On Tue 2024-01-09 21:24:56, Marcos Paulo de Souza wrote: > The test proves that a syscall can be livepatched. It is interesting > because syscalls are called a tricky way. Also the process gets > livepatched either when sleeping in the userspace or when entering > or leaving the kernel space. > > The livepatch is a bit tricky: > 1. The syscall function name is architecture specific. Also > ARCH_HAS_SYSCALL_WRAPPER must be taken in account. > > 2. The syscall must stay working the same way for other processes > on the system. It is solved by decrementing a counter only > for PIDs of the test processes. It means that the test processes > has to call the livepatched syscall at least once. > > The test creates one userspace process per online cpu. The processes > are calling getpid in a busy loop. The intention is to create random > locations when the livepatch gets enabled. Nothing is guarantted. > The magic is in the randomness. > > Reviewed-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> > Signed-off-by: Marcos Paulo de Souza <mpdesouza@xxxxxxxx> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Best Regards, Petr
