@@ -186,6 +186,7 @@ config PPC
select HAVE_EBPF_JIT if PPC64
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
select HAVE_FTRACE_MCOUNT_RECORD
+ select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
new file mode 100644
@@ -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>
+
+void override_function_with_return(struct pt_regs *regs);
+
+#endif /* _ASM_ERROR_INJECTION_H */
@@ -101,6 +101,11 @@ static inline long regs_return_value(struct pt_regs *regs)
return -regs->gpr[3];
}
+static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
+{
+ regs->gpr[3] = rc;
+}
+
#ifdef __powerpc64__
#define user_mode(regs) ((((regs)->msr) >> MSR_PR_LG) & 0x1)
#else
@@ -14,6 +14,8 @@ obj-y += string.o alloc.o code-patching.o feature-fixups.o
obj-$(CONFIG_PPC32) += div64.o copy_32.o crtsavres.o
+obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
+
# See corresponding test in arch/powerpc/Makefile
# 64-bit linker creates .sfpr on demand for final link (vmlinux),
# so it is only needed for modules, and only for older linkers which
new file mode 100644
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+
+void override_function_with_return(struct pt_regs *regs)
+{
+ /* Emulate 'blr' instruction */
+ regs->nip = regs->link;
+}
+NOKPROBE_SYMBOL(override_function_with_return);
We implement regs_set_return_value() and override_function_with_return() for this purpose. On powerpc, a return from a function (blr) just branches to the location contained in the link register. So, we can just update pt_regs rather than redirecting execution to a dummy function that returns. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/error-injection.h | 13 +++++++++++++ arch/powerpc/include/asm/ptrace.h | 5 +++++ arch/powerpc/lib/Makefile | 2 ++ arch/powerpc/lib/error-inject.c | 12 ++++++++++++ 5 files changed, 33 insertions(+) create mode 100644 arch/powerpc/include/asm/error-injection.h create mode 100644 arch/powerpc/lib/error-inject.c