From ebb5e78cc63417a35254a791de66e1cc84f963cc Mon Sep 17 00:00:00 2001 From: Alex Smith Date: Wed, 21 Oct 2015 09:54:38 +0100 Subject: MIPS: Initial implementation of a VDSO 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 Signed-off-by: Markos Chandras Cc: Matthew Fortune Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11337/ Signed-off-by: Ralf Baechle --- arch/mips/vdso/sigreturn.S | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 arch/mips/vdso/sigreturn.S (limited to 'arch/mips/vdso/sigreturn.S') diff --git a/arch/mips/vdso/sigreturn.S b/arch/mips/vdso/sigreturn.S new file mode 100644 index 000000000000..715bf5993529 --- /dev/null +++ b/arch/mips/vdso/sigreturn.S @@ -0,0 +1,49 @@ +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Alex Smith + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#include "vdso.h" + +#include + +#include +#include + + .section .text + .cfi_sections .debug_frame + +LEAF(__vdso_rt_sigreturn) + .cfi_startproc + .frame sp, 0, ra + .mask 0x00000000, 0 + .fmask 0x00000000, 0 + .cfi_signal_frame + + li v0, __NR_rt_sigreturn + syscall + + .cfi_endproc + END(__vdso_rt_sigreturn) + +#if _MIPS_SIM == _MIPS_SIM_ABI32 + +LEAF(__vdso_sigreturn) + .cfi_startproc + .frame sp, 0, ra + .mask 0x00000000, 0 + .fmask 0x00000000, 0 + .cfi_signal_frame + + li v0, __NR_sigreturn + syscall + + .cfi_endproc + END(__vdso_sigreturn) + +#endif -- cgit v1.2.3-59-g8ed1b