Message ID | 20180607095202.29189-1-naveen.n.rao@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | Accepted |
Commit | 7cd01b08d35f1b7d55686ed8cd57c94d3406ec8f |
Headers | show |
Series | [v3] powerpc: Add support for function error injection | expand |
On Thu, 2018-06-07 at 15:22 +0530, Naveen N. Rao wrote: > 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> > --- > 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'. Reviewed-by: Samuel Mendoza-Jonas <sam@mendozajonas.com> > > - 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 <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 */ > 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 <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);
On Thu, 2018-06-07 at 09:52:02 UTC, "Naveen N. Rao" wrote: > 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> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/7cd01b08d35f1b7d55686ed8cd57c9 cheers
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 <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 */ 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 <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);
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> --- 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