Messages in this thread | | | Date | Thu, 27 Nov 2014 14:53:36 +0900 | From | AKASHI Takahiro <> | Subject | Re: [PATCH v9 1/6] arm64: ptrace: add NT_ARM_SYSTEM_CALL regset |
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On 11/26/2014 09:41 PM, Will Deacon wrote: > 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.akashi@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.
Right. I will fix it. Do you prefer to use s32, instead of int, like other regsets?
Thanks, -Takahiro AKASHI
> Will >
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