sylveos

commit 0114e36802535d7acfd9e7f98e1810defe4d6d5b
parent e69b68e0abbb1777e8d83267057d60861049c7c5
Author: Sylvia Ivory <git@sivory.net>
Date:   Sat, 14 Mar 2026 16:28:43 -0700

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Diffstat:
M
sylveos/memory.zig
 | 
12
++++++++++++
M
sylveos/pages.zig
 | 
9
+++++++++

2 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/sylveos/memory.zig b/sylveos/memory.zig
@@ -7,6 +7,8 @@ const pinned = pi.pinned;
 const mmu = pi.mmu;
 
 pub const MB: u32 = 1024 * 1024;
+pub const KB64: u32 = 1024 * 32;
+pub const KB4: u32 = 1024 * 4;
 
 extern const __program_start__: u32;
 extern const __program_end__: u32;
@@ -196,3 +198,13 @@ pub fn translate(va: u32) !u32 {
 
     return physical_base | offset;
 }
+
+pub fn request_1mb(alloc: std.mem.Allocator) ![]u8 {
+    return try alloc.alignedAlloc(u8, std.mem.Alignment.fromByteUnits(MB), MB);
+}
+pub fn request_64kb(alloc: std.mem.Allocator) ![]u8 {
+    return try alloc.alignedAlloc(u8, std.mem.Alignment.fromByteUnits(KB64), KB64);
+}
+pub fn request_4kb(alloc: std.mem.Allocator) ![]u8 {
+    return try alloc.alignedAlloc(u8, std.mem.Alignment.fromByteUnits(KB4), KB4);
+}
diff --git a/sylveos/pages.zig b/sylveos/pages.zig
@@ -1,6 +1,8 @@
 const std = @import("std");
 const pi = @import("pi");
 
+const memory = @import("./memory.zig");
+
 const mmu = pi.mmu;
 const pt = pi.pt;
 
@@ -35,6 +37,7 @@ pub const Error = error{
     TossingSection,
     Map64To4,
     Map4To64,
+    Unaligned,
 } || std.mem.Allocator.Error;
 
 // XKCD 927
@@ -65,6 +68,8 @@ fn va_to_index(va: u32) usize {
 }
 
 pub fn map_1mb(self: *Self, va: u32, pa: u32, attr: Attributes) !void {
+    if (std.mem.isAligned(pa, memory.MB)) return Error.Unaligned;
+
     // Whole section, yippee
     // Just check we aren't chucking a coarse page
     const idx = va_to_index(va);
@@ -92,6 +97,8 @@ pub fn map_1mb(self: *Self, va: u32, pa: u32, attr: Attributes) !void {
 }
 // Assume user isn't stupid and tries to map 4kb then 64kb
 pub fn map_64kb(self: *Self, va: u32, pa: u32, attr: Attributes) !void {
+    if (std.mem.isAligned(pa, memory.KB64)) return Error.Unaligned;
+
     const idx = va_to_index(va);
     var current = &self.sectors[idx];
 
@@ -133,6 +140,8 @@ pub fn map_64kb(self: *Self, va: u32, pa: u32, attr: Attributes) !void {
     mmu.sync_pte();
 }
 pub fn map_4kb(self: *Self, va: u32, pa: u32, attr: Attributes) !void {
+    if (std.mem.isAligned(pa, memory.KB4)) return Error.Unaligned;
+
     const idx = va_to_index(va);
     var current = &self.sectors[idx];