From 6f4441ef7009b9ec063678d906eb762318689494 Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Thu, 5 Dec 2013 11:42:40 +0800 Subject: [PATCH] powerpc: Dynamically allocate slb_shadow from memblock Currently, the slb_shadow buffer is our largest symbol: [jk@pablo linux]$ nm --size-sort -r -S obj/vmlinux | head -1 c000000000da0000 0000000000040000 d slb_shadow - we allocate 128 bytes per cpu; so 256k with NR_CPUS=2048. As we have constant initialisers, it's allocated in .text, causing a larger vmlinux image. We may also allocate unecessary slb_shadow buffers (> no. pacas), since we use the build-time NR_CPUS rather than the run-time nr_cpu_ids. We could move this to the bss, but then we still have the NR_CPUS vs nr_cpu_ids potential for overallocation. This change dynamically allocates the slb_shadow array, during initialise_pacas(). At a cost of 104 bytes of text, we save 256k of data: [jk@pablo linux]$ size obj/vmlinux{.orig,} text data bss dec hex filename 9202795 5244676 1169576 15617047 ee4c17 obj/vmlinux.orig 9202899 4982532 1169576 15355007 ea4c7f obj/vmlinux Tested on pseries. Signed-off-by: Jeremy Kerr Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/paca.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c index 9095a6f7ac2c..623c356fe34f 100644 --- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -99,12 +99,28 @@ static inline void free_lppacas(void) { } * 3 persistent SLBs are registered here. The buffer will be zero * initially, hence will all be invaild until we actually write them. */ -static struct slb_shadow slb_shadow[] __cacheline_aligned = { - [0 ... (NR_CPUS-1)] = { - .persistent = cpu_to_be32(SLB_NUM_BOLTED), - .buffer_length = cpu_to_be32(sizeof(struct slb_shadow)), - }, -}; +static struct slb_shadow *slb_shadow; + +static void __init allocate_slb_shadows(int nr_cpus, int limit) +{ + int size = PAGE_ALIGN(sizeof(struct slb_shadow) * nr_cpus); + slb_shadow = __va(memblock_alloc_base(size, PAGE_SIZE, limit)); + memset(slb_shadow, 0, size); +} + +static struct slb_shadow * __init init_slb_shadow(int cpu) +{ + struct slb_shadow *s = &slb_shadow[cpu]; + + s->persistent = cpu_to_be32(SLB_NUM_BOLTED); + s->buffer_length = cpu_to_be32(sizeof(*s)); + + return s; +} + +#else /* CONFIG_PPC_STD_MMU_64 */ + +static void __init allocate_slb_shadows(int nr_cpus, int limit) { } #endif /* CONFIG_PPC_STD_MMU_64 */ @@ -142,7 +158,7 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu) new_paca->__current = &init_task; new_paca->data_offset = 0xfeeeeeeeeeeeeeeeULL; #ifdef CONFIG_PPC_STD_MMU_64 - new_paca->slb_shadow_ptr = &slb_shadow[cpu]; + new_paca->slb_shadow_ptr = init_slb_shadow(cpu); #endif /* CONFIG_PPC_STD_MMU_64 */ } @@ -190,6 +206,8 @@ void __init allocate_pacas(void) allocate_lppacas(nr_cpu_ids, limit); + allocate_slb_shadows(nr_cpu_ids, limit); + /* Can't use for_each_*_cpu, as they aren't functional yet */ for (cpu = 0; cpu < nr_cpu_ids; cpu++) initialise_paca(&paca[cpu], cpu); -- 2.30.2