6.12-stable review patch. If anyone has any objections, please let me know.
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From: Niklas Schnelle schnelle@linux.ibm.com
[ Upstream commit c94bff63e49302d4ce36502a85a2710a67332a4f ]
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: b02002cc4c0f ("s390/pci: Implement ioremap_wc/prot() with MIO") Fixes: b43b3fff042d ("s390: mm: convert to GENERIC_IOREMAP") Acked-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Niklas Schnelle schnelle@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/io.h | 2 -- arch/s390/include/asm/pgtable.h | 3 --- arch/s390/mm/pgtable.c | 10 ---------- 3 files changed, 15 deletions(-)
diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h index fc9933a743d69..251e0372ccbd0 100644 --- a/arch/s390/include/asm/io.h +++ b/arch/s390/include/asm/io.h @@ -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) { diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 0ffbaf7419558..5ee73f245a0c0 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1365,9 +1365,6 @@ 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
/* diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 2c944bafb0309..b03c665d72426 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -34,16 +34,6 @@ 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) {