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authorJeremy Kerr <jk@ozlabs.org>2013-12-05 11:42:40 +0800
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-12-09 11:40:26 +1100
commit6f4441ef7009b9ec063678d906eb762318689494 (patch)
tree1915c5320503665a0a1dedf24b8c97a88caccc64 /arch/powerpc/kernel/paca.c
parent1a8f6f97ea4dbaaa21b05cae2dacea47e4aea37b (diff)
downloadop-kernel-dev-6f4441ef7009b9ec063678d906eb762318689494.zip
op-kernel-dev-6f4441ef7009b9ec063678d906eb762318689494.tar.gz
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>
Diffstat (limited to 'arch/powerpc/kernel/paca.c')
-rw-r--r--arch/powerpc/kernel/paca.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index 9095a6f..623c356 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);
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