[PATCH v2 4/6] powerpc64/bpf: Add arch_bpf_stack_walk() for BPF JIT

adubey
2026-01-14T11:47:56Z

From: Abhishek Dubey <adubey@linux.ibm.com>

This function is used by bpf_throw() to unwind the stack
until frame of exception-boundary during BPF exception
handling.

This function is necessary to support BPF exceptions on
PowerPC.

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
arch/powerpc/net/bpf_jit_comp64.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index cebf81fbd59f..ec58395f74f7 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -247,6 +247,34 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
bpf_jit_build_fentry_stubs(image, ctx);
}

+void arch_bpf_stack_walk(bool (*consume_fn)(void *, u64, u64, u64), void *cookie)
+{
+ // callback processing always in current context
+ unsigned long fp = current_stack_frame();
+
+ for (;;) {
+ unsigned long *frame = (unsigned long *) fp;
+ unsigned long ip;
+
+ if (!validate_sp(fp, current))
+ return;
+
+ ip = frame[STACK_FRAME_LR_SAVE];
+ if (!ip)
+ break;
+
+ /*
+ * consume_fn common code expects stack pointer(sp) in third
+ * argument. There is no sp in ppc64, rather pass frame
+ * pointer.
+ */
+ if (ip && !consume_fn(cookie, ip, fp, fp))
+ break;
+
+ fp = frame[0];
+ }
+}
+
int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func)
{
unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0;
--
2.48.1