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[IA64] Ensure cpu0 can access per-cpu variables in early boot code

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ia64 handles per-cpu variables a litle differently from other architectures
in that it maps the physical memory allocated for each cpu at a constant
virtual address (0xffffffffffff0000). This mapping is not enabled until
the architecture specific cpu_init() function is run, which causes problems
since some generic code is run before this point. In particular when
CONFIG_PRINTK_TIME is enabled, the boot cpu will trap on the access to
per-cpu memory at the first printk() call so the boot will fail without
the kernel printing anything to the console.

Fix this by allocating percpu memory for cpu0 in the kernel data section
and doing all initialization to enable percpu access in head.S before
calling any generic code.

Other cpus must take care not to access per-cpu variables too early, but
their code path from start_secondary() to cpu_init() is all in arch/ia64

Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Tony Luck 2008-08-12 10:34:20 -07:00
parent 45fc3c4d9b
commit 10617bbe84
6 changed files with 53 additions and 12 deletions
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26
arch/ia64/kernel/head.S
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@ -359,7 +359,31 @@ 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
mov r18=PERCPU_PAGE_SIZE
;;
#ifndef CONFIG_SMP
add r19=r19,r18
;;
#else
(isAP) br.few 2f
mov r20=r19
sub r19=r19,r18
;;
shr.u r18=r18,3
1:
ld8 r21=[r20],8;;
st8[r19]=r21,8
adds r18=-1,r18;;
cmp4.lt p7,p6=0,r18
(p7) br.cond.dptk.few 1b
2:
#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
;;

18
arch/ia64/kernel/setup.c
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@ -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();
/*

2
arch/ia64/kernel/smpboot.c
View File

@ -467,7 +467,9 @@ start_secondary (void *unused)
{
/* Early console may use I/O ports */
ia64_set_kr(IA64_KR_IO_BASE, __pa(ia64_iobase));
#ifndef CONFIG_PRINTK_TIME
Dprintk("start_secondary: starting CPU 0x%x\n", hard_smp_processor_id());
#endif
efi_map_pal_code();
cpu_init();
preempt_disable();

3
arch/ia64/kernel/vmlinux.lds.S
View File

@ -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)
{

10
arch/ia64/mm/contig.c
View File

@ -163,8 +163,14 @@ 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++) {
__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 +183,7 @@ 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

6
arch/ia64/mm/discontig.c
View File

@ -143,7 +143,11 @@ 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;
__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) -