Added basic shared memory support

This will be improved soon. It's very insecure right now.

3 files changed, 101 insertions, 42 deletions

diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index d14bd81..a8e7e22 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -8,6 +8,7 @@
 #include <mem.h>
 #include <mm.h>
 #include <print.h>
+#include <random.h>
 
 static struct page_dir kernel_dir ALIGNED(PAGE_SIZE) = { 0 };
 static struct page_table kernel_tables[PAGE_KERNEL_COUNT] ALIGNED(PAGE_SIZE) = { 0 };
@@ -353,7 +354,7 @@ void *memory_alloc(struct page_dir *dir, u32 size, u32 flags)
 	return (void *)vaddr;
 
 err:
-	printf("Memory allocation error!\n");
+	print("Memory allocation error!\n");
 	return NULL;
 }
 
@@ -374,10 +375,96 @@ void *memory_alloc_identity(struct page_dir *dir, u32 flags)
 	return 0;
 }
 
+#define SHARED_MEMORY_MAX 128
+struct shared_memory {
+	u32 id;
+	u32 refs;
+	u8 used;
+	struct memory_range prange;
+};
+static struct shared_memory shmem[SHARED_MEMORY_MAX] = { 0 };
+u32 memory_shalloc(struct page_dir *dir, u32 size, u32 flags)
+{
+	u32 slot = SHARED_MEMORY_MAX + 1;
+
+	for (u32 i = 0; i < SHARED_MEMORY_MAX; i++) {
+		if (!shmem[i].used) {
+			slot = i;
+			break;
+		}
+	}
+
+	if (slot >= SHARED_MEMORY_MAX)
+		return 0;
+
+	void *addr = memory_alloc(dir, size, flags);
+	if (!addr)
+		return 0;
+
+	// TODO: Verify that shid isn't used already
+	// TODO: Check for colliding prange
+	u32 shid = rand() + 1;
+	shmem[slot].id = shid;
+	shmem[slot].used = 1;
+	shmem[slot].prange = memory_range(virtual_to_physical(dir, (u32)addr), size);
+
+	return shid;
+}
+
+static struct shared_memory memory_shresolve_range(struct memory_range prange)
+{
+	for (u32 i = 0; i < SHARED_MEMORY_MAX; i++) {
+		if (!shmem[i].used)
+			continue;
+
+		struct memory_range shrange = shmem[i].prange;
+		if (prange.base < shrange.base + shrange.size &&
+		    prange.base + prange.size > shrange.base)
+			return shmem[i];
+	}
+
+	return (struct shared_memory){ 0, 0, 0, memory_range(0, 0) };
+}
+
+static struct shared_memory memory_shresolve_id(u32 shid)
+{
+	for (u32 i = 0; i < SHARED_MEMORY_MAX; i++) {
+		if (!shmem[i].used)
+			continue;
+
+		if (shmem[i].id == shid)
+			return shmem[i];
+	}
+
+	return shmem[0];
+}
+
+void *memory_shaccess(struct page_dir *dir, u32 shid)
+{
+	struct shared_memory sh = memory_shresolve_id(shid);
+	struct memory_range prange = sh.prange;
+	if (sh.used == 0 || prange.base == 0 || prange.size == 0)
+		return NULL;
+
+	sh.refs++;
+
+	return (void *)virtual_alloc(dir, prange, MEMORY_CLEAR | MEMORY_USER).base;
+}
+
+// TODO: Free by address instead of vrange (combine with shmem map?)
 void memory_free(struct page_dir *dir, struct memory_range vrange)
 {
 	assert(PAGE_ALIGNED(vrange.base) && PAGE_ALIGNED(vrange.size));
 
+	struct memory_range prange =
+		memory_range(virtual_to_physical(dir, vrange.base), vrange.size);
+	struct shared_memory sh = memory_shresolve_range(prange);
+	if (sh.used != 0 && sh.refs > 1) {
+		panic("Freeing busy memory!\n");
+		return;
+	}
+	/* sh.used = 0; */
+
 	for (u32 i = 0; i < vrange.size / PAGE_SIZE; i++) {
 		u32 vaddr = vrange.base + i * PAGE_SIZE;
 		if (virtual_present(dir, vaddr)) {
diff --git a/kernel/features/syscall.c b/kernel/features/syscall.c
index 7d68d93..c59c423 100644
--- a/kernel/features/syscall.c
+++ b/kernel/features/syscall.c
@@ -29,10 +29,19 @@ static void syscall_handler(struct regs *r)
 		break;
 	}
 	case SYS_ALLOC: {
-		r->eax = (u32)memory_alloc(proc_current()->page_dir, r->ebx,
+		r->eax = (u32)memory_alloc(proc_current()->page_dir, PAGE_ALIGN_UP(r->ebx),
 					   MEMORY_CLEAR | MEMORY_USER);
 		break;
 	}
+	case SYS_SHALLOC: {
+		r->eax = (u32)memory_shalloc(proc_current()->page_dir, PAGE_ALIGN_UP(r->ebx),
+					     MEMORY_CLEAR | MEMORY_USER);
+		break;
+	}
+	case SYS_SHACCESS: {
+		r->eax = (u32)memory_shaccess(proc_current()->page_dir, r->ebx);
+		break;
+	}
 	case SYS_FREE: {
 		memory_free(proc_current()->page_dir, memory_range(r->ebx, r->ecx));
 		break;
@@ -123,45 +132,6 @@ static void syscall_handler(struct regs *r)
 		break;
 	}
 	// TODO: Reimplement network functions using VFS
-	case SYS_NET_OPEN:
-	case SYS_NET_CLOSE:
-	case SYS_NET_CONNECT:
-	case SYS_NET_SEND:
-	case SYS_NET_RECEIVE:
-#if 0
-	case SYS_NET_OPEN: {
-		r->eax = (int)net_open(r->ebx);
-		break;
-	}
-	case SYS_NET_CLOSE: {
-		struct socket *s = (void *)r->ebx;
-		int status = net_close(s);
-		if (!status) {
-			proc_yield(r);
-			return;
-		}
-		r->eax = net_close(s);
-		break;
-	}
-	case SYS_NET_CONNECT: {
-		struct socket *s = (void *)r->ebx;
-		if (s->state == S_CONNECTED)
-			r->eax = 1;
-		else if (s->state == S_FAILED || s->state == S_CLOSED)
-			r->eax = 0;
-		else if (s->state == S_OPEN)
-			r->eax = net_connect(s, r->ecx, r->edx);
-		break;
-	}
-	case SYS_NET_SEND: {
-		net_send((void *)r->ebx, (void *)r->ecx, r->edx);
-		break;
-	}
-	case SYS_NET_RECEIVE: {
-		r->eax = net_receive((void *)r->ebx, (void *)r->ecx, r->edx);
-		break;
-	}
-#endif
 	default: {
 		printf("Unknown syscall %d!\n", num);
 		break;
diff --git a/kernel/inc/mm.h b/kernel/inc/mm.h
index e506331..5e30be6 100644
--- a/kernel/inc/mm.h
+++ b/kernel/inc/mm.h
@@ -104,8 +104,10 @@ struct memory_range memory_range_around(u32 base, u32 size);
 
 void *memory_alloc(struct page_dir *dir, u32 size, u32 flags);
 void *memory_alloc_identity(struct page_dir *dir, u32 flags);
-void memory_map_identity(struct page_dir *dir, struct memory_range prange, u32 flags);
+u32 memory_shalloc(struct page_dir *dir, u32 size, u32 flags);
+void *memory_shaccess(struct page_dir *dir, u32 shid);
 void memory_free(struct page_dir *dir, struct memory_range vrange);
+void memory_map_identity(struct page_dir *dir, struct memory_range prange, u32 flags);
 void memory_switch_dir(struct page_dir *dir);
 void memory_backup_dir(struct page_dir **backup);