kern/amd64: mu: Add pmap unmap function

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 40 insertions, 0 deletions

diff --git a/sys/arch/amd64/cpu/mmu.c b/sys/arch/amd64/cpu/mmu.c
index b709ee1..2be4b12 100644
--- a/sys/arch/amd64/cpu/mmu.c
+++ b/sys/arch/amd64/cpu/mmu.c
@@ -193,6 +193,27 @@ mu_pmap_map(struct mmu_vas *vas, uintptr_t pa, uintptr_t va,
 }
 
 int
+mu_pmap_unmap(struct mmu_vas *vas, uintptr_t va, pagesize_t ps)
+{
+    uintptr_t *pagetbl;
+    size_t index;
+
+    if (vas == NULL) {
+        return -EINVAL;
+    }
+
+    pagetbl = pmap_get_level(vas, va, false, PMAP_PML1);
+    if (pagetbl == NULL) {
+        return 0;
+    }
+
+    index = pmap_get_index(va, PMAP_PML1);
+    pagetbl[index] = 0;
+    pmap_invlpg(va);
+    return 0;
+}
+
+int
 mu_pmap_readvas(struct mmu_vas *vas)
 {
     __asmv(
diff --git a/sys/inc/mu/mmu.h b/sys/inc/mu/mmu.h
index da2a286..d9be17a 100644
--- a/sys/inc/mu/mmu.h
+++ b/sys/inc/mu/mmu.h
@@ -50,6 +50,15 @@ __strong int mu_pmap_map(
 );
 
 /*
+ * Destroy a virtual to physical address mapping
+ *
+ * @vas: Virtual addres space to unmap from
+ * @va: Virtual address to unmap
+ * @ps: Pagesize of region covered by virtual address
+ */
+__strong int mu_pmap_unmap(struct mmu_vas *vas, uintptr_t va, pagesize_t ps);
+
+/*
  * Copy the current VAS leaving the user-side
  * zeroed
  */
diff --git a/sys/mu/mmu_stub.c b/sys/mu/mmu_stub.c
index 586edd4..729303b 100644
--- a/sys/mu/mmu_stub.c
+++ b/sys/mu/mmu_stub.c
@@ -43,6 +43,16 @@ mu_pmap_map(struct mmu_vas *vas, uintptr_t pa, uintptr_t va, uint16_t prot,
 }
 
 __weak int
+mu_pmap_unmap(struct mmu_vas *vas, uintptr_t va, pagesize_t ps)
+{
+    (void)vas;
+    (void)va;
+    (void)ps;
+
+    return 0;
+}
+
+__weak int
 mu_pmap_forkvas(struct mmu_vas *result)
 {
     (void)result;