syscall

arch/x86_64/sched.c

@@ -5,7 +5,6 @@
 #include <zinnia/pmap.h>
 #include <zinnia/sched.h>
 #include <zinnia/vas.h>
-#include <zinnia/virt.h>
 #include <bits/sched.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -21,7 +20,7 @@ struct task_frame {
 };
 
 [[__naked]]
-static void perform_switch(uint64_t* old_rsp, uint64_t new_rsp) {
+static struct task* perform_switch(uint64_t* old_rsp, uint64_t new_rsp, struct task* prev) {
     asm volatile(
         "sub rsp, 0x30\n" // Make room for all regs (except RIP).
         "mov [rsp + %c0], rbx\n"
@@ -39,7 +38,7 @@ static void perform_switch(uint64_t* old_rsp, uint64_t new_rsp) {
         "mov r14, [rsp + %c4]\n"
         "mov r15, [rsp + %c5]\n"
         "add rsp, 0x30\n"
-        "call %c6\n"
+        "mov rax, rdx\n"
         "ret" // This will conveniently move us to the RIP we put at this stack entry.
         :
         : "i"(offsetof(struct task_frame, rbx)),
@@ -47,13 +46,12 @@ static void perform_switch(uint64_t* old_rsp, uint64_t new_rsp) {
           "i"(offsetof(struct task_frame, r12)),
           "i"(offsetof(struct task_frame, r13)),
           "i"(offsetof(struct task_frame, r14)),
-          "i"(offsetof(struct task_frame, r15)),
-          "i"(irq_unlock)
+          "i"(offsetof(struct task_frame, r15))
         : "memory"
     );
 }
 
-void arch_sched_switch(struct task* from, struct task* to) {
+struct task* arch_sched_switch(struct task* from, struct task* to) {
     struct arch_percpu* cpu = &percpu_get()->arch;
     struct arch_task_context* from_ctx = &from->context;
     struct arch_task_context* to_ctx = &to->context;
@@ -87,7 +85,7 @@ void arch_sched_switch(struct task* from, struct task* to) {
         asm_wrmsr(MSR_KERNEL_GS_BASE, to_ctx->gs_base);
     }
 
-    perform_switch(&from_ctx->rsp, to_ctx->rsp);
+    return perform_switch(&from_ctx->rsp, to_ctx->rsp, from);
 }
 
 [[__naked]]