From 9031fefde6f2ac1d1e5e0f8f4b22db4a091229bb Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 5 Mar 2012 11:49:31 +0000 Subject: 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 Signed-off-by: Catalin Marinas Acked-by: Tony Lindgren Acked-by: Nicolas Pitre Acked-by: Olof Johansson Acked-by: Santosh Shilimkar Acked-by: Arnd Bergmann --- arch/arm64/kernel/vdso.c | 261 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 261 insertions(+) create mode 100644 arch/arm64/kernel/vdso.c (limited to 'arch/arm64/kernel/vdso.c') diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c new file mode 100644 index 000000000000..17948fc7d663 --- /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 . + * + * Author: Will Deacon + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +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; +} -- cgit v1.2.3