On 14/01/26 6:50 pm, adubey wrote:
On 2026-01-14 18:07, Christophe Leroy (CS GROUP) wrote:
Le 14/01/2026 à 12:44, [email protected] a écrit :
From: Abhishek Dubey <[email protected]>
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 <[email protected]>
---
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];
+ }
+}
+
This fonction looks very close to arch_stack_walk(). Would it be
possible to refactor and have a common part used by both functions,
like ARM64 for instance ?
Yes, its inspired from arch_stack_walk(). consume_entry() have different
parameter count in both cases.
If merged, it need additional handling to identify which call_back to
invoke.
Also, we need to define arch-specific weak function
arch_bpf_stack_walk(), so renaming of arch_stack_walk is needed on merge.
Stack walker logic with "bpf" name might be confusing when used at other
places. Thoughts?
Not sure what you mean by renaming of arch_stack_walk is needed on
merge but refactoring does not have to change API signature or any
common code for that matter..
- Hari
