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authorDaniel Vetter <daniel.vetter@ffwll.ch>2015-11-23 09:04:05 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2015-11-23 09:04:05 +0100
commit92907cbbef8625bb3998d1eb385fc88f23c97a3f (patch)
tree15626ff9287e37c3cb81c7286d6db5a7fd77c854 /arch/x86/kernel/process.c
parent15fbfccfe92c62ae8d1ecc647c44157ed01ac02e (diff)
parent1ec218373b8ebda821aec00bb156a9c94fad9cd4 (diff)
Merge tag 'v4.4-rc2' into drm-intel-next-queued
Linux 4.4-rc2 Backmerge to get at commit 1b0e3a049efe471c399674fd954500ce97438d30 Author: Imre Deak <imre.deak@intel.com> Date: Thu Nov 5 23:04:11 2015 +0200 drm/i915/skl: disable display side power well support for now so that we can proplery re-eanble skl power wells in -next. Conflicts are just adjacent lines changed, except for intel_fbdev.c where we need to interleave the changs. Nothing nefarious. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Diffstat (limited to 'arch/x86/kernel/process.c')
-rw-r--r--arch/x86/kernel/process.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 6d0e62ae8516..9f7c21c22477 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -84,6 +84,9 @@ EXPORT_SYMBOL_GPL(idle_notifier_unregister);
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
memcpy(dst, src, arch_task_struct_size);
+#ifdef CONFIG_VM86
+ dst->thread.vm86 = NULL;
+#endif
return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
}
@@ -506,3 +509,58 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}
+/*
+ * Called from fs/proc with a reference on @p to find the function
+ * which called into schedule(). This needs to be done carefully
+ * because the task might wake up and we might look at a stack
+ * changing under us.
+ */
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long start, bottom, top, sp, fp, ip;
+ int count = 0;
+
+ if (!p || p == current || p->state == TASK_RUNNING)
+ return 0;
+
+ start = (unsigned long)task_stack_page(p);
+ if (!start)
+ return 0;
+
+ /*
+ * Layout of the stack page:
+ *
+ * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
+ * PADDING
+ * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
+ * stack
+ * ----------- bottom = start + sizeof(thread_info)
+ * thread_info
+ * ----------- start
+ *
+ * The tasks stack pointer points at the location where the
+ * framepointer is stored. The data on the stack is:
+ * ... IP FP ... IP FP
+ *
+ * We need to read FP and IP, so we need to adjust the upper
+ * bound by another unsigned long.
+ */
+ top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
+ top -= 2 * sizeof(unsigned long);
+ bottom = start + sizeof(struct thread_info);
+
+ sp = READ_ONCE(p->thread.sp);
+ if (sp < bottom || sp > top)
+ return 0;
+
+ fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
+ do {
+ if (fp < bottom || fp > top)
+ return 0;
+ ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
+ if (!in_sched_functions(ip))
+ return ip;
+ fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
+ } while (count++ < 16 && p->state != TASK_RUNNING);
+ return 0;
+}