4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> commit 8d4b067895791ab9fdb1aadfc505f64d71239dd2 upstream. Force the entry through the trampoline only when PTI is active. Otherwise go through the normal entry code. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Borislav Petkov <bp@xxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Eduardo Valentin <eduval@xxxxxxxxxx> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: aliguori@xxxxxxxxxx Cc: daniel.gruss@xxxxxxxxxxxxxx Cc: hughd@xxxxxxxxxx Cc: keescook@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -1339,7 +1339,10 @@ 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 (static_cpu_has(X86_FEATURE_PTI)) + 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);