ld: use shared mappings for read-only elf segments

lib/libc/io/unistd/mmap.c

@@ -25,6 +25,21 @@ static vm_prot_t vm_prot_from_mmap_prot(int prot)
 	return vm_prot;
 }
 
+static vm_flags_t vm_flags_from_mmap_flags(int flags)
+{
+	vm_flags_t out = 0;
+
+	if (flags & MAP_PRIVATE) {
+		out |= VM_PRIVATE;
+	}
+
+	if (flags & (MAP_SHARED | MAP_SHARED_VALIDATE)) {
+		out |= VM_SHARED;
+	}
+
+	return out;
+}
+
 static int get_vmo_anon(
 	int fd,
 	int prot,
@@ -109,6 +124,7 @@ void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 	kern_status_t status = KERN_OK;
 	kern_handle_t self = KERN_HANDLE_INVALID,
 		      address_space = KERN_HANDLE_INVALID;
+	vm_flags_t vm_flags = vm_flags_from_mmap_flags(flags);
 
 	status = task_self(&self);
 	if (status != KERN_OK) {
@@ -146,6 +162,7 @@ void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 			vmo,
 			offset,
 			length,
+			vm_flags,
 			vm_prot,
 			&map_address);
 	} else {
@@ -155,6 +172,7 @@ void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 			vmo,
 			offset,
 			length,
+			vm_flags,
 			vm_prot,
 			&map_address);
 	}

lib/libc/malloc/heap.c

@@ -79,6 +79,7 @@ static kern_status_t expand_heap(heap_t *heap)
 		vmo,
 		0,
 		HEAP_EXPAND_INCREMENT,
+		VM_PRIVATE,
 		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
 		&base);
 

lib/libfs/context.c

@@ -73,6 +73,7 @@ struct fs_context *fs_context_create(struct fs_allocator *alloc)
 		ctx->ctx_temp_object,
 		0,
 		TEMP_OBJECT_SIZE,
+		VM_PRIVATE,
 		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
 		&temp_buffer);
 	kern_handle_close(address_space);

lib/libfs/interface/map.c

@@ -8,7 +8,6 @@
 #include <mango/handle.h>
 #include <mango/log.h>
 #include <mango/vm.h>
-#include <stdio.h>
 #include <sys/mman.h>
 
 static int create_file_mapping(

lib/liblaunch/elf.c

@@ -233,13 +233,15 @@ static enum launch_status map_executable(struct elf_image *image)
 
 		kern_handle_t vmo = image->e_image;
 		vm_prot_t prot = VM_PROT_USER;
+		vm_flags_t flags = VM_SHARED;
 		size_t offset = phdr.p_offset;
 
-		phdr.p_flags &PF_R && (prot |= VM_PROT_READ);
+		phdr.p_flags & PF_R && (prot |= VM_PROT_READ);
-		phdr.p_flags &PF_W && (prot |= VM_PROT_WRITE);
+		phdr.p_flags & PF_W && (prot |= VM_PROT_WRITE);
-		phdr.p_flags &PF_X && (prot |= VM_PROT_EXEC);
+		phdr.p_flags & PF_X && (prot |= VM_PROT_EXEC);
 		if (phdr.p_flags & PF_W) {
 			vmo = image->e_data;
+			flags = VM_PRIVATE;
 			offset = data_offset;
 			size_t tmp = 0;
 
@@ -267,6 +269,7 @@ static enum launch_status map_executable(struct elf_image *image)
 				vmo,
 				offset,
 				phdr.p_memsz,
+				flags,
 				prot,
 				NULL);
 		}
@@ -282,6 +285,7 @@ static enum launch_status map_executable(struct elf_image *image)
 				vmo,
 				offset,
 				phdr.p_memsz,
+				flags,
 				prot,
 				NULL);
 		}

lib/liblaunch/launch.c

@@ -183,6 +183,7 @@ enum launch_status launch_ctx_execute(
 		stack_vmo,
 		0,
 		STACK_SIZE,
+		VM_PRIVATE,
 		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
 		&remote_stack_buf);
 	kstatus = address_space_map(
@@ -191,6 +192,7 @@ enum launch_status launch_ctx_execute(
 		stack_vmo,
 		0,
 		STACK_SIZE,
+		VM_PRIVATE,
 		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
 		&local_stack_buf);
 	kern_handle_close(stack_vmo);

sys/ld/elf.c

@@ -147,7 +147,7 @@ static int map_image(struct elf_image *image)
 		}
 
 		int fd = image->e_fd;
-		int flags = MAP_PRIVATE | MAP_EXECUTABLE | MAP_FIXED;
+		int flags = MAP_SHARED | MAP_EXECUTABLE | MAP_FIXED;
 
 		if (phdr.p_flags & PF_W) {
 			fd = -1;