x86/entry: Remove outdated comment about SYSCALL targets

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>

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 6ef55e8..e374c19 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -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);