Hi Rolf, On 1/29/22 15:55, Rolf Eike Beer wrote: > Am Samstag, 29. Januar 2022, 12:03:42 CET schrieb Helge Deller: >> Add minimal vDSO support, which provides the signal trampoline helpers, but >> none of the userspace syscall helpers like time functions. >> >> The big benefit of this vDSO implementation is, that we now don't need an >> executeable stack any longer. PA-RISC is one of the last architectures where >> an executeable stack was needed in oder to implement the signal trampolines >> by putting assembly instructions on the stack which then gets executed. >> With this implementation the kernel will utilize the assembler statements >> in the vDSO page which is mapped into each userspace application instead >> and just put the pointers to the signal information on the stack. >> By dropping the need for executable stacks we now avoid running into issues >> with various applications in Debian which nowadays want non-executable >> stacks for security reasons. Additionally, alternative stacks are supported >> better as well. >> >> This code is based on an initial implementation by Randolph Chung from 2006: >> https://lore.kernel.org/linux-parisc/4544A34A.6080700@xxxxxxxxx/ >> >> I did the porting and lifted the code to current code base. Dave fixed the >> unwind code so that gdb and glibc are able to backtrace through the code. An >> additional patch to gdb will be pushed upstream by Dave. > > There are a few extra newlines in the first few files which you may or may not > want to remove. Thanks for noticing. I fixed them up now. > OTOH I would split out the change to mm_context_t into it's own patch, without > adding the vdso_base there. This would reduce the overall size of the actual > vdso patch and eases review. Yes, maybe I'll do that. Not sure yet. Helge
