forked from Minki/linux
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 <jk@ozlabs.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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@ -99,12 +99,28 @@ static inline void free_lppacas(void) { }
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* 3 persistent SLBs are registered here. The buffer will be zero
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* initially, hence will all be invaild until we actually write them.
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*/
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static struct slb_shadow slb_shadow[] __cacheline_aligned = {
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[0 ... (NR_CPUS-1)] = {
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.persistent = cpu_to_be32(SLB_NUM_BOLTED),
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.buffer_length = cpu_to_be32(sizeof(struct slb_shadow)),
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},
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};
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static struct slb_shadow *slb_shadow;
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static void __init allocate_slb_shadows(int nr_cpus, int limit)
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{
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int size = PAGE_ALIGN(sizeof(struct slb_shadow) * nr_cpus);
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slb_shadow = __va(memblock_alloc_base(size, PAGE_SIZE, limit));
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memset(slb_shadow, 0, size);
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}
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static struct slb_shadow * __init init_slb_shadow(int cpu)
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{
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struct slb_shadow *s = &slb_shadow[cpu];
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s->persistent = cpu_to_be32(SLB_NUM_BOLTED);
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s->buffer_length = cpu_to_be32(sizeof(*s));
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return s;
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}
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#else /* CONFIG_PPC_STD_MMU_64 */
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static void __init allocate_slb_shadows(int nr_cpus, int limit) { }
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#endif /* CONFIG_PPC_STD_MMU_64 */
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@ -142,7 +158,7 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu)
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new_paca->__current = &init_task;
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new_paca->data_offset = 0xfeeeeeeeeeeeeeeeULL;
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#ifdef CONFIG_PPC_STD_MMU_64
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new_paca->slb_shadow_ptr = &slb_shadow[cpu];
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new_paca->slb_shadow_ptr = init_slb_shadow(cpu);
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#endif /* CONFIG_PPC_STD_MMU_64 */
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}
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@ -190,6 +206,8 @@ void __init allocate_pacas(void)
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allocate_lppacas(nr_cpu_ids, limit);
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allocate_slb_shadows(nr_cpu_ids, limit);
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/* Can't use for_each_*_cpu, as they aren't functional yet */
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for (cpu = 0; cpu < nr_cpu_ids; cpu++)
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initialise_paca(&paca[cpu], cpu);
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