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Date:   Wed, 31 Aug 2022 11:23:55 -0700
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Subject: Re: [PATCH 6/6] selftests/sgx: Add a bpftrace script for tracking
 allocation errors
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To:     Jarkko Sakkinen <jarkko@kernel.org>, linux-sgx@vger.kernel.org
Cc:     Haitao Huang <haitao.huang@linux.intel.com>,
        Vijay Dhanraj <vijay.dhanraj@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Shuah Khan <shuah@kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>
References: <20220830031206.13449-1-jarkko@kernel.org>
 <20220830031206.13449-7-jarkko@kernel.org>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <20220830031206.13449-7-jarkko@kernel.org>
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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.