From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Brian Gerst <brgerst@gmail.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v4 4/9] kentry: Simplify the common syscall API
Date: Fri, 19 Mar 2021 17:09:53 +0100 [thread overview]
Message-ID: <87sg4r5dm6.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <0e04f8d34cb52320110057021184d8facec7e1a6.1616004689.git.luto@kernel.org>
On Wed, Mar 17 2021 at 11:12, Andy Lutomirski wrote:
> The new common syscall API had a large and confusing API surface. Simplify
> it. Now there is exactly one way to use it. It's a bit more verbose than
> the old way for the simple x86_64 native case, but it's much easier to use
> right,
and therefore much easier to get wrong...
> __visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
> {
> - nr = syscall_enter_from_user_mode(regs, nr);
> -
> + kentry_enter_from_user_mode(regs);
> + local_irq_enable();
... That needs to be _after_ instrumentation_begin(). If you fiddle
with this then please make sure that objtool validates noinstr...
> + kentry_enter_from_user_mode(regs);
> + local_irq_enable();
Ditto
> + instrumentation_begin();
> static noinstr bool __do_fast_syscall_32(struct pt_regs *regs)
> {
> unsigned int nr = syscall_32_enter(regs);
> + bool ret;
> int res;
>
> - /*
> - * This cannot use syscall_enter_from_user_mode() as it has to
> - * fetch EBP before invoking any of the syscall entry work
> - * functions.
> - */
> - syscall_enter_from_user_mode_prepare(regs);
> -
> + kentry_enter_from_user_mode(regs);
> + local_irq_enable();
...
> instrumentation_begin();
Thanks,
tglx
next prev parent reply other threads:[~2021-03-19 16:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 18:12 [PATCH v4 0/9] kentry: A stable bugfix and a bunch of improvements Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 1/9] x86/dumpstack: Remove unnecessary range check fetching opcode bytes Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 2/9] x86/kthread,dumpstack: Set task_pt_regs->cs.RPL=3 for kernel threads Andy Lutomirski
2021-03-18 0:36 ` Josh Poimboeuf
2021-03-17 18:12 ` [PATCH v4 3/9] x86/entry: Convert ret_from_fork to C Andy Lutomirski
2021-03-18 0:38 ` Josh Poimboeuf
2021-03-19 16:05 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 4/9] kentry: Simplify the common syscall API Andy Lutomirski
2021-03-19 16:09 ` Thomas Gleixner [this message]
2021-03-19 18:07 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 5/9] kentry: Remove enter_from/exit_to_user_mode() Andy Lutomirski
2021-03-19 18:08 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 6/9] entry: Make CONFIG_DEBUG_ENTRY available outside x86 Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 7/9] kentry: Add debugging checks for proper kentry API usage Andy Lutomirski
2021-03-19 16:17 ` Thomas Gleixner
2021-03-19 18:16 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 8/9] kentry: Check that syscall entries and syscall exits match Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 9/9] kentry: Verify kentry state in instrumentation_begin/end() Andy Lutomirski
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