IOMEM_ERR_PTR(ret);
 
-       /*
-        * Mappings have to be page-aligned
-        */
-       offset = addr & ~PAGE_MASK;
-       p = addr & PAGE_MASK;
-       size = PAGE_ALIGN(last_addr + 1) - p;
-
-       if (unlikely(!mem_init_done)) {
-               if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
-                       return IOMEM_ERR_PTR(ret);
-               v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
-               fixmaps_used += (size >> PAGE_SHIFT);
-
-               if (ioremap_page_range(v, v + size, p, __pgprot(*prot_val))) {
-                       fixmaps_used -= (size >> PAGE_SHIFT);
-                       return IOMEM_ERR_PTR(ret);
-               }
-
-               return (void __iomem *)(offset + (char *)v);
-       }
-
        return NULL;
 }