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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: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Shan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-12-xin3.li@intel.com
This commit is contained in:
H. Peter Anvin (Intel) 2023-12-05 02:50:00 -08:00 committed by Borislav Petkov (AMD)
parent cd19bab825
commit ff45746fbf
2 changed files with 9 additions and 3 deletions
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7
arch/x86/include/uapi/asm/processor-flags.h
View File

@ -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
*/

5
arch/x86/kernel/cpu/common.c
View File

@ -382,9 +382,8 @@ out:
}
/* 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;