From: Brian Gerst <brgerst@gmail.com>
To: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 0/5] Enable pt_regs based syscalls for x86-32 native
Date: Fri, 21 Feb 2020 08:15:19 -0500 [thread overview]
Message-ID: <CAMzpN2iQuaNdTdL6G1rGbUFo+r16iRFo1zbiD_VMrrjtGf0acw@mail.gmail.com> (raw)
In-Reply-To: <20200221060756.GA3368@light.dominikbrodowski.net>
On Fri, Feb 21, 2020 at 2:07 AM Dominik Brodowski
<linux@dominikbrodowski.net> wrote:
>
> Brian,
>
> On Fri, Feb 21, 2020 at 12:09:29AM -0500, Brian Gerst wrote:
> > This patch series cleans up the x86 syscall wrapper code and converts
> > the 32-bit native kernel over to pt_regs based syscalls.
>
> thanks for your patchset. Could you explain a bit more what the rationale
> is. Due to asmlinkage, it doesn't leak "random user-provided register
> content down the call chain" (as was the case for x86-64). But it may be
> cleaner, and you mention in patch 5/5 that the new way is "a bit more
> efficient" -- do you have numbers?
The main rationale for this patch set is to make the 32-bit native
kernel consistent with the 64-bit kernel. It's also slightly more
efficient because the old code pushed all 6 arguments onto the stack
whereas the new code only reads the args the syscall needs, with the
pt_regs pointer passed in through a register. By efficient I mean
that it uses fewer instructions and stack accesses, not that it will
actually have a significant difference on a benchmark.
--
Brian Gerst
next prev parent reply other threads:[~2020-02-21 13:15 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 5:09 [PATCH 0/5] Enable pt_regs based syscalls for x86-32 native Brian Gerst
2020-02-21 5:09 ` [PATCH 1/5] x86: Refactor syscall_wrapper.h Brian Gerst
2020-02-21 6:47 ` Dominik Brodowski
2020-02-21 14:05 ` Brian Gerst
2020-02-21 5:09 ` [PATCH 2/5] x86: Move 32-bit compat syscalls to common location Brian Gerst
2020-02-21 7:07 ` Dominik Brodowski
2020-02-21 13:41 ` Brian Gerst
2020-02-21 15:29 ` Dominik Brodowski
2020-02-21 5:09 ` [PATCH 3/5] x86-32: Enable syscall wrappers Brian Gerst
2020-02-21 7:05 ` Dominik Brodowski
2020-02-21 5:09 ` [PATCH 4/5] x86-64: Use syscall wrappers for x32_rt_sigreturn Brian Gerst
2020-02-21 6:56 ` Dominik Brodowski
2020-02-21 5:09 ` [PATCH 5/5] x86: Drop asmlinkage from syscalls Brian Gerst
2020-02-21 6:56 ` Dominik Brodowski
2020-02-21 6:07 ` [PATCH 0/5] Enable pt_regs based syscalls for x86-32 native Dominik Brodowski
2020-02-21 13:15 ` Brian Gerst [this message]
2020-02-21 15:28 ` Dominik Brodowski
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