We've been fighting a long running battle with the use of per-cpu variables in early boot code on ia64. In current code accessing them before cpu_init() has a chance to initialize ar.k3 with the physical address of the per-cpu page results in the system hanging. This is the reason that CONFIG_PRINTK_TIME results in a kernel that does not boot. This patch fixes this by allocating the memory for the per-cpu page in kernel .data segment and initializing ar.k3 to point to it[1] in head.S before any C code has the opportunity to access a per-cpu variable. Life is a little complex because the SMP=n case uses the __phys_per_cpu_start copy of the per cpu variables directly. Tested with tiger_defconfig and generic_defconfig kernels on Intel tiger system (to check both the contig.c and discontig.c allocations). But I'd appreciate hearing whether this works on a real NUMA system. -Tony [1] ar.k3 actually points at the physical address of the *END* of the per-cpu page to make life easy for the MCA code to use it in assembly code. --- diff --git a/arch/ia64/kernel/head.S b/arch/ia64/kernel/head.S index 41c7129..ae650f1 100644 --- a/arch/ia64/kernel/head.S +++ b/arch/ia64/kernel/head.S @@ -359,7 +359,18 @@ start_ap: mov ar.rsc=0 // place RSE in enforced lazy mode ;; loadrs // clear the dirty partition - mov IA64_KR(PER_CPU_DATA)=r0 // clear physical per-CPU base + movl r19=__phys_per_cpu_start +#ifndef CONFIG_SMP + mov r18=PERCPU_PAGE_SIZE + ;; + add r19=r19,r18 +#endif + ;; + tpa r19=r19 + ;; + .pred.rel.mutex isBP,isAP +(isBP) mov IA64_KR(PER_CPU_DATA)=r19 // per-CPU base for cpu0 +(isAP) mov IA64_KR(PER_CPU_DATA)=r0 // clear physical per-CPU base ;; mov ar.bspstore=r2 // establish the new RSE stack ;; diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c index 593279f..c27d5b2 100644 --- a/arch/ia64/kernel/setup.c +++ b/arch/ia64/kernel/setup.c @@ -927,17 +927,19 @@ cpu_init (void) if (smp_processor_id() == 0) { cpu_set(0, per_cpu(cpu_sibling_map, 0)); cpu_set(0, cpu_core_map[0]); + } else { + /* + * Set ar.k3 so that assembly code in MCA handler can compute + * physical addresses of per cpu variables with a simple: + * phys = ar.k3 + &per_cpu_var + * and the alt-dtlb-miss handler can set per-cpu mapping into + * the TLB when needed. head.S already did this for cpu0. + */ + ia64_set_kr(IA64_KR_PER_CPU_DATA, + ia64_tpa(cpu_data) - (long) __per_cpu_start); } #endif - /* - * We set ar.k3 so that assembly code in MCA handler can compute - * physical addresses of per cpu variables with a simple: - * phys = ar.k3 + &per_cpu_var - */ - ia64_set_kr(IA64_KR_PER_CPU_DATA, - ia64_tpa(cpu_data) - (long) __per_cpu_start); - get_max_cacheline_size(); /* diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S index 5a77206..de71da8 100644 --- a/arch/ia64/kernel/vmlinux.lds.S +++ b/arch/ia64/kernel/vmlinux.lds.S @@ -215,6 +215,9 @@ SECTIONS /* Per-cpu data: */ percpu : { } :percpu . = ALIGN(PERCPU_PAGE_SIZE); +#ifdef CONFIG_SMP + . = . + PERCPU_PAGE_SIZE; /* cpu0 per-cpu space */ +#endif __phys_per_cpu_start = .; .data.percpu PERCPU_ADDR : AT(__phys_per_cpu_start - LOAD_OFFSET) { diff --git a/arch/ia64/mm/contig.c b/arch/ia64/mm/contig.c index 798bf98..35ae83b 100644 --- a/arch/ia64/mm/contig.c +++ b/arch/ia64/mm/contig.c @@ -163,8 +163,15 @@ per_cpu_init (void) * get_zeroed_page(). */ if (first_time) { + void *cpu0_data = __phys_per_cpu_start - PERCPU_PAGE_SIZE; + first_time=0; - for (cpu = 0; cpu < NR_CPUS; cpu++) { + + memcpy(cpu0_data, __phys_per_cpu_start, __per_cpu_end - __per_cpu_start); + __per_cpu_offset[0] = (char *) cpu0_data - __per_cpu_start; + per_cpu(local_per_cpu_offset, 0) = __per_cpu_offset[0]; + + for (cpu = 1; cpu < NR_CPUS; cpu++) { memcpy(cpu_data, __phys_per_cpu_start, __per_cpu_end - __per_cpu_start); __per_cpu_offset[cpu] = (char *) cpu_data - __per_cpu_start; cpu_data += PERCPU_PAGE_SIZE; @@ -177,7 +184,7 @@ per_cpu_init (void) static inline void alloc_per_cpu_data(void) { - cpu_data = __alloc_bootmem(PERCPU_PAGE_SIZE * NR_CPUS, + cpu_data = __alloc_bootmem(PERCPU_PAGE_SIZE * NR_CPUS-1, PERCPU_PAGE_SIZE, __pa(MAX_DMA_ADDRESS)); } #else diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c index d83125e..7690710 100644 --- a/arch/ia64/mm/discontig.c +++ b/arch/ia64/mm/discontig.c @@ -143,7 +143,13 @@ static void *per_cpu_node_setup(void *cpu_data, int node) int cpu; for_each_possible_early_cpu(cpu) { - if (node == node_cpuid[cpu].nid) { + if (cpu == 0) { + void *cpu0_data = __phys_per_cpu_start - PERCPU_PAGE_SIZE; + memcpy(cpu0_data, __phys_per_cpu_start, + __per_cpu_end - __per_cpu_start); + __per_cpu_offset[cpu] = (char*)cpu0_data - + __per_cpu_start; + } else if (node == node_cpuid[cpu].nid) { memcpy(__va(cpu_data), __phys_per_cpu_start, __per_cpu_end - __per_cpu_start); __per_cpu_offset[cpu] = (char*)__va(cpu_data) - -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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