add at24 driver

hc

2023-11-06 15ade055295d13f95d49e3d99b09f3bbfb4a43e7

 kernel/arch/x86/kernel/process_32.c
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@@ -38,6 +38,7 @@
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 #include <linux/io.h>
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 #include <linux/kdebug.h>
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 #include <linux/syscalls.h>
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+#include <linux/highmem.h>
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 #include <asm/pgtable.h>
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 #include <asm/ldt.h>
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@@ -205,6 +206,35 @@
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 }
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 EXPORT_SYMBOL_GPL(start_thread);
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+static void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
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+{
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+	int i;
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+
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+	/*
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+	 * Clear @prev's kmap_atomic mappings
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+	 */
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+	for (i = 0; i < prev_p->kmap_idx; i++) {
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+		int idx = i + KM_TYPE_NR * smp_processor_id();
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+		pte_t *ptep = kmap_pte - idx;
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+
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+		kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
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+	}
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+	/*
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+	 * Restore @next_p's kmap_atomic mappings
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+	 */
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+	for (i = 0; i < next_p->kmap_idx; i++) {
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+		int idx = i + KM_TYPE_NR * smp_processor_id();
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+
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+		if (!pte_none(next_p->kmap_pte[i]))
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+			set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
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+	}
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+}
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+#else
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+static inline void
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+switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) { }
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+#endif
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+
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 /*
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  *	switch_to(x,y) should switch tasks from x to y.
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@@ -274,6 +304,8 @@
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 	switch_to_extra(prev_p, next_p);
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+	switch_kmaps(prev_p, next_p);
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+
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 	/*
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 	 * Leave lazy mode, flushing any hypercalls made here.
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 	 * This must be done before restoring TLS segments so