From 01001c2aa2216c92603e1bdc334613e5adcacb04 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 21 Nov 2025 22:45:41 -0500
Subject: kern/amd64: mu: Add pmap unmap function

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/cpu/mmu.c | 21 +++++++++++++++++++++
 sys/inc/mu/mmu.h         |  9 +++++++++
 sys/mu/mmu_stub.c        | 10 ++++++++++
 3 files changed, 40 insertions(+)

(limited to 'sys')

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
@@ -192,6 +192,27 @@ mu_pmap_map(struct mmu_vas *vas, uintptr_t pa, uintptr_t va,
     return 0;
 }
 
+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)
 {
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
@@ -49,6 +49,15 @@ __strong int mu_pmap_map(
     uint16_t prot, pagesize_t ps
 );
 
+/*
+ * 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
@@ -42,6 +42,16 @@ mu_pmap_map(struct mmu_vas *vas, uintptr_t pa, uintptr_t va, uint16_t prot,
     (void)ps;
 }
 
+__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)
 {
-- 
cgit v1.2.3