bpf: Fix improper int-to-ptr cast in dump_stack_cb

On 32-bit platforms, we'll try to convert a u64 directly to a pointer
type which is 32-bit, which causes the compiler to complain about cast
from an integer of a different size to a pointer type. Cast to long
before casting to the pointer type to match the pointer width.

Reported-by: kernelci.org bot <[email protected]>
Reported-by: Randy Dunlap <[email protected]>
Fixes: d7c431c ("bpf: Add dump_stack() analogue to print to BPF stderr")
Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
Acked-by: Randy Dunlap <[email protected]>
Tested-by: Randy Dunlap <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: kkdwivedi

kernel/bpf/stream.c

@@ -498,11 +498,11 @@ static bool dump_stack_cb(void *cookie, u64 ip, u64 sp, u64 bp)
 		if (ret < 0)
 			goto end;
 		ctxp->err = bpf_stream_stage_printk(ctxp->ss, "%pS\n  %s @ %s:%d\n",
-						    (void *)ip, line, file, num);
+						    (void *)(long)ip, line, file, num);
 		return !ctxp->err;
 	}
 end:
-	ctxp->err = bpf_stream_stage_printk(ctxp->ss, "%pS\n", (void *)ip);
+	ctxp->err = bpf_stream_stage_printk(ctxp->ss, "%pS\n", (void *)(long)ip);
 	return !ctxp->err;
 }