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Subject[PATCH 3.13 053/162] sparc64: Kill unnecessary tables and increase MAX_BANKS.
Date
3.13.11.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "David S. Miller" <davem@davemloft.net>

[ Upstream commit d195b71bad4347d2df51072a537f922546a904f1 ]

swapper_low_pmd_dir and swapper_pud_dir are actually completely
useless and unnecessary.

We just need swapper_pg_dir[]. Naturally the other page table chunks
will be allocated on an as-needed basis. Since the kernel actually
accesses these tables in the PAGE_OFFSET view, there is not even a TLB
locality advantage of placing them in the kernel image.

Use the hard coded vmlinux.ld.S slot for swapper_pg_dir which is
naturally page aligned.

Increase MAX_BANKS to 1024 in order to handle heavily fragmented
virtual guests.

Even with this MAX_BANKS increase, the kernel is 20K+ smaller.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Bob Picco <bob.picco@oracle.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
arch/sparc/include/asm/pgtable_64.h | 1 -
arch/sparc/kernel/vmlinux.lds.S | 5 +++--
arch/sparc/mm/init_64.c | 25 ++-----------------------
3 files changed, 5 insertions(+), 26 deletions(-)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index ad1def4..e8dfabf 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -927,7 +927,6 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
#endif

extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
-extern pmd_t swapper_low_pmd_dir[PTRS_PER_PMD];

extern void paging_init(void);
extern unsigned long find_ecache_flush_span(unsigned long size);
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index 0bacceb..0924305 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -35,8 +35,9 @@ jiffies = jiffies_64;

SECTIONS
{
- /* swapper_low_pmd_dir is sparc64 only */
- swapper_low_pmd_dir = 0x0000000000402000;
+#ifdef CONFIG_SPARC64
+ swapper_pg_dir = 0x0000000000402000;
+#endif
. = INITIAL_ADDRESS;
.text TEXTSTART :
{
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index ca634b3..39c52fc 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -85,7 +85,7 @@ extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];

static unsigned long cpu_pgsz_mask;

-#define MAX_BANKS 32
+#define MAX_BANKS 1024

static struct linux_prom64_registers pavail[MAX_BANKS];
static int pavail_ents;
@@ -1936,12 +1936,6 @@ static void __init sun4v_linear_pte_xor_finalize(void)

static unsigned long last_valid_pfn;

-/* These must be page aligned in order to not trigger the
- * alignment tests of pgd_bad() and pud_bad().
- */
-pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__ ((aligned (PAGE_SIZE)));
-static pud_t swapper_pud_dir[PTRS_PER_PUD] __attribute__ ((aligned (PAGE_SIZE)));
-
static void sun4u_pgprot_init(void);
static void sun4v_pgprot_init(void);

@@ -1949,8 +1943,6 @@ void __init paging_init(void)
{
unsigned long end_pfn, shift, phys_base;
unsigned long real_end, i;
- pud_t *pud;
- pmd_t *pmd;
int node;

setup_page_offset();
@@ -2045,20 +2037,7 @@ void __init paging_init(void)
*/
init_mm.pgd += ((shift) / (sizeof(pgd_t)));

- memset(swapper_low_pmd_dir, 0, sizeof(swapper_low_pmd_dir));
-
- /* The kernel page tables we publish into what the rest of the
- * world sees must be adjusted so that they see the PAGE_OFFSET
- * address of these in-kerenel data structures. However right
- * here we must access them from the kernel image side, because
- * the trap tables haven't been taken over and therefore we cannot
- * take TLB misses in the PAGE_OFFSET linear mappings yet.
- */
- pud = swapper_pud_dir + (shift / sizeof(pud_t));
- pgd_set(&swapper_pg_dir[0], pud);
-
- pmd = swapper_low_pmd_dir + (shift / sizeof(pmd_t));
- pud_set(&swapper_pud_dir[0], pmd);
+ memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));

inherit_prom_mappings();

--
1.9.1


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