Hi Akashi, On Wed, Nov 26, 2014 at 04:49:46AM +0000, AKASHI Takahiro wrote: > This regeset is intended to be used to get and set a system call number > while tracing. > There was some discussion about possible approaches to do so: > > (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, > and update regs->syscallno later on in syscall_trace_enter(), or > (2) define a dedicated regset for this purpose as on s390, or > (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm > > Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to > tracer as well as that secure_computing() expects a changed syscall number, > especially case of -1, to be visible before this function returns in > syscall_trace_enter(), (1) doesn't work well. > We will take (2) since it looks much cleaner. > > Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> > --- > arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 2 files changed, 36 insertions(+) > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 8a4ae8e..8b98781 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const > struct user_regset *regset, > return ret; > } > > +static int system_call_get(struct task_struct *target, > + const struct user_regset *regset, > + unsigned int pos, unsigned int count, > + void *kbuf, void __user *ubuf) > +{ > + struct pt_regs *regs = task_pt_regs(target); > + > + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, > + ®s->syscallno, 0, -1);
Does this work for big-endian machines? regs->syscallno is a u64, but the regset defines it as an int. I think you need to copy to a temporary register first. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/