Re: [PATCH v3 16/18] arm64: sync_icache_aliases to take end parameter instead of size

Mark Rutland
2021-05-20T16:36:35Z

On Thu, May 20, 2021 at 01:44:04PM +0100, Fuad Tabba wrote:
> To be consistent with other functions with similar names and
> functionality in cacheflush.h, cache.S, and cachetlb.rst, change
> to specify the range in terms of start and end, as opposed to
> start and size.
>
> No functional change intended.
>
> Reported-by: Will Deacon <will@kernel.org>
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
> arch/arm64/include/asm/cacheflush.h | 2 +-
> arch/arm64/kernel/probes/uprobes.c | 2 +-
> arch/arm64/mm/flush.c | 21 +++++++++++----------
> 3 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
> index f86723047315..70b389a8dea5 100644
> --- a/arch/arm64/include/asm/cacheflush.h
> +++ b/arch/arm64/include/asm/cacheflush.h
> @@ -64,7 +64,7 @@ extern void __clean_dcache_area_poc(unsigned long start, unsigned long end);
> extern void __clean_dcache_area_pop(unsigned long start, unsigned long end);
> extern void __clean_dcache_area_pou(unsigned long start, unsigned long end);
> extern long __flush_cache_user_range(unsigned long start, unsigned long end);
> -extern void sync_icache_aliases(void *kaddr, unsigned long len);
> +extern void sync_icache_aliases(unsigned long start, unsigned long end);
>
> static inline void flush_icache_range(unsigned long start, unsigned long end)
> {
> diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c
> index 2c247634552b..9be668f3f034 100644
> --- a/arch/arm64/kernel/probes/uprobes.c
> +++ b/arch/arm64/kernel/probes/uprobes.c
> @@ -21,7 +21,7 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
> memcpy(dst, src, len);
>
> /* flush caches (dcache/icache) */
> - sync_icache_aliases(dst, len);
> + sync_icache_aliases((unsigned long)dst, (unsigned long)dst + len);
>
> kunmap_atomic(xol_page_kaddr);
> }
> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
> index a69d745fb1dc..143f625e7727 100644
> --- a/arch/arm64/mm/flush.c
> +++ b/arch/arm64/mm/flush.c
> @@ -14,28 +14,26 @@
> #include <asm/cache.h>
> #include <asm/tlbflush.h>
>
> -void sync_icache_aliases(void *kaddr, unsigned long len)
> +void sync_icache_aliases(unsigned long start, unsigned long end)
> {
> - unsigned long addr = (unsigned long)kaddr;
> -
> if (icache_is_aliasing()) {
> - __clean_dcache_area_pou(kaddr, kaddr + len);
> + __clean_dcache_area_pou(start, end);
> __flush_icache_all();
> } else {
> /*
> * Don't issue kick_all_cpus_sync() after I-cache invalidation
> * for user mappings.
> */
> - __flush_icache_range(addr, addr + len);
> + __flush_icache_range(start, end);
> }
> }
>
> static void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
> - unsigned long uaddr, void *kaddr,
> - unsigned long len)
> + unsigned long uaddr, unsigned long start,
> + unsigned long end)

Can we please drop the `uaddr` argument here?

Generally, for functions which take both a `uaddr` and a `kaddr`, it's
best to pass a length argument, since that can be applied to either
base. Since we don't use the `uaddr` here it's simpler to remove that.

With that gone:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> {
> if (vma->vm_flags & VM_EXEC)
> - sync_icache_aliases(kaddr, len);
> + sync_icache_aliases(start, end);
> }
>
> /*
> @@ -48,7 +46,8 @@ void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
> unsigned long len)
> {
> memcpy(dst, src, len);
> - flush_ptrace_access(vma, page, uaddr, dst, len);
> + flush_ptrace_access(vma, page, uaddr, (unsigned long)dst,
> + (unsigned long)dst + len);
> }
>
> void __sync_icache_dcache(pte_t pte)
> @@ -56,7 +55,9 @@ void __sync_icache_dcache(pte_t pte)
> struct page *page = pte_page(pte);
>
> if (!test_and_set_bit(PG_dcache_clean, &page->flags))
> - sync_icache_aliases(page_address(page), page_size(page));
> + sync_icache_aliases((unsigned long)page_address(page),
> + (unsigned long)page_address(page) +
> + page_size(page));
> }
> EXPORT_SYMBOL_GPL(__sync_icache_dcache);
>
> --
> 2.31.1.751.gd2f1c929bd-goog