From: "H. Peter Anvin (Intel)" <hpa@xxxxxxxxx> Add X86_CR4_FRED macro for the FRED bit in %cr4. This bit must not be changed after initialization, so add it to the pinned CR4 bits. Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx> Tested-by: Shan Kang <shan.kang@xxxxxxxxx> Signed-off-by: Xin Li <xin3.li@xxxxxxxxx> --- Changes since v9: * Avoid a type cast by defining X86_CR4_FRED as 0 on 32-bit (Thomas Gleixner). --- arch/x86/include/uapi/asm/processor-flags.h | 7 +++++++ arch/x86/kernel/cpu/common.c | 5 ++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h index d898432947ff..f1a4adc78272 100644 --- a/arch/x86/include/uapi/asm/processor-flags.h +++ b/arch/x86/include/uapi/asm/processor-flags.h @@ -139,6 +139,13 @@ #define X86_CR4_LAM_SUP_BIT 28 /* LAM for supervisor pointers */ #define X86_CR4_LAM_SUP _BITUL(X86_CR4_LAM_SUP_BIT) +#ifdef __x86_64__ +#define X86_CR4_FRED_BIT 32 /* enable FRED kernel entry */ +#define X86_CR4_FRED _BITUL(X86_CR4_FRED_BIT) +#else +#define X86_CR4_FRED (0) +#endif + /* * x86-64 Task Priority Register, CR8 */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 68102acd63b0..132f41f7c27f 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -389,9 +389,8 @@ static __always_inline void setup_umip(struct cpuinfo_x86 *c) } /* These bits should not change their value after CPU init is finished. */ -static const unsigned long cr4_pinned_mask = - X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP | - X86_CR4_FSGSBASE | X86_CR4_CET; +static const unsigned long cr4_pinned_mask = X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP | + X86_CR4_FSGSBASE | X86_CR4_CET | X86_CR4_FRED; static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning); static unsigned long cr4_pinned_bits __ro_after_init; -- 2.43.0
