diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2024-03-04 11:12:23 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2024-03-04 12:09:07 +0100 |
| commit | 71eb4893cfaf37f8884515c8f71717044b97bf44 (patch) | |
| tree | c5bcb3cb3ddae2cf99e55aba7cbd2221e7f3b287 | |
| parent | 712610725c48c829e42bebfc9908cd92468e2731 (diff) | |
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 <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240304005104.622511517@linutronix.de
| -rw-r--r-- | arch/x86/include/asm/processor.h | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/setup.c | 10 | ||||
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 4 |
4 files changed, 13 insertions, 9 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index a61f76990b6a..e2262aca6561 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -185,13 +185,8 @@ extern struct cpuinfo_x86 new_cpu_data; extern __u32 cpu_caps_cleared[NCAPINTS + NBUGINTS]; extern __u32 cpu_caps_set[NCAPINTS + NBUGINTS]; -#ifdef CONFIG_SMP DECLARE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info); #define cpu_data(cpu) per_cpu(cpu_info, cpu) -#else -#define cpu_info boot_cpu_data -#define cpu_data(cpu) boot_cpu_data -#endif extern const struct seq_operations cpuinfo_op; diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index fbc4e60d027c..6057a9ecac93 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -70,6 +70,9 @@ #include "cpu.h" +DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info); +EXPORT_PER_CPU_SYMBOL(cpu_info); + u32 elf_hwcap2 __read_mostly; /* Number of siblings per CPU package */ diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 84201071dfac..8f669d3be445 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1211,6 +1211,16 @@ void __init i386_reserve_resources(void) #endif /* CONFIG_X86_32 */ +#ifndef CONFIG_SMP +void __init smp_prepare_boot_cpu(void) +{ + struct cpuinfo_x86 *c = &cpu_data(0); + + *c = boot_cpu_data; + c->initialized = true; +} +#endif + static struct notifier_block kernel_offset_notifier = { .notifier_call = dump_kernel_offset }; 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; |