From a0d14b8909de55139b8702fe0c7e80b69763dcfb Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 11 Jul 2019 13:40:59 +0200 Subject: x86/mm, tracing: Fix CR2 corruption Despite the current efforts to read CR2 before tracing happens there still exist a number of possible holes: idtentry page_fault do_page_fault has_error_code=1 call error_entry TRACE_IRQS_OFF call trace_hardirqs_off* #PF // modifies CR2 CALL_enter_from_user_mode __context_tracking_exit() trace_user_exit(0) #PF // modifies CR2 call do_page_fault address = read_cr2(); /* whoopsie */ And similar for i386. Fix it by pulling the CR2 read into the entry code, before any of that stuff gets a chance to run and ruin things. Reported-by: He Zhe Reported-by: Eiichi Tsukata Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Cc: bp@alien8.de Cc: rostedt@goodmis.org Cc: torvalds@linux-foundation.org Cc: hpa@zytor.com Cc: dave.hansen@linux.intel.com Cc: jgross@suse.com Cc: joel@joelfernandes.org Link: https://lkml.kernel.org/r/20190711114336.116812491@infradead.org Debugged-by: Steven Rostedt --- arch/x86/kernel/kvm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/x86/kernel/kvm.c') diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 82caf01b63dd..3231440d6253 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -242,23 +242,23 @@ EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason); NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason); dotraplinkage void -do_async_page_fault(struct pt_regs *regs, unsigned long error_code) +do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address) { enum ctx_state prev_state; switch (kvm_read_and_reset_pf_reason()) { default: - do_page_fault(regs, error_code); + do_page_fault(regs, error_code, address); break; case KVM_PV_REASON_PAGE_NOT_PRESENT: /* page is swapped out by the host. */ prev_state = exception_enter(); - kvm_async_pf_task_wait((u32)read_cr2(), !user_mode(regs)); + kvm_async_pf_task_wait((u32)address, !user_mode(regs)); exception_exit(prev_state); break; case KVM_PV_REASON_PAGE_READY: rcu_irq_enter(); - kvm_async_pf_task_wake((u32)read_cr2()); + kvm_async_pf_task_wake((u32)address); rcu_irq_exit(); break; } -- cgit v1.2.3