riscv: patch: Flush the icache right after patching to avoid illegal insns

riscv: patch: Flush the icache right after patching to avoid illegal insns

We cannot delay the icache flush after patching some functions as we may
have patched a function that will get called before the icache flush.

The only way to completely avoid such scenario is by flushing the icache
as soon as we patch a function. This will probably be costly as we don't
batch the icache maintenance anymore.

Fixes: 6ca445d8af0e ("riscv: Fix early ftrace nop patching")
Reported-by: Conor Dooley <[email protected]>
Closes: https://lore.kernel.org/linux-riscv/20240613-lubricant-breath-061192a9489a@wendy/
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Andy Chiu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>