From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Fri, 28 Nov 2014 14:25:50 +0900 Subject: [PATCH v9 1/6] arm64: ptrace: add NT_ARM_SYSTEM_CALL regset In-Reply-To: <20141127141052.GP20649@arm.com> References: <1416977391-24231-1-git-send-email-takahiro.akashi@linaro.org> <1416977391-24231-2-git-send-email-takahiro.akashi@linaro.org> <20141126124128.GH14866@arm.com> <5476BC60.6060005@linaro.org> <20141127141052.GP20649@arm.com> Message-ID: <5478075E.4000203@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/27/2014 11:10 PM, Will Deacon wrote: > On Thu, Nov 27, 2014 at 05:53:36AM +0000, AKASHI Takahiro wrote: >> On 11/26/2014 09:41 PM, Will Deacon wrote: >>> 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 >>>> --- >>>> 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? > > I don't have a preference either way. > > It would be great to have a new revision of these patches ASAP if you're > targetting 3.19. Yeah, definitely. -Takahiro AKASHI > Will > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >