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powerpc64/bpf: Add arch_bpf_stack_walk() for BPF JIT

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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>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260124075223.6033-5-adubey@linux.ibm.com
This commit is contained in:
Abhishek Dubey 2026-01-24 13:22:21 +05:30 committed by Madhavan Srinivasan
parent 88cb7f4034
commit b1c24f089b
1 changed files with 41 additions and 0 deletions
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41
arch/powerpc/net/bpf_jit_comp64.c
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@ -247,6 +247,47 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
bpf_jit_build_fentry_stubs(image, ctx);
}
/*
* arch_bpf_stack_walk() - BPF stack walker for PowerPC
*
* Based on arch_stack_walk() from stacktrace.c.
* PowerPC uses stack frames rather than stack pointers. See [1] for
* the equivalence between frame pointers and stack pointers.
* Additional reference at [2].
* TODO: refactor with arch_stack_walk()
*
* [1]: https://lore.kernel.org/all/20200220115141.2707-1-mpe@ellerman.id.au/
* [2]: https://lore.kernel.org/bpf/20260122211854.5508-5-adubey@linux.ibm.com/
*/
void arch_bpf_stack_walk(bool (*consume_fn)(void *, u64, u64, u64), void *cookie)
{
// callback processing always in current context
unsigned long sp = current_stack_frame();
for (;;) {
unsigned long *stack = (unsigned long *) sp;
unsigned long ip;
if (!validate_sp(sp, current))
return;
ip = stack[STACK_FRAME_LR_SAVE];
if (!ip)
break;
/*
* consume_fn common code expects stack pointer in third
* argument. There is no sp in ppc64, rather pass frame
* pointer(named sp here).
*/
if (ip && !consume_fn(cookie, ip, sp, sp))
break;
sp = stack[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;