linux/arch/mips/vdso/sigreturn.S

/*
 * Copyright (C) 2015 Imagination Technologies
 * Author: Alex Smith <alex.smith@imgtec.com>
 *
 * 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 <uapi/asm/unistd.h>

#include <asm/regdef.h>
#include <asm/asm.h>

	.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
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 <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> 2015-10-21 08:54:38 +00:00			`/*`
			`* Copyright (C) 2015 Imagination Technologies`
			`* Author: Alex Smith <alex.smith@imgtec.com>`
			`*`
			`* 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 <uapi/asm/unistd.h>`

			`#include <asm/regdef.h>`
			`#include <asm/asm.h>`

			`.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`