error-injection: Consolidate override function definition

The function override_function_with_return() is defined separately for
each architecture and every architecture's definition is almost same
with each other.  E.g. x86 and powerpc both define function in its own
asm/error-injection.h header and override_function_with_return() has
the same definition, the only difference is that x86 defines an extra
function just_return_func() but it is specific for x86 and is only used
by x86's override_function_with_return(), so don't need to export this
function.

This patch consolidates override_function_with_return() definition into
asm-generic/error-injection.h header, thus all architectures can use the
common definition.  As result, the architecture specific headers are
removed; the include/linux/error-injection.h header also changes to
include asm-generic/error-injection.h header rather than architecture
header, furthermore, it includes linux/compiler.h for successful
compilation.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>

arch/powerpc/include/asm/error-injection.h

-/* SPDX-License-Identifier: GPL-2.0+ */
-
-#ifndef _ASM_ERROR_INJECTION_H
-#define _ASM_ERROR_INJECTION_H
-
-#include <linux/compiler.h>
-#include <linux/linkage.h>
-#include <asm/ptrace.h>
-#include <asm-generic/error-injection.h>
-
-void override_function_with_return(struct pt_regs *regs);
-
-#endif /* _ASM_ERROR_INJECTION_H */

arch/x86/include/asm/error-injection.h

-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_ERROR_INJECTION_H
-#define _ASM_ERROR_INJECTION_H
-
-#include <linux/compiler.h>
-#include <linux/linkage.h>
-#include <asm/ptrace.h>
-#include <asm-generic/error-injection.h>
-
-asmlinkage void just_return_func(void);
-void override_function_with_return(struct pt_regs *regs);
-
-#endif /* _ASM_ERROR_INJECTION_H */

include/asm-generic/error-injection.h

@@ -16,6 +16,8 @@ struct error_injection_entry {
 	int		etype;
 };
 
+struct pt_regs;
+
 #ifdef CONFIG_FUNCTION_ERROR_INJECTION
 /*
  * Whitelist ganerating macro. Specify functions which can be
@@ -28,8 +30,12 @@ static struct error_injection_entry __used				\
 		.addr = (unsigned long)fname,				\
 		.etype = EI_ETYPE_##_etype,				\
 	};
+
+void override_function_with_return(struct pt_regs *regs);
 #else
 #define ALLOW_ERROR_INJECTION(fname, _etype)
+
+static inline void override_function_with_return(struct pt_regs *regs) { }
 #endif
 #endif
 

include/linux/error-injection.h

@@ -2,16 +2,16 @@
 #ifndef _LINUX_ERROR_INJECTION_H
 #define _LINUX_ERROR_INJECTION_H
 
-#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+#include <linux/compiler.h>
+#include <asm-generic/error-injection.h>
 
-#include <asm/error-injection.h>
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
 
 extern bool within_error_injection_list(unsigned long addr);
 extern int get_injectable_error_type(unsigned long addr);
 
 #else /* !CONFIG_FUNCTION_ERROR_INJECTION */
 
-#include <asm-generic/error-injection.h>
 static inline bool within_error_injection_list(unsigned long addr)
 {
 	return false;