From 6582b7f7743da6ce3e3714e9e8b18e0e073d4acd Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 18 Aug 2011 20:03:19 +0100 Subject: um: merge arch/um/sys-{i386,x86_64} Signed-off-by: Al Viro Signed-off-by: Richard Weinberger --- arch/um/sys-i386/tls.c | 396 ------------------------------------------------- 1 file changed, 396 deletions(-) delete mode 100644 arch/um/sys-i386/tls.c (limited to 'arch/um/sys-i386/tls.c') diff --git a/arch/um/sys-i386/tls.c b/arch/um/sys-i386/tls.c deleted file mode 100644 index c6c7131..0000000 --- a/arch/um/sys-i386/tls.c +++ /dev/null @@ -1,396 +0,0 @@ -/* - * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso - * Licensed under the GPL - */ - -#include "linux/percpu.h" -#include "linux/sched.h" -#include "asm/uaccess.h" -#include "os.h" -#include "skas.h" -#include "sysdep/tls.h" - -/* - * If needed we can detect when it's uninitialized. - * - * These are initialized in an initcall and unchanged thereafter. - */ -static int host_supports_tls = -1; -int host_gdt_entry_tls_min; - -int do_set_thread_area(struct user_desc *info) -{ - int ret; - u32 cpu; - - cpu = get_cpu(); - ret = os_set_thread_area(info, userspace_pid[cpu]); - put_cpu(); - - if (ret) - printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, " - "index = %d\n", ret, info->entry_number); - - return ret; -} - -int do_get_thread_area(struct user_desc *info) -{ - int ret; - u32 cpu; - - cpu = get_cpu(); - ret = os_get_thread_area(info, userspace_pid[cpu]); - put_cpu(); - - if (ret) - printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, " - "index = %d\n", ret, info->entry_number); - - return ret; -} - -/* - * sys_get_thread_area: get a yet unused TLS descriptor index. - * XXX: Consider leaving one free slot for glibc usage at first place. This must - * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else. - * - * Also, this must be tested when compiling in SKAS mode with dynamic linking - * and running against NPTL. - */ -static int get_free_idx(struct task_struct* task) -{ - struct thread_struct *t = &task->thread; - int idx; - - if (!t->arch.tls_array) - return GDT_ENTRY_TLS_MIN; - - for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) - if (!t->arch.tls_array[idx].present) - return idx + GDT_ENTRY_TLS_MIN; - return -ESRCH; -} - -static inline void clear_user_desc(struct user_desc* info) -{ - /* Postcondition: LDT_empty(info) returns true. */ - memset(info, 0, sizeof(*info)); - - /* - * Check the LDT_empty or the i386 sys_get_thread_area code - we obtain - * indeed an empty user_desc. - */ - info->read_exec_only = 1; - info->seg_not_present = 1; -} - -#define O_FORCE 1 - -static int load_TLS(int flags, struct task_struct *to) -{ - int ret = 0; - int idx; - - for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) { - struct uml_tls_struct* curr = - &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN]; - - /* - * Actually, now if it wasn't flushed it gets cleared and - * flushed to the host, which will clear it. - */ - if (!curr->present) { - if (!curr->flushed) { - clear_user_desc(&curr->tls); - curr->tls.entry_number = idx; - } else { - WARN_ON(!LDT_empty(&curr->tls)); - continue; - } - } - - if (!(flags & O_FORCE) && curr->flushed) - continue; - - ret = do_set_thread_area(&curr->tls); - if (ret) - goto out; - - curr->flushed = 1; - } -out: - return ret; -} - -/* - * Verify if we need to do a flush for the new process, i.e. if there are any - * present desc's, only if they haven't been flushed. - */ -static inline int needs_TLS_update(struct task_struct *task) -{ - int i; - int ret = 0; - - for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { - struct uml_tls_struct* curr = - &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; - - /* - * Can't test curr->present, we may need to clear a descriptor - * which had a value. - */ - if (curr->flushed) - continue; - ret = 1; - break; - } - return ret; -} - -/* - * On a newly forked process, the TLS descriptors haven't yet been flushed. So - * we mark them as such and the first switch_to will do the job. - */ -void clear_flushed_tls(struct task_struct *task) -{ - int i; - - for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { - struct uml_tls_struct* curr = - &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; - - /* - * Still correct to do this, if it wasn't present on the host it - * will remain as flushed as it was. - */ - if (!curr->present) - continue; - - curr->flushed = 0; - } -} - -/* - * In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a - * common host process. So this is needed in SKAS0 too. - * - * However, if each thread had a different host process (and this was discussed - * for SMP support) this won't be needed. - * - * And this will not need be used when (and if) we'll add support to the host - * SKAS patch. - */ - -int arch_switch_tls(struct task_struct *to) -{ - if (!host_supports_tls) - return 0; - - /* - * We have no need whatsoever to switch TLS for kernel threads; beyond - * that, that would also result in us calling os_set_thread_area with - * userspace_pid[cpu] == 0, which gives an error. - */ - if (likely(to->mm)) - return load_TLS(O_FORCE, to); - - return 0; -} - -static int set_tls_entry(struct task_struct* task, struct user_desc *info, - int idx, int flushed) -{ - struct thread_struct *t = &task->thread; - - if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) - return -EINVAL; - - t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info; - t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1; - t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed; - - return 0; -} - -int arch_copy_tls(struct task_struct *new) -{ - struct user_desc info; - int idx, ret = -EFAULT; - - if (copy_from_user(&info, - (void __user *) UPT_ESI(&new->thread.regs.regs), - sizeof(info))) - goto out; - - ret = -EINVAL; - if (LDT_empty(&info)) - goto out; - - idx = info.entry_number; - - ret = set_tls_entry(new, &info, idx, 0); -out: - return ret; -} - -/* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */ -static int get_tls_entry(struct task_struct *task, struct user_desc *info, - int idx) -{ - struct thread_struct *t = &task->thread; - - if (!t->arch.tls_array) - goto clear; - - if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) - return -EINVAL; - - if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present) - goto clear; - - *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls; - -out: - /* - * Temporary debugging check, to make sure that things have been - * flushed. This could be triggered if load_TLS() failed. - */ - if (unlikely(task == current && - !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) { - printk(KERN_ERR "get_tls_entry: task with pid %d got here " - "without flushed TLS.", current->pid); - } - - return 0; -clear: - /* - * When the TLS entry has not been set, the values read to user in the - * tls_array are 0 (because it's cleared at boot, see - * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that. - */ - clear_user_desc(info); - info->entry_number = idx; - goto out; -} - -int sys_set_thread_area(struct user_desc __user *user_desc) -{ - struct user_desc info; - int idx, ret; - - if (!host_supports_tls) - return -ENOSYS; - - if (copy_from_user(&info, user_desc, sizeof(info))) - return -EFAULT; - - idx = info.entry_number; - - if (idx == -1) { - idx = get_free_idx(current); - if (idx < 0) - return idx; - info.entry_number = idx; - /* Tell the user which slot we chose for him.*/ - if (put_user(idx, &user_desc->entry_number)) - return -EFAULT; - } - - ret = do_set_thread_area(&info); - if (ret) - return ret; - return set_tls_entry(current, &info, idx, 1); -} - -/* - * Perform set_thread_area on behalf of the traced child. - * Note: error handling is not done on the deferred load, and this differ from - * i386. However the only possible error are caused by bugs. - */ -int ptrace_set_thread_area(struct task_struct *child, int idx, - struct user_desc __user *user_desc) -{ - struct user_desc info; - - if (!host_supports_tls) - return -EIO; - - if (copy_from_user(&info, user_desc, sizeof(info))) - return -EFAULT; - - return set_tls_entry(child, &info, idx, 0); -} - -int sys_get_thread_area(struct user_desc __user *user_desc) -{ - struct user_desc info; - int idx, ret; - - if (!host_supports_tls) - return -ENOSYS; - - if (get_user(idx, &user_desc->entry_number)) - return -EFAULT; - - ret = get_tls_entry(current, &info, idx); - if (ret < 0) - goto out; - - if (copy_to_user(user_desc, &info, sizeof(info))) - ret = -EFAULT; - -out: - return ret; -} - -/* - * Perform get_thread_area on behalf of the traced child. - */ -int ptrace_get_thread_area(struct task_struct *child, int idx, - struct user_desc __user *user_desc) -{ - struct user_desc info; - int ret; - - if (!host_supports_tls) - return -EIO; - - ret = get_tls_entry(child, &info, idx); - if (ret < 0) - goto out; - - if (copy_to_user(user_desc, &info, sizeof(info))) - ret = -EFAULT; -out: - return ret; -} - -/* - * This code is really i386-only, but it detects and logs x86_64 GDT indexes - * if a 32-bit UML is running on a 64-bit host. - */ -static int __init __setup_host_supports_tls(void) -{ - check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min); - if (host_supports_tls) { - printk(KERN_INFO "Host TLS support detected\n"); - printk(KERN_INFO "Detected host type: "); - switch (host_gdt_entry_tls_min) { - case GDT_ENTRY_TLS_MIN_I386: - printk(KERN_CONT "i386"); - break; - case GDT_ENTRY_TLS_MIN_X86_64: - printk(KERN_CONT "x86_64"); - break; - } - printk(KERN_CONT " (GDT indexes %d to %d)\n", - host_gdt_entry_tls_min, - host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES); - } else - printk(KERN_ERR " Host TLS support NOT detected! " - "TLS support inside UML will not work\n"); - return 0; -} - -__initcall(__setup_host_supports_tls); -- cgit v1.1