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/cpu/common.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index bed0cb83fe24..82042f40fc45 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -387,7 +387,28 @@ set_register: bits_missing); } } -EXPORT_SYMBOL(native_write_cr4); +EXPORT_SYMBOL_GPL(native_write_cr4); + +void cr4_update_irqsoff(unsigned long set, unsigned long clear) +{ + unsigned long newval, cr4 = this_cpu_read(cpu_tlbstate.cr4); + + lockdep_assert_irqs_disabled(); + + newval = (cr4 & ~clear) | set; + if (newval != cr4) { + this_cpu_write(cpu_tlbstate.cr4, newval); + __write_cr4(newval); + } +} +EXPORT_SYMBOL(cr4_update_irqsoff); + +/* Read the CR4 shadow. */ +unsigned long cr4_read_shadow(void) +{ + return this_cpu_read(cpu_tlbstate.cr4); +} +EXPORT_SYMBOL_GPL(cr4_read_shadow); void cr4_init(void) { -- cgit v1.2.3