From 73cf3eddd480f2bd7e987c58da82c243861a5314 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex.auvolat@ens.fr>
Date: Sat, 14 Feb 2015 22:37:35 +0100
Subject: Many things :

- fix context switching (it actually worked only because of optimizations!)
- complete mchmap implementation
- adjust elf parser to load binaries correctly even without FM_MMAP
---
 src/kernel/user/elf.c     | 21 ++++++++++++++-------
 src/kernel/user/process.c | 43 ++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 54 insertions(+), 10 deletions(-)

(limited to 'src/kernel/user')

diff --git a/src/kernel/user/elf.c b/src/kernel/user/elf.c
index 00b3c54..a3dada7 100644
--- a/src/kernel/user/elf.c
+++ b/src/kernel/user/elf.c
@@ -34,9 +34,10 @@ proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
 		if (read_phdr_r != sizeof(elf_phdr_t)) goto error;
 
 		if (phdr.p_type == PT_LOAD) {
-			if (phdr.p_flags & PF_W) {
-				mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
+			if ((phdr.p_flags & PF_W) || !(file_get_mode(f) & FM_MMAP)) {
+				bool mmap_ok = mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
 						((phdr.p_flags & PF_R) ? MM_READ : 0) | MM_WRITE);
+				if (!mmap_ok) goto error;
 
 				size_t read_r = file_read(f, phdr.p_offset, phdr.p_filesz, (char*)phdr.p_vaddr);
 				if (read_r != phdr.p_filesz) goto error;
@@ -44,16 +45,22 @@ proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
 				if (phdr.p_memsz > phdr.p_filesz) {
 					memset((char*)phdr.p_vaddr + phdr.p_filesz, 0, phdr.p_memsz - phdr.p_filesz);
 				}
+
+				if (!(phdr.p_flags & PF_W)) {
+					bool mchmap_ok = mchmap(process, (void*)phdr.p_vaddr,
+							((phdr.p_flags & PF_R) ? MM_READ : 0));
+					if (!mchmap_ok) goto error;
+				}
 			} else {
 				if (phdr.p_filesz != phdr.p_memsz) {
 					dbg_printf("Strange ELF file...\n");
-					goto error;
 				}
 
-				mmap_file(process,
-						f, phdr.p_offset,
-						(void*)phdr.p_vaddr, phdr.p_memsz,
-						((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
+				bool mmap_ok = mmap_file(process,
+							f, phdr.p_offset,
+							(void*)phdr.p_vaddr, phdr.p_memsz,
+							((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
+				if (!mmap_ok) goto error;
 			}
 		}
 	}
diff --git a/src/kernel/user/process.c b/src/kernel/user/process.c
index a4383f7..72042d9 100644
--- a/src/kernel/user/process.c
+++ b/src/kernel/user/process.c
@@ -177,6 +177,10 @@ bool mmap_file(process_t *proc, fs_handle_t *h, size_t offset, void* addr, size_
 
 	if ((uint32_t)addr & (~PAGE_MASK)) return false;
 
+	int fmode = file_get_mode(h);
+	if (!(fmode & FM_MMAP) || !(fmode & FM_READ)) return false;
+	if ((mode & MM_WRITE) && !(fmode & FM_WRITE)) return false;
+
 	user_region_t *r = (user_region_t*)malloc(sizeof(user_region_t));
 	if (r == 0) return false;
 
@@ -212,6 +216,24 @@ bool mchmap(process_t *proc, void* addr, int mode) {
 	if (r == 0) return false;
 	
 	r->mode = mode;
+
+	// change mode on already mapped pages
+	pagedir_t *save_pd = get_current_pagedir();
+	switch_pagedir(proc->pd);
+	for (void* it = r->addr; it < r->addr + r->size; r += PAGE_SIZE) {
+		uint32_t ent = pd_get_entry(it);
+		uint32_t frame = pd_get_frame(it);
+
+		if (ent & PTE_PRESENT) {
+			bool can_w = (ent & PTE_RW) != 0;
+			bool should_w = (mode & MM_WRITE) != 0;
+			if (can_w != should_w) {
+				pd_map_page(it, frame, should_w);
+			}
+		}
+	}
+	switch_pagedir(save_pd);
+
 	return true;
 }
 
@@ -230,12 +252,27 @@ bool munmap(process_t *proc, void* addr) {
 		}
 	}
 
-	// TODO : write modified pages back to file!
-	// TODO : unmap mapped page for region...
+	btree_remove_v(proc->regions_idx, r->addr, r);
+
+	// Unmap that stuff
+	pagedir_t *save_pd = get_current_pagedir();
+	switch_pagedir(proc->pd);
+	for (void* it = r->addr; it < r->addr + r->size; r += PAGE_SIZE) {
+		uint32_t ent = pd_get_entry(it);
+		uint32_t frame = pd_get_frame(it);
+
+		if (ent & PTE_PRESENT) {
+			if ((ent & PTE_DIRTY) && (r->mode & MM_WRITE) && r->file != 0) {
+				file_write(r->file, it - r->addr + r->file_offset, PAGE_SIZE, it);
+			}
+			pd_unmap_page(it);
+			frame_free(frame, 1);
+		}
+	}
+	switch_pagedir(save_pd);
 
 	if (r->file != 0) unref_file(r->file);
 
-	btree_remove_v(proc->regions_idx, r->addr, r);
 	free(r);
 
 	return true;
-- 
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