On 6/10/19 11:16 PM, Christoph Hellwig wrote: > Most of the patch is just stubbing out code not needed without page > tables, but there is an interesting detail in the signals implementation: > > - The normal RISC-V syscall ABI only implements rt_sigreturn as VDSO > entry point, but the ELF VDSO is not supported for nommu Linux. > We instead copy the code to call the syscall onto the stack.
On ARM we perform I/D cache synchronization after stack manipulation. OTOH, ARM port of uClibc provides SA_RESTORER with intention to avoid manipulation with stack and cache maintenance operations (yet kernel still performs such manipulation, IIUC, for backward compatibility) Cheers Vladimir
