Commit b1c24f08 authored by Abhishek Dubey's avatar Abhishek Dubey Committed by Madhavan Srinivasan
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powerpc64/bpf: Add arch_bpf_stack_walk() for BPF JIT 



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: default avatarAbhishek Dubey <adubey@linux.ibm.com>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260124075223.6033-5-adubey@linux.ibm.com
parent 88cb7f40

arch/powerpc/net/bpf_jit_comp64.c

+41 −0
Original line number Diff line number Diff line
@@ -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;