From 7485f7e441ca892876d9401380aa77610eb85f76 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Fri, 16 Apr 2021 23:22:02 +0200
Subject: New elegant I/O blocking solution

This is done using an internal scheduler syscall (127).

Very nice!
---
 kernel/features/mm.c | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'kernel/features/mm.c')

diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index d9e4577..9f0bd07 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -602,11 +602,17 @@ void memory_bypass_disable(void)
 
 u8 memory_is_user(const void *addr)
 {
+	if (!addr)
+		return 0;
+
 	return PDI((u32)addr) >= PAGE_KERNEL_COUNT;
 }
 
 u8 memory_readable(const void *addr)
 {
+	if (!addr)
+		return 0;
+
 	struct proc *proc = proc_current();
 	if (proc && !memory_bypass_validity)
 		return memory_is_user(addr) && virtual_user_readable(proc->page_dir, (u32)addr);
@@ -616,6 +622,9 @@ u8 memory_readable(const void *addr)
 
 u8 memory_writable(const void *addr)
 {
+	if (!addr)
+		return 0;
+
 	struct proc *proc = proc_current();
 	if (proc && !memory_bypass_validity)
 		return memory_is_user(addr) && virtual_user_writable(proc->page_dir, (u32)addr);
-- 
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