feat(mm): initial mm work

2026-10-29 06:28:21 +00:00 · 2026-04-03 17:01:26 -04:00
parent c7c145f4e3
commit 5b60f08db5
11 changed files with 709 additions and 3 deletions
@@ -0,0 +1,86 @@
+const b = @import("base");
+const pl = b.pl;
+const mm = b.mm;
+const mi = mm.private;
+
+extern var text_start_addr: u8;
+extern var text_end_addr: u8;
+extern var rodata_start_addr: u8;
+extern var rodata_end_addr: u8;
+extern var data_start_addr: u8;
+extern var data_end_addr: u8;
+
+fn map_kernel(boot_info: *pl.BootInfo) void {
+    const kaddr = boot_info.kernel_address;
+
+    const text_start = @intFromPtr(&text_start_addr);
+    const text_end = @intFromPtr(&text_end_addr);
+    const rodata_start = @intFromPtr(&rodata_start_addr);
+    const rodata_end = @intFromPtr(&rodata_end_addr);
+    const data_start = @intFromPtr(&data_start_addr);
+    const data_end = @intFromPtr(&data_end_addr);
+
+    const text_size = text_end - text_start;
+    const rodata_size = rodata_end - rodata_start;
+    const data_size = data_end - data_start;
+
+    mi.kernel_pmap.map_contiguous_range(text_start, kaddr.physical_base + (text_start - kaddr.virtual_base), text_size, .{
+        .read = true,
+        .execute = true,
+        .global = true,
+    });
+
+    mi.kernel_pmap.map_contiguous_range(rodata_start, kaddr.physical_base + (rodata_start - kaddr.virtual_base), rodata_size, .{
+        .read = true,
+        .global = true,
+    });
+
+    mi.kernel_pmap.map_contiguous_range(data_start, kaddr.physical_base + (data_start - kaddr.virtual_base), data_size, .{
+        .read = true,
+        .write = true,
+        .global = true,
+    });
+
+    mi.kernel_pmap.map_contiguous_range(mm.p2v(0), 0, mi.impl.hhdm_minimum_max_address, .{
+        .read = true,
+        .write = true,
+        .global = true,
+    });
+
+    // Now go through every usable entry and map to the HHDM every part that isnt covered by [0, hhdm_minimum_max_address).
+    // We can't blindly map until the maximum usable physical address because on some CPUs this might cause MCEs.
+    // See https://github.com/torvalds/linux/commit/66520ebc2df3fe52eb4792f8101fac573b766baf
+    for (0..boot_info.memory_map.entry_count) |i| {
+        const entry = boot_info.memory_map.entries[i];
+
+        if ((entry.type != .Free and entry.type != .LoaderReclaimable) or entry.size < mm.page_size) {
+            continue;
+        }
+
+        if (entry.base + entry.size <= mi.impl.hhdm_minimum_max_address) {
+            continue;
+        }
+
+        var entry_start = entry.base;
+        var entry_size = entry.size;
+
+        if (entry.base < mi.impl.hhdm_minimum_max_address) {
+            const adjust = mi.impl.hhdm_minimum_max_address - entry.base;
+            entry_start += adjust;
+            entry_size -= adjust;
+        }
+
+        mi.kernel_pmap.map_contiguous_range(mm.p2v(entry_start), entry_start, entry_size, .{
+            .read = true,
+            .write = true,
+            .global = true,
+        });
+    }
+}
+
+pub fn init(boot_info: *pl.BootInfo) linksection(b.init) void {
+    mi.phys.init(boot_info);
+    map_kernel(boot_info);
+    mi.kernel_pmap.activate();
+    mi.phys.init_pfndb();
+}