[PATCH v4 3/6] powerpc64/bpf: Avoid tailcall restore from trampoline
From: <hidden>
Date: 2026-01-22 21:21:19
Also in:
bpf, linux-kselftest, lkml
Subsystem:
bpf jit for powerpc (32-bit and 64-bit), bpf [general] (safe dynamic programs and tools), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Hari Bathini, Christophe Leroy, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Madhavan Srinivasan, Linus Torvalds
From: Abhishek Dubey <redacted> Back propagation of tailcall count is no longer needed for powerpc64 due to use of reference, which updates the tailcall count in the tail_call_info field in the frame of the main program only. Back propagation is still required for 32-bit powerpc. Signed-off-by: Abhishek Dubey <redacted> --- arch/powerpc/net/bpf_jit_comp.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 93355ba5382a..1a305f0fed27 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c@@ -662,14 +662,11 @@ static void bpf_trampoline_setup_tail_call_info(u32 *image, struct codegen_conte static void bpf_trampoline_restore_tail_call_cnt(u32 *image, struct codegen_context *ctx, int func_frame_offset, int r4_off) { - if (IS_ENABLED(CONFIG_PPC64)) { - /* See bpf_jit_stack_tailcallcnt() */ - int tailcallcnt_offset = BPF_PPC_TAILCALL; - - EMIT(PPC_RAW_LL(_R3, _R1, -tailcallcnt_offset)); - EMIT(PPC_RAW_STL(_R3, _R1, func_frame_offset - tailcallcnt_offset)); - } else { - /* See bpf_jit_stack_offsetof() and BPF_PPC_TC */ + if (IS_ENABLED(CONFIG_PPC32)) { + /* + * Restore tailcall for 32-bit powerpc + * See bpf_jit_stack_offsetof() and BPF_PPC_TC + */ EMIT(PPC_RAW_STL(_R4, _R1, r4_off)); } }
--
2.48.1