From f317b0de5f8b3a5d8719e7d30433aa0b454dd4a8 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Fri, 16 Feb 2024 13:01:30 +0100
Subject: [PATCH 1/3] Don't error if a kernel page is already mapped to the
 correct frame

This can happen if one frame contains two loadable sections.
---
 src/page_table.rs | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/page_table.rs b/src/page_table.rs
index ed2ac136..c28890fe 100644
--- a/src/page_table.rs
+++ b/src/page_table.rs
@@ -96,8 +96,15 @@ pub(crate) fn map_segment(
             for frame in PhysFrame::range_inclusive(start_frame, end_frame) {
                 let offset = frame - start_frame;
                 let page = start_page + offset;
-                unsafe { map_page(page, frame, page_table_flags, page_table, frame_allocator)? }
-                    .flush();
+                match unsafe {
+                    map_page(page, frame, page_table_flags, page_table, frame_allocator)
+                } {
+                    Ok(flusher) => flusher.flush(),
+                    Err(MapToError::PageAlreadyMapped(to)) if to == frame => {
+                        // nothing to do, page is already mapped to the correct frame
+                    }
+                    Err(err) => return Err(err),
+                }
             }
 
             if mem_size > file_size {

From 949a297d91bb33bc5bf374a090c495b51371d52a Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Fri, 16 Feb 2024 13:03:05 +0100
Subject: [PATCH 2/3] Fix: unmap temp page again to enable multiple bss-like
 sections

---
 src/page_table.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/page_table.rs b/src/page_table.rs
index c28890fe..c666de79 100644
--- a/src/page_table.rs
+++ b/src/page_table.rs
@@ -124,7 +124,7 @@ pub(crate) fn map_segment(
                     unsafe {
                         map_page(
                             temp_page.clone(),
-                            new_frame.clone(),
+                            new_frame,
                             page_table_flags,
                             page_table,
                             frame_allocator,
@@ -152,6 +152,11 @@ pub(crate) fn map_segment(
                         });
                     }
 
+                    // unmap temp page again
+                    let (new_frame, flusher) = page_table.unmap(temp_page).unwrap();
+                    flusher.flush();
+
+                    // map last page to new frame
                     unsafe {
                         map_page(
                             last_page,

From 9209b0c34cd9446810b9fceef4de0091292471d3 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Fri, 16 Feb 2024 13:06:47 +0100
Subject: [PATCH 3/3] Update changelog for #422

---
 Changelog.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Changelog.md b/Changelog.md
index 2c409bbf..24cd6238 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,10 @@
 # Unreleased
 
+
+- [Fix map errors during kernel loading](https://github.com/rust-osdev/bootloader/pull/422)
+    - Don't error if a kernel page is already mapped to the correct frame
+    - Fix: unmap temp page again to enable multiple bss-like sections
+
 # 0.9.25 – 2024-02-16
 
 - [Fix data layout for custom targets for LLVM 18](https://github.com/rust-osdev/bootloader/pull/421)