From ee35b9b9f6d52ba134b4e75442531935f295be7a Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 17 Jan 2019 13:02:05 +0100 Subject: [PATCH] x86/traps: Have read_cr0() only once in the #NM handler ... instead of twice in the code. In any case, CR0 ends up being read once anyway: 1. The CONFIG_MATH_EMULATION case does so and exits. 2. The normal case does it once too. However, read it on function entry instead to make the code even simpler to follow. No functional changes. Signed-off-by: Borislav Petkov Reviewed-by: Andy Lutomirski Acked-by: Sebastian Andrzej Siewior Cc: x86@kernel.org Link: https://lkml.kernel.org/r/20190117120728.3811-1-bp@alien8.de --- arch/x86/kernel/traps.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 9b7c4ca8f0a73..2684a9d11e661 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -880,12 +880,12 @@ 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; + unsigned long cr0 = read_cr0(); RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); #ifdef CONFIG_MATH_EMULATION - if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) { + if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) { struct math_emu_info info = { }; cond_local_irq_enable(regs); @@ -897,7 +897,6 @@ do_device_not_available(struct pt_regs *regs, long error_code) #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); -- 2.30.2