Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32
On Fri, Jan 06, 2017 at 02:10:03AM +0530, Yury Norov wrote: > On Wed, Dec 07, 2016 at 09:40:13PM +0100, Arnd Bergmann wrote: > > On Wednesday, December 7, 2016 4:59:13 PM CET Catalin Marinas wrote: > > > On Tue, Dec 06, 2016 at 11:55:08AM +0530, Yury Norov wrote: > > > > On Mon, Dec 05, 2016 at 04:34:23PM +, Catalin Marinas wrote: > > > > > On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote: > > > > > > New aarch32 ptrace syscall handler is introduced to avoid run-time > > > > > > detection of the task type. > > > > > > > > > > What's wrong with the run-time detection? If it's just to avoid a > > > > > negligible overhead, I would rather keep the code simpler by avoiding > > > > > duplicating the generic compat_sys_ptrace(). > > > > > > > > Nothing wrong. This is how Arnd asked me to do. You already asked this > > > > question: http://lkml.iu.edu/hypermail/linux/kernel/1604.3/00930.html > > > > > > Hmm, I completely forgot about this ;). There is still an advantage to > > > doing run-time checking if we avoid touching core code (less acks to > > > gather and less code duplication). > > > > > > Let's see what Arnd says but the initial patch looked simpler. > > > > I don't currently have either version of the patch in my inbox > > (the archive is on a different machine), but in general I'd still > > think it's best to avoid the runtime check for aarch64-ilp32 > > altogether. I'd have to look at the overall kernel source to > > see if it's worth avoiding one or two instances though, or > > if there are an overwhelming number of other checks that we > > can't avoid at all. > > > > Regarding ptrace, I notice that arch/tile doesn't even use > > the compat entry point for its ilp32 user space on 64-bit > > kernels, it just calls the regular 64-bit one. Would that > > help here? > > ILP32 tasks has unique context that is not like aarch64 or aarch32, > so we have to have unique ptrace handler. I prepared the patch for > ptrace with runtime ABI detection, as Catalin said, see there: > https://github.com/norov/linux/commit/1f66dc22a4450b192e83458f2c3cc0e79f53e670 > > If it's OK, I'd like to update submission. This looks better to me (and even better if you no longer need to touch the generic ptrace code). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32
On Wed, Dec 07, 2016 at 09:40:13PM +0100, Arnd Bergmann wrote: > On Wednesday, December 7, 2016 4:59:13 PM CET Catalin Marinas wrote: > > On Tue, Dec 06, 2016 at 11:55:08AM +0530, Yury Norov wrote: > > > On Mon, Dec 05, 2016 at 04:34:23PM +, Catalin Marinas wrote: > > > > On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote: > > > > > New aarch32 ptrace syscall handler is introduced to avoid run-time > > > > > detection of the task type. > > > > > > > > What's wrong with the run-time detection? If it's just to avoid a > > > > negligible overhead, I would rather keep the code simpler by avoiding > > > > duplicating the generic compat_sys_ptrace(). > > > > > > Nothing wrong. This is how Arnd asked me to do. You already asked this > > > question: http://lkml.iu.edu/hypermail/linux/kernel/1604.3/00930.html > > > > Hmm, I completely forgot about this ;). There is still an advantage to > > doing run-time checking if we avoid touching core code (less acks to > > gather and less code duplication). > > > > Let's see what Arnd says but the initial patch looked simpler. > > I don't currently have either version of the patch in my inbox > (the archive is on a different machine), but in general I'd still > think it's best to avoid the runtime check for aarch64-ilp32 > altogether. I'd have to look at the overall kernel source to > see if it's worth avoiding one or two instances though, or > if there are an overwhelming number of other checks that we > can't avoid at all. > > Regarding ptrace, I notice that arch/tile doesn't even use > the compat entry point for its ilp32 user space on 64-bit > kernels, it just calls the regular 64-bit one. Would that > help here? ILP32 tasks has unique context that is not like aarch64 or aarch32, so we have to have unique ptrace handler. I prepared the patch for ptrace with runtime ABI detection, as Catalin said, see there: https://github.com/norov/linux/commit/1f66dc22a4450b192e83458f2c3cc0e79f53e670 If it's OK, I'd like to update submission. Yury -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32
On Wed, Dec 07, 2016 at 09:40:13PM +0100, Arnd Bergmann wrote: > On Wednesday, December 7, 2016 4:59:13 PM CET Catalin Marinas wrote: > > On Tue, Dec 06, 2016 at 11:55:08AM +0530, Yury Norov wrote: > > > On Mon, Dec 05, 2016 at 04:34:23PM +, Catalin Marinas wrote: > > > > On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote: > > > > > New aarch32 ptrace syscall handler is introduced to avoid run-time > > > > > detection of the task type. > > > > > > > > What's wrong with the run-time detection? If it's just to avoid a > > > > negligible overhead, I would rather keep the code simpler by avoiding > > > > duplicating the generic compat_sys_ptrace(). > > > > > > Nothing wrong. This is how Arnd asked me to do. You already asked this > > > question: http://lkml.iu.edu/hypermail/linux/kernel/1604.3/00930.html > > > > Hmm, I completely forgot about this ;). There is still an advantage to > > doing run-time checking if we avoid touching core code (less acks to > > gather and less code duplication). > > > > Let's see what Arnd says but the initial patch looked simpler. > > I don't currently have either version of the patch in my inbox > (the archive is on a different machine), but in general I'd still > think it's best to avoid the runtime check for aarch64-ilp32 > altogether. I'd have to look at the overall kernel source to > see if it's worth avoiding one or two instances though, or > if there are an overwhelming number of other checks that we > can't avoid at all. Just in case you haven't found them already, current version: https://marc.info/?l=linux-arm-kernel=147708276818318=2 Original version: https://patchwork.kernel.org/patch/7980521/ The old one looks more readable and given that ptrace is not really a fast path, I'm not two worried about run-time checks > Regarding ptrace, I notice that arch/tile doesn't even use > the compat entry point for its ilp32 user space on 64-bit > kernels, it just calls the regular 64-bit one. Would that > help here? I don't know whether it would work, we have incompatible siginfo_t on AArch64/ILP32. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32
On Tue, Dec 06, 2016 at 11:55:08AM +0530, Yury Norov wrote: > On Mon, Dec 05, 2016 at 04:34:23PM +, Catalin Marinas wrote: > > On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote: > > > New aarch32 ptrace syscall handler is introduced to avoid run-time > > > detection of the task type. > > > > What's wrong with the run-time detection? If it's just to avoid a > > negligible overhead, I would rather keep the code simpler by avoiding > > duplicating the generic compat_sys_ptrace(). > > Nothing wrong. This is how Arnd asked me to do. You already asked this > question: http://lkml.iu.edu/hypermail/linux/kernel/1604.3/00930.html Hmm, I completely forgot about this ;). There is still an advantage to doing run-time checking if we avoid touching core code (less acks to gather and less code duplication). Let's see what Arnd says but the initial patch looked simpler. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32
On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote: > New aarch32 ptrace syscall handler is introduced to avoid run-time > detection of the task type. What's wrong with the run-time detection? If it's just to avoid a negligible overhead, I would rather keep the code simpler by avoiding duplicating the generic compat_sys_ptrace(). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
