From: Kees Cook <kees@kernel.org>
To: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
oleg@redhat.com, luto@amacapital.net, wad@chromium.org,
peterz@infradead.org, ada.coupriediaz@arm.com, linusw@kernel.org,
yeoreum.yun@arm.com, kevin.brodsky@arm.com,
anshuman.khandual@arm.com, james.morse@arm.com, thuth@redhat.com,
vladimir.murzin@arm.com, tglx@kernel.org, broonie@kernel.org,
liqiang01@kylinos.cn, ryan.roberts@arm.com, pengcan@kylinos.cn,
kmehltretter@gmail.com, linux-arm-kernel@lists.infradead.org,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test
Date: Thu, 24 Sep 2026 16:56:41 -0700 [thread overview]
Message-ID: <202609241654.F545D3A88@keescook> (raw)
In-Reply-To: <bbd65e4d-8096-4939-8308-f0f54c5cb3bc@huawei.com>
On Thu, Sep 24, 2026 at 12:11:31PM +0800, Jinjie Ruan wrote:
>
>
> 在 2026/9/23 3:57, Kees Cook 写道:
> > ptrace(2) states that no syscall-exit-stop occurs when a tracee is
> > continued with PTRACE_SYSEMU or PTRACE_SYSEMU_SINGLESTEP. arm64 gated
> > its syscall-exit report on
> >
> > flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)
>
> Hi Kees,
>
> The original fix description is a bit off: on arm64 there is no extra
> syscall-exit-stop; instead, there's an additional pseudo single-step
> injection.
>
> As sashiko pointed out, as commit ac2081cdc4d9 ("arm64: ptrace:
> Consistently use pseudo-singlestep exceptions") described, for
> PTRACE_SYSEMU_SINGLESTEP, arm64 still needs the pseudo single-step
> because its hardware single-step state machine is fast-forwarded over
> the SVC instruction.
Ah! Okay. So this test should be tweaked to deal with that? Feel free to
snag/update this test for the series. We didn't have anything testing
syscall exit stops, so it seemed reasonable to get it written.
-Kees
--
Kees Cook
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <kees@kernel.org>
To: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: mark.rutland@arm.com, peterz@infradead.org,
catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org, linux-kselftest@vger.kernel.org,
will@kernel.org, Shuah Khan <shuah@kernel.org>,
thuth@redhat.com, vladimir.murzin@arm.com, ryan.roberts@arm.com,
anshuman.khandual@arm.com, kevin.brodsky@arm.com,
kmehltretter@gmail.com, pengcan@kylinos.cn, broonie@kernel.org,
linux-arm-kernel@lists.infradead.org, wad@chromium.org,
linusw@kernel.org, oleg@redhat.com, luto@amacapital.net,
james.morse@arm.com, tglx@kernel.org, liqiang01@kylinos.cn,
yeoreum.yun@arm.com
Subject: Re: [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test
Date: Thu, 24 Sep 2026 16:56:41 -0700 [thread overview]
Message-ID: <202609241654.F545D3A88@keescook> (raw)
In-Reply-To: <bbd65e4d-8096-4939-8308-f0f54c5cb3bc@huawei.com>
On Thu, Sep 24, 2026 at 12:11:31PM +0800, Jinjie Ruan wrote:
>
>
> 在 2026/9/23 3:57, Kees Cook 写道:
> > ptrace(2) states that no syscall-exit-stop occurs when a tracee is
> > continued with PTRACE_SYSEMU or PTRACE_SYSEMU_SINGLESTEP. arm64 gated
> > its syscall-exit report on
> >
> > flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)
>
> Hi Kees,
>
> The original fix description is a bit off: on arm64 there is no extra
> syscall-exit-stop; instead, there's an additional pseudo single-step
> injection.
>
> As sashiko pointed out, as commit ac2081cdc4d9 ("arm64: ptrace:
> Consistently use pseudo-singlestep exceptions") described, for
> PTRACE_SYSEMU_SINGLESTEP, arm64 still needs the pseudo single-step
> because its hardware single-step state machine is fast-forwarded over
> the SVC instruction.
Ah! Okay. So this test should be tweaked to deal with that? Feel free to
snag/update this test for the series. We didn't have anything testing
syscall exit stops, so it seemed reasonable to get it written.
-Kees
--
Kees Cook
next prev parent reply other threads:[~2026-09-24 23:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-22 19:57 [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test Kees Cook
2026-09-22 19:57 ` Kees Cook
2026-09-23 11:07 ` Oleg Nesterov
2026-09-23 11:07 ` Oleg Nesterov
2026-09-24 4:11 ` Jinjie Ruan
2026-09-24 4:11 ` Jinjie Ruan
2026-09-24 23:56 ` Kees Cook [this message]
2026-09-24 23:56 ` Kees Cook
2026-09-28 1:58 ` Jinjie Ruan
2026-09-28 1:58 ` Jinjie Ruan
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