summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--arch/x86/kernel/setup_percpu.c37
-rw-r--r--include/linux/percpu.h35
2 files changed, 40 insertions, 32 deletions
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index dd4eabc747c8..efa615f2bf43 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -42,6 +42,19 @@ unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
};
EXPORT_SYMBOL(__per_cpu_offset);
+/*
+ * On x86_64 symbols referenced from code should be reachable using
+ * 32bit relocations. Reserve space for static percpu variables in
+ * modules so that they are always served from the first chunk which
+ * is located at the percpu segment base. On x86_32, anything can
+ * address anywhere. No need to reserve space in the first chunk.
+ */
+#ifdef CONFIG_X86_64
+#define PERCPU_FIRST_CHUNK_RESERVE PERCPU_MODULE_RESERVE
+#else
+#define PERCPU_FIRST_CHUNK_RESERVE 0
+#endif
+
/**
* pcpu_need_numa - determine percpu allocation needs to consider NUMA
*
@@ -141,7 +154,7 @@ static ssize_t __init setup_pcpu_remap(size_t static_size)
{
static struct vm_struct vm;
pg_data_t *last;
- size_t ptrs_size;
+ size_t ptrs_size, dyn_size;
unsigned int cpu;
ssize_t ret;
@@ -169,12 +182,14 @@ proceed:
* Currently supports only single page. Supporting multiple
* pages won't be too difficult if it ever becomes necessary.
*/
- pcpur_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+ pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
+ PERCPU_DYNAMIC_RESERVE);
if (pcpur_size > PMD_SIZE) {
pr_warning("PERCPU: static data is larger than large page, "
"can't use large page\n");
return -EINVAL;
}
+ dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
/* allocate pointer array and alloc large pages */
ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
@@ -217,8 +232,9 @@ proceed:
pr_info("PERCPU: Remapped at %p with large pages, static data "
"%zu bytes\n", vm.addr, static_size);
- ret = pcpu_setup_first_chunk(pcpur_get_page, static_size, 0, PMD_SIZE,
- pcpur_size - static_size, vm.addr, NULL);
+ ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
+ PERCPU_FIRST_CHUNK_RESERVE,
+ PMD_SIZE, dyn_size, vm.addr, NULL);
goto out_free_ar;
enomem:
@@ -276,9 +292,10 @@ static ssize_t __init setup_pcpu_embed(size_t static_size)
return -EINVAL;
/* allocate and copy */
- pcpue_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+ pcpue_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
+ PERCPU_DYNAMIC_RESERVE);
pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
- dyn_size = pcpue_size - static_size;
+ dyn_size = pcpue_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
PAGE_SIZE);
@@ -297,7 +314,8 @@ static ssize_t __init setup_pcpu_embed(size_t static_size)
pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);
- return pcpu_setup_first_chunk(pcpue_get_page, static_size, 0,
+ return pcpu_setup_first_chunk(pcpue_get_page, static_size,
+ PERCPU_FIRST_CHUNK_RESERVE,
pcpue_unit_size, dyn_size,
pcpue_ptr, NULL);
}
@@ -356,8 +374,9 @@ static ssize_t __init setup_pcpu_4k(size_t static_size)
pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
pcpu4k_nr_static_pages, static_size);
- ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, 0, -1, -1,
- NULL, pcpu4k_populate_pte);
+ ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
+ PERCPU_FIRST_CHUNK_RESERVE, -1, -1, NULL,
+ pcpu4k_populate_pte);
goto out_free_ar;
enomem:
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 8ff15153ae20..54a968b4b924 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -85,31 +85,20 @@
/*
* PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
- * back on the first chunk if arch is manually allocating and mapping
- * it for faster access (as a part of large page mapping for example).
- * Note that dynamic percpu allocator covers both static and dynamic
- * areas, so these values are bigger than PERCPU_MODULE_RESERVE.
+ * back on the first chunk for dynamic percpu allocation if arch is
+ * manually allocating and mapping it for faster access (as a part of
+ * large page mapping for example).
*
- * On typical configuration with modules, the following values leave
- * about 8k of free space on the first chunk after boot on both x86_32
- * and 64 when module support is enabled. When module support is
- * disabled, it's much tighter.
+ * The following values give between one and two pages of free space
+ * after typical minimal boot (2-way SMP, single disk and NIC) with
+ * both defconfig and a distro config on x86_64 and 32. More
+ * intelligent way to determine this would be nice.
*/
-#ifndef PERCPU_DYNAMIC_RESERVE
-# if BITS_PER_LONG > 32
-# ifdef CONFIG_MODULES
-# define PERCPU_DYNAMIC_RESERVE (24 << 10)
-# else
-# define PERCPU_DYNAMIC_RESERVE (16 << 10)
-# endif
-# else
-# ifdef CONFIG_MODULES
-# define PERCPU_DYNAMIC_RESERVE (16 << 10)
-# else
-# define PERCPU_DYNAMIC_RESERVE (8 << 10)
-# endif
-# endif
-#endif /* PERCPU_DYNAMIC_RESERVE */
+#if BITS_PER_LONG > 32
+#define PERCPU_DYNAMIC_RESERVE (20 << 10)
+#else
+#define PERCPU_DYNAMIC_RESERVE (12 << 10)
+#endif
extern void *pcpu_base_addr;