error-injection: Separate error-injection from kprobe

Since error-injection framework is not limited to be used
by kprobes, nor bpf. Other kernel subsystems can use it
freely for checking safeness of error-injection, e.g.
livepatch, ftrace etc.
So this separate error-injection framework from kprobes.

Some differences has been made:

- "kprobe" word is removed from any APIs/structures.
- BPF_ALLOW_ERROR_INJECTION() is renamed to
  ALLOW_ERROR_INJECTION() since it is not limited for BPF too.
- CONFIG_FUNCTION_ERROR_INJECTION is the config item of this
  feature. It is automatically enabled if the arch supports
  error injection feature for kprobe or ftrace etc.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

5 files changed, 34 insertions, 15 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 45dc623..366b19c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -154,7 +154,7 @@ config X86
 	select HAVE_KERNEL_XZ
 	select HAVE_KPROBES
 	select HAVE_KPROBES_ON_FTRACE
-	select HAVE_KPROBE_OVERRIDE
+	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_KRETPROBES
 	select HAVE_KVM
 	select HAVE_LIVEPATCH			if X86_64
diff --git a/arch/x86/include/asm/error-injection.h b/arch/x86/include/asm/error-injection.h
new file mode 100644
index 0000000..47b7a12
--- /dev/null
+++ b/arch/x86/include/asm/error-injection.h
@@ -0,0 +1,13 @@
+/* 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 */
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index b02a377..bd36f3c 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1183,17 +1183,3 @@ int arch_trampoline_kprobe(struct kprobe *p)
 {
 	return 0;
 }
-
-asmlinkage void override_func(void);
-asm(
-	".type override_func, @function\n"
-	"override_func:\n"
-	"	ret\n"
-	".size override_func, .-override_func\n"
-);
-
-void arch_kprobe_override_function(struct pt_regs *regs)
-{
-	regs->ip = (unsigned long)&override_func;
-}
-NOKPROBE_SYMBOL(arch_kprobe_override_function);
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 7b181b6..171377b 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -26,6 +26,7 @@ lib-y += memcpy_$(BITS).o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
 lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
+lib-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
 
 obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o
 
diff --git a/arch/x86/lib/error-inject.c b/arch/x86/lib/error-inject.c
new file mode 100644
index 0000000..7b881d0
--- /dev/null
+++ b/arch/x86/lib/error-inject.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+
+asmlinkage void just_return_func(void);
+
+asm(
+	".type just_return_func, @function\n"
+	"just_return_func:\n"
+	"	ret\n"
+	".size just_return_func, .-just_return_func\n"
+);
+
+void override_function_with_return(struct pt_regs *regs)
+{
+	regs->ip = (unsigned long)&just_return_func;
+}
+NOKPROBE_SYMBOL(override_function_with_return);