28596b6a87
Signed-off-by: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/1375740170-7446-17-git-send-email-andi@firstfloor.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/*
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* vvar.h: Shared vDSO/kernel variable declarations
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* Copyright (c) 2011 Andy Lutomirski
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* Subject to the GNU General Public License, version 2
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*
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* A handful of variables are accessible (read-only) from userspace
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* code in the vsyscall page and the vdso. They are declared here.
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* Some other file must define them with DEFINE_VVAR.
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*
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* In normal kernel code, they are used like any other variable.
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* In user code, they are accessed through the VVAR macro.
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*
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* These variables live in a page of kernel data that has an extra RO
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* mapping for userspace. Each variable needs a unique offset within
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* that page; specify that offset with the DECLARE_VVAR macro. (If
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* you mess up, the linker will catch it.)
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*/
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/* Base address of vvars. This is not ABI. */
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#define VVAR_ADDRESS (-10*1024*1024 - 4096)
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#if defined(__VVAR_KERNEL_LDS)
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/* The kernel linker script defines its own magic to put vvars in the
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* right place.
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*/
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#define DECLARE_VVAR(offset, type, name) \
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EMIT_VVAR(name, offset)
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#else
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#define DECLARE_VVAR(offset, type, name) \
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static type const * const vvaraddr_ ## name = \
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(void *)(VVAR_ADDRESS + (offset));
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#define DEFINE_VVAR(type, name) \
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type name \
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__attribute__((section(".vvar_" #name), aligned(16))) __visible
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#define VVAR(name) (*vvaraddr_ ## name)
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#endif
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/* DECLARE_VVAR(offset, type, name) */
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DECLARE_VVAR(0, volatile unsigned long, jiffies)
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DECLARE_VVAR(16, int, vgetcpu_mode)
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DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
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#undef DECLARE_VVAR
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