forked from luck/tmp_suning_uos_patched
54d8d3b5a0
Newly forked threads have no arch_switch_to_skas() called before their first run, because when schedule() switches to them they're resumed in the body of thread_wait() inside fork_handler() rather than in switch_threads() in switch_to_skas(). Compensate this missing call. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
334 lines
7.7 KiB
C
334 lines
7.7 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/config.h"
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#include "linux/kernel.h"
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#include "linux/sched.h"
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#include "linux/slab.h"
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#include "linux/types.h"
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#include "asm/uaccess.h"
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#include "asm/ptrace.h"
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#include "asm/segment.h"
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#include "asm/smp.h"
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#include "asm/desc.h"
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#include "choose-mode.h"
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#include "kern.h"
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#include "kern_util.h"
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#include "mode_kern.h"
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#include "os.h"
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#include "mode.h"
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#ifdef CONFIG_MODE_SKAS
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#include "skas.h"
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#endif
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#ifdef CONFIG_MODE_SKAS
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int do_set_thread_area_skas(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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return ret;
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}
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int do_get_thread_area_skas(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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return ret;
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}
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#endif
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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 dinamic 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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/* 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 = &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
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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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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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/* 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 = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
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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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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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/* 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 = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
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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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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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/* This in SKAS0 does not need to be used, since we have different host
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* processes. Nor will this need to be used when we'll add support to the host
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* SKAS patch. */
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int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
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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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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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int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to)
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{
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if (needs_TLS_update(to))
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return load_TLS(0, 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_ESI(&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, 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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/* 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 && !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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/* 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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asmlinkage int sys_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 (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 = CHOOSE_MODE_PROC(do_set_thread_area_tt, do_set_thread_area_skas, &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 (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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asmlinkage int sys_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 (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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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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