linux-kernel - [PATCH 1/3] cpumask: Add a x86-specific cpumask_clear

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Message-Id: <20220204083015.17317-2-bp@alien8.de>
Date:   Fri,  4 Feb 2022 09:30:13 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Marco Elver <elver@...gle.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/3] cpumask: Add a x86-specific cpumask_clear_cpu() helper

From: Borislav Petkov <bp@...e.de>

Add a x86-specific cpumask_clear_cpu() helper which will be used in
places where the explicit KASAN-instrumentation in the *_bit() helpers
is unwanted.

Also, always inline two more cpumask generic helpers.

allyesconfig:

   text    data     bss     dec     hex filename
190553143       159425889       32076404        382055436       16c5b40c vmlinux.before
190551812       159424945       32076404        382053161       16c5ab29 vmlinux.after

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/asm/cpumask.h | 10 ++++++++++
 include/linux/cpumask.h        |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/cpumask.h b/arch/x86/include/asm/cpumask.h
index 3afa990d756b..c5aed9e9226c 100644
--- a/arch/x86/include/asm/cpumask.h
+++ b/arch/x86/include/asm/cpumask.h
@@ -20,11 +20,21 @@ static __always_inline bool arch_cpu_online(int cpu)
 {
 	return arch_test_bit(cpu, cpumask_bits(cpu_online_mask));
 }
+
+static __always_inline void arch_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
+{
+	arch_clear_bit(cpumask_check(cpu), cpumask_bits(dstp));
+}
 #else
 static __always_inline bool arch_cpu_online(int cpu)
 {
 	return cpu == 0;
 }
+
+static __always_inline void arch_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
+{
+	return;
+}
 #endif
 
 #define arch_cpu_is_offline(cpu)	unlikely(!arch_cpu_online(cpu))
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 6b06c698cd2a..fe29ac7cc469 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -102,7 +102,7 @@ extern atomic_t __num_online_cpus;
 
 extern cpumask_t cpus_booted_once_mask;
 
-static inline void cpu_max_bits_warn(unsigned int cpu, unsigned int bits)
+static __always_inline void cpu_max_bits_warn(unsigned int cpu, unsigned int bits)
 {
 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
 	WARN_ON_ONCE(cpu >= bits);
@@ -110,7 +110,7 @@ static inline void cpu_max_bits_warn(unsigned int cpu, unsigned int bits)
 }
 
 /* verify cpu argument to cpumask_* operators */
-static inline unsigned int cpumask_check(unsigned int cpu)
+static __always_inline unsigned int cpumask_check(unsigned int cpu)
 {
 	cpu_max_bits_warn(cpu, nr_cpumask_bits);
 	return cpu;
-- 
2.29.2