RFR: 8277204: Implement PAC-RET branch protection on Linux/AArch64 [v18]

[Alan Hayward]

On Mon, 7 Feb 2022 11:43:13 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Are you sure? At the moment with PAC we get:
>> 
>> patch_pc at address 0x0000fffff58edf98 [0x0068ffffed17b5fc -> 0x00abffffed17b7f8]
>> 
>> With both signed and unsigned you'd have:
>> 
>> patch_pc at address 0x0000fffff58edf98 [0x0068ffffed17b5fc (0x0000ffffed17b5fc) -> 0x00abffffed17b7f8 (0x0000ffffed17b7f8)]
>> 
>> I prefer the first - it's shorter and you can infer the address from the signed version. Happy to go with the longer version if you think the shorter version is confusing.
>
> You've been looking at PAC-signed addresses for a long time. 
> Let's see "at address [prev true dest -> new true dest] [signed prev signed dest -> new signed dest]", but only show the signed dests if they're different. So it appears as 
> `patch_pc at address 0x0000fffff58edf98 [0x0068ffffed17b5fc -> 0x00abffffed17b7f8] [signed 0x0000ffffed17b5fc ->  0x0000ffffed17b7f8]` .

ok, that looks better than my longer version, I'll go with that

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PR: https://git.openjdk.java.net/jdk/pull/6334