Re: [PATCH net-next v4] net: skb: prevent the split of kfree_skb_reason() by gcc
From: Menglong Dong <hidden>
Date: 2022-08-18 16:32:04
Also in:
linux-toolchains, lkml
From: Menglong Dong <hidden>
Date: 2022-08-18 16:32:04
Also in:
linux-toolchains, lkml
Hello, On Wed, Aug 17, 2022 at 11:54 PM Nick Desaulniers [off-list ref] wrote:
On Mon, Aug 15, 2022 at 8:29 PM [off-list ref] wrote:quoted
From: Menglong Dong <redacted> Sometimes, gcc will optimize the function by spliting it to two or more functions. In this case, kfree_skb_reason() is splited to kfree_skb_reason and kfree_skb_reason.part.0. However, the function/tracepoint trace_kfree_skb() in it needs the return address of kfree_skb_reason().Does the existing __noclone function attribute help at all here? If not, surely there's an attribute that's more precise than "disable most optimization outright." https://unix.stackexchange.com/questions/223013/function-symbol-gets-part-suffix-after-compilation https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute Perhaps noipa might also work here?
In my testing, both 'noclone' and 'noipa' both work! As for the '-fdisable-ipa-fnsplit', it seems it's not supported by gcc, and I failed to find any documentation of it. I think that the '__noclone' is exactly what I needed! Just like what saied in this link: https://stackoverflow.com/questions/34086769/purpose-of-function-attribute-noclone I appreciate your advice, and it seems it's not needed to add new attributes to the compiler_attributes.h. Thanks! Menglong Dong