Commit c94bff63 authored by Niklas Schnelle's avatar Niklas Schnelle Committed by Vasily Gorbik
Browse files

s390: Remove ioremap_wt() and pgprot_writethrough() 



It turns out that while s390 architecture calls its memory-I/O mapping
variants write-through and write-back the implementation of ioremap_wt()
and pgprot_writethrough() does not match Linux notion of ioremap_wt().

In particular Linux expects ioremap_wt() to be weaker still than
ioremap_wc(), allowing not just gathering and re-ordering but also reads
to be served from cache. Instead s390's implementation is equivalent to
normal ioremap() while its ioremap_wc() allows re-ordering.

Note that there are no known users of ioremap_wt() on s390 and the
resulting behavior is in line with asm-generic defining ioremap_wt() as
ioremap(), if undefined, so no breakage is expected.

As s390 does not have a mapping type matching the Linux notion of
ioremap_wt() and pgprot_writethrough(), simply drop them and rely on the
asm-generic fallbacks instead.

Fixes: b02002cc ("s390/pci: Implement ioremap_wc/prot() with MIO")
Fixes: b43b3fff ("s390: mm: convert to GENERIC_IOREMAP")
Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 08d95a12

arch/s390/include/asm/io.h

+0 −2
Original line number Diff line number Diff line
@@ -34,8 +34,6 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr); 


#define ioremap_wc(addr, size)  \

	ioremap_prot((addr), (size), pgprot_val(pgprot_writecombine(PAGE_KERNEL)))

#define ioremap_wt(addr, size)  \

	ioremap_prot((addr), (size), pgprot_val(pgprot_writethrough(PAGE_KERNEL)))



static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)

{

arch/s390/include/asm/pgtable.h

+0 −3
Original line number Diff line number Diff line
@@ -1403,9 +1403,6 @@ void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr); 
#define pgprot_writecombine	pgprot_writecombine

pgprot_t pgprot_writecombine(pgprot_t prot);



#define pgprot_writethrough	pgprot_writethrough

pgprot_t pgprot_writethrough(pgprot_t prot);



#define PFN_PTE_SHIFT		PAGE_SHIFT



/*

arch/s390/mm/pgtable.c

+0 −10
Original line number Diff line number Diff line
@@ -36,16 +36,6 @@ pgprot_t pgprot_writecombine(pgprot_t prot) 
}

EXPORT_SYMBOL_GPL(pgprot_writecombine);



pgprot_t pgprot_writethrough(pgprot_t prot)

{

	/*

	 * mio_wb_bit_mask may be set on a different CPU, but it is only set

	 * once at init and only read afterwards.

	 */

	return __pgprot(pgprot_val(prot) & ~mio_wb_bit_mask);

}

EXPORT_SYMBOL_GPL(pgprot_writethrough);



static inline void ptep_ipte_local(struct mm_struct *mm, unsigned long addr,

				   pte_t *ptep, int nodat)

{