From: Carlos Llamas <cmllamas@google.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
Peter Zijlstra <peterz@infradead.org>,
Sean Christopherson <seanjc@google.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
kvm@vger.kernel.org, Will McVicker <willmcvicker@google.com>
Subject: Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks
Date: Wed, 11 Mar 2026 23:05:22 +0000 [thread overview]
Message-ID: <abH1Mkm-MV7fLNsp@google.com> (raw)
In-Reply-To: <20260309223156.GA73501@google.com>
On Mon, Mar 09, 2026 at 10:31:56PM +0000, Sami Tolvanen wrote:
> Hi Carlos,
>
> If you need a stub with a matching CFI type for an arbitrary function,
> perhaps you can do something like this (arm64, untested):
>
> #define DEFINE_TYPED_STUB_RET0(name, reffunc) \
> typeof(reffunc) name; \
> __ADDRESSABLE(name); \
> asm( \
> " " __ALIGN_STR " \n" \
> " .4byte __kcfi_typeid_" #name " \n" \
> #name ": \n" \
> " bti c \n" \
> " mov x0, xzr \n" \
> " ret " \
> )
>
> For the !CONFIG_CFI case, or architectures that implement static calls,
> you can probably just point the stub to __static_call_return0:
>
> #define DEFINE_TYPED_STUB_RET0(name, reffunc) \
> typeof(reffunc) name __asm__("__static_call_return0")
>
> Sami
Alright, I've sent out a patch for this here:
https://lore.kernel.org/all/20260311225822.1565895-1-cmllamas@google.com/
It might seem "incomplete" because it only handles the RET0 case and it
doesn't export the stubs either. However, I didn't find any static_calls
for which the lack of these things would be an issue.
I can address such things in a v2 if really needed though.
Cheers,
--
Carlos Llamas
next prev parent reply other threads:[~2026-03-11 23:05 UTC|newest]
Thread overview: 59+ 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
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 02/17] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for 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
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 04/17] perf: Stop pretending that perf can handle multiple guest callbacks Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for 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
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 06/17] perf/core: Rework guest callbacks to prepare for static_call support Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Like Xu
2021-11-11 2:07 ` [PATCH v4 07/17] perf: Add wrappers for invoking guest callbacks Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 08/17] perf: Force architectures to opt-in to " Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2022-02-02 18:43 ` [PATCH v4 09/17] " 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
2022-02-07 2:55 ` Kees Cook
2022-02-18 22:35 ` Will McVicker
2022-08-24 16:45 ` Sean Christopherson
2026-03-09 19:27 ` Carlos Llamas
2026-03-09 22:31 ` Sami Tolvanen
2026-03-10 3:26 ` Carlos Llamas
2026-03-11 22:57 ` [PATCH] static_call: use CFI-compliant return0 stubs Carlos Llamas
2026-03-11 23:14 ` Peter Zijlstra
2026-03-12 0:16 ` Carlos Llamas
2026-03-12 7:40 ` Ard Biesheuvel
2026-03-12 8:07 ` Peter Zijlstra
2026-03-12 17:18 ` Carlos Llamas
2026-03-11 23:05 ` Carlos Llamas [this message]
2021-11-11 2:07 ` [PATCH v4 10/17] KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 11/17] KVM: x86: More precisely identify NMI from guest when handling PMI Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 12/17] KVM: Move x86's perf guest info callbacks to generic KVM Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 13/17] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 14/17] KVM: arm64: Convert to the generic perf callbacks Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for 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
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
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
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for Sean Christopherson
2021-11-11 2:07 ` [PATCH v4 17/17] perf: Drop guest callback (un)register stubs Sean Christopherson
2021-11-18 14:34 ` [tip: perf/core] " tip-bot2 for 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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