kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/include/linux/scs.h
..
..
@@ -9,48 +9,59 @@
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 #define _LINUX_SCS_H
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 #include <linux/gfp.h>
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+#include <linux/poison.h>
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 #include <linux/sched.h>
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-#include <asm/page.h>
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+#include <linux/sizes.h>
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 #ifdef CONFIG_SHADOW_CALL_STACK
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-/*
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- * In testing, 1 KiB shadow stack size (i.e. 128 stack frames on a 64-bit
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- * architecture) provided ~40% safety margin on stack usage while keeping
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- * memory allocation overhead reasonable.
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- */
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-#define SCS_SIZE	1024UL
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-#define GFP_SCS		(GFP_KERNEL | __GFP_ZERO)
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+#define SCS_ORDER		0
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+#define SCS_SIZE		(PAGE_SIZE << SCS_ORDER)
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+#define GFP_SCS			(GFP_KERNEL | __GFP_ZERO)
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-/*
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- * A random number outside the kernel's virtual address space to mark the
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- * end of the shadow stack.
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- */
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-#define SCS_END_MAGIC	0xaf0194819b1635f6UL
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+/* An illegal pointer value to mark the end of the shadow stack. */
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+#define SCS_END_MAGIC		(0x5f6UL + POISON_POINTER_DELTA)
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-#define task_scs(tsk)	(task_thread_info(tsk)->shadow_call_stack)
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+#define task_scs(tsk)		(task_thread_info(tsk)->scs_base)
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+#define task_scs_sp(tsk)	(task_thread_info(tsk)->scs_sp)
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-static inline void task_set_scs(struct task_struct *tsk, void *s)
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+void *scs_alloc(int node);
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+void scs_free(void *s);
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+void scs_init(void);
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+int scs_prepare(struct task_struct *tsk, int node);
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+void scs_release(struct task_struct *tsk);
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+
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+static inline void scs_task_reset(struct task_struct *tsk)
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 {
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-	task_scs(tsk) = s;
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+	/*
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+	 * Reset the shadow stack to the base address in case the task
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+	 * is reused.
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+	 */
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+	task_scs_sp(tsk) = task_scs(tsk);
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 }
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-extern void scs_init(void);
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-extern void scs_task_reset(struct task_struct *tsk);
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-extern int scs_prepare(struct task_struct *tsk, int node);
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-extern bool scs_corrupted(struct task_struct *tsk);
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-extern void scs_release(struct task_struct *tsk);
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+static inline unsigned long *__scs_magic(void *s)
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+{
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+	return (unsigned long *)(s + SCS_SIZE) - 1;
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+}
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+
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+static inline bool task_scs_end_corrupted(struct task_struct *tsk)
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+{
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+	unsigned long *magic = __scs_magic(task_scs(tsk));
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+	unsigned long sz = task_scs_sp(tsk) - task_scs(tsk);
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+
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+	return sz >= SCS_SIZE - 1 || READ_ONCE_NOCHECK(*magic) != SCS_END_MAGIC;
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+}
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 #else /* CONFIG_SHADOW_CALL_STACK */
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-#define task_scs(tsk)	NULL
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-
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-static inline void task_set_scs(struct task_struct *tsk, void *s) {}
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+static inline void *scs_alloc(int node) { return NULL; }
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+static inline void scs_free(void *s) {}
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 static inline void scs_init(void) {}
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 static inline void scs_task_reset(struct task_struct *tsk) {}
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 static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; }
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-static inline bool scs_corrupted(struct task_struct *tsk) { return false; }
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 static inline void scs_release(struct task_struct *tsk) {}
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+static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; }
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 #endif /* CONFIG_SHADOW_CALL_STACK */
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