um/Stop conflating task_struct::stack with thread_info

thread_info may move in the future, so use the accessors.

[ Andy Lutomirski wrote this changelog message and changed
  "task_thread_info(child)->cpu" to "task_cpu(child)". ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3439705d9838940cc82733a7335fa8c654c37db8.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index a7ef7b1..5766ead 100644 (file)
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -194,7 +194,7 @@ int peek_user(struct task_struct *child, long addr, long data)
 
 static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
 {
-       int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
+       int err, n, cpu = task_cpu(child);
        struct user_i387_struct fpregs;
 
        err = save_i387_registers(userspace_pid[cpu],
@@ -211,7 +211,7 @@ static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
 
 static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
 {
-       int n, cpu = ((struct thread_info *) child->stack)->cpu;
+       int n, cpu = task_cpu(child);
        struct user_i387_struct fpregs;
 
        n = copy_from_user(&fpregs, buf, sizeof(fpregs));
@@ -224,7 +224,7 @@ static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
 
 static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
 {
-       int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
+       int err, n, cpu = task_cpu(child);
        struct user_fxsr_struct fpregs;
 
        err = save_fpx_registers(userspace_pid[cpu], (unsigned long *) &fpregs);
@@ -240,7 +240,7 @@ static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *
 
 static int set_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
 {
-       int n, cpu = ((struct thread_info *) child->stack)->cpu;
+       int n, cpu = task_cpu(child);
        struct user_fxsr_struct fpregs;
 
        n = copy_from_user(&fpregs, buf, sizeof(fpregs));