Commit-ID: bef8b6da95229f780a0a7f63e23124058bfad6d3 Gitweb: http://git.kernel.org/tip/bef8b6da95229f780a0a7f63e23124058bfad6d3 Author: Andy Lutomirski <[email protected]> AuthorDate: Mon, 31 Oct 2016 15:18:47 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 1 Nov 2016 07:47:54 +0100
x86/fpu: Handle #NM without FPU emulation as an error Don't use CR0.TS. Make it an error rather than making nonsensical changes to the FPU state. (The cond_local_irq_enable() appears to have been pointless, too.) Signed-off-by: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Rusty Russell <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: kvm list <[email protected]> Link: http://lkml.kernel.org/r/f1ee6bf73ed1025fccaab321ba43d0594245f927.1477951965.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/traps.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bd4e3d4..bf0c6d0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -853,6 +853,8 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) dotraplinkage void do_device_not_available(struct pt_regs *regs, long error_code) { + unsigned long cr0; + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); #ifdef CONFIG_MATH_EMULATION @@ -866,10 +868,20 @@ do_device_not_available(struct pt_regs *regs, long error_code) return; } #endif - fpu__restore(¤t->thread.fpu); /* interrupts still off */ -#ifdef CONFIG_X86_32 - cond_local_irq_enable(regs); -#endif + + /* This should not happen. */ + cr0 = read_cr0(); + if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) { + /* Try to fix it up and carry on. */ + write_cr0(cr0 & ~X86_CR0_TS); + } else { + /* + * Something terrible happened, and we're better off trying + * to kill the task than getting stuck in a never-ending + * loop of #NM faults. + */ + die("unexpected #NM exception", regs, error_code); + } } NOKPROBE_SYMBOL(do_device_not_available);
