s390: enable HAVE_FUNCTION_ERROR_INJECTION

This kernel feature is required for enabling BPF_KPROBE_OVERRIDE.

Define override_function_with_return() and regs_set_return_value()
functions, and fix compile errors in syscall_wrapper.h.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index d95d323..9cfd8de 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -145,6 +145,7 @@ config S390
        select HAVE_EFFICIENT_UNALIGNED_ACCESS
        select HAVE_FENTRY
        select HAVE_FTRACE_MCOUNT_RECORD
+       select HAVE_FUNCTION_ERROR_INJECTION
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_FUNCTION_TRACER
        select HAVE_FUTEX_CMPXCHG if FUTEX

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index f009a13..16b3e43 100644 (file)
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -184,5 +184,10 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
        return regs->gprs[15];
 }
 
+static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
+{
+       regs->gprs[2] = rc;
+}
+
 #endif /* __ASSEMBLY__ */
 #endif /* _S390_PTRACE_H */

diff --git a/arch/s390/include/asm/syscall_wrapper.h b/arch/s390/include/asm/syscall_wrapper.h
index 3c3d6fe..1320f42 100644 (file)
--- a/arch/s390/include/asm/syscall_wrapper.h
+++ b/arch/s390/include/asm/syscall_wrapper.h
@@ -30,7 +30,7 @@
 })
 
 #define __S390_SYS_STUBx(x, name, ...)                                 \
-       asmlinkage long __s390_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))\
+       asmlinkage long __s390_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));\
        ALLOW_ERROR_INJECTION(__s390_sys##name, ERRNO);                 \
        asmlinkage long __s390_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))\
        {                                                               \
@@ -46,7 +46,7 @@
 #define COMPAT_SYSCALL_DEFINE0(sname)                                  \
        SYSCALL_METADATA(_##sname, 0);                                  \
        asmlinkage long __s390_compat_sys_##sname(void);                \
-       ALLOW_ERROR_INJECTION(__s390_compat__sys_##sname, ERRNO);       \
+       ALLOW_ERROR_INJECTION(__s390_compat_sys_##sname, ERRNO);        \
        asmlinkage long __s390_compat_sys_##sname(void)
 
 #define SYSCALL_DEFINE0(sname)                                         \
@@ -72,7 +72,7 @@
        asmlinkage long __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));        \
        asmlinkage long __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
                __attribute__((alias(__stringify(__se_compat_sys##name))));     \
-       ALLOW_ERROR_INJECTION(compat_sys##name, ERRNO);                         \
+       ALLOW_ERROR_INJECTION(__s390_compat_sys##name, ERRNO);                  \
        static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
        asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));  \
        asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))   \

diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index 28fd66d..6783339 100644 (file)
--- a/arch/s390/lib/Makefile
+++ b/arch/s390/lib/Makefile
@@ -14,3 +14,5 @@ KASAN_SANITIZE_uaccess.o := n
 
 obj-$(CONFIG_S390_UNWIND_SELFTEST) += test_unwind.o
 CFLAGS_test_unwind.o += -fno-optimize-sibling-calls
+
+lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

diff --git a/arch/s390/lib/error-inject.c b/arch/s390/lib/error-inject.c
new file mode 100644 (file)
index 0000000..8c9d4da
--- /dev/null
+++ b/arch/s390/lib/error-inject.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <asm/ptrace.h>
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+
+void override_function_with_return(struct pt_regs *regs)
+{
+       /*
+        * Emulate 'br 14'. 'regs' is captured by kprobes on entry to some
+        * kernel function.
+        */
+       regs->psw.addr = regs->gprs[14];
+}
+NOKPROBE_SYMBOL(override_function_with_return);