[PATCH 5/5] x86/mm/kaiser: Disable the SYSCALL-64 trampoline along with KAISER

[Peter Zijlstra]

If we don't use KAISER we don't need the trampoline, use the old entry
code.

Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
 arch/x86/kernel/cpu/common.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1442,7 +1442,10 @@ void syscall_init(void)
                (entry_SYSCALL_64_trampoline - _entry_trampoline);
 
        wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
-       wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
+       if (kaiser_enabled)
+               wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
+       else
+               wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
 
 #ifdef CONFIG_IA32_EMULATION
        wrmsrl(MSR_CSTAR, (unsigned long)entry_SYSCALL_compat);