From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Kees Cook" <keescook@chromium.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
"Sami Tolvanen" <samitolvanen@google.com>,
"Colin Ian King" <colin.king@canonical.com>,
"Frederic Weisbecker" <frederic@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"YiFei Zhu" <yifeifz2@illinois.edu>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Andrey Konovalov" <andreyknvl@gmail.com>,
"Wang Kefeng" <wangkefeng.wang@huawei.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Nathan Chancellor" <nathan@kernel.org>,
"Nick Desaulniers" <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
bpf@vger.kernel.org
Subject: Re: [PATCH v2 1/2] arch/Kconfig: Make CONFIG_CPU_SPECTRE available for all architectures
Date: Fri, 29 Oct 2021 11:08:35 +0100 [thread overview]
Message-ID: <YXvIIwkfYcXEBf97@shell.armlinux.org.uk> (raw)
In-Reply-To: <20211028193658.7n2oehp6yogyqbwq@gupta-dev2.localdomain>
On Thu, Oct 28, 2021 at 12:36:58PM -0700, Pawan Gupta wrote:
> Isn't ARM already using CPU_SPECTRE for selecting things:
>
> config HARDEN_BRANCH_PREDICTOR
> bool "Harden the branch predictor against aliasing attacks" if EXPERT
> depends on CPU_SPECTRE
>
> This was the whole motivation for doing the same for x86.
>
> Adding a condition for all architectures is also okay, but its going to
> a little messier:
>
> config BPF_UNPRIV_DEFAULT_OFF
> default y if X86 || ARM || ...
It doesn't have to be (but sadly we end up repeating "DEFAULT"):
config BPF_UNPRIV_DEFAULT_OFF_DEFAULT
bool
config BPF_UNPRIV_DEFAULT_OFF
bool "Disable unprivileged BPF by default"
default BPF_UNPRIV_DEFAULT_OFF_DEFAULT
Then architectures can select BPF_UNPRIV_DEFAULT_OFF_DEFAULT if they
wish this to be defaulted to "yes".
However, please note that this has limited use given that the
BPF_UNPRIV_DEFAULT_OFF option has been around for a while now. Any
existing configuration that mentions this symbol will override any
default specified in the Kconfig files if the option is user-visible.
So, IMHO, defaults need to be set correctly from the point in time
that the option is introduced.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2021-10-29 10:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-28 1:32 [PATCH ebpf v2 0/2] Unprivileged BPF default Pawan Gupta
2021-10-28 1:35 ` [PATCH ebpf v2 2/2] bpf: Make unprivileged bpf depend on CONFIG_CPU_SPECTRE Pawan Gupta
2021-10-28 5:34 ` Greg KH
2021-10-28 19:38 ` Pawan Gupta
2021-10-28 13:57 ` Mark Rutland
2021-10-28 16:44 ` Greg KH
[not found] ` <232b692cd79e4f6e4c3ee7055b5f02792a28d2c4.1635383031.git.pawan.kumar.gupta@linux.intel.com>
[not found] ` <20211028134918.GB48435@lakrids.cambridge.arm.com>
2021-10-28 19:36 ` [PATCH v2 1/2] arch/Kconfig: Make CONFIG_CPU_SPECTRE available for all architectures Pawan Gupta
2021-10-29 9:22 ` Mark Rutland
2021-10-29 16:05 ` Daniel Borkmann
2021-10-29 19:15 ` Pawan Gupta
2021-10-29 10:08 ` Russell King (Oracle) [this message]
2021-10-29 22:51 ` Pawan Gupta
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