arm64: VDSO support
This patch adds VDSO support for 64-bit applications. The VDSO code is
currently used for sys_rt_sigreturn() and optimised gettimeofday()
(using the user-accessible generic counter).
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
new file mode 100644
index 0000000..17948fc
--- /dev/null
+++ b/arch/arm64/kernel/vdso.c
@@ -0,0 +1,261 @@
+/*
+ * 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;
+}