From 39d4aa3a106f898d09b98e41ef44fb4891eda1ce Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 13 Mar 2024 21:40:06 -0400
Subject: kernel/amd64: machdep: Add context switch helper

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/amd64/machdep.c | 13 +++++++++++++
 sys/include/sys/machdep.h      |  1 +
 sys/kern/kern_sched.c          |  4 ++++
 3 files changed, 18 insertions(+)

(limited to 'sys')

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 0789f5a..5327189 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -179,6 +179,19 @@ processor_init_pcb(struct proc *proc)
     amd64_fxsave(pcb->fpu_state);
     return 0;
 }
+
+void
+processor_switch_to(struct proc *old_td, struct proc *new_td)
+{
+    struct pcb *old_pcb = (old_td != NULL) ? &old_td->pcb : NULL;
+    struct pcb *new_pcb = &new_td->pcb;
+
+    if (old_pcb != NULL) {
+        amd64_fxsave(old_pcb->fpu_state);
+    }
+    amd64_fxrstor(new_pcb->fpu_state);
+}
+
 void
 processor_init(void)
 {
diff --git a/sys/include/sys/machdep.h b/sys/include/sys/machdep.h
index 151d5f8..b6edf14 100644
--- a/sys/include/sys/machdep.h
+++ b/sys/include/sys/machdep.h
@@ -39,6 +39,7 @@
 #define MAXCPUS 32
 
 int processor_init_pcb(struct proc *proc);
+void processor_switch_to(struct proc *old_td, struct proc *new_td);
 void processor_init(void);
 void processor_halt(void);
 void intr_mask(void);
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index f8f09c4..bc96146 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -311,6 +311,10 @@ sched_context_switch(struct trapframe *tf)
         sched_enqueue_td(td);
     }
 
+    /* Do architecture specific context switch logic */
+    processor_switch_to(td, next_td);
+
+    /* Done, switch out our vas and oneshot */
     pmap_switch_vas(vm_get_ctx(), next_td->addrsp);
     sched_oneshot();
 }
-- 
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