syscall, runtime/internal/syscall: zero r2 before mips linux syscalls

All mips variant perform syscalls similarly. R2 (v0) holds r1 and R3
(v1) holds r2 of a syscall. The latter is only used by 2-ret syscalls.
A 1-ret syscall would not touch R3 but keeps it as is, making r2 be a
random value. Always reset it to 0 before SYSCALL to fix the issue.

Fixes #56426

Change-Id: Ie49965c0c3c224c4a895703ac659205cd040ff56
TryBot-Result: Gopher Robot <>
Run-TryBot: Meng Zhuo <>
Reviewed-by: Austin Clements <>
Reviewed-by: Cherry Mui <>
Reviewed-by: Meng Zhuo <>
4 files changed
tree: ccf0377dd82c0a1e3e953b23c3c515fb73387a80
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg

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