arm64: VDSO support

/*

 * Copyright (C) 2012 ARM Limited

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef __ASM_VDSO_H

#define __ASM_VDSO_H

#ifdef __KERNEL__

/*

 * Default link address for the vDSO.

 * Since we randomise the VDSO mapping, there's little point in trying

 * to prelink this.

 */

#define VDSO_LBASE	0x0

#ifndef __ASSEMBLY__

#include <generated/vdso-offsets.h>

#define VDSO_SYMBOL(base, name)						   \

({									   \

	(void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \

})

#endif /* !__ASSEMBLY__ */

#endif /* __KERNEL__ */

#endif /* __ASM_VDSO_H */

/*

 * Copyright (C) 2012 ARM Limited

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef __ASM_VDSO_DATAPAGE_H

#define __ASM_VDSO_DATAPAGE_H

#ifdef __KERNEL__

#ifndef __ASSEMBLY__

struct vdso_data {

	__u64 cs_cycle_last;	/* Timebase at clocksource init */

	__u64 xtime_clock_sec;	/* Kernel time */

	__u64 xtime_clock_nsec;

	__u64 xtime_coarse_sec;	/* Coarse time */

	__u64 xtime_coarse_nsec;

	__u64 wtm_clock_sec;	/* Wall to monotonic time */

	__u64 wtm_clock_nsec;

	__u32 tb_seq_count;	/* Timebase sequence counter */

	__u32 cs_mult;		/* Clocksource multiplier */

	__u32 cs_shift;		/* Clocksource shift */

	__u32 tz_minuteswest;	/* Whacky timezone stuff */

	__u32 tz_dsttime;

	__u32 use_syscall;

};

#endif /* !__ASSEMBLY__ */

#endif /* __KERNEL__ */

#endif /* __ASM_VDSO_DATAPAGE_H */

/*

 * VDSO implementation for AArch64 and vector page setup for AArch32.

 *

 * Copyright (C) 2012 ARM Limited

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 *

 * Author: Will Deacon <will.deacon@arm.com>

 */

#include <linux/kernel.h>

#include <linux/clocksource.h>

#include <linux/elf.h>

#include <linux/err.h>

#include <linux/errno.h>

#include <linux/gfp.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/signal.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <asm/cacheflush.h>

#include <asm/signal32.h>

#include <asm/vdso.h>

#include <asm/vdso_datapage.h>

extern char vdso_start, vdso_end;

static unsigned long vdso_pages;

static struct page **vdso_pagelist;

/*

 * The vDSO data page.

 */

static union {

	struct vdso_data	data;

	u8			page[PAGE_SIZE];

} vdso_data_store __page_aligned_data;

struct vdso_data *vdso_data = &vdso_data_store.data;

#ifdef CONFIG_COMPAT

/*

 * Create and map the vectors page for AArch32 tasks.

 */

static struct page *vectors_page[1];

static int alloc_vectors_page(void)

{

	extern char __kuser_helper_start[], __kuser_helper_end[];

	int kuser_sz = __kuser_helper_end - __kuser_helper_start;

	unsigned long vpage;

	vpage = get_zeroed_page(GFP_ATOMIC);

	if (!vpage)

		return -ENOMEM;

	/* kuser helpers */

	memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,

		kuser_sz);

	/* sigreturn code */

	memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,

		aarch32_sigret_code, sizeof(aarch32_sigret_code));

	flush_icache_range(vpage, vpage + PAGE_SIZE);

	vectors_page[0] = virt_to_page(vpage);

	return 0;

}

arch_initcall(alloc_vectors_page);

int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)

{

	struct mm_struct *mm = current->mm;

	unsigned long addr = AARCH32_VECTORS_BASE;

	int ret;

	down_write(&mm->mmap_sem);

	current->mm->context.vdso = (void *)addr;

	/* Map vectors page at the high address. */

	ret = install_special_mapping(mm, addr, PAGE_SIZE,

				      VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,

				      vectors_page);

	up_write(&mm->mmap_sem);

	return ret;

}

#endif /* CONFIG_COMPAT */

static int __init vdso_init(void)

{

	struct page *pg;

	char *vbase;

	int i, ret = 0;

	vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;

	pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n",

		vdso_pages + 1, vdso_pages, 1L, &vdso_start);

	/* Allocate the vDSO pagelist, plus a page for the data. */

	vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1),

				GFP_KERNEL);

	if (vdso_pagelist == NULL) {

		pr_err("Failed to allocate vDSO pagelist!\n");

		return -ENOMEM;

	}

	/* Grab the vDSO code pages. */

	for (i = 0; i < vdso_pages; i++) {

		pg = virt_to_page(&vdso_start + i*PAGE_SIZE);

		ClearPageReserved(pg);

		get_page(pg);

		vdso_pagelist[i] = pg;

	}

	/* Sanity check the shared object header. */

	vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL);

	if (vbase == NULL) {

		pr_err("Failed to map vDSO pagelist!\n");

		return -ENOMEM;

	} else if (memcmp(vbase, "\177ELF", 4)) {

		pr_err("vDSO is not a valid ELF object!\n");

		ret = -EINVAL;

		goto unmap;

	}

	/* Grab the vDSO data page. */

	pg = virt_to_page(vdso_data);

	get_page(pg);

	vdso_pagelist[i] = pg;

unmap:

	vunmap(vbase);

	return ret;

}

arch_initcall(vdso_init);

int arch_setup_additional_pages(struct linux_binprm *bprm,

				int uses_interp)

{

	struct mm_struct *mm = current->mm;

	unsigned long vdso_base, vdso_mapping_len;

	int ret;

	/* Be sure to map the data page */

	vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;

	down_write(&mm->mmap_sem);

	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);

	if (IS_ERR_VALUE(vdso_base)) {

		ret = vdso_base;

		goto up_fail;

	}

	mm->context.vdso = (void *)vdso_base;

	ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,

				      VM_READ|VM_EXEC|

				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,

				      vdso_pagelist);

	if (ret) {

		mm->context.vdso = NULL;

		goto up_fail;

	}

up_fail:

	up_write(&mm->mmap_sem);

	return ret;

}

const char *arch_vma_name(struct vm_area_struct *vma)

{

	/*

	 * We can re-use the vdso pointer in mm_context_t for identifying

	 * the vectors page for compat applications. The vDSO will always

	 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about

	 * it conflicting with the vectors base.

	 */

	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) {

#ifdef CONFIG_COMPAT

		if (vma->vm_start == AARCH32_VECTORS_BASE)

			return "[vectors]";

#endif

		return "[vdso]";

	}

	return NULL;

}

/*

 * We define AT_SYSINFO_EHDR, so we need these function stubs to keep

 * Linux happy.

 */

int in_gate_area_no_mm(unsigned long addr)

{

	return 0;

}

int in_gate_area(struct mm_struct *mm, unsigned long addr)

{

	return 0;

}

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)

{

	return NULL;

}

/*

 * Update the vDSO data page to keep in sync with kernel timekeeping.

 */

void update_vsyscall(struct timespec *ts, struct timespec *wtm,

		     struct clocksource *clock, u32 mult)

{

	struct timespec xtime_coarse;

	u32 use_syscall = strcmp(clock->name, "arch_sys_counter");

	++vdso_data->tb_seq_count;

	smp_wmb();

	xtime_coarse = __current_kernel_time();

	vdso_data->use_syscall			= use_syscall;

	vdso_data->xtime_coarse_sec		= xtime_coarse.tv_sec;

	vdso_data->xtime_coarse_nsec		= xtime_coarse.tv_nsec;

	if (!use_syscall) {

		vdso_data->cs_cycle_last	= clock->cycle_last;

		vdso_data->xtime_clock_sec	= ts->tv_sec;

		vdso_data->xtime_clock_nsec	= ts->tv_nsec;

		vdso_data->cs_mult		= mult;

		vdso_data->cs_shift		= clock->shift;

		vdso_data->wtm_clock_sec	= wtm->tv_sec;

		vdso_data->wtm_clock_nsec	= wtm->tv_nsec;

	}

	smp_wmb();

	++vdso_data->tb_seq_count;

}

void update_vsyscall_tz(void)

{

	++vdso_data->tb_seq_count;

	smp_wmb();

	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;

	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;

	smp_wmb();

	++vdso_data->tb_seq_count;

}

vdso.lds

vdso-offsets.h

#

# Building a vDSO image for AArch64.

#

# Author: Will Deacon <will.deacon@arm.com>

# Heavily based on the vDSO Makefiles for other archs.

#

obj-vdso := gettimeofday.o note.o sigreturn.o

# Build rules

targets := $(obj-vdso) vdso.so vdso.so.dbg

obj-vdso := $(addprefix $(obj)/, $(obj-vdso))

ccflags-y := -shared -fno-common -fno-builtin

ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \

		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)

obj-y += vdso.o

extra-y += vdso.lds vdso-offsets.h

CPPFLAGS_vdso.lds += -P -C -U$(ARCH)

# Force dependency (incbin is bad)

$(obj)/vdso.o : $(obj)/vdso.so

# Link rule for the .so file, .lds has to be first

$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso)

	$(call if_changed,vdsold)

# Strip rule for the .so file

$(obj)/%.so: OBJCOPYFLAGS := -S

$(obj)/%.so: $(obj)/%.so.dbg FORCE

	$(call if_changed,objcopy)

# Generate VDSO offsets using helper script

gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh

quiet_cmd_vdsosym = VDSOSYM $@

define cmd_vdsosym

	$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ && \

	cp $@ include/generated/

endef

$(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE

	$(call if_changed,vdsosym)

# Assembly rules for the .S files

$(obj-vdso): %.o: %.S

	$(call if_changed_dep,vdsoas)

# Actual build commands

quiet_cmd_vdsold = VDSOL $@

      cmd_vdsold = $(CC) $(c_flags) -Wl,-T $^ -o $@

quiet_cmd_vdsoas = VDSOA $@

      cmd_vdsoas = $(CC) $(a_flags) -c -o $@ $<

# Install commands for the unstripped file

quiet_cmd_vdso_install = INSTALL $@

      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@

vdso.so: $(obj)/vdso.so.dbg

	@mkdir -p $(MODLIB)/vdso

	$(call cmd,vdso_install)

vdso_install: vdso.so