retsnoop's build on powerpc (ppc64le) architecture ([0]) failed due to
wrong definition of PT_REGS_SP() macro. Looking at powerpc's
implementation of stack unwinding in perf_callchain_user_64() clearly
shows that stack pointer register is gpr[1].
Fix libbpf's definition of __PT_SP_REG for powerpc to fix all this.
[0] https://kojipkgs.fedoraproject.org/work/tasks/1544/
137921544/build.log
Fixes: 138d6153a139 ("samples/bpf: Enable powerpc support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://lore.kernel.org/r/20251020203643.989467-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
#define __PT_RET_REG regs[31]
#define __PT_FP_REG __unsupported__
#define __PT_RC_REG gpr[3]
-#define __PT_SP_REG sp
+#define __PT_SP_REG gpr[1]
#define __PT_IP_REG nip
#elif defined(bpf_target_sparc)