syscalls: mprotect

kernel-src/sys/syscalls/mprotect.c

@@ -0,0 +1,39 @@
+#include <kernel/syscalls.h>
+#include <kernel/abi.h>
+#include <errno.h>
+#include <kernel/vmm.h>
+#include <logging.h>
+
+#define PROT_READ  0x01
+#define PROT_WRITE 0x02
+#define PROT_EXEC  0x04
+
+#define KNOWN_PROT (PROT_READ | PROT_WRITE | PROT_EXEC)
+
+syscallret_t syscall_mprotect(context_t *context, void *address, size_t len, int prot) {
+	syscallret_t ret = {
+		.errno = 0,
+		.ret = -1
+	};
+
+	__assert((~KNOWN_PROT & prot) == 0);
+
+	// check alignment
+	if (len == 0 || (uintptr_t)address % PAGE_SIZE || address > USERSPACE_END) {
+		ret.errno = EINVAL;
+		return ret;
+	}
+
+	mmuflags_t mmuflags = ARCH_MMU_FLAGS_USER;
+	if (prot & PROT_READ)
+		mmuflags |= ARCH_MMU_FLAGS_READ;
+	if (prot & PROT_WRITE)
+		mmuflags |= ARCH_MMU_FLAGS_WRITE;
+	if ((prot & PROT_EXEC) == 0)
+		mmuflags |= ARCH_MMU_FLAGS_NOEXEC;
+
+	ret.errno = vmm_changemmuflags(address, len, mmuflags, 0) ? 0 : ENOMEM;
+	ret.ret = ret.errno ? -1 : 0;
+
+	return ret;
+}