x86/asm/entry: Simplify task_pt_regs() macro definition
Before this change, task_pt_regs() was using KSTK_TOP(),
and it was the only use of that macro. In turn, KSTK_TOP used
THREAD_SIZE_LONGS, and it was the only use of that macro too.
Fold these macros into task_pt_regs(). Tweak comment
about "- 8" - we now use a symbolic constant, not literal 8.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1426255743-5394-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b262089..6a5c0ec 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -847,15 +847,8 @@
extern unsigned long thread_saved_pc(struct task_struct *tsk);
-#define THREAD_SIZE_LONGS (THREAD_SIZE/sizeof(unsigned long))
-#define KSTK_TOP(info) \
-({ \
- unsigned long *__ptr = (unsigned long *)(info); \
- (unsigned long)(&__ptr[THREAD_SIZE_LONGS]); \
-})
-
/*
- * The below -8 is to reserve 8 bytes on top of the ring0 stack.
+ * TOP_OF_KERNEL_STACK_PADDING reserves 8 bytes on top of the ring0 stack.
* This is necessary to guarantee that the entire "struct pt_regs"
* is accessible even if the CPU haven't stored the SS/ESP registers
* on the stack (interrupt gate does not save these registers
@@ -864,12 +857,11 @@
* "struct pt_regs" is possible, but they may contain the
* completely wrong values.
*/
-#define task_pt_regs(task) \
-({ \
- struct pt_regs *__regs__; \
- __regs__ = (struct pt_regs *)(KSTK_TOP(task_stack_page(task)) - \
- TOP_OF_KERNEL_STACK_PADDING); \
- __regs__ - 1; \
+#define task_pt_regs(task) \
+({ \
+ unsigned long __ptr = (unsigned long)task_stack_page(task); \
+ __ptr += THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; \
+ ((struct pt_regs *)__ptr) - 1; \
})
#define KSTK_ESP(task) (task_pt_regs(task)->sp)