From 990784b57731192b7d90c8d4049e6318d81e887d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 28 Aug 2019 16:24:47 +0200 Subject: x86/mm/pti: Do not invoke PTI functions when PTI is disabled When PTI is disabled at boot time either because the CPU is not affected or PTI has been disabled on the command line, the boot code still calls into pti_finalize() which then unconditionally invokes: pti_clone_entry_text() pti_clone_kernel_text() pti_clone_kernel_text() was called unconditionally before the 32bit support was added and 32bit added the call to pti_clone_entry_text(). The call has no side effects as cloning the page tables into the available second one, which was allocated for PTI does not create damage. But it does not make sense either and in case that this functionality would be extended later this might actually lead to hard to diagnose issues. Neither function should be called when PTI is runtime disabled. Make the invocation conditional. Signed-off-by: Thomas Gleixner Reviewed-by: Dave Hansen Acked-by: Ingo Molnar Acked-by: Song Liu Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20190828143124.063353972@linutronix.de --- arch/x86/mm/pti.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index a24487bbc2c4..7f2140414440 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -668,6 +668,8 @@ void __init pti_init(void) */ void pti_finalize(void) { + if (!boot_cpu_has(X86_FEATURE_PTI)) + return; /* * We need to clone everything (again) that maps parts of the * kernel image. -- cgit v1.2.3