From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Juergen Gross <jgross@suse.com>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] x86/paravirt: Detect oversized patching bugs as they happen and BUG_ON() to avoid later crashes
Date: Thu, 25 Apr 2019 11:21:31 +0200 [thread overview]
Message-ID: <20190425092131.GL4038@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190425091717.GA72229@gmail.com>
On Thu, Apr 25, 2019 at 11:17:17AM +0200, Ingo Molnar wrote:
> It basically means that we silently won't do any patching and the kernel
> will crash later on in mysterious ways, because paravirt patching is
> usually relied on.
That's OK. The compiler emits an indirect CALL/JMP to the pv_ops
structure contents. That _should_ stay valid and function correctly at
all times.
Not patching should at the very least cause a WARN with RETPOLINE
kernels though, we hard rely on the patching actually working and
writing at least a direct call.
next prev parent reply other threads:[~2019-04-25 9:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 13:41 [patch 0/3] x86/paravirt: Rework paravirt patching Thomas Gleixner
2019-04-24 13:41 ` [patch 1/3] x86/paravirt: Remove bogus extern declarations Thomas Gleixner
2019-04-25 7:31 ` [tip:x86/paravirt] " tip-bot for Thomas Gleixner
2019-05-24 7:58 ` tip-bot for Thomas Gleixner
2019-04-24 13:41 ` [patch 2/3] x86/paravirt: Unify 32/64 bit patch code Thomas Gleixner
2019-04-25 7:32 ` [tip:x86/paravirt] " tip-bot for Thomas Gleixner
2019-05-24 8:00 ` [tip:x86/paravirt] x86/paravirt: Unify the 32/64 bit paravirt patching code tip-bot for Thomas Gleixner
2019-04-24 13:41 ` [patch 3/3] x86/paravirt: Replace paravirt patch asm magic Thomas Gleixner
2019-04-25 6:52 ` Ingo Molnar
2019-04-25 7:22 ` Thomas Gleixner
2019-04-25 7:46 ` Juergen Gross
2019-04-25 8:10 ` [PATCH] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering Ingo Molnar
2019-04-25 9:17 ` [PATCH] x86/paravirt: Detect oversized patching bugs as they happen and BUG_ON() to avoid later crashes Ingo Molnar
2019-04-25 9:21 ` Peter Zijlstra [this message]
2019-04-25 9:50 ` x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call() Ingo Molnar
2019-04-25 10:22 ` Peter Zijlstra
2019-04-25 10:57 ` Ingo Molnar
2019-04-25 11:30 ` Juergen Gross
2019-04-25 12:30 ` Juergen Gross
2019-04-25 11:40 ` Peter Zijlstra
2019-04-25 12:30 ` Peter Zijlstra
2019-05-24 7:59 ` [tip:x86/paravirt] " tip-bot for Ingo Molnar
2019-05-24 7:58 ` [tip:x86/paravirt] x86/paravirt: Detect over-sized patching bugs in paravirt_patch_insns() tip-bot for Ingo Molnar
2019-05-24 8:01 ` [tip:x86/paravirt] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering tip-bot for Ingo Molnar
2019-04-25 8:08 ` [patch 3/3] x86/paravirt: Replace paravirt patch asm magic Peter Zijlstra
2019-04-25 8:19 ` Peter Zijlstra
2019-04-25 9:20 ` Ingo Molnar
2019-05-24 8:00 ` [tip:x86/paravirt] x86/paravirt: Replace the " tip-bot for Thomas Gleixner
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