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ebb5e78cc6
Add an initial implementation of a proper (i.e. an ELF shared library)
VDSO. With this commit it does not export any symbols, it only replaces
the current signal return trampoline page. A later commit will add user
implementations of gettimeofday()/clock_gettime().
To support both new toolchains and old ones which don't generate ABI
flags section, we define its content manually and then use a tool
(genvdso) to patch up the section to have the correct name and type.
genvdso also extracts symbol offsets ({,rt_}sigreturn) needed by the
kernel, and generates a C file containing a "struct mips_vdso_image"
containing both the VDSO data and these offsets. This C file is
compiled into the kernel.
On 64-bit kernels we require a different VDSO for each supported ABI,
so we may build up to 3 different VDSOs. The VDSO to use is selected by
the mips_abi structure.
A kernel/user shared data page is created and mapped below the VDSO
image. This is currently empty, but will be used by the user time
function implementations which are added later.
[markos.chandras@imgtec.com:
- Add more comments
- Move abi detection in genvdso.h since it's the get_symbol function
that needs it.
- Add an R6 specific way to calculate the base address of VDSO in order
to avoid the branch instruction which affects performance.
- Do not patch .gnu.attributes since it's not needed for dynamic linking.
- Simplify Makefile a little bit.
- checkpatch fixes
- Restrict VDSO support for binutils < 2.25 for pre-R6
- Include atomic64.h for O32 variant on MIPS64]
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
69 lines
1.8 KiB
ArmAsm
69 lines
1.8 KiB
ArmAsm
/*
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* Copyright (C) 2015 Imagination Technologies
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* Author: Alex Smith <alex.smith@imgtec.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include "vdso.h"
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#include <linux/elfnote.h>
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#include <linux/version.h>
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ELFNOTE_START(Linux, 0, "a")
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.long LINUX_VERSION_CODE
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ELFNOTE_END
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/*
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* The .MIPS.abiflags section must be defined with the FP ABI flags set
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* to 'any' to be able to link with both old and new libraries.
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* Newer toolchains are capable of automatically generating this, but we want
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* to work with older toolchains as well. Therefore, we define the contents of
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* this section here (under different names), and then genvdso will patch
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* it to have the correct name and type.
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*
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* We base the .MIPS.abiflags section on preprocessor definitions rather than
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* CONFIG_* because we need to match the particular ABI we are building the
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* VDSO for.
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*
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* See https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
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* for the .MIPS.abiflags section description.
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*/
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.section .mips_abiflags, "a"
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.align 3
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__mips_abiflags:
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.hword 0 /* version */
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.byte __mips /* isa_level */
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/* isa_rev */
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#ifdef __mips_isa_rev
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.byte __mips_isa_rev
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#else
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.byte 0
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#endif
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/* gpr_size */
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#ifdef __mips64
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.byte 2 /* AFL_REG_64 */
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#else
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.byte 1 /* AFL_REG_32 */
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#endif
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/* cpr1_size */
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#if (defined(__mips_isa_rev) && __mips_isa_rev >= 6) || defined(__mips64)
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.byte 2 /* AFL_REG_64 */
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#else
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.byte 1 /* AFL_REG_32 */
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#endif
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.byte 0 /* cpr2_size (AFL_REG_NONE) */
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.byte 0 /* fp_abi (Val_GNU_MIPS_ABI_FP_ANY) */
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.word 0 /* isa_ext */
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.word 0 /* ases */
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.word 0 /* flags1 */
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.word 0 /* flags2 */
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