From 485172b3dff29f888a88d3dba8caec5d589a4049 Mon Sep 17 00:00:00 2001 From: David Daney Date: Tue, 14 Aug 2012 11:08:01 -0700 Subject: MIPS: Align swapper_pg_dir to 64K for better TLB Refill code. We can save an instruction in the TLB Refill path for kernel mappings by aligning swapper_pg_dir on a 64K boundary. The address of swapper_pg_dir can be generated with a single LUI instead of LUI/{D}ADDUI. The alignment of __init_end is bumped up to 64K so there are no holes between it and swapper_pg_dir, which is placed at the very beginning of .bss. The alignment of invalid_pmd_table and invalid_pte_table can be relaxed to PAGE_SIZE. We do this by using __page_aligned_bss, which has the added benefit of eliminating alignment holes in .bss. Signed-off-by: David Daney Cc: linux-mips@linux-mips.org Cc: linux-arch@vger.kernel.org, Cc: linux-kernel@vger.kernel.org Acked-by: Arnd Bergmann Patchwork: https://patchwork.linux-mips.org/patch/4220/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/vmlinux.lds.S | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'arch/mips/kernel') diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S index df243a64f430..007ccbe1e264 100644 --- a/arch/mips/kernel/vmlinux.lds.S +++ b/arch/mips/kernel/vmlinux.lds.S @@ -1,6 +1,13 @@ #include #include #include + +/* + * Put .bss..swapper_pg_dir as the first thing in .bss. This will + * ensure that it has .bss alignment (64K). + */ +#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir) + #include #undef mips @@ -119,11 +126,21 @@ SECTIONS } PERCPU_SECTION(1 << CONFIG_MIPS_L1_CACHE_SHIFT) - . = ALIGN(PAGE_SIZE); + /* + * Align to 64K in attempt to eliminate holes before the + * .bss..swapper_pg_dir section at the start of .bss. This + * also satisfies PAGE_SIZE alignment as the largest page size + * allowed is 64K. + */ + . = ALIGN(0x10000); __init_end = .; /* freed after init ends here */ - BSS_SECTION(0, 0, 0) + /* + * Force .bss to 64K alignment so that .bss..swapper_pg_dir + * gets that alignment. .sbss should be empty, so there will be + * no holes after __init_end. */ + BSS_SECTION(0, 0x10000, 0) _end = . ; -- cgit v1.2.3