From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f181.google.com (mail-pl1-f181.google.com [209.85.214.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E7A4123AE9B for ; Wed, 16 Apr 2025 06:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744785642; cv=none; b=iTHCb3Qm3RlhlS/bIMiuXQU0bxaeu2V87Tn2NSBz8kGio7YAAxTnOJvJgrVSKMHpmcmOcvI3IqFEqwXcB3kJ6pIG43Vj6sYq4cZfgHcrtOXFBDF4rxhLa+KxFZVONPJWluSLBFkR6vc2iayKEV/pslPiedKyTDLefIDo8+LGEYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744785642; c=relaxed/simple; bh=G0pmXNLUXAb3eCePQJZ5QhL56ydxt1gjfb8YB65k1eU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ju9bGY2bi70VPzKQBHeiOWXL5YnCyLuuPXdvSbQt9fGCWasPsdbJT9krY1ep7rXLllbpgzgoZNSKnx2bPE/MhBdNLzqv9sjfLhzluQHg6aOhtTcXpdWT2ImZokc+qkeoeHnqxyvT2M1YvaiStYeSW3hTZ510GKae9tMuDSiSZtY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=EFVXURQk; arc=none smtp.client-ip=209.85.214.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="EFVXURQk" Received: by mail-pl1-f181.google.com with SMTP id d9443c01a7336-22c33e4fdb8so3670035ad.2 for ; Tue, 15 Apr 2025 23:40:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1744785639; x=1745390439; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=5uv8QgainGGqFWtfVNXtqhQ8aLq7TNgS+wvUJbfZwLM=; b=EFVXURQkdBpipKrj9UZzNgReYsPLbZrVq1w7sIfE0i7wILQt+9RqE4A2sqyCduMFEG amBYWLl/zRHxSk03hp3sr/1SxdG192dW5DNLAa7+murfIB+4nE+C/s0o4qcBHUAV2s8I z6rJCOQbmtjujwJPWVBiZS1wFjSbG6MTJCPouX5UBAgScZnR3/umsys7dyyjRVMHsqEO WkFHOCtMjFVlFlZ9ymXst08SZ/gpK810u0c3FV9+b3uQi/bdZta+gG0pF+Qm88aXfbSH R7GfKtdMeI+SdQ5oPjEv/vMIEk74vW8wP7wxnqkN3L1kYdU943ebNZBjlVNuY8YOVfcg R+1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744785639; x=1745390439; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=5uv8QgainGGqFWtfVNXtqhQ8aLq7TNgS+wvUJbfZwLM=; b=mlmj640RwYVDkw/1jFHqWEj+J+h3UobwLASbf+zFWONuYNVTlLvclgeEnTQWyqYxVn qcmrfBej7PVcPLN4RgYoFw+Qgq8B/YzfnaN0putHuL95uzdSeWjckkiaxw3oTJ/yv0l3 Ys2jOMOS1a9PZGXe7SUBjWDY9rgkQQVfuNsns2j57d/HW/QEup7a7jsgmdRebSQsqdyU QgCNa6qWfIDQnAf2XwLHEhm9SnhJZMdMFL2FpvJvebiQ2nv2jUYj6tWZKnJrkPub0Y1Z jaJV9JcL5Rw3Ho2F8Vj9DisrgWmAHDoIbGT6lLGvOOKM9/TZbVpXoI8y1jreciMhSTXS iEAg== X-Forwarded-Encrypted: i=1; AJvYcCUGqkjgTtMso35J5yubB2ARAMwfLu4BG70GXGGnl4uzvoXdmH+Ee+ZRvjixORyx94zAKDKdoE2lVH+h/4Wzew==@vger.kernel.org X-Gm-Message-State: AOJu0YxnIFbTXiDSbWJly/CMTXtOdUb3busKkKQFyPbLeJjsaaa8sLal Yxsq30ldVhGWIf7LtJE7h7QPo+hwT35tNaKD/VzVaAPhjhrnpPhB40ufdyS3bGw= X-Gm-Gg: ASbGncsdzcXwweIEwnWl6X75a8KxXHaybux9Va1hzYmbwT84Efyg5tGxnbnSSyYa/1i Eo9dTb6LSsMNNVfekQcd48+8G6M8kDmWNgY44R8RRYehKO/CcsgDnY4aDwEM4reKfPx6Xjgsznb QrdxxHkpcUW/9CekeFh27eqnd98PojKxabqJbemTXAw7mvjY+waGQk9jEH6mwXZsuCEtdYzQSdX RziXT9shgt5FmIXC0tZFI4DQfpWGpy/9z7zF4fIXNjSS/R+8W2+asApqN7M85T5F/ASRJL/x04v 0z4mVc9kaxOKuxq4wGcNhjwXSL123yXxa1FCQnNi6w== X-Google-Smtp-Source: AGHT+IGHJ+14d4c94eNRvjN1xaiY12FX4RhJFywwuHYvJRpGkssRqu3ulNzKFKTVxkvjUfnSKiNxfw== X-Received: by 2002:a17:903:238a:b0:224:2207:5130 with SMTP id d9443c01a7336-22c35983cccmr9959655ad.45.1744785639023; Tue, 15 Apr 2025 23:40:39 -0700 (PDT) Received: from localhost ([122.172.83.32]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22c33f1cd87sm6463245ad.73.2025.04.15.23.40.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Apr 2025 23:40:38 -0700 (PDT) From: Viresh Kumar To: "Rafael J. Wysocki" , Miguel Ojeda , Danilo Krummrich , Viresh Kumar , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich Cc: linux-pm@vger.kernel.org, Vincent Guittot , Stephen Boyd , Nishanth Menon , rust-for-linux@vger.kernel.org, Manos Pitsidianakis , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Joakim Bech , Rob Herring , Yury Norov , Burak Emir , Rasmus Villemoes , Russell King , linux-clk@vger.kernel.org, Michael Turquette , linux-kernel@vger.kernel.org Subject: [PATCH V10 12/15] rust: cpufreq: Extend abstractions for policy and driver ops Date: Wed, 16 Apr 2025 12:09:29 +0530 Message-Id: <7a859b2da97e44a7b8e9d694bb7ffdd34e886cdc.1744783509.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.31.1.272.g89b43f80a514 In-Reply-To: References: Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Extend the cpufreq abstractions to include support for policy handling and driver operations. Signed-off-by: Viresh Kumar --- rust/kernel/cpufreq.rs | 457 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 456 insertions(+), 1 deletion(-) diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index d9face425d47..fd605921add4 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -9,15 +9,24 @@ //! Reference: use crate::{ - error::{code::*, to_result, Result}, + clk::{Clk, Hertz}, + cpumask, + device::Device, + error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR}, ffi::c_ulong, prelude::*, + types::ForeignOwnable, + types::Opaque, }; use core::{ + ops::{Deref, DerefMut}, pin::Pin, + ptr, }; +use macros::vtable; + /// Default transition latency value in nanoseconds. pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32; @@ -346,3 +355,449 @@ pub fn to_table(mut self) -> Result { TableBox::new(self.entries) } } + +/// CPU frequency policy. +/// +/// Rust abstraction for the C `struct cpufreq_policy`. +/// +/// # Invariants +/// +/// A [`Policy`] instance always corresponds to a valid C `struct cpufreq_policy`. +/// +/// The callers must ensure that the `struct cpufreq_policy` is valid for access and remains valid +/// for the lifetime of the returned reference. +/// +/// ## Examples +/// +/// The following example demonstrates how to create a CPU frequency table. +/// +/// ``` +/// use kernel::cpufreq::{ETERNAL_LATENCY_NS, Policy}; +/// +/// fn update_policy(policy: &mut Policy) { +/// policy +/// .set_dvfs_possible_from_any_cpu(true) +/// .set_fast_switch_possible(true) +/// .set_transition_latency_ns(ETERNAL_LATENCY_NS); +/// +/// pr_info!("The policy details are: {:?}\n", (policy.cpu(), policy.cur())); +/// } +/// ``` +#[repr(transparent)] +pub struct Policy(Opaque); + +impl Policy { + /// Creates a reference to an existing `struct cpufreq_policy` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *const bindings::cpufreq_policy) -> &'a Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the + // lifetime of the returned reference. + unsafe { &*ptr.cast() } + } + + /// Creates a mutable reference to an existing `struct cpufreq_policy` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpufreq_policy) -> &'a mut Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the + // lifetime of the returned reference. + unsafe { &mut *ptr.cast() } + } + + // Returns a raw mutable pointer to the C `struct cpufreq_policy`. + #[inline] + fn as_raw(&self) -> *mut bindings::cpufreq_policy { + let this: *const Self = self; + this.cast_mut().cast() + } + + #[inline] + fn as_ref(&self) -> &bindings::cpufreq_policy { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { &*self.as_raw() } + } + + #[inline] + fn as_mut_ref(&mut self) -> &mut bindings::cpufreq_policy { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { &mut *self.as_raw() } + } + + /// Returns the primary CPU for the [`Policy`]. + #[inline] + pub fn cpu(&self) -> u32 { + self.as_ref().cpu + } + + /// Returns the minimum frequency for the [`Policy`]. + #[inline] + pub fn min(&self) -> Hertz { + Hertz::from_khz(self.as_ref().min as usize) + } + + /// Set the minimum frequency for the [`Policy`]. + #[inline] + pub fn set_min(&mut self, min: Hertz) -> &mut Self { + self.as_mut_ref().min = min.as_khz() as u32; + self + } + + /// Returns the maximum frequency for the [`Policy`]. + #[inline] + pub fn max(&self) -> Hertz { + Hertz::from_khz(self.as_ref().max as usize) + } + + /// Set the maximum frequency for the [`Policy`]. + #[inline] + pub fn set_max(&mut self, max: Hertz) -> &mut Self { + self.as_mut_ref().max = max.as_khz() as u32; + self + } + + /// Returns the current frequency for the [`Policy`]. + #[inline] + pub fn cur(&self) -> Hertz { + Hertz::from_khz(self.as_ref().cur as usize) + } + + /// Returns the suspend frequency for the [`Policy`]. + #[inline] + pub fn suspend_freq(&self) -> Hertz { + Hertz::from_khz(self.as_ref().suspend_freq as usize) + } + + /// Sets the suspend frequency for the [`Policy`]. + #[inline] + pub fn set_suspend_freq(&mut self, freq: Hertz) -> &mut Self { + self.as_mut_ref().suspend_freq = freq.as_khz() as u32; + self + } + + /// Provides a wrapper to the generic suspend routine. + #[inline] + pub fn generic_suspend(&mut self) -> Result<()> { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + to_result(unsafe { bindings::cpufreq_generic_suspend(self.as_mut_ref()) }) + } + + /// Provides a wrapper to the generic get routine. + #[inline] + pub fn generic_get(&self) -> Result { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) }) + } + + /// Provides a wrapper to the register with energy model using the OPP core. + #[cfg(CONFIG_PM_OPP)] + #[inline] + pub fn register_em_opp(&mut self) { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { bindings::cpufreq_register_em_with_opp(self.as_mut_ref()) }; + } + + /// Gets [`cpumask::Cpumask`] for a cpufreq [`Policy`]. + #[inline] + pub fn cpus(&mut self) -> &mut cpumask::Cpumask { + // SAFETY: The pointer to `cpus` is valid for writing and remains valid for the lifetime of + // the returned reference. + unsafe { cpumask::CpumaskVar::as_mut_ref(&mut self.as_mut_ref().cpus) } + } + + /// Sets clock for the [`Policy`]. + /// + /// # Safety + /// + /// The caller must guarantee that the returned [`Clk`] is not dropped while it is getting used + /// by the C code. + pub unsafe fn set_clk(&mut self, dev: &Device, name: Option<&CStr>) -> Result { + let clk = Clk::get(dev, name)?; + self.as_mut_ref().clk = clk.as_raw(); + Ok(clk) + } + + /// Allows / disallows frequency switching code to run on any CPU. + #[inline] + pub fn set_dvfs_possible_from_any_cpu(&mut self, val: bool) -> &mut Self { + self.as_mut_ref().dvfs_possible_from_any_cpu = val; + self + } + + /// Returns if fast switching of frequencies is possible or not. + #[inline] + pub fn fast_switch_possible(&self) -> bool { + self.as_ref().fast_switch_possible + } + + /// Enables / disables fast frequency switching. + #[inline] + pub fn set_fast_switch_possible(&mut self, val: bool) -> &mut Self { + self.as_mut_ref().fast_switch_possible = val; + self + } + + /// Sets transition latency (in nanoseconds) for the [`Policy`]. + #[inline] + pub fn set_transition_latency_ns(&mut self, latency_ns: u32) -> &mut Self { + self.as_mut_ref().cpuinfo.transition_latency = latency_ns; + self + } + + /// Sets cpuinfo `min_freq`. + #[inline] + pub fn set_cpuinfo_min_freq(&mut self, min_freq: Hertz) -> &mut Self { + self.as_mut_ref().cpuinfo.min_freq = min_freq.as_khz() as u32; + self + } + + /// Sets cpuinfo `max_freq`. + #[inline] + pub fn set_cpuinfo_max_freq(&mut self, max_freq: Hertz) -> &mut Self { + self.as_mut_ref().cpuinfo.max_freq = max_freq.as_khz() as u32; + self + } + + /// Set `transition_delay_us`, i.e. the minimum time between successive frequency change + /// requests. + #[inline] + pub fn set_transition_delay_us(&mut self, transition_delay_us: u32) -> &mut Self { + self.as_mut_ref().transition_delay_us = transition_delay_us; + self + } + + /// Returns reference to the CPU frequency [`Table`] for the [`Policy`]. + pub fn freq_table(&self) -> Result<&Table> { + if self.as_ref().freq_table.is_null() { + return Err(EINVAL); + } + + // SAFETY: The `freq_table` is guaranteed to be valid for reading and remains valid for the + // lifetime of the returned reference. + Ok(unsafe { Table::from_raw(self.as_ref().freq_table) }) + } + + /// Sets the CPU frequency [`Table`] for the [`Policy`]. + /// + /// # Safety + /// + /// The caller must guarantee that the [`Table`] is not dropped while it is getting used by the + /// C code. + #[inline] + pub unsafe fn set_freq_table(&mut self, table: &Table) -> &mut Self { + self.as_mut_ref().freq_table = table.as_raw(); + self + } + + /// Returns the [`Policy`]'s private data. + pub fn data(&mut self) -> Option<::Borrowed<'_>> { + if self.as_ref().driver_data.is_null() { + None + } else { + // SAFETY: The data is earlier set from [`set_data`]. + Some(unsafe { T::borrow(self.as_ref().driver_data) }) + } + } + + // Sets the private data of the [`Policy`] using a foreign-ownable wrapper. + // + // # Errors + // + // Returns `EBUSY` if private data is already set. + fn set_data(&mut self, data: T) -> Result<()> { + if self.as_ref().driver_data.is_null() { + // Transfer the ownership of the data to the foreign interface. + self.as_mut_ref().driver_data = ::into_foreign(data) as _; + Ok(()) + } else { + Err(EBUSY) + } + } + + // Clears and returns ownership of the private data. + fn clear_data(&mut self) -> Option { + if self.as_ref().driver_data.is_null() { + None + } else { + let data = Some( + // SAFETY: The data is earlier set by us from [`set_data`]. It is safe to take + // back the ownership of the data from the foreign interface. + unsafe { ::from_foreign(self.as_ref().driver_data) }, + ); + self.as_mut_ref().driver_data = ptr::null_mut(); + data + } + } +} + +// CPU frequency policy created from a CPU number. +// +// This struct represents the CPU frequency policy obtained for a specific CPU, providing safe +// access to the underlying `cpufreq_policy` and ensuring proper cleanup when the `PolicyCpu` is +// dropped. +struct PolicyCpu<'a>(&'a mut Policy); + +impl<'a> PolicyCpu<'a> { + fn from_cpu(cpu: u32) -> Result { + // SAFETY: It is safe to call `cpufreq_cpu_get` for any valid CPU. + let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?; + + Ok(Self( + // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of + // the returned reference. + unsafe { Policy::from_raw_mut(ptr) }, + )) + } +} + +impl<'a> Deref for PolicyCpu<'a> { + type Target = Policy; + + fn deref(&self) -> &Self::Target { + self.0 + } +} + +impl<'a> DerefMut for PolicyCpu<'a> { + fn deref_mut(&mut self) -> &mut Policy { + self.0 + } +} + +impl<'a> Drop for PolicyCpu<'a> { + fn drop(&mut self) { + // SAFETY: The underlying pointer is guaranteed to be valid for the lifetime of `self`. + unsafe { bindings::cpufreq_cpu_put(self.0.as_raw()) }; + } +} + +/// CPU frequency driver. +/// +/// Implement this trait to provide a CPU frequency driver and its callbacks. +/// +/// Reference: +#[vtable] +pub trait Driver { + /// Driver's name. + const NAME: &'static CStr; + + /// Driver's flags. + const FLAGS: u16; + + /// Boost support. + const BOOST_ENABLED: bool; + + /// Policy specific data. + /// + /// Require that `PData` implements `ForeignOwnable`. We guarantee to never move the underlying + /// wrapped data structure. + type PData: ForeignOwnable; + + /// Driver's `init` callback. + fn init(policy: &mut Policy) -> Result; + + /// Driver's `exit` callback. + fn exit(_policy: &mut Policy, _data: Option) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `online` callback. + fn online(_policy: &mut Policy) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `offline` callback. + fn offline(_policy: &mut Policy) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `suspend` callback. + fn suspend(_policy: &mut Policy) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `resume` callback. + fn resume(_policy: &mut Policy) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `ready` callback. + fn ready(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `verify` callback. + fn verify(data: &mut PolicyData) -> Result<()>; + + /// Driver's `setpolicy` callback. + fn setpolicy(_policy: &mut Policy) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target` callback. + fn target(_policy: &mut Policy, _target_freq: u32, _relation: Relation) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target_index` callback. + fn target_index(_policy: &mut Policy, _index: u32) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `fast_switch` callback. + fn fast_switch(_policy: &mut Policy, _target_freq: u32) -> u32 { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `adjust_perf` callback. + fn adjust_perf(_policy: &mut Policy, _min_perf: usize, _target_perf: usize, _capacity: usize) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `get_intermediate` callback. + fn get_intermediate(_policy: &mut Policy, _index: u32) -> u32 { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target_intermediate` callback. + fn target_intermediate(_policy: &mut Policy, _index: u32) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `get` callback. + fn get(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `update_limits` callback. + fn update_limits(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `bios_limit` callback. + fn bios_limit(_policy: &mut Policy, _limit: &mut u32) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `set_boost` callback. + fn set_boost(_policy: &mut Policy, _state: i32) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `register_em` callback. + fn register_em(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } +} -- 2.31.1.272.g89b43f80a514