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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2018-06-07 15:22:02 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2018-10-20 13:26:43 +1100
commit7cd01b08d35f1b7d55686ed8cd57c94d3406ec8f (patch)
treeba2112d797cf4e9ba7c690fe9bbe07dad8d5a873 /arch/powerpc/lib
parentb4d16ab58c41ff0125822464bdff074cebd0fe47 (diff)
powerpc: Add support for function error injection
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> Reviewed-by: Samuel Mendoza-Jonas <sam@mendozajonas.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/lib')
-rw-r--r--arch/powerpc/lib/Makefile2
-rw-r--r--arch/powerpc/lib/error-inject.c16
2 files changed, 18 insertions, 0 deletions
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 703afa1808ed..3bf9fc6fd36c 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -12,6 +12,8 @@ obj-y += string.o alloc.o code-patching.o feature-fixups.o
obj-$(CONFIG_PPC32) += div64.o copy_32.o crtsavres.o strlen_32.o
+obj-$(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
diff --git a/arch/powerpc/lib/error-inject.c b/arch/powerpc/lib/error-inject.c
new file mode 100644
index 000000000000..407b992fb02f
--- /dev/null
+++ b/arch/powerpc/lib/error-inject.c
@@ -0,0 +1,16 @@
+// 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'. 'regs' represents the state on entry of a predefined
+ * function in the kernel/module, captured on a kprobe. We don't need
+ * to worry about 32-bit userspace on a 64-bit kernel.
+ */
+ regs->nip = regs->link;
+}
+NOKPROBE_SYMBOL(override_function_with_return);