da028d5e54
Don't include ptrace uapi stuff in arch headers, it will pollute the kernel namespace and conflict with existing stuff. In this case it fixes clashes with common names like R8. Signed-off-by: Richard Weinberger <richard@nod.at>
398 lines
8.9 KiB
C
398 lines
8.9 KiB
C
/*
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* Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
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* Licensed under the GPL
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*/
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#include <linux/percpu.h>
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <asm/uaccess.h>
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#include <asm/ptrace-abi.h>
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#include <os.h>
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#include <skas.h>
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#include <sysdep/tls.h>
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/*
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* If needed we can detect when it's uninitialized.
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*
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* These are initialized in an initcall and unchanged thereafter.
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*/
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static int host_supports_tls = -1;
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int host_gdt_entry_tls_min;
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int do_set_thread_area(struct user_desc *info)
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{
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int ret;
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u32 cpu;
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cpu = get_cpu();
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ret = os_set_thread_area(info, userspace_pid[cpu]);
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put_cpu();
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if (ret)
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printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
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"index = %d\n", ret, info->entry_number);
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return ret;
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}
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int do_get_thread_area(struct user_desc *info)
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{
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int ret;
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u32 cpu;
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cpu = get_cpu();
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ret = os_get_thread_area(info, userspace_pid[cpu]);
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put_cpu();
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if (ret)
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printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
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"index = %d\n", ret, info->entry_number);
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return ret;
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}
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/*
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* sys_get_thread_area: get a yet unused TLS descriptor index.
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* XXX: Consider leaving one free slot for glibc usage at first place. This must
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* be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else.
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*
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* Also, this must be tested when compiling in SKAS mode with dynamic linking
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* and running against NPTL.
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*/
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static int get_free_idx(struct task_struct* task)
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{
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struct thread_struct *t = &task->thread;
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int idx;
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if (!t->arch.tls_array)
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return GDT_ENTRY_TLS_MIN;
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for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
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if (!t->arch.tls_array[idx].present)
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return idx + GDT_ENTRY_TLS_MIN;
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return -ESRCH;
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}
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static inline void clear_user_desc(struct user_desc* info)
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{
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/* Postcondition: LDT_empty(info) returns true. */
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memset(info, 0, sizeof(*info));
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/*
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* Check the LDT_empty or the i386 sys_get_thread_area code - we obtain
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* indeed an empty user_desc.
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*/
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info->read_exec_only = 1;
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info->seg_not_present = 1;
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}
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#define O_FORCE 1
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static int load_TLS(int flags, struct task_struct *to)
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{
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int ret = 0;
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int idx;
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for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
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struct uml_tls_struct* curr =
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&to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
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/*
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* Actually, now if it wasn't flushed it gets cleared and
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* flushed to the host, which will clear it.
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*/
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if (!curr->present) {
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if (!curr->flushed) {
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clear_user_desc(&curr->tls);
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curr->tls.entry_number = idx;
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} else {
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WARN_ON(!LDT_empty(&curr->tls));
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continue;
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}
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}
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if (!(flags & O_FORCE) && curr->flushed)
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continue;
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ret = do_set_thread_area(&curr->tls);
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if (ret)
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goto out;
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curr->flushed = 1;
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}
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out:
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return ret;
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}
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/*
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* Verify if we need to do a flush for the new process, i.e. if there are any
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* present desc's, only if they haven't been flushed.
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*/
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static inline int needs_TLS_update(struct task_struct *task)
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{
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int i;
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int ret = 0;
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for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
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struct uml_tls_struct* curr =
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&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
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/*
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* Can't test curr->present, we may need to clear a descriptor
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* which had a value.
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*/
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if (curr->flushed)
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continue;
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ret = 1;
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break;
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}
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return ret;
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}
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/*
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* On a newly forked process, the TLS descriptors haven't yet been flushed. So
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* we mark them as such and the first switch_to will do the job.
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*/
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void clear_flushed_tls(struct task_struct *task)
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{
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int i;
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for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
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struct uml_tls_struct* curr =
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&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
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/*
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* Still correct to do this, if it wasn't present on the host it
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* will remain as flushed as it was.
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*/
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if (!curr->present)
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continue;
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curr->flushed = 0;
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}
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}
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/*
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* In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a
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* common host process. So this is needed in SKAS0 too.
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*
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* However, if each thread had a different host process (and this was discussed
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* for SMP support) this won't be needed.
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*
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* And this will not need be used when (and if) we'll add support to the host
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* SKAS patch.
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*/
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int arch_switch_tls(struct task_struct *to)
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{
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if (!host_supports_tls)
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return 0;
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/*
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* We have no need whatsoever to switch TLS for kernel threads; beyond
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* that, that would also result in us calling os_set_thread_area with
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* userspace_pid[cpu] == 0, which gives an error.
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*/
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if (likely(to->mm))
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return load_TLS(O_FORCE, to);
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return 0;
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}
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static int set_tls_entry(struct task_struct* task, struct user_desc *info,
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int idx, int flushed)
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{
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struct thread_struct *t = &task->thread;
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
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t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
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t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
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return 0;
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}
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int arch_copy_tls(struct task_struct *new)
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{
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struct user_desc info;
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int idx, ret = -EFAULT;
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if (copy_from_user(&info,
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(void __user *) UPT_SI(&new->thread.regs.regs),
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sizeof(info)))
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goto out;
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ret = -EINVAL;
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if (LDT_empty(&info))
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goto out;
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idx = info.entry_number;
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ret = set_tls_entry(new, &info, idx, 0);
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out:
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return ret;
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}
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/* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */
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static int get_tls_entry(struct task_struct *task, struct user_desc *info,
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int idx)
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{
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struct thread_struct *t = &task->thread;
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if (!t->arch.tls_array)
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goto clear;
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
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goto clear;
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*info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
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out:
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/*
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* Temporary debugging check, to make sure that things have been
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* flushed. This could be triggered if load_TLS() failed.
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*/
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if (unlikely(task == current &&
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!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
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printk(KERN_ERR "get_tls_entry: task with pid %d got here "
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"without flushed TLS.", current->pid);
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}
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return 0;
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clear:
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/*
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* When the TLS entry has not been set, the values read to user in the
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* tls_array are 0 (because it's cleared at boot, see
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* arch/i386/kernel/head.S:cpu_gdt_table). Emulate that.
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*/
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clear_user_desc(info);
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info->entry_number = idx;
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goto out;
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}
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SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
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{
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struct user_desc info;
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int idx, ret;
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if (!host_supports_tls)
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return -ENOSYS;
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if (copy_from_user(&info, user_desc, sizeof(info)))
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return -EFAULT;
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idx = info.entry_number;
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if (idx == -1) {
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idx = get_free_idx(current);
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if (idx < 0)
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return idx;
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info.entry_number = idx;
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/* Tell the user which slot we chose for him.*/
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if (put_user(idx, &user_desc->entry_number))
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return -EFAULT;
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}
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ret = do_set_thread_area(&info);
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if (ret)
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return ret;
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return set_tls_entry(current, &info, idx, 1);
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}
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/*
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* Perform set_thread_area on behalf of the traced child.
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* Note: error handling is not done on the deferred load, and this differ from
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* i386. However the only possible error are caused by bugs.
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*/
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int ptrace_set_thread_area(struct task_struct *child, int idx,
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struct user_desc __user *user_desc)
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{
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struct user_desc info;
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if (!host_supports_tls)
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return -EIO;
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if (copy_from_user(&info, user_desc, sizeof(info)))
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return -EFAULT;
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return set_tls_entry(child, &info, idx, 0);
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}
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SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
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{
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struct user_desc info;
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int idx, ret;
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if (!host_supports_tls)
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return -ENOSYS;
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if (get_user(idx, &user_desc->entry_number))
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return -EFAULT;
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ret = get_tls_entry(current, &info, idx);
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if (ret < 0)
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goto out;
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if (copy_to_user(user_desc, &info, sizeof(info)))
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ret = -EFAULT;
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out:
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return ret;
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}
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/*
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* Perform get_thread_area on behalf of the traced child.
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*/
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int ptrace_get_thread_area(struct task_struct *child, int idx,
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struct user_desc __user *user_desc)
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{
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struct user_desc info;
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int ret;
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if (!host_supports_tls)
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return -EIO;
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ret = get_tls_entry(child, &info, idx);
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if (ret < 0)
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goto out;
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if (copy_to_user(user_desc, &info, sizeof(info)))
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ret = -EFAULT;
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out:
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return ret;
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}
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/*
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* This code is really i386-only, but it detects and logs x86_64 GDT indexes
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* if a 32-bit UML is running on a 64-bit host.
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*/
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static int __init __setup_host_supports_tls(void)
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{
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check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
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if (host_supports_tls) {
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printk(KERN_INFO "Host TLS support detected\n");
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printk(KERN_INFO "Detected host type: ");
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switch (host_gdt_entry_tls_min) {
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case GDT_ENTRY_TLS_MIN_I386:
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printk(KERN_CONT "i386");
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break;
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case GDT_ENTRY_TLS_MIN_X86_64:
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printk(KERN_CONT "x86_64");
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break;
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}
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printk(KERN_CONT " (GDT indexes %d to %d)\n",
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host_gdt_entry_tls_min,
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host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES);
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} else
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printk(KERN_ERR " Host TLS support NOT detected! "
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"TLS support inside UML will not work\n");
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return 0;
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}
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__initcall(__setup_host_supports_tls);
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