2021-07-21 21:21:13

by Arnd Bergmann

Subject: [PATCH net-next] bpf: fix pointer cast warning

From: Arnd Bergmann <[email protected]>

kp->addr is a pointer, so it cannot be cast directly to a 'u64'
when it gets interpreted as an integer value:

kernel/trace/bpf_trace.c: In function '____bpf_get_func_ip_kprobe':
kernel/trace/bpf_trace.c:968:21: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
968 | return kp ? (u64) kp->addr : 0;

Use the uintptr_t type instead.

Fixes: 9ffd9f3ff719 ("bpf: Add bpf_get_func_ip helper for kprobe programs")
Signed-off-by: Arnd Bergmann <[email protected]>
---
kernel/trace/bpf_trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0de09f068697..a428d1ef0085 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -965,7 +965,7 @@ BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
{
struct kprobe *kp = kprobe_running();

- return kp ? (u64) kp->addr : 0;
+ return kp ? (uintptr_t)kp->addr : 0;
}

static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
--
2.29.2

2021-07-21 21:50:35

by Andrii Nakryiko

Subject: Re: [PATCH net-next] bpf: fix pointer cast warning

On Wed, Jul 21, 2021 at 2:20 PM Arnd Bergmann <[email protected]> wrote:
>
> From: Arnd Bergmann <[email protected]>
>
> kp->addr is a pointer, so it cannot be cast directly to a 'u64'
> when it gets interpreted as an integer value:
>
> kernel/trace/bpf_trace.c: In function '____bpf_get_func_ip_kprobe':
> kernel/trace/bpf_trace.c:968:21: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
> 968 | return kp ? (u64) kp->addr : 0;
>
> Use the uintptr_t type instead.
>
> Fixes: 9ffd9f3ff719 ("bpf: Add bpf_get_func_ip helper for kprobe programs")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---

I'll take this through the bpf-next tree, if no one objects. Thanks for the fix!


> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 0de09f068697..a428d1ef0085 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -965,7 +965,7 @@ BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
> {
> struct kprobe *kp = kprobe_running();
>
> - return kp ? (u64) kp->addr : 0;
> + return kp ? (uintptr_t)kp->addr : 0;
> }
>
> static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> --
> 2.29.2
>