From d8f0b35331c4423e033f81f10eb5e0c7e4e1dcec Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 21 Apr 2020 11:20:29 +0200 Subject: x86/cpu: Uninline CR4 accessors cpu_tlbstate is exported because various TLB-related functions need access to it, but cpu_tlbstate is sensitive information which should only be accessed by well-contained kernel functions and not be directly exposed to modules. The various CR4 accessors require cpu_tlbstate as the CR4 shadow cache is located there. In preparation for unexporting cpu_tlbstate, create a builtin function for manipulating CR4 and rework the various helpers to use it. No functional change. [ bp: push the export of native_write_cr4() only when CONFIG_LKTDM=m to the last patch in the series. ] Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200421092558.939985695@linutronix.de --- arch/x86/kernel/process.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'arch/x86/kernel/process.c') diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 9da70b279dad..f2eab49d044e 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -612,6 +612,17 @@ void speculation_ctrl_update_current(void) preempt_enable(); } +static inline void cr4_toggle_bits_irqsoff(unsigned long mask) +{ + unsigned long newval, cr4 = this_cpu_read(cpu_tlbstate.cr4); + + newval = cr4 ^ mask; + if (newval != cr4) { + this_cpu_write(cpu_tlbstate.cr4, newval); + __write_cr4(newval); + } +} + void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p) { unsigned long tifp, tifn; -- cgit v1.2.3