Commit a3675b32 authored Mar 30, 2015 by Denys Vlasenko Committed by Ingo Molnar Mar 31, 2015

x86/asm/entry/64: Do not GET_THREAD_INFO() too early



At exit_intr, we GET_THREAD_INFO(%rcx) and then jump to
retint_kernel if saved CS was from kernel. But the code at
retint_kernel doesn't need %rcx.

Move GET_THREAD_INFO(%rcx) down, after CS check and branch.

While at it, remove "has a correct top of stack" comment.
After recent changes which eliminated FIXUP_TOP_OF_STACK,
we always have a correct pt_regs layout.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
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: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1427738975-7391-5-git-send-email-dvlasenk@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 627276cb

arch/x86/kernel/entry_64.S

+2 −3

Original line number	Diff line number	Diff line
		@@ -658,13 +658,12 @@ ret_from_intr:
		CFI_ADJUST_CFA_OFFSET RBP

		exit_intr:
		GET_THREAD_INFO(%rcx)
		testl $3,CS(%rsp)
		je retint_kernel

		/* Interrupt came from user space */

		GET_THREAD_INFO(%rcx)
		/*
		* Has a correct top of stack.
		* %rcx: thread info. Interrupts off.
		*/
		retint_with_reschedule:

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