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Date:   Mon, 26 Jun 2023 10:45:03 +0800
From:   Baoquan He <bhe@redhat.com>
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc:     linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, arnd@arndb.de, hch@lst.de,
        christophe.leroy@csgroup.eu, rppt@kernel.org, willy@infradead.org,
        agordeev@linux.ibm.com, wangkefeng.wang@huawei.com,
        schnelle@linux.ibm.com, David.Laight@aculab.com, shorne@gmail.com,
        deller@gmx.de, nathan@kernel.org,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, linux-sh@vger.kernel.org
Subject: Re: [PATCH v7 12/19] sh: mm: Convert to GENERIC_IOREMAP
Message-ID: <ZJj7r+FCPu/tWDyV@MiWiFi-R3L-srv>
References: <20230620131356.25440-1-bhe@redhat.com>
 <20230620131356.25440-13-bhe@redhat.com>
 <20fdf89dde5eee365ab15d9f4753e3c9fc43d46e.camel@physik.fu-berlin.de>
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On 06/25/23 at 11:12pm, John Paul Adrian Glaubitz wrote:
> Hi Baoquan!
> 
> On Tue, 2023-06-20 at 21:13 +0800, Baoquan He wrote:
> > By taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(),
> > generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap()
> > and iounmap() are all visible and available to arch. Arch needs to
> > provide wrapper functions to override the generic versions if there's
> > arch specific handling in its ioremap_prot(), ioremap() or iounmap().
> > This change will simplify implementation by removing duplicated codes
>                                                                   ^^^^^
> Nit-pick: It should be "code", not "codes".

Will change.

> 
> I'll review and test the rest tomorrow. There are quite some changes.

That would be great, thanks a lot for your help.

> 
> > with generic_ioremap_prot() and generic_iounmap(), and has the equivalent
> > functioality as before.
> > 
> > Here, add wrapper functions ioremap_prot() and iounmap() for SuperH's
> > special operation when ioremap() and iounmap().
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> > Cc: Rich Felker <dalias@libc.org>
> > Cc: linux-sh@vger.kernel.org
> > ---
> >  arch/sh/Kconfig          |  1 +
> >  arch/sh/include/asm/io.h | 40 +++++--------------------
> >  arch/sh/mm/ioremap.c     | 65 +++++++---------------------------------
> >  3 files changed, 20 insertions(+), 86 deletions(-)
> > 
> > diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> > index 9652d367fc37..f326985e46e0 100644
> > --- a/arch/sh/Kconfig
> > +++ b/arch/sh/Kconfig
> > @@ -28,6 +28,7 @@ config SUPERH
> >  	select GENERIC_SMP_IDLE_THREAD
> >  	select GUP_GET_PXX_LOW_HIGH if X2TLB
> >  	select HAS_IOPORT if HAS_IOPORT_MAP
> > +	select GENERIC_IOREMAP if MMU
> >  	select HAVE_ARCH_AUDITSYSCALL
> >  	select HAVE_ARCH_KGDB
> >  	select HAVE_ARCH_SECCOMP_FILTER
> > diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h
> > index 270e7952950c..b3a26b405c8d 100644
> > --- a/arch/sh/include/asm/io.h
> > +++ b/arch/sh/include/asm/io.h
> > @@ -266,40 +266,16 @@ unsigned long long poke_real_address_q(unsigned long long addr,
> >  #endif
> >  
> >  #ifdef CONFIG_MMU
> > -void iounmap(void __iomem *addr);
> > -void __iomem *__ioremap_caller(phys_addr_t offset, unsigned long size,
> > -			       pgprot_t prot, void *caller);
> > -
> > -static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size)
> > -{
> > -	return __ioremap_caller(offset, size, PAGE_KERNEL_NOCACHE,
> > -			__builtin_return_address(0));
> > -}
> > -
> > -static inline void __iomem *
> > -ioremap_cache(phys_addr_t offset, unsigned long size)
> > -{
> > -	return __ioremap_caller(offset, size, PAGE_KERNEL,
> > -			__builtin_return_address(0));
> > -}
> > -#define ioremap_cache ioremap_cache
> > -
> > -#ifdef CONFIG_HAVE_IOREMAP_PROT
> > -static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
> > -		unsigned long flags)
> > -{
> > -	return __ioremap_caller(offset, size, __pgprot(flags),
> > -			__builtin_return_address(0));
> > -}
> > -#endif /* CONFIG_HAVE_IOREMAP_PROT */
> > +/*
> > + * I/O memory mapping functions.
> > + */
> > +#define ioremap_prot ioremap_prot
> > +#define iounmap iounmap
> >  
> > -#else /* CONFIG_MMU */
> > -static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
> > -{
> > -	return (void __iomem *)(unsigned long)offset;
> > -}
> > +#define _PAGE_IOREMAP pgprot_val(PAGE_KERNEL_NOCACHE)
> >  
> > -static inline void iounmap(volatile void __iomem *addr) { }
> > +#define ioremap_cache(addr, size)  \
> > +	ioremap_prot((addr), (size), pgprot_val(PAGE_KERNEL))
> >  #endif /* CONFIG_MMU */
> >  
> >  #define ioremap_uc	ioremap
> > diff --git a/arch/sh/mm/ioremap.c b/arch/sh/mm/ioremap.c
> > index 21342581144d..c33b3daa4ad1 100644
> > --- a/arch/sh/mm/ioremap.c
> > +++ b/arch/sh/mm/ioremap.c
> > @@ -72,22 +72,11 @@ __ioremap_29bit(phys_addr_t offset, unsigned long size, pgprot_t prot)
> >  #define __ioremap_29bit(offset, size, prot)		NULL
> >  #endif /* CONFIG_29BIT */
> >  
> > -/*
> > - * Remap an arbitrary physical address space into the kernel virtual
> > - * address space. Needed when the kernel wants to access high addresses
> > - * directly.
> > - *
> > - * NOTE! We need to allow non-page-aligned mappings too: we will obviously
> > - * have to convert them into an offset in a page-aligned mapping, but the
> > - * caller shouldn't need to know that small detail.
> > - */
> > -void __iomem * __ref
> > -__ioremap_caller(phys_addr_t phys_addr, unsigned long size,
> > -		 pgprot_t pgprot, void *caller)
> > +void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
> > +			   unsigned long prot)
> >  {
> > -	struct vm_struct *area;
> > -	unsigned long offset, last_addr, addr, orig_addr;
> >  	void __iomem *mapped;
> > +	pgprot_t pgprot = __pgprot(prot);
> >  
> >  	mapped = __ioremap_trapped(phys_addr, size);
> >  	if (mapped)
> > @@ -97,11 +86,6 @@ __ioremap_caller(phys_addr_t phys_addr, unsigned long size,
> >  	if (mapped)
> >  		return mapped;
> >  
> > -	/* Don't allow wraparound or zero size */
> > -	last_addr = phys_addr + size - 1;
> > -	if (!size || last_addr < phys_addr)
> > -		return NULL;
> > -
> >  	/*
> >  	 * If we can't yet use the regular approach, go the fixmap route.
> >  	 */
> > @@ -112,34 +96,14 @@ __ioremap_caller(phys_addr_t phys_addr, unsigned long size,
> >  	 * First try to remap through the PMB.
> >  	 * PMB entries are all pre-faulted.
> >  	 */
> > -	mapped = pmb_remap_caller(phys_addr, size, pgprot, caller);
> > +	mapped = pmb_remap_caller(phys_addr, size, pgprot,
> > +			__builtin_return_address(0));
> >  	if (mapped && !IS_ERR(mapped))
> >  		return mapped;
> >  
> > -	/*
> > -	 * Mappings have to be page-aligned
> > -	 */
> > -	offset = phys_addr & ~PAGE_MASK;
> > -	phys_addr &= PAGE_MASK;
> > -	size = PAGE_ALIGN(last_addr+1) - phys_addr;
> > -
> > -	/*
> > -	 * Ok, go for it..
> > -	 */
> > -	area = get_vm_area_caller(size, VM_IOREMAP, caller);
> > -	if (!area)
> > -		return NULL;
> > -	area->phys_addr = phys_addr;
> > -	orig_addr = addr = (unsigned long)area->addr;
> > -
> > -	if (ioremap_page_range(addr, addr + size, phys_addr, pgprot)) {
> > -		vunmap((void *)orig_addr);
> > -		return NULL;
> > -	}
> > -
> > -	return (void __iomem *)(offset + (char *)orig_addr);
> > +	return generic_ioremap_prot(phys_addr, size, pgprot);
> >  }
> > -EXPORT_SYMBOL(__ioremap_caller);
> > +EXPORT_SYMBOL(ioremap_prot);
> >  
> >  /*
> >   * Simple checks for non-translatable mappings.
> > @@ -158,10 +122,9 @@ static inline int iomapping_nontranslatable(unsigned long offset)
> >  	return 0;
> >  }
> >  
> > -void iounmap(void __iomem *addr)
> > +void iounmap(volatile void __iomem *addr)
> >  {
> >  	unsigned long vaddr = (unsigned long __force)addr;
> > -	struct vm_struct *p;
> >  
> >  	/*
> >  	 * Nothing to do if there is no translatable mapping.
> > @@ -172,21 +135,15 @@ void iounmap(void __iomem *addr)
> >  	/*
> >  	 * There's no VMA if it's from an early fixed mapping.
> >  	 */
> > -	if (iounmap_fixed(addr) == 0)
> > +	if (iounmap_fixed((void __iomem *)addr) == 0)
> >  		return;
> >  
> >  	/*
> >  	 * If the PMB handled it, there's nothing else to do.
> >  	 */
> > -	if (pmb_unmap(addr) == 0)
> > +	if (pmb_unmap((void __iomem *)addr) == 0)
> >  		return;
> >  
> > -	p = remove_vm_area((void *)(vaddr & PAGE_MASK));
> > -	if (!p) {
> > -		printk(KERN_ERR "%s: bad address %p\n", __func__, addr);
> > -		return;
> > -	}
> > -
> > -	kfree(p);
> > +	generic_iounmap(addr);
> >  }
> >  EXPORT_SYMBOL(iounmap);
> 
> -- 
>  .''`.  John Paul Adrian Glaubitz
> : :' :  Debian Developer
> `. `'   Physicist
>   `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913
>