From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 411gnD1bSZzF0WH for ; Thu, 7 Jun 2018 19:52:16 +1000 (AEST) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w579n88q108029 for ; Thu, 7 Jun 2018 05:52:13 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2jeyd60jek-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 07 Jun 2018 05:52:13 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 7 Jun 2018 10:52:11 +0100 From: "Naveen N. Rao" To: Michael Ellerman Cc: Segher Boessenkool , linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3] powerpc: Add support for function error injection Date: Thu, 7 Jun 2018 15:22:02 +0530 Message-Id: <20180607095202.29189-1-naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- The only change is to add a comment in override_function_with_return() to clarify that we don't need to worry about 32-bit userspace while emulating 'blr'. - Naveen 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 | 16 ++++++++++++++++ 5 files changed, 37 insertions(+) create mode 100644 arch/powerpc/include/asm/error-injection.h create mode 100644 arch/powerpc/lib/error-inject.c diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 076fe3094856..00dad3c759a0 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -187,6 +187,7 @@ 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 diff --git a/arch/powerpc/include/asm/error-injection.h b/arch/powerpc/include/asm/error-injection.h new file mode 100644 index 000000000000..740c3075bdf4 --- /dev/null +++ b/arch/powerpc/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 +#include +#include +#include + +void override_function_with_return(struct pt_regs *regs); + +#endif /* _ASM_ERROR_INJECTION_H */ diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h index e4923686e43a..c0705296c2f0 100644 --- a/arch/powerpc/include/asm/ptrace.h +++ b/arch/powerpc/include/asm/ptrace.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 diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile index d0ca13ad8231..dd43c5a53396 100644 --- a/arch/powerpc/lib/Makefile +++ b/arch/powerpc/lib/Makefile @@ -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 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 +#include +#include + +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); -- 2.17.0