[cmer81]

SourceHook: hook manager generator for Linux x86_64

Why

SourceMod's DHooks virtual hooks go through IHookManagerAutoGen::MakeHookMan, which on Linux x86_64 had no working generator. Without it DHooks can't run on 64-bit Linux servers (CS:S, TF2, DoD:S, HL2:DM). We need it to move our CS:S servers to x64.

What

• Brings in rtldg's unfinished linux64hooks work (x64 linux sourcehook hookmangen alliedmodders/metamod-source#212, closed when upstream moved to KHook). Authorship is kept on all 18 commits. It's rebased on the current 1.12-dev (cb47755, the 1.12.0-git1228 build), and the only conflict was the xor → xorreg rename done upstream.
• Our fixes on top:
  • removes a breakpoint() (int3) that was left at the start of every generated hook function and made the server stop with SIGTRAP on the first hooked call;
  • System V PushParameters reloaded every saved argument register, including the original this, but never loaded v_this. Delegates were therefore called with the hooked entity as this and crashed in ISHDelegate::Call. It now loads v_this into the this register, after the hidden return pointer when there is one, like the MSVC path.
  • the Vector (12-byte object) return path read xmm0/xmm1 from the v_retptr slot itself rather than from the value it points to, so callers got the pointer's bytes. It now dereferences it, like the generic path below.

Testing

• Built linux x86_64 (css) with clang 18.
• Tested on a CS:S x64 dedicated server (build 11003710, same binaries as our production x64 server) with bots and the DHooks branch from srcdslab/sourcemod:
  • virtual hooks with pointer/vector/object params: Teleport is caught and the teleport really happens;
  • OnTakeDamage pre-hook changes the damage through SetObjectVar and the change applies in game (20 → 10 HP);
  • the post-hook reads the return value;
  • Weapon_ShootPosition returns a Vector: the post-hook reads it and a pre-hook supercede reaches the caller;
  • GetPlayerMaxSpeed returns a float and is superseded;
  • AcceptInput passes variant_t by hidden reference.
• No crash.

Companion PR: srcdslab/sourcemod#9 (DHooks Linux x86_64).