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MIPS: Initial implementation of a VDSO

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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>
This commit is contained in:
Alex Smith
2015-10-21 09:54:38 +01:00
committed by Ralf Baechle
parent 22773aa9b9
commit ebb5e78cc6
19 changed files with 1113 additions and 123 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
arch/mips/include/asm/abi.h
View File

@@ -11,19 +11,20 @@
#include <asm/signal.h>
#include <asm/siginfo.h>
#include <asm/vdso.h>
struct mips_abi {
int (* const setup_frame)(void *sig_return, struct ksignal *ksig,
struct pt_regs *regs, sigset_t *set);
const unsigned long signal_return_offset;
int (* const setup_rt_frame)(void *sig_return, struct ksignal *ksig,
struct pt_regs *regs, sigset_t *set);
const unsigned long rt_signal_return_offset;
const unsigned long restart;
unsigned off_sc_fpregs;
unsigned off_sc_fpc_csr;
unsigned off_sc_used_math;
struct mips_vdso_image *vdso;
};
#endif /* _ASM_ABI_H */

7
arch/mips/include/asm/elf.h
View File

@@ -8,6 +8,7 @@
#ifndef _ASM_ELF_H
#define _ASM_ELF_H
#include <linux/auxvec.h>
#include <linux/fs.h>
#include <uapi/linux/elf.h>
@@ -419,6 +420,12 @@ extern const char *__elf_platform;
#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2)
#endif
#define ARCH_DLINFO \
do { \
NEW_AUX_ENT(AT_SYSINFO_EHDR, \
(unsigned long)current->mm->context.vdso); \
} while (0)
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,

8
arch/mips/include/asm/processor.h
View File

@@ -36,12 +36,6 @@ extern unsigned int vced_count, vcei_count;
*/
#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
/*
* A special page (the vdso) is mapped into all processes at the very
* top of the virtual memory space.
*/
#define SPECIAL_PAGES_SIZE PAGE_SIZE
#ifdef CONFIG_32BIT
#ifdef CONFIG_KVM_GUEST
/* User space process size is limited to 1GB in KVM Guest Mode */
@@ -80,7 +74,7 @@ extern unsigned int vced_count, vcei_count;
#endif
#define STACK_TOP ((TASK_SIZE & PAGE_MASK) - SPECIAL_PAGES_SIZE)
#define STACK_TOP (TASK_SIZE & PAGE_MASK)
/*
* This decides where the kernel will search for a free chunk of vm

73
arch/mips/include/asm/vdso.h
View File

@@ -1,29 +1,70 @@
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
* Copyright (C) 2015 Imagination Technologies
* Author: Alex Smith <alex.smith@imgtec.com>
*
* Copyright (C) 2009 Cavium Networks
* 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.
*/
#ifndef __ASM_VDSO_H
#define __ASM_VDSO_H
#include <linux/types.h>
#include <linux/mm_types.h>
/**
* struct mips_vdso_image - Details of a VDSO image.
* @data: Pointer to VDSO image data (page-aligned).
* @size: Size of the VDSO image data (page-aligned).
* @off_sigreturn: Offset of the sigreturn() trampoline.
* @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
* @mapping: Special mapping structure.
*
* This structure contains details of a VDSO image, including the image data
* and offsets of certain symbols required by the kernel. It is generated as
* part of the VDSO build process, aside from the mapping page array, which is
* populated at runtime.
*/
struct mips_vdso_image {
void *data;
unsigned long size;
#ifdef CONFIG_32BIT
struct mips_vdso {
u32 signal_trampoline[2];
u32 rt_signal_trampoline[2];
unsigned long off_sigreturn;
unsigned long off_rt_sigreturn;
struct vm_special_mapping mapping;
};
#else /* !CONFIG_32BIT */
struct mips_vdso {
u32 o32_signal_trampoline[2];
u32 o32_rt_signal_trampoline[2];
u32 rt_signal_trampoline[2];
u32 n32_rt_signal_trampoline[2];
/*
* The following structures are auto-generated as part of the build for each
* ABI by genvdso, see arch/mips/vdso/Makefile.
*/
extern struct mips_vdso_image vdso_image;
#ifdef CONFIG_MIPS32_O32
extern struct mips_vdso_image vdso_image_o32;
#endif
#ifdef CONFIG_MIPS32_N32
extern struct mips_vdso_image vdso_image_n32;
#endif
/**
* union mips_vdso_data - Data provided by the kernel for the VDSO.
*
* This structure contains data needed by functions within the VDSO. It is
* populated by the kernel and mapped read-only into user memory.
*
* Note: Care should be taken when modifying as the layout must remain the same
* for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).
*/
union mips_vdso_data {
struct {
};
u8 page[PAGE_SIZE];
};
#endif /* CONFIG_32BIT */
#endif /* __ASM_VDSO_H */