Re: [PATCH 2/4] objtool: Implement jump_assert for _static_cpu_has()

[Borislav Petkov]

Right,

I've been putting away extending struct alt_instr for a long time now,
trying to be conservative about it but I guess this might be the right
time to change that. How about:

struct alt_instr {
        s32 instr_offset;       /* original instruction */
        s32 repl_offset;        /* offset to replacement instruction */
        u16 cpuid;              /* cpuid bit set for replacement */
        u8  instrlen;           /* length of original instruction */
        u8  replacementlen;     /* length of new instruction */
        u8  padlen;             /* length of build-time padding */
	u64 flags;		/* alternative flags, see <some enum> */
} __packed;

This way we have 64 settings. So we could do:

...
	.flags 	= ALT_FLAGS_STATIC_CPU_HAS,

or something like that and then we can do additional processing/matching
for the alternatives.

Or, we can do

struct alt_instr {
        s32 instr_offset;       /* original instruction */
        s32 repl_offset;        /* offset to replacement instruction */
        u16 cpuid;              /* cpuid bit set for replacement */
        u8  instrlen;           /* length of original instruction */
        u8  replacementlen;     /* length of new instruction */
        u8  padlen;             /* length of build-time padding */
	u8 type;		/* types */
} __packed;

and have 256 types but that would be limiting as we won't be able to set
more than one.

Hmmm?

-- 
Regards/Gruss,
    Boris.

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