Hi,
On Sat, Jun 17, 2023 at 01:31:38AM +0000, Nadav Amit wrote:
> From: Nadav Amit <namit@xxxxxxxxxx>
>
> While no real problem was encountered, having an inline assembly without
> volatile keyword and output can allow the compiler to ignore it. And
> without a memory clobber, potentially reorder it.
>
> Add volatile and memory clobber.
>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
> ---
> lib/arm64/asm/mmu.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/arm64/asm/mmu.h b/lib/arm64/asm/mmu.h
> index 5c27edb..cf94403 100644
> --- a/lib/arm64/asm/mmu.h
> +++ b/lib/arm64/asm/mmu.h
> @@ -14,7 +14,7 @@
> static inline void flush_tlb_all(void)
> {
> dsb(ishst);
> - asm("tlbi vmalle1is");
>From the gas manual [1]:
"asm statements that have no output operands and asm goto statements, are
implicitly volatile."
Looks to me like both TLBIs fall into this category.
And I think the "memory" clobber is not needed because the dsb macro before and
after the TLBI already have it.
[1] https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Volatile
Thanks,
Alex
> + asm volatile("tlbi vmalle1is" ::: "memory");
> dsb(ish);
> isb();
> }
> @@ -23,7 +23,7 @@ static inline void flush_tlb_page(unsigned long vaddr)
> {
> unsigned long page = vaddr >> 12;
> dsb(ishst);
> - asm("tlbi vaae1is, %0" :: "r" (page));
> + asm volatile("tlbi vaae1is, %0" :: "r" (page) : "memory");
> dsb(ish);
> isb();
> }
> --
> 2.34.1
>
>
