core: Get platform memory map and exit boot services

Signed-off-by: Ian M. <ian@aptel.org>

3 files changed, 112 insertions, 0 deletions

diff --git a/core/memmap.c b/core/memmap.c
new file mode 100644
index 0000000..f02e538
--- /dev/null
+++ b/core/memmap.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2026, Apollo Telephone Laboratories.
+ * Provided under the BSD-3 clause.
+ */
+
+#include <sboot/memmap.h>
+
+EFI_STATUS
+SBootGetMemmap(OUT PLATFORM_MEMMAP *Map)
+{
+    EFI_STATUS Status;
+
+    if (Map == NULL) {
+        return EFI_INVALID_PARAMETER;
+    }
+
+    Map->Map = NULL;
+    Map->MapSize = 0;
+    Map->MapKey = 0;
+    Map->DescriptorSize = 0;
+    Map->DescriptorVersion = 0;
+
+    Status = uefi_call_wrapper(
+        gBS->GetMemoryMap,
+        5,
+        &Map->MapSize,
+        Map->Map,
+        &Map->MapKey,
+        &Map->DescriptorSize,
+        &Map->DescriptorVersion
+    );
+
+    Map->Map = AllocatePool(Map->MapSize);
+    if (Map->Map == NULL) {
+        return EFI_OUT_OF_RESOURCES;
+    }
+
+    /*
+     * We have to call this twice as the act of allocating memory
+     * alters the memory map.
+     */
+    for (UINTN Idx = 0; Idx < 2; ++Idx) {
+        Status = uefi_call_wrapper(
+            gBS->GetMemoryMap,
+            5,
+            &Map->MapSize,
+            Map->Map,
+            &Map->MapKey,
+            &Map->DescriptorSize,
+            &Map->DescriptorVersion
+        );
+
+        if (!EFI_ERROR(Status)) {
+            break;
+        }
+    }
+
+    if (EFI_ERROR(Status)) {
+        Print(L"fatal: failed to get memory map\n");
+    }
+
+    return EFI_SUCCESS;
+}
diff --git a/core/sboot.c b/core/sboot.c
index 604c768..53366a0 100644
--- a/core/sboot.c
+++ b/core/sboot.c
@@ -7,11 +7,13 @@
 #include <efilib.h>
 #include <sboot/sboot.h>
 #include <sboot/config.h>
+#include <sboot/memmap.h>
 #include <sboot/fwi.h>
 #include <sboot/file.h>
 
 /* Private globals */
 static UINT8 *KernelBin = NULL;
+static PLATFORM_MEMMAP MemMap;
 
 /* Globals */
 EFI_FILE_HANDLE gBootVolume;
@@ -50,5 +52,22 @@ efi_main(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
         Hcf();
     }
 
+    Status = SBootGetMemmap(&MemMap);
+    if (EFI_ERROR(Status)) {
+        Hcf();
+    }
+
+    /* Get out of here! */
+    Status = uefi_call_wrapper(
+        gBS->ExitBootServices,
+        2,
+        ImageHandle,
+        MemMap.MapKey
+    );
+
+    if (EFI_ERROR(Status)) {
+        Hcf();
+    }
+
     for (;;);
 }
diff --git a/head/sboot/memmap.h b/head/sboot/memmap.h
new file mode 100644
index 0000000..daad502
--- /dev/null
+++ b/head/sboot/memmap.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2026, Apollo Telephone Laboratories.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef _SBOOT_MEMMAP_H_
+#define _SBOOT_MEMMAP_H_ 1
+
+#include <efi.h>
+#include <efilib.h>
+
+/*
+ * EFI memory map
+ */
+typedef struct {
+    EFI_MEMORY_DESCRIPTOR *Map;
+    UINTN MapSize;
+    UINTN MapKey;
+    UINTN DescriptorSize;
+    UINT32 DescriptorVersion;
+} PLATFORM_MEMMAP;
+
+/*
+ * Obtain the platform memory map
+ *
+ * @Map:  Result is written here
+ */
+EFI_STATUS SBootGetMemmap(OUT PLATFORM_MEMMAP *Map);
+
+#endif  /* !_SBOOT_MEMMAP_H_ */