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From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <keescook@chromium.org>
Cc: Will McVicker <willmcvicker@google.com>,
	kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	kvmarm <kvmarm@lists.cs.columbia.edu>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks
Date: Sun, 6 Feb 2022 21:28:52 +0100	[thread overview]
Message-ID: <YgAvhG4wvnslbTqP@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <202202061011.A255DE55B@keescook>

On Sun, Feb 06, 2022 at 10:45:15AM -0800, Kees Cook wrote:

> I'm digging through the macros to sort this out, but IIUC, an example of
> the problem is:
> 

> so the caller is expecting "unsigned int (*)(void)" but the prototype
> of __static_call_return0 is "long (*)(void)":
> 
> long __static_call_return0(void);
> 
> Could we simply declare a type-matched ret0 trampoline too?

That'll work for this case, but the next case the function will have
arguments we'll need even more nonsense...

And as stated in that other email, there's tb_stub_func() having the
exact same problem as well.

The x86_64 CFI patches had a work-around for this, that could trivially
be lifted I suppose.
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  reply	other threads:[~2022-02-06 20:29 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-11  2:07 [PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU Sean Christopherson
2021-11-11  7:26   ` Paolo Bonzini
2021-11-11 10:47     ` Peter Zijlstra
2021-11-12  7:55       ` Paolo Bonzini
2021-11-11  2:07 ` [PATCH v4 02/17] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 03/17] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 04/17] perf: Stop pretending that perf can handle multiple guest callbacks Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 05/17] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 06/17] perf/core: Rework guest callbacks to prepare for static_call support Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 07/17] perf: Add wrappers for invoking guest callbacks Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 08/17] perf: Force architectures to opt-in to " Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks Sean Christopherson
2022-02-02 18:43   ` Sean Christopherson
2022-02-04 17:35     ` Sami Tolvanen
2022-02-06 13:08       ` Peter Zijlstra
2022-02-06 18:45       ` Kees Cook
2022-02-06 20:28         ` Peter Zijlstra [this message]
2022-02-07  2:55           ` Kees Cook
2022-02-18 22:35             ` Will McVicker
2022-08-24 16:45               ` Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 10/17] KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 11/17] KVM: x86: More precisely identify NMI from guest when handling PMI Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 12/17] KVM: Move x86's perf guest info callbacks to generic KVM Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 13/17] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 14/17] KVM: arm64: Convert to the generic perf callbacks Sean Christopherson
2021-11-11  2:07 ` [PATCH v4 15/17] KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y Sean Christopherson
2021-11-11 21:49   ` Marc Zyngier
2021-11-11  2:07 ` [PATCH v4 16/17] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c Sean Christopherson
2021-11-11 21:49   ` Marc Zyngier
2021-11-11  2:07 ` [PATCH v4 17/17] perf: Drop guest callback (un)register stubs Sean Christopherson
2021-11-11 11:19 ` [PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks Peter Zijlstra

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