x86/process: Unify 32bit and 64bit implementations of get_wchan()

The stack layout and the functionality is identical. Use the 64bit
version for all of x86.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: kasan-dev <kasan-dev@googlegroups.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>
Link: http://lkml.kernel.org/r/20150930083302.779694618@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 55 insertions, 84 deletions

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 6d0e62ae8516..39e585a554b7 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -506,3 +506,58 @@ 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(*(unsigned long *)sp);
+        do {
+                if (fp < bottom || fp > top)
+                        return 0;
+                ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));
+                if (!in_sched_functions(ip))
+                        return ip;
+                fp = READ_ONCE(*(unsigned long *)fp);
+        } while (count++ < 16 && p->state != TASK_RUNNING);
+        return 0;
+}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index c13df2c735f8..737527b40e5b 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -324,31 +324,3 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
         return prev_p;
 }
-
-#define top_esp                (THREAD_SIZE - sizeof(unsigned long))
-#define top_ebp                (THREAD_SIZE - 2*sizeof(unsigned long))
-
-unsigned long get_wchan(struct task_struct *p)
-{
-        unsigned long bp, sp, ip;
-        unsigned long stack_page;
-        int count = 0;
-        if (!p || p == current || p->state == TASK_RUNNING)
-                return 0;
-        stack_page = (unsigned long)task_stack_page(p);
-        sp = p->thread.sp;
-        if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
-                return 0;
-        /* include/asm-i386/system.h:switch_to() pushes bp last. */
-        bp = *(unsigned long *) sp;
-        do {
-                if (bp < stack_page || bp > top_ebp+stack_page)
-                        return 0;
-                ip = *(unsigned long *) (bp+4);
-                if (!in_sched_functions(ip))
-                        return ip;
-                bp = *(unsigned long *) bp;
-        } while (count++ < 16);
-        return 0;
-}
-
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index f1fd0889e8af..b35921a670b2 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -499,62 +499,6 @@ void set_personality_ia32(bool x32)
 }
 EXPORT_SYMBOL_GPL(set_personality_ia32);
 
-/*
- * 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(*(unsigned long *)sp);
-        do {
-                if (fp < bottom || fp > top)
-                        return 0;
-                ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));
-                if (!in_sched_functions(ip))
-                        return ip;
-                fp = READ_ONCE(*(unsigned long *)fp);
-        } while (count++ < 16 && p->state != TASK_RUNNING);
-        return 0;
-}
-
 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 {
         int ret = 0;