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SubjectRE: [RFC PATCH 14/32] x86/fred: header file with FRED definitions
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> > +/*
> > + * FRED return instructions
> > + *
> > + * Replace with "ERETS"/"ERETU" once binutils support FRED return
> instructions.
>
> binutils version that supports these instructions goes here...
>
> > + */
> > +#define ERETS _ASM_BYTES(0xf2,0x0f,0x01,0xca)
> > +#define ERETU _ASM_BYTES(0xf3,0x0f,0x01,0xca)
> > +
> > +/*
> > + * Event stack level macro for the FRED_STKLVLS MSR.
> > + * Usage example: FRED_STKLVL(X86_TRAP_DF, 3)
> > + * Multiple values can be ORd together.
> > + */
> > +#define FRED_STKLVL(v,l) (_AT(unsigned long, l) << (2*(v)))
> > +
> > +/* FRED_CONFIG MSR */
> > +#define FRED_CONFIG_CSL_MASK 0x3
> > +#define FRED_CONFIG_SHADOW_STACK_SPACE _BITUL(3)
> > +#define FRED_CONFIG_REDZONE(b) __ALIGN_KERNEL_MASK((b),
> _UL(0x3f))
> > +#define FRED_CONFIG_INT_STKLVL(l) (_AT(unsigned long, l) << 9)
> > +#define FRED_CONFIG_ENTRYPOINT(p) _AT(unsigned long, (p))
> > +
> > +/* FRED event type and vector bit width and counts */
> > +#define FRED_EVENT_TYPE_BITS 3 /* only 3 bits used in FRED 3.0
> */
> > +#define FRED_EVENT_TYPE_COUNT _BITUL(FRED_EVENT_TYPE_BITS)
> > +#define FRED_EVENT_VECTOR_BITS 8
> > +#define FRED_EVENT_VECTOR_COUNT
> _BITUL(FRED_EVENT_VECTOR_BITS)
> > +
> > +/* FRED EVENT_TYPE_OTHER vector numbers */
> > +#define FRED_SYSCALL 1
> > +#define FRED_SYSENTER 2
> > +
> > +/* Flags above the CS selector (regs->csl) */
> > +#define FRED_CSL_ENABLE_NMI _BITUL(28)
> > +#define FRED_CSL_ALLOW_SINGLE_STEP _BITUL(25)
> > +#define FRED_CSL_INTERRUPT_SHADOW _BITUL(24)
>
> What's the state of IBT WAIT-FOR-ENDBR vs this? That really should also get a
> high CS bit.

FRED does provide more possibilities :)

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