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arch/sparc: support NR_CPUS = 4096 

Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
only allocates a single page for NR_CPUS mondo entries. Thus we cannot
use all 4096 CPUs on some SPARC platforms.

To fix, allocate (2^order) pages where order is set according to the size
of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
are not used in asm code, there are no imm13 offsets from the base PA
that will break because they can only reach one page.

Orabug: 25505750

Signed-off-by: Jane Chu <jane.chu@oracle.com>

Reviewed-by: Bob Picco <bob.picco@oracle.com>
Reviewed-by: Atish Patra <atish.patra@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jane Chu 2017-06-06 14:32:29 -06:00 committed by David S. Miller
parent 1b4af13ff2
commit c79a13734d
2 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/sparc/Kconfig
View File

@ -192,9 +192,9 @@ config NR_CPUS
int "Maximum number of CPUs"
depends on SMP
range 2 32 if SPARC32
range 2 1024 if SPARC64
range 2 4096 if SPARC64
default 32 if SPARC32
default 64 if SPARC64
default 4096 if SPARC64
source kernel/Kconfig.hz

17
arch/sparc/kernel/irq_64.c
View File

@ -1034,17 +1034,26 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
{
#ifdef CONFIG_SMP
unsigned long page;
void *mondo, *p;
BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
/* Make sure mondo block is 64byte aligned */
p = kzalloc(127, GFP_KERNEL);
if (!p) {
prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
prom_halt();
}
mondo = (void *)(((unsigned long)p + 63) & ~0x3f);
tb->cpu_mondo_block_pa = __pa(mondo);
page = get_zeroed_page(GFP_KERNEL);
if (!page) {
prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
prom_printf("SUN4V: Error, cannot allocate cpu list page.\n");
prom_halt();
}
tb->cpu_mondo_block_pa = __pa(page);
tb->cpu_list_pa = __pa(page + 64);
tb->cpu_list_pa = __pa(page);
#endif
}