[PATCH 4.14 048/159] x86/entry: Add task_top_of_stack() to find the top of a tasks stack

Greg Kroah-Hartman
2017-12-22T09:01:26Z

From: Andy Lutomirski <luto@kernel.org>

commit 3500130b84a3cdc5b6796eba1daf178944935efe upstream.

This will let us get rid of a few places that hardcode accesses to
thread.sp0.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b49b3f95a8ff858c40c9b0f5b32be0355324327d.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/processor.h | 2 ++
1 file changed, 2 insertions(+)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -796,6 +796,8 @@ static inline void spin_lock_prefetch(co
#define TOP_OF_INIT_STACK ((unsigned long)&init_stack + sizeof(init_stack) - \
TOP_OF_KERNEL_STACK_PADDING)

+#define task_top_of_stack(task) ((unsigned long)(task_pt_regs(task) + 1))
+
#ifdef CONFIG_X86_32
/*
* User space process size: 3GB (default).