From 3e5d8f978435bb9ba4dfe3f4514e65e7885db1a9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: make percpu symbols zerobased on SMP [ Based on original patch from Christoph Lameter and Mike Travis. ] This patch makes percpu symbols zerobased on x86_64 SMP by adding PERCPU_VADDR() to vmlinux.lds.h which helps setting explicit vaddr on the percpu output section and using it in vmlinux_64.lds.S. A new PHDR is added as existing ones cannot contain sections near address zero. PERCPU_VADDR() also adds a new symbol __per_cpu_load which always points to the vaddr of the loaded percpu data.init region. The following adjustments have been made to accomodate the address change. * code to locate percpu gdt_page in head_64.S is updated to add the load address to the gdt_page offset. * __per_cpu_load is used in places where access to the init data area is necessary. * pda->data_offset is initialized soon after C code is entered as zero value doesn't work anymore. This patch is mostly taken from Mike Travis' "x86_64: Base percpu variables at zero" patch. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- include/asm-generic/sections.h | 2 +- include/asm-generic/vmlinux.lds.h | 51 ++++++++++++++++++++++++++++++++++----- 2 files changed, 46 insertions(+), 7 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index 79a7ff9..4ce48e8 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -9,7 +9,7 @@ extern char __bss_start[], __bss_stop[]; extern char __init_begin[], __init_end[]; extern char _sinittext[], _einittext[]; extern char _end[]; -extern char __per_cpu_start[], __per_cpu_end[]; +extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[]; extern char __kprobes_text_start[], __kprobes_text_end[]; extern char __initdata_begin[], __initdata_end[]; extern char __start_rodata[], __end_rodata[]; diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index c61fab1..fc2f55f 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -430,12 +430,51 @@ *(.initcall7.init) \ *(.initcall7s.init) -#define PERCPU(align) \ - . = ALIGN(align); \ - VMLINUX_SYMBOL(__per_cpu_start) = .; \ - .data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) { \ +#define PERCPU_PROLOG(vaddr) \ + VMLINUX_SYMBOL(__per_cpu_load) = .; \ + .data.percpu vaddr : AT(__per_cpu_load - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__per_cpu_start) = .; + +#define PERCPU_EPILOG(phdr) \ + VMLINUX_SYMBOL(__per_cpu_end) = .; \ + } phdr \ + . = __per_cpu_load + SIZEOF(.data.percpu); + +/** + * PERCPU_VADDR - define output section for percpu area + * @vaddr: explicit base address (optional) + * @phdr: destination PHDR (optional) + * + * Macro which expands to output section for percpu area. If @vaddr + * is not blank, it specifies explicit base address and all percpu + * symbols will be offset from the given address. If blank, @vaddr + * always equals @laddr + LOAD_OFFSET. + * + * @phdr defines the output PHDR to use if not blank. Be warned that + * output PHDR is sticky. If @phdr is specified, the next output + * section in the linker script will go there too. @phdr should have + * a leading colon. + * + * This macro defines three symbols, __per_cpu_load, __per_cpu_start + * and __per_cpu_end. The first one is the vaddr of loaded percpu + * init data. __per_cpu_start equals @vaddr and __per_cpu_end is the + * end offset. + */ +#define PERCPU_VADDR(vaddr, phdr) \ + PERCPU_PROLOG(vaddr) \ *(.data.percpu.page_aligned) \ *(.data.percpu) \ *(.data.percpu.shared_aligned) \ - } \ - VMLINUX_SYMBOL(__per_cpu_end) = .; + PERCPU_EPILOG(phdr) + +/** + * PERCPU - define output section for percpu area, simple version + * @align: required alignment + * + * Align to @align and outputs output section for percpu area. This + * macro doesn't maniuplate @vaddr or @phdr and __per_cpu_load and + * __per_cpu_start will be identical. + */ +#define PERCPU(align) \ + . = ALIGN(align); \ + PERCPU_VADDR( , ) -- cgit v1.1