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SubjectRe: [PATCH] bpf: mark get_entry_ip as __maybe_unused
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On 11/3/22 4:32 PM, Jonas Rabenstein wrote:
> Hi again,
> after sending this out, I noticed this is only a problem in the stable
> versions (starting from v6.0.3), as c09eb2e578eb1668bbc has been applied (as
> 03f148c159a250dd454) but not 0e253f7e558a3e250902 ("bpf: Return value in kprobe
> get_func_ip only for entry address") which makes always use of get_entry_ip.
> I therefore think, 0e253f7e558a3e250902 needs to be added to the stable v6.0
> series as well as otherwise it can't be compiled with -Werror if
> CONFIG_X6_KERNEL_IBT is set but CONFIG_FPROBE isn't.

Thanks for the info, Jonas. Added Greg wrt stable cherry-pick.

> On Thu, Nov 03, 2022 at 04:03:03PM +0100, Jonas Rabenstein wrote:
>> Commit c09eb2e578eb1668bbc ("bpf: Adjust kprobe_multi entry_ip
>> for CONFIG_X86_KERNEL_IBT") introduced the get_entry_ip() function.
>> Depending on CONFIG_X86_KERNEL_IBT it is a static function or only
>> a macro definition. The only user of this symbol so far is in
>> kprobe_multi_link_handler() if CONFIG_FPROBE is enabled.
>> If CONFIG_FROBE is not set, the symbol is not used and - depending
>> on CONFIG_X86_KERNEL_IBT - a warning for get_entry_ip() is emitted.
>> To solve this, the function should be marked as __maybe_unused.
>>
>> Signed-off-by: Jonas Rabenstein <rabenstein@cs.fau.de>
>> ---
>> 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 f2d8d070d024..19131aae0bc3 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -1032,7 +1032,7 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
>> };
>>
>> #ifdef CONFIG_X86_KERNEL_IBT
>> -static unsigned long get_entry_ip(unsigned long fentry_ip)
>> +static unsigned long __maybe_unused get_entry_ip(unsigned long fentry_ip)
>> {
>> u32 instr;
>>
>> --
>> 2.37.4
>>

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