From 2cf6fe3f4d0811f1d62ed3ba73d15c8a187f600f Mon Sep 17 00:00:00 2001
From: Freya Murphy <freya@freyacat.org>
Date: Fri, 25 Apr 2025 18:42:30 -0400
Subject: mem_get_phys fn

---
 kernel/include/comus/memory.h | 13 +++++++++++++
 kernel/memory/memory.c        |  5 +++++
 kernel/memory/paging.c        | 23 +++++++++++++++++------
 kernel/memory/physalloc.c     |  3 ++-
 4 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/kernel/include/comus/memory.h b/kernel/include/comus/memory.h
index 92525da..408521b 100644
--- a/kernel/include/comus/memory.h
+++ b/kernel/include/comus/memory.h
@@ -123,6 +123,13 @@ void *mem_mapaddr(mem_ctx_t ctx, void *phys, void *virt, size_t len,
  */
 void mem_unmapaddr(mem_ctx_t ctx, const void *virt);
 
+/**
+ * Gets the physical address for a given vitural address
+ * @param ctx - the memory context
+ * @param virt - the vitural address
+ */
+void *mem_get_phys(mem_ctx_t ctx, const void *virt);
+
 /**
  * Allocate a single page of memory with the given paging structure
  *
@@ -194,6 +201,12 @@ void *kmapaddr(void *phys, void *virt, size_t len, unsigned int flags);
  */
 void *kmapuseraddr(mem_ctx_t ctx, const void *virt, size_t len);
 
+/**
+ * Gets the physical address for a given vitural address
+ * @param virt - the vitural address
+ */
+void *kget_phys(const void *virt);
+
 /**
  * Unmaps mapped address from the kmapaddr function
  * @param virt - the vitural address returned from kmapaddr
diff --git a/kernel/memory/memory.c b/kernel/memory/memory.c
index 295823e..bd3e06b 100644
--- a/kernel/memory/memory.c
+++ b/kernel/memory/memory.c
@@ -31,6 +31,11 @@ void kunmapaddr(const void *virt)
 	mem_unmapaddr(kernel_mem_ctx, virt);
 }
 
+void *kget_phys(const void *virt)
+{
+	return mem_get_phys(kernel_mem_ctx, virt);
+}
+
 void *kalloc_page(void)
 {
 	return mem_alloc_page(kernel_mem_ctx, F_PRESENT | F_WRITEABLE);
diff --git a/kernel/memory/paging.c b/kernel/memory/paging.c
index 5a0b285..d54a26b 100644
--- a/kernel/memory/paging.c
+++ b/kernel/memory/paging.c
@@ -5,6 +5,7 @@
 #include "physalloc.h"
 #include "paging.h"
 #include "memory.h"
+#include <stdint.h>
 
 // PAGE MAP LEVEL 4 ENTRY
 struct pml4e {
@@ -753,15 +754,11 @@ void *mem_mapaddr(mem_ctx_t ctx, void *phys, void *virt, size_t len,
 void *kmapuseraddr(mem_ctx_t ctx, const void *vADDR, size_t len)
 {
 	char *pADDR;
-	volatile struct pte *vPTE;
 
-	vPTE = page_locate((volatile struct pml4 *)ctx->pml4, vADDR);
-	if (vPTE == NULL)
+	pADDR = mem_get_phys(ctx, vADDR);
+	if (pADDR == NULL)
 		return NULL;
 
-	pADDR = (void *)((uintptr_t)vPTE->address << 12);
-	pADDR += ((uint64_t)vADDR % PAGE_SIZE);
-
 	return kmapaddr(pADDR, NULL, len, F_PRESENT | F_WRITEABLE);
 }
 
@@ -776,6 +773,20 @@ void mem_unmapaddr(mem_ctx_t ctx, const void *virt)
 	unmap_pages(&kernel_pml4, virt, pages);
 }
 
+void *mem_get_phys(mem_ctx_t ctx, const void *vADDR)
+{
+	char *pADDR;
+	volatile struct pte *vPTE;
+
+	vPTE = page_locate((volatile struct pml4 *)ctx->pml4, vADDR);
+	if (vPTE == NULL)
+		return NULL;
+
+	pADDR = (void *)((uintptr_t)vPTE->address << 12);
+	pADDR += ((uint64_t)vADDR % PAGE_SIZE);
+	return pADDR;
+}
+
 void *mem_alloc_page(mem_ctx_t ctx, unsigned int flags)
 {
 	return mem_alloc_pages(ctx, 1, flags);
diff --git a/kernel/memory/physalloc.c b/kernel/memory/physalloc.c
index 01464ee..48d2e3f 100644
--- a/kernel/memory/physalloc.c
+++ b/kernel/memory/physalloc.c
@@ -88,7 +88,8 @@ void *alloc_phys_pages_exact(size_t pages)
 	if (bitmap == NULL || page_start == NULL) {
 		// temporary bump allocator
 		void *addr = (void *)memory_start;
-        assert(pages == 1, "caller expects more pages, but is only getting one");
+		assert(pages == 1,
+			   "caller expects more pages, but is only getting one");
 		memory_start += PAGE_SIZE;
 		return addr;
 	}
-- 
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