x86/entry: Remove outdated comment about SYSCALL targets
authorBorislav Petkov <bp@suse.de>
Tue, 23 Aug 2016 17:23:56 +0000 (19:23 +0200)
committerIngo Molnar <mingo@kernel.org>
Wed, 24 Aug 2016 09:20:31 +0000 (11:20 +0200)
The comment probably meant some old AMD64 incarnation which most likely
never saw the light of day. STAR and LSTAR are two different registers
and STAR sets CS/SS(DS) selectors for *all* modes, not only 32-bit.

So simply remove that comment.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: 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: Josh Poimboeuf <jpoimboe@redhat.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/20160823172356.15879-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/cpu/common.c

index 6ef55e83fb8a5d778dcf58602e95fb241b3a6c58..e374c19b9ddcff0ee67ad1017922179801d08290 100644 (file)
@@ -1305,11 +1305,6 @@ static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
 /* May not be marked __init: used by software suspend */
 void syscall_init(void)
 {
-       /*
-        * LSTAR and STAR live in a bit strange symbiosis.
-        * They both write to the same internal register. STAR allows to
-        * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.
-        */
        wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
        wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);