On 17/07/2024 12:10, Dev Jain wrote:
> Post my improvement of the test:
> https://lore.kernel.org/all/[email protected]/
> The test begins to fail on 4k and 16k pages, on non-LPA2 systems. To
> reduce noise in the CI systems, let us skip the test when higher address
> space is not implemented.
>
> Signed-off-by: Dev Jain <[email protected]>
> ---
> The patch applies on linux-next.
>
> tools/testing/selftests/mm/va_high_addr_switch.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/va_high_addr_switch.c
> b/tools/testing/selftests/mm/va_high_addr_switch.c
> index fa7eabfaf841..c6040e1d6e53 100644
> --- a/tools/testing/selftests/mm/va_high_addr_switch.c
> +++ b/tools/testing/selftests/mm/va_high_addr_switch.c
> @@ -293,6 +293,18 @@ static int run_test(struct testcase *test, int count)
> return ret;
> }
>
> +/* Check if userspace VA > 48 bits */
> +static int high_address_present(void)
> +{
> + void *ptr = mmap((void *)(1UL << 50), 1, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
I think there is (very unlikely) possibility that something is already mapped at
this address so it will be replaced due to MAP_FIXED. That could break the test.
But the only way something could be already mapped is if ARM64_FORCE_52BIT is
set and in that case, the test will fail anyway, right? So I think this is fine.
> + if (ptr == MAP_FAILED)
> + return 0;
> +
> + munmap(ptr, 1);
> + return 1;
> +}
I'm guessing this will cause a function-not-used warning on arches other than
arm64? Perhaps wrap it in `#ifdef __aarch64__`?
Thanks,
Ryan
> +
> static int supported_arch(void)
> {
> #if defined(__powerpc64__)
> @@ -300,7 +312,7 @@ static int supported_arch(void)
> #elif defined(__x86_64__)
> return 1;
> #elif defined(__aarch64__)
> - return 1;
> + return high_address_present();
> #else
> return 0;
> #endif
