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authorTejun Heo <tj@kernel.org>2009-01-13 20:41:35 +0900
committerIngo Molnar <mingo@elte.hu>2009-01-16 14:19:14 +0100
commit3e5d8f978435bb9ba4dfe3f4514e65e7885db1a9 (patch)
tree1ce55b2ec16a0bd59a29857e05215960d463a1d8 /include/asm-generic
parenta698c823e15149941b0f0281527d0c0d1daf2639 (diff)
downloadop-kernel-dev-3e5d8f978435bb9ba4dfe3f4514e65e7885db1a9.zip
op-kernel-dev-3e5d8f978435bb9ba4dfe3f4514e65e7885db1a9.tar.gz
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 <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/sections.h2
-rw-r--r--include/asm-generic/vmlinux.lds.h51
2 files changed, 46 insertions, 7 deletions
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( , )
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