From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
"keescook@chromium.org" <keescook@chromium.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
"arndb@arndb.de" <arndb@arndb.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"dsaxena@linaro.org" <dsaxena@linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 2/6] arm64: ptrace: allow tracer to skip a system call
Date: Tue, 25 Nov 2014 14:14:00 +0000 [thread overview]
Message-ID: <20141125141400.GG3836@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <546D7860.2010300@linaro.org>
On Thu, Nov 20, 2014 at 02:13:04PM +0900, AKASHI Takahiro wrote:
> On 11/20/2014 04:06 AM, Will Deacon wrote:
> >What does x86 do?
>
> On x86, syscall(-1) returns -ENOSYS if not traced, and we can change a return
> value if traced.
... which is used for UML (user mode Linux). UML works by spawning
processes under the host kernel, which run with syscall tracing enabled,
with the UML kernel as the tracer. The UML kernel tracer receives the
syscall trace event when the child tries to execute a syscall, decodes
the syscall, executes syscall in the UML kernel, and then cancels the
syscall in the host kernel, setting the return code appropriately.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2014-11-25 14:14 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-18 1:10 [PATCH v8 0/6] arm64: add seccomp support AKASHI Takahiro
2014-11-18 1:10 ` [PATCH v8 1/6] arm64: ptrace: add NT_ARM_SYSTEM_CALL regset AKASHI Takahiro
2014-11-18 1:10 ` [PATCH v8 2/6] arm64: ptrace: allow tracer to skip a system call AKASHI Takahiro
2014-11-18 14:04 ` Will Deacon
2014-11-19 8:46 ` AKASHI Takahiro
2014-11-19 19:06 ` Will Deacon
2014-11-20 5:13 ` AKASHI Takahiro
2014-11-20 5:52 ` AKASHI Takahiro
2014-11-25 13:56 ` Will Deacon
2014-11-20 19:17 ` Will Deacon
2014-11-25 7:42 ` AKASHI Takahiro
2014-11-25 10:30 ` Will Deacon
2014-11-25 14:14 ` Russell King - ARM Linux [this message]
2014-11-18 1:10 ` [PATCH v8 3/6] asm-generic: add generic seccomp.h for secure computing mode 1 AKASHI Takahiro
2014-11-18 1:10 ` [PATCH v8 4/6] arm64: add seccomp syscall for compat task AKASHI Takahiro
2014-11-18 1:10 ` [PATCH v8 5/6] arm64: add SIGSYS siginfo " AKASHI Takahiro
2014-11-18 1:10 ` [PATCH v8 6/6] arm64: add seccomp support AKASHI Takahiro
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