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Message-ID: <YxFGb2387CC3vOHb@kernel.org>
Date: Fri, 2 Sep 2022 02:55:40 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Dave Hansen <dave.hansen@...el.com>
Cc: linux-sgx@...r.kernel.org,
Haitao Huang <haitao.huang@...ux.intel.com>,
Vijay Dhanraj <vijay.dhanraj@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Shuah Khan <shuah@...nel.org>,
open list <linux-kernel@...r.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH 6/6] selftests/sgx: Add a bpftrace script for tracking
allocation errors
On Thu, Sep 01, 2022 at 03:34:49PM -0700, Dave Hansen wrote:
> On 9/1/22 15:20, Jarkko Sakkinen wrote:
> >>> +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 $retval'
> >>
> >> Even *that* can be replicated in a few scant lines of shell code echoing
> >> into /sys/kernel/debug/tracing.
> > Thanks, I have not used perf that much. What if I replace
> > this with a shell script using perf? How do you use that
> > for two kretprobes?
>
> The manpage is pretty good.
>
> But, I'd proably be doing something along these lines:
>
> perf probe 'sgx_encl_page_alloc%return ret=$retval'
> perf record -e probe:sgx_encl_page_alloc -aR \
> --filter='ret >= 0xwhatever' sleep 1
> perf script
>
> There are probably shorter ways to do it, but I'm pretty sure that works.
Thanks, will give it a shot.
BR, Jarkko
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