diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/fbos/sched.h | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/include/fbos/sched.h b/include/fbos/sched.h index e05d0a1..3d35f9f 100644 --- a/include/fbos/sched.h +++ b/include/fbos/sched.h @@ -12,18 +12,30 @@ enum task_id { TASK_FIZZBUZZ = 3, }; -// TODO: if we only care about the absolute address, it can be further -// simplified. +// All the information we need to grab for processes. struct task_struct { + // The stack allocated for the process. As you can see when initializing + // each process on `kernel/main.c`, we go over the top for its size. There + // is also the fact that we need to keep this as the first attribue to allow + // for simple `sp` values. void *stack; - const void *addr; - uint64_t entry_offset; + + // The address for the binary entry. + const void *entry_addr; }; // Tasks available on this kernel. extern struct task_struct tasks[4]; -// Switch execution to the given task id. -void switch_to(int task_id); +// Switch execution to the given U-mode task. Note that this function will not +// do the actual returning, but it prepares the relevant registers for an +// eventual jump. +__kernel __always_inline void switch_to(int task_id) +{ + asm volatile("csrc sstatus, %0\n\t" + "mv ra, %1\n\t" + "csrw sepc, ra" ::"r"(1 << 8), + "r"(tasks[task_id].entry_addr)); +} #endif // __FBOS_SCHED_H_ |