From 71eb4893cfaf37f8884515c8f71717044b97bf44 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 4 Mar 2024 11:12:23 +0100 Subject: x86/percpu: Cure per CPU madness on UP On UP builds Sparse complains rightfully about accesses to cpu_info with per CPU accessors: cacheinfo.c:282:30: sparse: warning: incorrect type in initializer (different address spaces) cacheinfo.c:282:30: sparse: expected void const [noderef] __percpu *__vpp_verify cacheinfo.c:282:30: sparse: got unsigned int * The reason is that on UP builds cpu_info which is a per CPU variable on SMP is mapped to boot_cpu_info which is a regular variable. There is a hideous accessor cpu_data() which tries to hide this, but it's not sufficient as some places require raw accessors and generates worse code than the regular per CPU accessors. Waste sizeof(struct x86_cpuinfo) memory on UP and provide the per CPU cpu_info unconditionally. This requires to update the CPU info on the boot CPU as SMP does. (Ab)use the weakly defined smp_prepare_boot_cpu() function and implement exactly that. This allows to use regular per CPU accessors uncoditionally and paves the way to remove the cpu_data() hackery. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20240304005104.622511517@linutronix.de --- arch/x86/kernel/smpboot.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 980782bd2c97..37ea8c872e4a 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -101,10 +101,6 @@ EXPORT_PER_CPU_SYMBOL(cpu_core_map); DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_die_map); EXPORT_PER_CPU_SYMBOL(cpu_die_map); -/* Per CPU bogomips and other parameters */ -DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info); -EXPORT_PER_CPU_SYMBOL(cpu_info); - /* CPUs which are the primary SMT threads */ struct cpumask __cpu_primary_thread_mask __read_mostly; -- cgit