From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/include/linux/scs.h | 61 ++++++++++++++++++------------
1 files changed, 36 insertions(+), 25 deletions(-)
diff --git a/kernel/include/linux/scs.h b/kernel/include/linux/scs.h
index c5572fd..18122d9 100644
--- a/kernel/include/linux/scs.h
+++ b/kernel/include/linux/scs.h
@@ -9,48 +9,59 @@
#define _LINUX_SCS_H
#include <linux/gfp.h>
+#include <linux/poison.h>
#include <linux/sched.h>
-#include <asm/page.h>
+#include <linux/sizes.h>
#ifdef CONFIG_SHADOW_CALL_STACK
-/*
- * In testing, 1 KiB shadow stack size (i.e. 128 stack frames on a 64-bit
- * architecture) provided ~40% safety margin on stack usage while keeping
- * memory allocation overhead reasonable.
- */
-#define SCS_SIZE 1024UL
-#define GFP_SCS (GFP_KERNEL | __GFP_ZERO)
+#define SCS_ORDER 0
+#define SCS_SIZE (PAGE_SIZE << SCS_ORDER)
+#define GFP_SCS (GFP_KERNEL | __GFP_ZERO)
-/*
- * A random number outside the kernel's virtual address space to mark the
- * end of the shadow stack.
- */
-#define SCS_END_MAGIC 0xaf0194819b1635f6UL
+/* An illegal pointer value to mark the end of the shadow stack. */
+#define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA)
-#define task_scs(tsk) (task_thread_info(tsk)->shadow_call_stack)
+#define task_scs(tsk) (task_thread_info(tsk)->scs_base)
+#define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp)
-static inline void task_set_scs(struct task_struct *tsk, void *s)
+void *scs_alloc(int node);
+void scs_free(void *s);
+void scs_init(void);
+int scs_prepare(struct task_struct *tsk, int node);
+void scs_release(struct task_struct *tsk);
+
+static inline void scs_task_reset(struct task_struct *tsk)
{
- task_scs(tsk) = s;
+ /*
+ * Reset the shadow stack to the base address in case the task
+ * is reused.
+ */
+ task_scs_sp(tsk) = task_scs(tsk);
}
-extern void scs_init(void);
-extern void scs_task_reset(struct task_struct *tsk);
-extern int scs_prepare(struct task_struct *tsk, int node);
-extern bool scs_corrupted(struct task_struct *tsk);
-extern void scs_release(struct task_struct *tsk);
+static inline unsigned long *__scs_magic(void *s)
+{
+ return (unsigned long *)(s + SCS_SIZE) - 1;
+}
+
+static inline bool task_scs_end_corrupted(struct task_struct *tsk)
+{
+ unsigned long *magic = __scs_magic(task_scs(tsk));
+ unsigned long sz = task_scs_sp(tsk) - task_scs(tsk);
+
+ return sz >= SCS_SIZE - 1 || READ_ONCE_NOCHECK(*magic) != SCS_END_MAGIC;
+}
#else /* CONFIG_SHADOW_CALL_STACK */
-#define task_scs(tsk) NULL
-
-static inline void task_set_scs(struct task_struct *tsk, void *s) {}
+static inline void *scs_alloc(int node) { return NULL; }
+static inline void scs_free(void *s) {}
static inline void scs_init(void) {}
static inline void scs_task_reset(struct task_struct *tsk) {}
static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; }
-static inline bool scs_corrupted(struct task_struct *tsk) { return false; }
static inline void scs_release(struct task_struct *tsk) {}
+static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; }
#endif /* CONFIG_SHADOW_CALL_STACK */
--
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