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SubjectRe: [PATCH 2/4] arc: fix type warnings in arc/mm/cache.c
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On 07/24/2018 01:46 PM, Randy Dunlap wrote:
> From: Randy Dunlap <rdunlap@infradead.org>
>
> ../arch/arc/mm/cache.c: In function 'flush_anon_page':
> ../arch/arc/mm/cache.c:1062:55: warning: passing argument 2 of '__flush_dcache_page' makes integer from pointer without a cast [-Wint-conversion]
> __flush_dcache_page((phys_addr_t)page_address(page), page_address(page));
> ^~~~~~~~~~~~~~~~~~
> ../arch/arc/mm/cache.c:1013:59: note: expected 'long unsigned int' but argument is of type 'void *'
> void __flush_dcache_page(phys_addr_t paddr, unsigned long vaddr)
> ~~~~~~~~~~~~~~^~~~~
>
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Cc: Vineet Gupta <vgupta@synopsys.com>
> Cc: Ofer Levi <oferle@mellanox.com>
> Cc: linux-snps-arc@lists.infradead.org
> ---
> arch/arc/mm/cache.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> --- linux-next-20180723.orig/arch/arc/mm/cache.c
> +++ linux-next-20180723/arch/arc/mm/cache.c
> @@ -1038,7 +1038,7 @@ void flush_cache_mm(struct mm_struct *mm
> void flush_cache_page(struct vm_area_struct *vma, unsigned long u_vaddr,
> unsigned long pfn)
> {
> - unsigned int paddr = pfn << PAGE_SHIFT;
> + phys_addr_t paddr = pfn << PAGE_SHIFT;
>
> u_vaddr &= PAGE_MASK;
>
> @@ -1058,8 +1058,9 @@ void flush_anon_page(struct vm_area_stru
> unsigned long u_vaddr)
> {
> /* TBD: do we really need to clear the kernel mapping */
> - __flush_dcache_page(page_address(page), u_vaddr);
> - __flush_dcache_page(page_address(page), page_address(page));
> + __flush_dcache_page((phys_addr_t)page_address(page), u_vaddr);
> + __flush_dcache_page((phys_addr_t)page_address(page),
> + (phys_addr_t)page_address(page));

CONFIG_ARC_CACHE_VIPT_ALIASING is a total bitrot and I'm considering removing it
as no sane systems should use it. There's none which I know are using it.
But for now this will do.


>
> }
>
> @@ -1084,7 +1085,7 @@ void copy_user_highpage(struct page *to,
> * addr_not_cache_congruent() is 0
> */
> if (page_mapcount(from) && addr_not_cache_congruent(kfrom, u_vaddr)) {
> - __flush_dcache_page((unsigned long)kfrom, u_vaddr);
> + __flush_dcache_page((phys_addr_t)kfrom, u_vaddr);

Was this needed really ? I can't seem to trigger any warnings here.
All of this (original code before your change) is technically incorrect due to the
combination of CONFIG_ARC_CACHE_VIPT_ALIASING and CONFIG_HIGHMEM. @kfrom is
returned by kmap_atomic() and in highmem regime it could be a kernel virtual
address, so calling the low level cache flush interface with a kvaddr, pretending
it is paddr (whethe runsigned long or phys_addr_t) is just not right. This
combinations needs to be disallowed from Kconfig !

> clean_src_k_mappings = 1;
> }
>
> @@ -1105,7 +1106,7 @@ void copy_user_highpage(struct page *to,
> * sync the kernel mapping back to physical page
> */
> if (clean_src_k_mappings) {
> - __flush_dcache_page((unsigned long)kfrom, (unsigned long)kfrom);
> + __flush_dcache_page((phys_addr_t)kfrom, (unsigned long)kfrom);
> set_bit(PG_dc_clean, &from->flags);
> } else {
> clear_bit(PG_dc_clean, &from->flags);
>

Ditto !

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