This patch converts the x86_cpu_to_apicid array to be a per cpu variable. This saves sizeof(apicid) * NR unused cpus. Access is mostly from startup and CPU HOTPLUG functions. MP_processor_info() is one of the functions that require access to the x86_cpu_to_apicid array before the per_cpu data area is setup. For this case, a pointer to the __initdata array is initialized in setup_arch() and removed in smp_prepare_cpus() after the per_cpu data area is initialized. A second change is included to change the initial array value of ARCH i386 from 0xff to BAD_APICID to be consistent with ARCH x86_64. Signed-off-by: Mike Travis --- arch/i386/kernel/acpi/boot.c | 2 +- arch/i386/kernel/smp.c | 2 +- arch/i386/kernel/smpboot.c | 22 +++++++++++++++------- arch/x86_64/kernel/genapic.c | 15 ++++++++++++--- arch/x86_64/kernel/genapic_flat.c | 2 +- arch/x86_64/kernel/mpparse.c | 15 +++++++++++++-- arch/x86_64/kernel/setup.c | 5 +++++ arch/x86_64/kernel/smpboot.c | 23 ++++++++++++++++++++++- arch/x86_64/mm/numa.c | 2 +- include/asm-i386/smp.h | 6 ++++-- include/asm-x86_64/ipi.h | 2 +- include/asm-x86_64/smp.h | 6 ++++-- 12 files changed, 80 insertions(+), 22 deletions(-) --- a/arch/i386/kernel/acpi/boot.c +++ b/arch/i386/kernel/acpi/boot.c @@ -555,7 +555,7 @@ int acpi_unmap_lsapic(int cpu) { - x86_cpu_to_apicid[cpu] = -1; + per_cpu(x86_cpu_to_apicid, cpu) = -1; cpu_clear(cpu, cpu_present_map); num_processors--; --- a/arch/i386/kernel/smp.c +++ b/arch/i386/kernel/smp.c @@ -673,7 +673,7 @@ int i; for (i = 0; i < NR_CPUS; i++) { - if (x86_cpu_to_apicid[i] == apic_id) + if (per_cpu(x86_cpu_to_apicid, i) == apic_id) return i; } return -1; --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -92,9 +92,17 @@ struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned; EXPORT_SYMBOL(cpu_data); -u8 x86_cpu_to_apicid[NR_CPUS] __read_mostly = - { [0 ... NR_CPUS-1] = 0xff }; -EXPORT_SYMBOL(x86_cpu_to_apicid); +/* + * The following static array is used during kernel startup + * and the x86_cpu_to_apicid_ptr contains the address of the + * array during this time. Is it zeroed when the per_cpu + * data area is removed. + */ +u8 x86_cpu_to_apicid_init[NR_CPUS] __initdata = + { [0 ... NR_CPUS-1] = BAD_APICID }; +void *x86_cpu_to_apicid_ptr; +DEFINE_PER_CPU(u8, x86_cpu_to_apicid) = BAD_APICID; +EXPORT_PER_CPU_SYMBOL(x86_cpu_to_apicid); u8 apicid_2_node[MAX_APICID]; @@ -804,7 +812,7 @@ irq_ctx_init(cpu); - x86_cpu_to_apicid[cpu] = apicid; + per_cpu(x86_cpu_to_apicid, cpu) = apicid; /* * This grunge runs the startup process for * the targeted processor. @@ -866,7 +874,7 @@ cpu_clear(cpu, cpu_initialized); /* was set by cpu_init() */ cpucount--; } else { - x86_cpu_to_apicid[cpu] = apicid; + per_cpu(x86_cpu_to_apicid, cpu) = apicid; cpu_set(cpu, cpu_present_map); } @@ -915,7 +923,7 @@ struct warm_boot_cpu_info info; int apicid, ret; - apicid = x86_cpu_to_apicid[cpu]; + apicid = per_cpu(x86_cpu_to_apicid, cpu); if (apicid == BAD_APICID) { ret = -ENODEV; goto exit; @@ -965,7 +973,7 @@ boot_cpu_physical_apicid = GET_APIC_ID(apic_read(APIC_ID)); boot_cpu_logical_apicid = logical_smp_processor_id(); - x86_cpu_to_apicid[0] = boot_cpu_physical_apicid; + per_cpu(x86_cpu_to_apicid, 0) = boot_cpu_physical_apicid; current_thread_info()->cpu = 0; --- a/arch/x86_64/kernel/mpparse.c +++ b/arch/x86_64/kernel/mpparse.c @@ -86,7 +86,7 @@ return sum & 0xFF; } -static void __cpuinit MP_processor_info (struct mpc_config_processor *m) +static void __cpuinit MP_processor_info(struct mpc_config_processor *m) { int cpu; cpumask_t tmp_map; @@ -123,7 +123,18 @@ cpu = 0; } bios_cpu_apicid[cpu] = m->mpc_apicid; - x86_cpu_to_apicid[cpu] = m->mpc_apicid; + /* + * We get called early in the the start_kernel initialization + * process when the per_cpu data area is not yet setup, so we + * use a static array that is removed after the per_cpu data + * area is created. + */ + if (x86_cpu_to_apicid_ptr) { + u8 *x86_cpu_to_apicid = (u8 *)x86_cpu_to_apicid_ptr; + x86_cpu_to_apicid[cpu] = m->mpc_apicid; + } else { + per_cpu(x86_cpu_to_apicid, cpu) = m->mpc_apicid; + } cpu_set(cpu, cpu_possible_map); cpu_set(cpu, cpu_present_map); --- a/arch/x86_64/kernel/smpboot.c +++ b/arch/x86_64/kernel/smpboot.c @@ -701,7 +701,7 @@ clear_node_cpumask(cpu); /* was set by numa_add_cpu */ cpu_clear(cpu, cpu_present_map); cpu_clear(cpu, cpu_possible_map); - x86_cpu_to_apicid[cpu] = BAD_APICID; + per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID; return -EIO; } @@ -848,6 +848,26 @@ } /* + * Copy apicid's found by MP_processor_info from initial array to the per cpu + * data area. The x86_cpu_to_apicid_init array is then expendable and the + * x86_cpu_to_apicid_ptr is zeroed indicating that the static array is no + * longer available. + */ +void __init smp_set_apicids(void) +{ + int cpu; + + for_each_cpu_mask(cpu, cpu_possible_map) { + if (per_cpu_offset(cpu)) + per_cpu(x86_cpu_to_apicid, cpu) = + x86_cpu_to_apicid_init[cpu]; + } + + /* indicate the static array will be going away soon */ + x86_cpu_to_apicid_ptr = NULL; +} + +/* * Prepare for SMP bootup. The MP table or ACPI has been read * earlier. Just do some sanity checking here and enable APIC mode. */ @@ -856,6 +876,7 @@ nmi_watchdog_default(); current_cpu_data = boot_cpu_data; current_thread_info()->cpu = 0; /* needed? */ + smp_set_apicids(); set_cpu_sibling_map(0); if (smp_sanity_check(max_cpus) < 0) { --- a/arch/x86_64/mm/numa.c +++ b/arch/x86_64/mm/numa.c @@ -612,7 +612,7 @@ { int i; for (i = 0; i < NR_CPUS; i++) { - u8 apicid = x86_cpu_to_apicid[i]; + u8 apicid = x86_cpu_to_apicid_init[i]; if (apicid == BAD_APICID) continue; if (apicid_to_node[apicid] == NUMA_NO_NODE) --- a/include/asm-i386/smp.h +++ b/include/asm-i386/smp.h @@ -39,9 +39,11 @@ extern void unlock_ipi_call_lock(void); #define MAX_APICID 256 -extern u8 x86_cpu_to_apicid[]; +extern u8 __initdata x86_cpu_to_apicid_init[]; +extern void *x86_cpu_to_apicid_ptr; +DECLARE_PER_CPU(u8, x86_cpu_to_apicid); -#define cpu_physical_id(cpu) x86_cpu_to_apicid[cpu] +#define cpu_physical_id(cpu) per_cpu(x86_cpu_to_apicid, cpu) extern void set_cpu_sibling_map(int cpu); --- a/include/asm-x86_64/ipi.h +++ b/include/asm-x86_64/ipi.h @@ -119,7 +119,7 @@ */ local_irq_save(flags); for_each_cpu_mask(query_cpu, mask) { - __send_IPI_dest_field(x86_cpu_to_apicid[query_cpu], + __send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, query_cpu), vector, APIC_DEST_PHYSICAL); } local_irq_restore(flags); --- a/include/asm-x86_64/smp.h +++ b/include/asm-x86_64/smp.h @@ -85,7 +85,9 @@ * Some lowlevel functions might want to know about * the real APIC ID <-> CPU # mapping. */ -extern u8 x86_cpu_to_apicid[NR_CPUS]; /* physical ID */ +extern u8 __initdata x86_cpu_to_apicid_init[]; +extern void *x86_cpu_to_apicid_ptr; +DECLARE_PER_CPU(u8, x86_cpu_to_apicid); /* physical ID */ extern u8 bios_cpu_apicid[]; static inline int cpu_present_to_apicid(int mps_cpu) @@ -116,7 +118,7 @@ } #ifdef CONFIG_SMP -#define cpu_physical_id(cpu) x86_cpu_to_apicid[cpu] +#define cpu_physical_id(cpu) per_cpu(x86_cpu_to_apicid, cpu) #else #define cpu_physical_id(cpu) boot_cpu_id #endif /* !CONFIG_SMP */ --- a/arch/x86_64/kernel/genapic_flat.c +++ b/arch/x86_64/kernel/genapic_flat.c @@ -172,7 +172,7 @@ */ cpu = first_cpu(cpumask); if ((unsigned)cpu < NR_CPUS) - return x86_cpu_to_apicid[cpu]; + return per_cpu(x86_cpu_to_apicid, cpu); else return BAD_APICID; } --- a/arch/x86_64/kernel/genapic.c +++ b/arch/x86_64/kernel/genapic.c @@ -24,10 +24,19 @@ #include #endif -/* which logical CPU number maps to which CPU (physical APIC ID) */ -u8 x86_cpu_to_apicid[NR_CPUS] __read_mostly +/* + * which logical CPU number maps to which CPU (physical APIC ID) + * + * The following static array is used during kernel startup + * and the x86_cpu_to_apicid_ptr contains the address of the + * array during this time. Is it zeroed when the per_cpu + * data area is removed. + */ +u8 x86_cpu_to_apicid_init[NR_CPUS] __initdata = { [0 ... NR_CPUS-1] = BAD_APICID }; -EXPORT_SYMBOL(x86_cpu_to_apicid); +void *x86_cpu_to_apicid_ptr; +DEFINE_PER_CPU(u8, x86_cpu_to_apicid) = BAD_APICID; +EXPORT_PER_CPU_SYMBOL(x86_cpu_to_apicid); struct genapic __read_mostly *genapic = &apic_flat; --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -276,6 +276,11 @@ dmi_scan_machine(); +#ifdef CONFIG_SMP + /* setup to use the static apicid table during kernel startup */ + x86_cpu_to_apicid_ptr = (void *)&x86_cpu_to_apicid_init; +#endif + #ifdef CONFIG_ACPI /* * Initialize the ACPI boot-time table parser (gets the RSDP and SDT). --