On Wed, Oct 16, 2024 at 08:47:20AM +0900, Masami Hiramatsu wrote: > On Tue, 15 Oct 2024 20:39:06 +0200 > Heiko Carstens <hca@xxxxxxxxxxxxx> wrote: > > > That would make things much simpler... e.g. your new patch is also > > writing r3 to fregs, why? > > BTW, according to the document [1], r3 is for "return value 1", isn't it > used usually? > > [1] https://www.kernel.org/doc/Documentation/s390/Debugging390.txt That is true for the 32 bit ABI, but not for the 64 bit ABI which we care about. Besides other this is also the reason why I removed the above file five years ago: f62f7dcbf023 ("Documentation/s390: remove outdated debugging390 documentation"). If you really want to understand the 64 bit s390 ABI then you need to look at https://github.com/IBM/s390x-abi . A PDF file of the latest release is available at https://github.com/IBM/s390x-abi/releases/download/v1.6.1/lzsabi_s390x.pdf See section "1.2.5. Return Values" for return value handling. All of that said, I would appreciate if you would just merge the provided patch, unless there is a reason for not doing that. Chances are that I missed something with all the recent fregs vs ptregs changes.
