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/include/asm/abi.h | 5 +-- arch/mips/include/asm/elf.h | 7 ++++ arch/mips/include/asm/processor.h | 8 +---- arch/mips/include/asm/vdso.h | 73 ++++++++++++++++++++++++++++++--------- 4 files changed, 68 insertions(+), 25 deletions(-) (limited to 'arch/mips/include/asm') diff --git a/arch/mips/include/asm/abi.h b/arch/mips/include/asm/abi.h index 37f84078e78a..940760844e2f 100644 --- a/arch/mips/include/asm/abi.h +++ b/arch/mips/include/asm/abi.h @@ -11,19 +11,20 @@ #include #include +#include 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 */ diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h index 53b26933b12c..b01a6ff468e0 100644 --- a/arch/mips/include/asm/elf.h +++ b/arch/mips/include/asm/elf.h @@ -8,6 +8,7 @@ #ifndef _ASM_ELF_H #define _ASM_ELF_H +#include #include #include @@ -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, diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 59ee6dcf6eed..3f832c3dd8f5 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -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 diff --git a/arch/mips/include/asm/vdso.h b/arch/mips/include/asm/vdso.h index cca56aa40ff4..db2d45be8f2e 100644 --- a/arch/mips/include/asm/vdso.h +++ b/arch/mips/include/asm/vdso.h @@ -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 * - * 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 +#include +/** + * 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 */ -- cgit v1.2.3