add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/arch/s390/include/asm/extable.h
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@@ -1,12 +1,20 @@
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 /* SPDX-License-Identifier: GPL-2.0 */
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 #ifndef __S390_EXTABLE_H
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 #define __S390_EXTABLE_H
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+
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+#include <asm/ptrace.h>
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+#include <linux/compiler.h>
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+
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 /*
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- * The exception table consists of pairs of addresses: the first is the
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- * address of an instruction that is allowed to fault, and the second is
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- * the address at which the program should continue.  No registers are
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- * modified, so it is entirely up to the continuation code to figure out
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- * what to do.
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+ * The exception table consists of three addresses:
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+ *
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+ * - Address of an instruction that is allowed to fault.
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+ * - Address at which the program should continue.
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+ * - Optional address of handler that takes pt_regs * argument and runs in
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+ *   interrupt context.
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+ *
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+ * No registers are modified, so it is entirely up to the continuation code
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+ * to figure out what to do.
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  *
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  * All the routines below use bits of fixup code that are out of line
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  * with the main instruction path.  This means when everything is well,
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@@ -17,13 +25,57 @@
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 struct exception_table_entry
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 {
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 	int insn, fixup;
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+	long handler;
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 };
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+
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+extern struct exception_table_entry *__start_dma_ex_table;
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+extern struct exception_table_entry *__stop_dma_ex_table;
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+
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+const struct exception_table_entry *s390_search_extables(unsigned long addr);
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 static inline unsigned long extable_fixup(const struct exception_table_entry *x)
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 {
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 	return (unsigned long)&x->fixup + x->fixup;
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 }
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+typedef bool (*ex_handler_t)(const struct exception_table_entry *,
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+			     struct pt_regs *);
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+
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+static inline ex_handler_t
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+ex_fixup_handler(const struct exception_table_entry *x)
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+{
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+	if (likely(!x->handler))
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+		return NULL;
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+	return (ex_handler_t)((unsigned long)&x->handler + x->handler);
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+}
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+
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+static inline bool ex_handle(const struct exception_table_entry *x,
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+			     struct pt_regs *regs)
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+{
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+	ex_handler_t handler = ex_fixup_handler(x);
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+
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+	if (unlikely(handler))
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+		return handler(x, regs);
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+	regs->psw.addr = extable_fixup(x);
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+	return true;
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+}
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+
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 #define ARCH_HAS_RELATIVE_EXTABLE
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+static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
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+				       struct exception_table_entry *b,
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+				       struct exception_table_entry tmp,
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+				       int delta)
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+{
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+	a->fixup = b->fixup + delta;
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+	b->fixup = tmp.fixup - delta;
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+	a->handler = b->handler;
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+	if (a->handler)
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+		a->handler += delta;
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+	b->handler = tmp.handler;
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+	if (b->handler)
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+		b->handler -= delta;
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+}
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+#define swap_ex_entry_fixup swap_ex_entry_fixup
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+
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 #endif