Commit ff45746f authored by H. Peter Anvin (Intel)'s avatar H. Peter Anvin (Intel) Committed by Borislav Petkov (AMD)
Browse files

x86/cpu: Add X86_CR4_FRED macro 



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: default avatarH. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: default avatarXin Li <xin3.li@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarShan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-12-xin3.li@intel.com
parent cd19bab8

arch/x86/include/uapi/asm/processor-flags.h

+7 −0
Original line number Diff line number Diff line
@@ -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

 */

arch/x86/kernel/cpu/common.c

+2 −3
Original line number Diff line number Diff line
@@ -382,9 +382,8 @@ 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;