hvcall_341.c:28:2: error: PIC register clobbered by 'r2' in 'asm' __asm__ __volatile__(

[crystalct]

Using last ps3toolchain (gcc 7.2).
PowerPC / PowerPC64 / RS6000
GCC now diagnoses inline assembly that clobbers register r2. This has always been invalid code, and is no longer quietly tolerated.
This could help:
#if GNUC >= 7
: "r31", "r0", "lr"
#else
: "r31", "r0", "r1", "r2", "lr"
#endif