Re: [PATCH 6/6] selftests/sgx: Add a bpftrace script for tracking allocation errors

Dave Hansen
2022-08-31T18:28:55Z

On 8/29/22 20:12, Jarkko Sakkinen wrote:
> diff --git a/tools/testing/selftests/sgx/alloc-error.bt b/tools/testing/selftests/sgx/alloc-error.bt
> new file mode 100644
> index 000000000000..9268d50dea29
> --- /dev/null
> +++ b/tools/testing/selftests/sgx/alloc-error.bt
> @@ -0,0 +1,7 @@
> +kr:sgx_alloc_epc_page /(uint64)retval >= (uint64)(-4095)/ {
> + printf("sgx_alloc_epc_page: retval=%d\n", (int64)retval);
> +}
> +
> +kr:sgx_encl_page_alloc /(uint64)retval >= (uint64)(-4095)/ {
> + printf("sgx_encl_page_alloc: retval=%d\n", (int64)retval);
> +}

I guess this doesn't _hurt_, but it's also not exactly the easiest way
to get this done. You need a whole bpf toolchain. You could also just do:

perf probe 'sgx_encl_page_alloc%return $retval'

Even *that* can be replicated in a few scant lines of shell code echoing
into /sys/kernel/debug/tracing.