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authorAlex Smith <alex.smith@imgtec.com>2015-10-21 09:54:38 +0100
committerRalf Baechle <ralf@linux-mips.org>2015-11-11 08:36:36 +0100
commitebb5e78cc63417a35254a791de66e1cc84f963cc (patch)
tree49814946abe594cb8e7a11ce8d0a5fdaabb49d31
parent22773aa9b95657f0adc2b5342428d9da7a6d5d02 (diff)
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>
-rw-r--r--arch/mips/Kbuild1
-rw-r--r--arch/mips/include/asm/abi.h5
-rw-r--r--arch/mips/include/asm/elf.h7
-rw-r--r--arch/mips/include/asm/processor.h8
-rw-r--r--arch/mips/include/asm/vdso.h73
-rw-r--r--arch/mips/include/uapi/asm/Kbuild2
-rw-r--r--arch/mips/include/uapi/asm/auxvec.h17
-rw-r--r--arch/mips/kernel/signal.c12
-rw-r--r--arch/mips/kernel/signal32.c7
-rw-r--r--arch/mips/kernel/signal_n32.c5
-rw-r--r--arch/mips/kernel/vdso.c160
-rw-r--r--arch/mips/vdso/.gitignore4
-rw-r--r--arch/mips/vdso/Makefile160
-rw-r--r--arch/mips/vdso/elf.S68
-rw-r--r--arch/mips/vdso/genvdso.c293
-rw-r--r--arch/mips/vdso/genvdso.h187
-rw-r--r--arch/mips/vdso/sigreturn.S49
-rw-r--r--arch/mips/vdso/vdso.h80
-rw-r--r--arch/mips/vdso/vdso.lds.S100
19 files changed, 1114 insertions, 124 deletions
diff --git a/arch/mips/Kbuild b/arch/mips/Kbuild
index dd295335891a..5c3f688a5232 100644
--- a/arch/mips/Kbuild
+++ b/arch/mips/Kbuild
@@ -17,6 +17,7 @@ obj- := $(platform-)
obj-y += kernel/
obj-y += mm/
obj-y += net/
+obj-y += vdso/
ifdef CONFIG_KVM
obj-y += kvm/
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 <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 */
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 <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,
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 <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 */
diff --git a/arch/mips/include/uapi/asm/Kbuild b/arch/mips/include/uapi/asm/Kbuild
index 96fe7395ed8d..f2cf41461146 100644
--- a/arch/mips/include/uapi/asm/Kbuild
+++ b/arch/mips/include/uapi/asm/Kbuild
@@ -1,9 +1,9 @@
# UAPI Header export list
include include/uapi/asm-generic/Kbuild.asm
-generic-y += auxvec.h
generic-y += ipcbuf.h
+header-y += auxvec.h
header-y += bitfield.h
header-y += bitsperlong.h
header-y += break.h
diff --git a/arch/mips/include/uapi/asm/auxvec.h b/arch/mips/include/uapi/asm/auxvec.h
new file mode 100644
index 000000000000..c9c7195272c4
--- /dev/null
+++ b/arch/mips/include/uapi/asm/auxvec.h
@@ -0,0 +1,17 @@
+/*
+ * 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.
+ */
+
+#ifndef __ASM_AUXVEC_H
+#define __ASM_AUXVEC_H
+
+/* Location of VDSO image. */
+#define AT_SYSINFO_EHDR 33
+
+#endif /* __ASM_AUXVEC_H */
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 2fec67bfc457..bf792e2839a6 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -36,7 +36,6 @@
#include <asm/ucontext.h>
#include <asm/cpu-features.h>
#include <asm/war.h>
-#include <asm/vdso.h>
#include <asm/dsp.h>
#include <asm/inst.h>
#include <asm/msa.h>
@@ -752,16 +751,15 @@ static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
struct mips_abi mips_abi = {
#ifdef CONFIG_TRAD_SIGNALS
.setup_frame = setup_frame,
- .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
#endif
.setup_rt_frame = setup_rt_frame,
- .rt_signal_return_offset =
- offsetof(struct mips_vdso, rt_signal_trampoline),
.restart = __NR_restart_syscall,
.off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
.off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
.off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
+
+ .vdso = &vdso_image,
};
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
@@ -801,11 +799,11 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
}
if (sig_uses_siginfo(&ksig->ka))
- ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
+ ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
ksig, regs, oldset);
else
- ret = abi->setup_frame(vdso + abi->signal_return_offset, ksig,
- regs, oldset);
+ ret = abi->setup_frame(vdso + abi->vdso->off_sigreturn,
+ ksig, regs, oldset);
signal_setup_done(ret, ksig, 0);
}
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index f7e89524e316..4909639aa35b 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -31,7 +31,6 @@
#include <asm/ucontext.h>
#include <asm/fpu.h>
#include <asm/war.h>
-#include <asm/vdso.h>
#include <asm/dsp.h>
#include "signal-common.h"
@@ -406,14 +405,12 @@ static int setup_rt_frame_32(void *sig_return, struct ksignal *ksig,
*/
struct mips_abi mips_abi_32 = {
.setup_frame = setup_frame_32,
- .signal_return_offset =
- offsetof(struct mips_vdso, o32_signal_trampoline),
.setup_rt_frame = setup_rt_frame_32,
- .rt_signal_return_offset =
- offsetof(struct mips_vdso, o32_rt_signal_trampoline),
.restart = __NR_O32_restart_syscall,
.off_sc_fpregs = offsetof(struct sigcontext32, sc_fpregs),
.off_sc_fpc_csr = offsetof(struct sigcontext32, sc_fpc_csr),
.off_sc_used_math = offsetof(struct sigcontext32, sc_used_math),
+
+ .vdso = &vdso_image_o32,
};
diff --git a/arch/mips/kernel/signal_n32.c b/arch/mips/kernel/signal_n32.c
index 0d017fdcaf07..a7bc38430500 100644
--- a/arch/mips/kernel/signal_n32.c
+++ b/arch/mips/kernel/signal_n32.c
@@ -38,7 +38,6 @@
#include <asm/fpu.h>
#include <asm/cpu-features.h>
#include <asm/war.h>
-#include <asm/vdso.h>
#include "signal-common.h"
@@ -151,11 +150,11 @@ static int setup_rt_frame_n32(void *sig_return, struct ksignal *ksig,
struct mips_abi mips_abi_n32 = {
.setup_rt_frame = setup_rt_frame_n32,
- .rt_signal_return_offset =
- offsetof(struct mips_vdso, n32_rt_signal_trampoline),
.restart = __NR_N32_restart_syscall,
.off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
.off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
.off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
+
+ .vdso = &vdso_image_n32,
};
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index ed2a278722a9..56cc3c4377fb 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -1,122 +1,116 @@
/*
- * 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, 2010 Cavium Networks, Inc.
+ * 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 <linux/kernel.h>
-#include <linux/err.h>
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/init.h>
#include <linux/binfmts.h>
#include <linux/elf.h>
-#include <linux/vmalloc.h>
-#include <linux/unistd.h>
-#include <linux/random.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <asm/abi.h>
#include <asm/vdso.h>
-#include <asm/uasm.h>
-#include <asm/processor.h>
+
+/* Kernel-provided data used by the VDSO. */
+static union mips_vdso_data vdso_data __page_aligned_data;
/*
- * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
+ * Mapping for the VDSO data pages. The real pages are mapped manually, as
+ * what we map and where within the area they are mapped is determined at
+ * runtime.
*/
-#define __NR_O32_sigreturn 4119
-#define __NR_O32_rt_sigreturn 4193
-#define __NR_N32_rt_sigreturn 6211
+static struct page *no_pages[] = { NULL };
+static struct vm_special_mapping vdso_vvar_mapping = {
+ .name = "[vvar]",
+ .pages = no_pages,
+};
-static struct page *vdso_page;
-
-static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
+static void __init init_vdso_image(struct mips_vdso_image *image)
{
- uasm_i_addiu(&tramp, 2, 0, sigreturn); /* li v0, sigreturn */
- uasm_i_syscall(&tramp, 0);
+ unsigned long num_pages, i;
+
+ BUG_ON(!PAGE_ALIGNED(image->data));
+ BUG_ON(!PAGE_ALIGNED(image->size));
+
+ num_pages = image->size / PAGE_SIZE;
+
+ for (i = 0; i < num_pages; i++) {
+ image->mapping.pages[i] =
+ virt_to_page(image->data + (i * PAGE_SIZE));
+ }
}
static int __init init_vdso(void)
{
- struct mips_vdso *vdso;
-
- vdso_page = alloc_page(GFP_KERNEL);
- if (!vdso_page)
- panic("Cannot allocate vdso");
-
- vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
- if (!vdso)
- panic("Cannot map vdso");
- clear_page(vdso);
-
- install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
-#ifdef CONFIG_32BIT
- install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
-#else
- install_trampoline(vdso->n32_rt_signal_trampoline,
- __NR_N32_rt_sigreturn);
- install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
- install_trampoline(vdso->o32_rt_signal_trampoline,
- __NR_O32_rt_sigreturn);
+ init_vdso_image(&vdso_image);
+
+#ifdef CONFIG_MIPS32_O32
+ init_vdso_image(&vdso_image_o32);
#endif
- vunmap(vdso);
+#ifdef CONFIG_MIPS32_N32
+ init_vdso_image(&vdso_image_n32);
+#endif
return 0;
}
subsys_initcall(init_vdso);
-static unsigned long vdso_addr(unsigned long start)
-{
- unsigned long offset = 0UL;
-
- if (current->flags & PF_RANDOMIZE) {
- offset = get_random_int();
- offset <<= PAGE_SHIFT;
- if (TASK_IS_32BIT_ADDR)
- offset &= 0xfffffful;
- else
- offset &= 0xffffffful;
- }
-
- return STACK_TOP + offset;
-}
-
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
- int ret;
- unsigned long addr;
+ struct mips_vdso_image *image = current->thread.abi->vdso;
struct mm_struct *mm = current->mm;
+ unsigned long base, vdso_addr;
+ struct vm_area_struct *vma;
+ int ret;
down_write(&mm->mmap_sem);
- addr = vdso_addr(mm->start_stack);
-
- addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
- if (IS_ERR_VALUE(addr)) {
- ret = addr;
- goto up_fail;
+ base = get_unmapped_area(NULL, 0, PAGE_SIZE + image->size, 0, 0);
+ if (IS_ERR_VALUE(base)) {
+ ret = base;
+ goto out;
}
- ret = install_special_mapping(mm, addr, PAGE_SIZE,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &vdso_page);
+ vdso_addr = base + PAGE_SIZE;
+
+ vma = _install_special_mapping(mm, base, PAGE_SIZE,
+ VM_READ | VM_MAYREAD,
+ &vdso_vvar_mapping);
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ goto out;
+ }
+ /* Map data page. */
+ ret = remap_pfn_range(vma, base,
+ virt_to_phys(&vdso_data) >> PAGE_SHIFT,
+ PAGE_SIZE, PAGE_READONLY);
if (ret)
- goto up_fail;
+ goto out;
+
+ /* Map VDSO image. */
+ vma = _install_special_mapping(mm, vdso_addr, image->size,
+ VM_READ | VM_EXEC |
+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+ &image->mapping);
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ goto out;
+ }
- mm->context.vdso = (void *)addr;
+ mm->context.vdso = (void *)vdso_addr;
+ ret = 0;
-up_fail:
+out:
up_write(&mm->mmap_sem);
return ret;
}
-
-const char *arch_vma_name(struct vm_area_struct *vma)
-{
- if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
- return "[vdso]";
- return NULL;
-}
diff --git a/arch/mips/vdso/.gitignore b/arch/mips/vdso/.gitignore
new file mode 100644
index 000000000000..5286a7d73d79
--- /dev/null
+++ b/arch/mips/vdso/.gitignore
@@ -0,0 +1,4 @@
+*.so*
+vdso-*image.c
+genvdso
+vdso*.lds
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
new file mode 100644
index 000000000000..ef5f348f386a
--- /dev/null
+++ b/arch/mips/vdso/Makefile
@@ -0,0 +1,160 @@
+# Objects to go into the VDSO.
+obj-vdso-y := elf.o gettimeofday.o sigreturn.o
+
+# Common compiler flags between ABIs.
+ccflags-vdso := \
+ $(filter -I%,$(KBUILD_CFLAGS)) \
+ $(filter -E%,$(KBUILD_CFLAGS)) \
+ $(filter -march=%,$(KBUILD_CFLAGS))
+cflags-vdso := $(ccflags-vdso) \
+ $(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
+ -O2 -g -fPIC -fno-common -fno-builtin -G 0 -DDISABLE_BRANCH_PROFILING \
+ $(call cc-option, -fno-stack-protector)
+aflags-vdso := $(ccflags-vdso) \
+ $(filter -I%,$(KBUILD_CFLAGS)) \
+ $(filter -E%,$(KBUILD_CFLAGS)) \
+ -D__ASSEMBLY__ -Wa,-gdwarf-2
+
+#
+# For the pre-R6 code in arch/mips/vdso/vdso.h for locating
+# the base address of VDSO, the linker will emit a R_MIPS_PC32
+# relocation in binutils > 2.25 but it will fail with older versions
+# because that relocation is not supported for that symbol. As a result
+# of which we are forced to disable the VDSO symbols when building
+# with < 2.25 binutils on pre-R6 kernels. For more references on why we
+# can't use other methods to get the base address of VDSO please refer to
+# the comments on that file.
+#
+ifndef CONFIG_CPU_MIPSR6
+ ifeq ($(call ld-ifversion, -gt, 22400000, y),)
+ $(warning MIPS VDSO requires binutils > 2.24)
+ obj-vdso-y := $(filter-out gettimeofday.o, $(obj-vdso-y))
+ ccflags-vdso += -DDISABLE_MIPS_VDSO
+ endif
+endif
+
+# VDSO linker flags.
+VDSO_LDFLAGS := \
+ -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \
+ -nostdlib -shared \
+ $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \
+ $(call cc-ldoption, -Wl$(comma)--build-id)
+
+GCOV_PROFILE := n
+
+#
+# Shared build commands.
+#
+
+quiet_cmd_vdsold = VDSO $@
+ cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \
+ -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
+
+hostprogs-y := genvdso
+
+quiet_cmd_genvdso = GENVDSO $@
+define cmd_genvdso
+ cp $< $(<:%.dbg=%) && \
+ $(OBJCOPY) -S $< $(<:%.dbg=%) && \
+ $(obj)/genvdso $< $(<:%.dbg=%) $@ $(VDSO_NAME)
+endef
+
+#
+# Build native VDSO.
+#
+
+native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS))
+
+targets += $(obj-vdso-y)
+targets += vdso.lds vdso.so.dbg vdso.so vdso-image.c
+
+obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o)
+
+$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi)
+$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
+
+$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(native-abi)
+
+$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
+ $(call if_changed,vdsold)
+
+$(obj)/vdso-image.c: $(obj)/vdso.so.dbg $(obj)/genvdso FORCE
+ $(call if_changed,genvdso)
+
+obj-y += vdso-image.o
+
+#
+# Build O32 VDSO.
+#
+
+# Define these outside the ifdef to ensure they are picked up by clean.
+targets += $(obj-vdso-y:%.o=%-o32.o)
+targets += vdso-o32.lds vdso-o32.so.dbg vdso-o32.so vdso-o32-image.c
+
+ifdef CONFIG_MIPS32_O32
+
+obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o)
+
+$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32
+$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32
+
+$(obj)/%-o32.o: $(src)/%.S FORCE
+ $(call if_changed_dep,as_o_S)
+
+$(obj)/%-o32.o: $(src)/%.c FORCE
+ $(call cmd,force_checksrc)
+ $(call if_changed_rule,cc_o_c)
+
+$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := -mabi=32
+$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
+ $(call if_changed_dep,cpp_lds_S)
+
+$(obj)/vdso-o32.so.dbg: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
+ $(call if_changed,vdsold)
+
+$(obj)/vdso-o32-image.c: VDSO_NAME := o32
+$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg $(obj)/genvdso FORCE
+ $(call if_changed,genvdso)
+
+obj-y += vdso-o32-image.o
+
+endif
+
+#
+# Build N32 VDSO.
+#
+
+targets += $(obj-vdso-y:%.o=%-n32.o)
+targets += vdso-n32.lds vdso-n32.so.dbg vdso-n32.so vdso-n32-image.c
+
+ifdef CONFIG_MIPS32_N32
+
+obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o)
+
+$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32
+$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32
+
+$(obj)/%-n32.o: $(src)/%.S FORCE
+ $(call if_changed_dep,as_o_S)
+
+$(obj)/%-n32.o: $(src)/%.c FORCE
+ $(call cmd,force_checksrc)
+ $(call if_changed_rule,cc_o_c)
+
+$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := -mabi=n32
+$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
+ $(call if_changed_dep,cpp_lds_S)
+
+$(obj)/vdso-n32.so.dbg: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
+ $(call if_changed,vdsold)
+
+$(obj)/vdso-n32-image.c: VDSO_NAME := n32
+$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg $(obj)/genvdso FORCE
+ $(call if_changed,genvdso)
+
+obj-y += vdso-n32-image.o
+
+endif
+
+# FIXME: Need install rule for debug.
+# Needs to deal with dependency for generation of dbg by cmd_genvdso...
diff --git a/arch/mips/vdso/elf.S b/arch/mips/vdso/elf.S
new file mode 100644
index 000000000000..be37bbb1f061
--- /dev/null
+++ b/arch/mips/vdso/elf.S
@@ -0,0 +1,68 @@
+/*
+ * 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 <linux/elfnote.h>
+#include <linux/version.h>
+
+ELFNOTE_START(Linux, 0, "a")
+ .long LINUX_VERSION_CODE
+ELFNOTE_END
+
+/*
+ * The .MIPS.abiflags section must be defined with the FP ABI flags set
+ * to 'any' to be able to link with both old and new libraries.
+ * Newer toolchains are capable of automatically generating this, but we want
+ * to work with older toolchains as well. Therefore, we define the contents of
+ * this section here (under different names), and then genvdso will patch
+ * it to have the correct name and type.
+ *
+ * We base the .MIPS.abiflags section on preprocessor definitions rather than
+ * CONFIG_* because we need to match the particular ABI we are building the
+ * VDSO for.
+ *
+ * See https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
+ * for the .MIPS.abiflags section description.
+ */
+
+ .section .mips_abiflags, "a"
+ .align 3
+__mips_abiflags:
+ .hword 0 /* version */
+ .byte __mips /* isa_level */
+
+ /* isa_rev */
+#ifdef __mips_isa_rev
+ .byte __mips_isa_rev
+#else
+ .byte 0
+#endif
+
+ /* gpr_size */
+#ifdef __mips64
+ .byte 2 /* AFL_REG_64 */
+#else
+ .byte 1 /* AFL_REG_32 */
+#endif
+
+ /* cpr1_size */
+#if (defined(__mips_isa_rev) && __mips_isa_rev >= 6) || defined(__mips64)
+ .byte 2 /* AFL_REG_64 */
+#else
+ .byte 1 /* AFL_REG_32 */
+#endif
+
+ .byte 0 /* cpr2_size (AFL_REG_NONE) */
+ .byte 0 /* fp_abi (Val_GNU_MIPS_ABI_FP_ANY) */
+ .word 0 /* isa_ext */
+ .word 0 /* ases */
+ .word 0 /* flags1 */
+ .word 0 /* flags2 */
diff --git a/arch/mips/vdso/genvdso.c b/arch/mips/vdso/genvdso.c
new file mode 100644
index 000000000000..530a36f465ce
--- /dev/null
+++ b/arch/mips/vdso/genvdso.c
@@ -0,0 +1,293 @@
+/*
+ * 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.
+ */
+
+/*
+ * This tool is used to generate the real VDSO images from the raw image. It
+ * first patches up the MIPS ABI flags and GNU attributes sections defined in
+ * elf.S to have the correct name and type. It then generates a C source file
+ * to be compiled into the kernel containing the VDSO image data and a
+ * mips_vdso_image struct for it, including symbol offsets extracted from the
+ * image.
+ *
+ * We need to be passed both a stripped and unstripped VDSO image. The stripped
+ * image is compiled into the kernel, but we must also patch up the unstripped
+ * image's ABI flags sections so that it can be installed and used for
+ * debugging.
+ */
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <byteswap.h>
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Define these in case the system elf.h is not new enough to have them. */
+#ifndef SHT_GNU_ATTRIBUTES
+# define SHT_GNU_ATTRIBUTES 0x6ffffff5
+#endif
+#ifndef SHT_MIPS_ABIFLAGS
+# define SHT_MIPS_ABIFLAGS 0x7000002a
+#endif
+
+enum {
+ ABI_O32 = (1 << 0),
+ ABI_N32 = (1 << 1),
+ ABI_N64 = (1 << 2),
+
+ ABI_ALL = ABI_O32 | ABI_N32 | ABI_N64,
+};
+
+/* Symbols the kernel requires offsets for. */
+static struct {
+ const char *name;
+ const char *offset_name;
+ unsigned int abis;
+} vdso_symbols[] = {
+ { "__vdso_sigreturn", "off_sigreturn", ABI_O32 },
+ { "__vdso_rt_sigreturn", "off_rt_sigreturn", ABI_ALL },
+ {}
+};
+
+static const char *program_name;
+static const char *vdso_name;
+static unsigned char elf_class;
+static unsigned int elf_abi;
+static bool need_swap;
+static FILE *out_file;
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+# define HOST_ORDER ELFDATA2LSB
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+# define HOST_ORDER ELFDATA2MSB
+#endif
+
+#define BUILD_SWAP(bits) \
+ static uint##bits##_t swap_uint##bits(uint##bits##_t val) \
+ { \
+ return need_swap ? bswap_##bits(val) : val; \
+ }
+
+BUILD_SWAP(16)
+BUILD_SWAP(32)
+BUILD_SWAP(64)
+
+#define __FUNC(name, bits) name##bits
+#define _FUNC(name, bits) __FUNC(name, bits)
+#define FUNC(name) _FUNC(name, ELF_BITS)
+
+#define __ELF(x, bits) Elf##bits##_##x
+#define _ELF(x, bits) __ELF(x, bits)
+#define ELF(x) _ELF(x, ELF_BITS)
+
+/*
+ * Include genvdso.h twice with ELF_BITS defined differently to get functions
+ * for both ELF32 and ELF64.
+ */
+
+#define ELF_BITS 64
+#include "genvdso.h"
+#undef ELF_BITS
+
+#define ELF_BITS 32
+#include "genvdso.h"
+#undef ELF_BITS
+
+static void *map_vdso(const char *path, size_t *_size)
+{
+ int fd;
+ struct stat stat;
+ void *addr;
+ const Elf32_Ehdr *ehdr;
+
+ fd = open(path, O_RDWR);
+ if (fd < 0) {
+ fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
+ path, strerror(errno));
+ return NULL;
+ }
+
+ if (fstat(fd, &stat) != 0) {
+ fprintf(stderr, "%s: Failed to stat '%s': %s\n", program_name,
+ path, strerror(errno));
+ return NULL;
+ }
+
+ addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+ 0);
+ if (addr == MAP_FAILED) {
+ fprintf(stderr, "%s: Failed to map '%s': %s\n", program_name,
+ path, strerror(errno));
+ return NULL;
+ }
+
+ /* ELF32/64 header formats are the same for the bits we're checking. */
+ ehdr = addr;
+
+ if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
+ fprintf(stderr, "%s: '%s' is not an ELF file\n", program_name,
+ path);
+ return NULL;
+ }
+
+ elf_class = ehdr->e_ident[EI_CLASS];
+ switch (elf_class) {
+ case ELFCLASS32:
+ case ELFCLASS64:
+ break;
+ default:
+ fprintf(stderr, "%s: '%s' has invalid ELF class\n",
+ program_name, path);
+ return NULL;
+ }
+
+ switch (ehdr->e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ case ELFDATA2MSB:
+ need_swap = ehdr->e_ident[EI_DATA] != HOST_ORDER;
+ break;
+ default:
+ fprintf(stderr, "%s: '%s' has invalid ELF data order\n",
+ program_name, path);
+ return NULL;
+ }
+
+ if (swap_uint16(ehdr->e_machine) != EM_MIPS) {
+ fprintf(stderr,
+ "%s: '%s' has invalid ELF machine (expected EM_MIPS)\n",
+ program_name, path);
+ return NULL;
+ } else if (swap_uint16(ehdr->e_type) != ET_DYN) {
+ fprintf(stderr,
+ "%s: '%s' has invalid ELF type (expected ET_DYN)\n",
+ program_name, path);
+ return NULL;
+ }
+
+ *_size = stat.st_size;
+ return addr;
+}
+
+static bool patch_vdso(const char *path, void *vdso)
+{
+ if (elf_class == ELFCLASS64)
+ return patch_vdso64(path, vdso);
+ else
+ return patch_vdso32(path, vdso);
+}
+
+static bool get_symbols(const char *path, void *vdso)
+{
+ if (elf_class == ELFCLASS64)
+ return get_symbols64(path, vdso);
+ else
+ return get_symbols32(path, vdso);
+}
+
+int main(int argc, char **argv)
+{
+ const char *dbg_vdso_path, *vdso_path, *out_path;
+ void *dbg_vdso, *vdso;
+ size_t dbg_vdso_size, vdso_size, i;
+
+ program_name = argv[0];
+
+ if (argc < 4 || argc > 5) {
+ fprintf(stderr,
+ "Usage: %s <debug VDSO> <stripped VDSO> <output file> [<name>]\n",
+ program_name);
+ return EXIT_FAILURE;
+ }
+
+ dbg_vdso_path = argv[1];
+ vdso_path = argv[2];
+ out_path = argv[3];
+ vdso_name = (argc > 4) ? argv[4] : "";
+
+ dbg_vdso = map_vdso(dbg_vdso_path, &dbg_vdso_size);
+ if (!dbg_vdso)
+ return EXIT_FAILURE;
+
+ vdso = map_vdso(vdso_path, &vdso_size);
+ if (!vdso)
+ return EXIT_FAILURE;
+
+ /* Patch both the VDSOs' ABI flags sections. */
+ if (!patch_vdso(dbg_vdso_path, dbg_vdso))
+ return EXIT_FAILURE;
+ if (!patch_vdso(vdso_path, vdso))
+ return EXIT_FAILURE;
+
+ if (msync(dbg_vdso, dbg_vdso_size, MS_SYNC) != 0) {
+ fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
+ dbg_vdso_path, strerror(errno));
+ return EXIT_FAILURE;
+ } else if (msync(vdso, vdso_size, MS_SYNC) != 0) {
+ fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
+ vdso_path, strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ out_file = fopen(out_path, "w");
+ if (!out_file) {
+ fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
+ out_path, strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ fprintf(out_file, "/* Automatically generated - do not edit */\n");
+ fprintf(out_file, "#include <linux/linkage.h>\n");
+ fprintf(out_file, "#include <linux/mm.h>\n");
+ fprintf(out_file, "#include <asm/vdso.h>\n");
+
+ /* Write out the stripped VDSO data. */
+ fprintf(out_file,
+ "static unsigned char vdso_data[PAGE_ALIGN(%zu)] __page_aligned_data = {\n\t",
+ vdso_size);
+ for (i = 0; i < vdso_size; i++) {
+ if (!(i % 10))
+ fprintf(out_file, "\n\t");
+ fprintf(out_file, "0x%02x, ", ((unsigned char *)vdso)[i]);
+ }
+ fprintf(out_file, "\n};\n");
+
+ /* Preallocate a page array. */
+ fprintf(out_file,
+ "static struct page *vdso_pages[PAGE_ALIGN(%zu) / PAGE_SIZE];\n",
+ vdso_size);
+
+ fprintf(out_file, "struct mips_vdso_image vdso_image%s%s = {\n",
+ (vdso_name[0]) ? "_" : "", vdso_name);
+ fprintf(out_file, "\t.data = vdso_data,\n");
+ fprintf(out_file, "\t.size = PAGE_ALIGN(%zu),\n", vdso_size);
+ fprintf(out_file, "\t.mapping = {\n");
+ fprintf(out_file, "\t\t.name = \"[vdso]\",\n");
+ fprintf(out_file, "\t\t.pages = vdso_pages,\n");
+ fprintf(out_file, "\t},\n");
+
+ /* Calculate and write symbol offsets to <output file> */
+ if (!get_symbols(dbg_vdso_path, dbg_vdso)) {
+ unlink(out_path);
+ return EXIT_FAILURE;
+ }
+
+ fprintf(out_file, "};\n");
+
+ return EXIT_SUCCESS;
+}
diff --git a/arch/mips/vdso/genvdso.h b/arch/mips/vdso/genvdso.h
new file mode 100644
index 000000000000..94334727059a
--- /dev/null
+++ b/arch/mips/vdso/genvdso.h
@@ -0,0 +1,187 @@
+/*
+ * 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.
+ */
+
+static inline bool FUNC(patch_vdso)(const char *path, void *vdso)
+{
+ const ELF(Ehdr) *ehdr = vdso;
+ void *shdrs;
+ ELF(Shdr) *shdr;
+ char *shstrtab, *name;
+ uint16_t sh_count, sh_entsize, i;
+ unsigned int local_gotno, symtabno, gotsym;
+ ELF(Dyn) *dyn = NULL;
+
+ shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
+ sh_count = swap_uint16(ehdr->e_shnum);
+ sh_entsize = swap_uint16(ehdr->e_shentsize);
+
+ shdr = shdrs + (sh_entsize * swap_uint16(ehdr->e_shstrndx));
+ shstrtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
+
+ for (i = 0; i < sh_count; i++) {
+ shdr = shdrs + (i * sh_entsize);
+ name = shstrtab + swap_uint32(shdr->sh_name);
+
+ /*
+ * Ensure there are no relocation sections - ld.so does not
+ * relocate the VDSO so if there are relocations things will
+ * break.
+ */
+ switch (swap_uint32(shdr->sh_type)) {
+ case SHT_REL:
+ case SHT_RELA:
+ fprintf(stderr,
+ "%s: '%s' contains relocation sections\n",
+ program_name, path);
+ return false;
+ case SHT_DYNAMIC:
+ dyn = vdso + FUNC(swap_uint)(shdr->sh_offset);
+ break;
+ }
+
+ /* Check for existing sections. */
+ if (strcmp(name, ".MIPS.abiflags") == 0) {
+ fprintf(stderr,
+ "%s: '%s' already contains a '.MIPS.abiflags' section\n",
+ program_name, path);
+ return false;
+ }
+
+ if (strcmp(name, ".mips_abiflags") == 0) {
+ strcpy(name, ".MIPS.abiflags");
+ shdr->sh_type = swap_uint32(SHT_MIPS_ABIFLAGS);
+ shdr->sh_entsize = shdr->sh_size;
+ }
+ }
+
+ /*
+ * Ensure the GOT has no entries other than the standard 2, for the same
+ * reason we check that there's no relocation sections above.
+ * The standard two entries are:
+ * - Lazy resolver
+ * - Module pointer
+ */
+ if (dyn) {
+ local_gotno = symtabno = gotsym = 0;
+
+ while (FUNC(swap_uint)(dyn->d_tag) != DT_NULL) {
+ switch (FUNC(swap_uint)(dyn->d_tag)) {
+ /*
+ * This member holds the number of local GOT entries.
+ */
+ case DT_MIPS_LOCAL_GOTNO:
+ local_gotno = FUNC(swap_uint)(dyn->d_un.d_val);
+ break;
+ /*
+ * This member holds the number of entries in the
+ * .dynsym section.
+ */
+ case DT_MIPS_SYMTABNO:
+ symtabno = FUNC(swap_uint)(dyn->d_un.d_val);
+ break;
+ /*
+ * This member holds the index of the first dynamic
+ * symbol table entry that corresponds to an entry in
+ * the GOT.
+ */
+ case DT_MIPS_GOTSYM:
+ gotsym = FUNC(swap_uint)(dyn->d_un.d_val);
+ break;
+ }
+
+ dyn++;
+ }
+
+ if (local_gotno > 2 || symtabno - gotsym) {
+ fprintf(stderr,
+ "%s: '%s' contains unexpected GOT entries\n",
+ program_name, path);
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static inline bool FUNC(get_symbols)(const char *path, void *vdso)
+{
+ const ELF(Ehdr) *ehdr = vdso;
+ void *shdrs, *symtab;
+ ELF(Shdr) *shdr;
+ const ELF(Sym) *sym;
+ char *strtab, *name;
+ uint16_t sh_count, sh_entsize, st_count, st_entsize, i, j;
+ uint64_t offset;
+ uint32_t flags;
+
+ shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
+ sh_count = swap_uint16(ehdr->e_shnum);
+ sh_entsize = swap_uint16(ehdr->e_shentsize);
+
+ for (i = 0; i < sh_count; i++) {
+ shdr = shdrs + (i * sh_entsize);
+
+ if (swap_uint32(shdr->sh_type) == SHT_SYMTAB)
+ break;
+ }
+
+ if (i == sh_count) {
+ fprintf(stderr, "%s: '%s' has no symbol table\n", program_name,
+ path);
+ return false;
+ }
+
+ /* Get flags */
+ flags = swap_uint32(ehdr->e_flags);
+ if (elf_class == ELFCLASS64)
+ elf_abi = ABI_N64;
+ else if (flags & EF_MIPS_ABI2)
+ elf_abi = ABI_N32;
+ else
+ elf_abi = ABI_O32;
+
+ /* Get symbol table. */
+ symtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
+ st_entsize = FUNC(swap_uint)(shdr->sh_entsize);
+ st_count = FUNC(swap_uint)(shdr->sh_size) / st_entsize;
+
+ /* Get string table. */
+ shdr = shdrs + (swap_uint32(shdr->sh_link) * sh_entsize);
+ strtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
+
+ /* Write offsets for symbols needed by the kernel. */
+ for (i = 0; vdso_symbols[i].name; i++) {
+ if (!(vdso_symbols[i].abis & elf_abi))
+ continue;
+
+ for (j = 0; j < st_count; j++) {
+ sym = symtab + (j * st_entsize);
+ name = strtab + swap_uint32(sym->st_name);
+
+ if (!strcmp(name, vdso_symbols[i].name)) {
+ offset = FUNC(swap_uint)(sym->st_value);
+
+ fprintf(out_file,
+ "\t.%s = 0x%" PRIx64 ",\n",
+ vdso_symbols[i].offset_name, offset);
+ break;
+ }
+ }
+
+ if (j == st_count) {
+ fprintf(stderr,
+ "%s: '%s' is missing required symbol '%s'\n",
+ program_name, path, vdso_symbols[i].name);
+ return false;
+ }
+ }
+
+ return true;
+}
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 <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
diff --git a/arch/mips/vdso/vdso.h b/arch/mips/vdso/vdso.h
new file mode 100644
index 000000000000..0bb6b1adc385
--- /dev/null
+++ b/arch/mips/vdso/vdso.h
@@ -0,0 +1,80 @@
+/*
+ * 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 <asm/sgidefs.h>
+
+#if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
+
+/* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
+#undef CONFIG_64BIT
+#define CONFIG_32BIT 1
+#ifndef __ASSEMBLY__
+#include <asm-generic/atomic64.h>
+#endif
+#endif
+
+#ifndef __ASSEMBLY__
+
+#include <asm/asm.h>
+#include <asm/page.h>
+#include <asm/vdso.h>
+
+static inline unsigned long get_vdso_base(void)
+{
+ unsigned long addr;
+
+ /*
+ * We can't use cpu_has_mips_r6 since it needs the cpu_data[]
+ * kernel symbol.
+ */
+#ifdef CONFIG_CPU_MIPSR6
+ /*
+ * lapc <symbol> is an alias to addiupc reg, <symbol> - .
+ *
+ * We can't use addiupc because there is no label-label
+ * support for the addiupc reloc
+ */
+ __asm__("lapc %0, _start \n"
+ : "=r" (addr) : :);
+#else
+ /*
+ * Get the base load address of the VDSO. We have to avoid generating
+ * relocations and references to the GOT because ld.so does not peform
+ * relocations on the VDSO. We use the current offset from the VDSO base
+ * and perform a PC-relative branch which gives the absolute address in
+ * ra, and take the difference. The assembler chokes on
+ * "li %0, _start - .", so embed the offset as a word and branch over
+ * it.
+ *
+ */
+
+ __asm__(
+ " .set push \n"
+ " .set noreorder \n"
+ " bal 1f \n"
+ " nop \n"
+ " .word _start - . \n"
+ "1: lw %0, 0($31) \n"
+ " " STR(PTR_ADDU) " %0, $31, %0 \n"
+ " .set pop \n"
+ : "=r" (addr)
+ :
+ : "$31");
+#endif /* CONFIG_CPU_MIPSR6 */
+
+ return addr;
+}
+
+static inline const union mips_vdso_data *get_vdso_data(void)
+{
+ return (const union mips_vdso_data *)(get_vdso_base() - PAGE_SIZE);
+}
+
+#endif /* __ASSEMBLY__ */
diff --git a/arch/mips/vdso/vdso.lds.S b/arch/mips/vdso/vdso.lds.S
new file mode 100644
index 000000000000..21655b6fefc5
--- /dev/null
+++ b/arch/mips/vdso/vdso.lds.S
@@ -0,0 +1,100 @@
+/*
+ * 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 <asm/sgidefs.h>
+
+#if _MIPS_SIM == _MIPS_SIM_ABI64
+OUTPUT_FORMAT("elf64-tradlittlemips", "elf64-tradbigmips", "elf64-tradlittlemips")
+#elif _MIPS_SIM == _MIPS_SIM_NABI32
+OUTPUT_FORMAT("elf32-ntradlittlemips", "elf32-ntradbigmips", "elf32-ntradlittlemips")
+#else
+OUTPUT_FORMAT("elf32-tradlittlemips", "elf32-tradbigmips", "elf32-tradlittlemips")
+#endif
+
+OUTPUT_ARCH(mips)
+
+SECTIONS
+{
+ PROVIDE(_start = .);
+ . = SIZEOF_HEADERS;
+
+ /*
+ * In order to retain compatibility with older toolchains we provide the
+ * ABI flags section ourself. Newer assemblers will automatically
+ * generate .MIPS.abiflags sections so we discard such input sections,
+ * and then manually define our own section here. genvdso will patch
+ * this section to have the correct name/type.
+ */
+ .mips_abiflags : { *(.mips_abiflags) } :text :abiflags
+
+ .reginfo : { *(.reginfo) } :text :reginfo
+
+ .hash : { *(.hash) } :text
+ .gnu.hash : { *(.gnu.hash) }
+ .dynsym : { *(.dynsym) }
+ .dynstr : { *(.dynstr) }
+ .gnu.version : { *(.gnu.version) }
+ .gnu.version_d : { *(.gnu.version_d) }
+ .gnu.version_r : { *(.gnu.version_r) }
+
+ .note : { *(.note.*) } :text :note
+
+ .text : { *(.text*) } :text
+ PROVIDE (__etext = .);
+ PROVIDE (_etext = .);
+ PROVIDE (etext = .);
+
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : { KEEP (*(.eh_frame)) } :text
+
+ .dynamic : { *(.dynamic) } :text :dynamic
+
+ .rodata : { *(.rodata*) } :text
+
+ _end = .;
+ PROVIDE(end = .);
+
+ /DISCARD/ : {
+ *(.MIPS.abiflags)
+ *(.gnu.attributes)
+ *(.note.GNU-stack)
+ *(.data .data.* .gnu.linkonce.d.* .sdata*)
+ *(.bss .sbss .dynbss .dynsbss)
+ }
+}
+
+PHDRS
+{
+ /*
+ * Provide a PT_MIPS_ABIFLAGS header to assign the ABI flags section
+ * to. We can specify the header type directly here so no modification
+ * is needed later on.
+ */
+ abiflags 0x70000003;
+
+ /*
+ * The ABI flags header must exist directly after the PT_INTERP header,
+ * so we must explicitly place the PT_MIPS_REGINFO header after it to
+ * stop the linker putting one in at the start.
+ */
+ reginfo 0x70000000;
+
+ text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+ dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
+ note PT_NOTE FLAGS(4); /* PF_R */
+ eh_frame_hdr PT_GNU_EH_FRAME;
+}
+
+VERSION
+{
+ LINUX_2.6 {
+ local: *;
+ };
+}