From: Asahi Lina <lina@asahilina.net> To: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>, "Maxime Ripard" <mripard@kernel.org>, "Thomas Zimmermann" <tzimmermann@suse.de>, "David Airlie" <airlied@gmail.com>, "Daniel Vetter" <daniel@ffwll.ch>, "Miguel Ojeda" <ojeda@kernel.org>, "Alex Gaynor" <alex.gaynor@gmail.com>, "Wedson Almeida Filho" <wedsonaf@gmail.com>, "Boqun Feng" <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>, "Sumit Semwal" <sumit.semwal@linaro.org>, "Christian König" <christian.koenig@amd.com>, "Luben Tuikov" <luben.tuikov@amd.com>, "Jarkko Sakkinen" <jarkko@kernel.org>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Alyssa Rosenzweig" <alyssa@rosenzweig.io>, "Karol Herbst" <kherbst@redhat.com>, "Ella Stanforth" <ella@iglunix.org>, "Faith Ekstrand" <faith.ekstrand@collabora.com>, Mary <mary@mary.zone>, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-sgx@vger.kernel.org, asahi@lists.linux.dev Subject: Re: [PATCH RFC 01/18] rust: drm: ioctl: Add DRM ioctl abstraction Date: Thu, 9 Mar 2023 15:04:13 +0900 [thread overview] Message-ID: <11ce9291-c17f-e73d-fb5d-13d5386fe6be@asahilina.net> (raw) In-Reply-To: <D9Cyx-9kbjaeb8QVBFqapDyctoDdVyu5uXEJDR41sdXUDXM1VgdRicV5huJDwfC3-T2J-R_DYHH8JZ1_aRdgbeYZFT78J9QveeeYbiTq4yU=@protonmail.com> On 08/03/2023 02.34, Björn Roy Baron wrote: >> + // SAFETY: This is just the ioctl argument, which hopefully has the right type >> + // (we've done our best checking the size). > > In the rust tree there is the ReadableFromBytes [1] trait which indicates that it is safe to read arbitrary bytes into the type. Maybe you could add it as bound on the argument type when it lands in rust-next? This way you can't end up with for example a struct containing a bool with the byte value 2, which is UB. There's actually a much bigger story here, because that trait isn't really very useful without a way to auto-derive it. I need the same kind of guarantee for all the GPU firmware structs... There's one using only declarative macros [1] and one using proc macros [2]. And then, since ioctl arguments are declared in C UAPI header files, we need a way to be able to derive those traits for them... which I guess means bindgen changes? For now though, I don't think this is something we need to worry about too much for this particular use case because the macro forces all struct types to be part of `bindings`, and any driver UAPI should already follow these constraints if it is well-formed (and UAPIs are going to already attract a lot of scrutiny anyway). Technically you could try taking a random kernel struct containing a `bool` in an ioctl list, but that would stand out as nonsense just as much as trying to unsafe impl ReadableFromBytes for it so... it's kind of an academic problem ^^ Actually, I think we talked of moving UAPI types to a separate crate (so drivers can get access to those types and only those types, not the main bindings crate). Then maybe we could just say that if the macro forces the type to be from that crate, it's inherently safe since all UAPIs should already be castable to/from bytes if properly designed. Aside: I'm not sure the ReadableFromBytes/WritableToBytes distinction is very useful. I know it exists (padding bytes, uninit fields, and technically bool should be WritableToBytes but not ReadableFromBytes), but I can't think of a good use case for it... I think I'd rather start with a single trait and just always enforce the union of the rules, because pretty much any time you're casting to/from bytes you want well-defined "bag of bytes" struct layouts anyway. ioctls can be R/W/RW so having separate traits depending on ioctl type complicates the code... [1] https://github.com/QubesOS/qubes-gui-rust/blob/940754bfefb7325548eece658c307a0c41c9bc7c/qubes-castable/src/lib.rs [2] https://docs.rs/pkbuffer/latest/pkbuffer/derive.Castable.html > > https://rust-for-linux.github.io/docs/kernel/io_buffer/trait.ReadableFromBytes.html [1] > ~~ Lina
WARNING: multiple messages have this Message-ID (diff)
From: Asahi Lina <lina@asahilina.net> To: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: "Karol Herbst" <kherbst@redhat.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, dri-devel@lists.freedesktop.org, Mary <mary@mary.zone>, "Gary Guo" <gary@garyguo.net>, "Ella Stanforth" <ella@iglunix.org>, "Sumit Semwal" <sumit.semwal@linaro.org>, "Alyssa Rosenzweig" <alyssa@rosenzweig.io>, "Luben Tuikov" <luben.tuikov@amd.com>, "Alex Gaynor" <alex.gaynor@gmail.com>, "Miguel Ojeda" <ojeda@kernel.org>, linux-media@vger.kernel.org, "Wedson Almeida Filho" <wedsonaf@gmail.com>, rust-for-linux@vger.kernel.org, "Boqun Feng" <boqun.feng@gmail.com>, linaro-mm-sig@lists.linaro.org, "Faith Ekstrand" <faith.ekstrand@collabora.com>, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, "Jarkko Sakkinen" <jarkko@kernel.org>, asahi@lists.linux.dev, "Thomas Zimmermann" <tzimmermann@suse.de>, "Christian König" <christian.koenig@amd.com> Subject: Re: [PATCH RFC 01/18] rust: drm: ioctl: Add DRM ioctl abstraction Date: Thu, 9 Mar 2023 15:04:13 +0900 [thread overview] Message-ID: <11ce9291-c17f-e73d-fb5d-13d5386fe6be@asahilina.net> (raw) In-Reply-To: <D9Cyx-9kbjaeb8QVBFqapDyctoDdVyu5uXEJDR41sdXUDXM1VgdRicV5huJDwfC3-T2J-R_DYHH8JZ1_aRdgbeYZFT78J9QveeeYbiTq4yU=@protonmail.com> On 08/03/2023 02.34, Björn Roy Baron wrote: >> + // SAFETY: This is just the ioctl argument, which hopefully has the right type >> + // (we've done our best checking the size). > > In the rust tree there is the ReadableFromBytes [1] trait which indicates that it is safe to read arbitrary bytes into the type. Maybe you could add it as bound on the argument type when it lands in rust-next? This way you can't end up with for example a struct containing a bool with the byte value 2, which is UB. There's actually a much bigger story here, because that trait isn't really very useful without a way to auto-derive it. I need the same kind of guarantee for all the GPU firmware structs... There's one using only declarative macros [1] and one using proc macros [2]. And then, since ioctl arguments are declared in C UAPI header files, we need a way to be able to derive those traits for them... which I guess means bindgen changes? For now though, I don't think this is something we need to worry about too much for this particular use case because the macro forces all struct types to be part of `bindings`, and any driver UAPI should already follow these constraints if it is well-formed (and UAPIs are going to already attract a lot of scrutiny anyway). Technically you could try taking a random kernel struct containing a `bool` in an ioctl list, but that would stand out as nonsense just as much as trying to unsafe impl ReadableFromBytes for it so... it's kind of an academic problem ^^ Actually, I think we talked of moving UAPI types to a separate crate (so drivers can get access to those types and only those types, not the main bindings crate). Then maybe we could just say that if the macro forces the type to be from that crate, it's inherently safe since all UAPIs should already be castable to/from bytes if properly designed. Aside: I'm not sure the ReadableFromBytes/WritableToBytes distinction is very useful. I know it exists (padding bytes, uninit fields, and technically bool should be WritableToBytes but not ReadableFromBytes), but I can't think of a good use case for it... I think I'd rather start with a single trait and just always enforce the union of the rules, because pretty much any time you're casting to/from bytes you want well-defined "bag of bytes" struct layouts anyway. ioctls can be R/W/RW so having separate traits depending on ioctl type complicates the code... [1] https://github.com/QubesOS/qubes-gui-rust/blob/940754bfefb7325548eece658c307a0c41c9bc7c/qubes-castable/src/lib.rs [2] https://docs.rs/pkbuffer/latest/pkbuffer/derive.Castable.html > > https://rust-for-linux.github.io/docs/kernel/io_buffer/trait.ReadableFromBytes.html [1] > ~~ Lina
next prev parent reply other threads:[~2023-03-09 6:04 UTC|newest] Thread overview: 242+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-07 14:25 [PATCH RFC 00/18] Rust DRM subsystem abstractions (& preview AGX driver) Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 01/18] rust: drm: ioctl: Add DRM ioctl abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:48 ` Karol Herbst 2023-03-07 14:48 ` Karol Herbst 2023-03-07 14:51 ` Karol Herbst 2023-03-07 14:51 ` Karol Herbst 2023-03-07 15:32 ` Maíra Canal 2023-03-07 15:32 ` Maíra Canal 2023-03-09 5:32 ` Asahi Lina 2023-03-09 5:32 ` Asahi Lina 2023-03-09 6:15 ` Dave Airlie 2023-03-09 6:15 ` Dave Airlie 2023-03-09 12:09 ` Maíra Canal 2023-03-07 17:34 ` Björn Roy Baron 2023-03-07 17:34 ` Björn Roy Baron 2023-03-09 6:04 ` Asahi Lina [this message] 2023-03-09 6:04 ` Asahi Lina 2023-03-09 20:24 ` Faith Ekstrand 2023-03-09 20:24 ` Faith Ekstrand 2023-03-09 20:39 ` Karol Herbst 2023-03-09 20:39 ` Karol Herbst 2023-03-10 6:21 ` Asahi Lina 2023-03-10 6:21 ` Asahi Lina 2023-04-13 9:23 ` Daniel Vetter 2023-04-13 9:23 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 02/18] rust: drm: Add Device and Driver abstractions Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 18:19 ` Björn Roy Baron 2023-03-07 18:19 ` Björn Roy Baron 2023-03-09 6:10 ` Asahi Lina 2023-03-09 6:10 ` Asahi Lina 2023-03-10 18:56 ` Boqun Feng 2023-03-10 18:56 ` Boqun Feng 2023-03-11 5:41 ` Boqun Feng 2023-03-11 5:41 ` Boqun Feng 2023-04-05 17:10 ` Daniel Vetter 2023-04-05 17:10 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 03/18] rust: drm: file: Add File abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-09 21:16 ` Faith Ekstrand 2023-03-09 21:16 ` Faith Ekstrand 2023-03-09 22:16 ` Asahi Lina 2023-03-09 22:16 ` Asahi Lina 2023-03-13 17:49 ` Faith Ekstrand 2023-03-13 17:49 ` Faith Ekstrand 2023-03-14 2:07 ` Boqun Feng 2023-03-14 2:07 ` Boqun Feng 2023-04-05 11:25 ` Daniel Vetter 2023-04-05 11:25 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 04/18] rust: drm: gem: Add GEM object abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 11:08 ` Daniel Vetter 2023-04-05 11:08 ` Daniel Vetter 2023-04-05 11:19 ` Miguel Ojeda 2023-04-05 11:19 ` Miguel Ojeda 2023-04-05 11:22 ` Daniel Vetter 2023-04-05 11:22 ` Daniel Vetter 2023-04-05 12:32 ` Miguel Ojeda 2023-04-05 12:32 ` Miguel Ojeda 2023-04-05 12:36 ` Daniel Vetter 2023-04-05 12:36 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 05/18] drm/gem-shmem: Export VM ops functions Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 06/18] rust: drm: gem: shmem: Add DRM shmem helper abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-08 13:38 ` Maíra Canal 2023-03-08 13:38 ` Maíra Canal 2023-03-09 5:25 ` Asahi Lina 2023-03-09 5:25 ` Asahi Lina 2023-03-09 11:47 ` Maíra Canal 2023-03-09 11:47 ` Maíra Canal 2023-03-09 14:16 ` Asahi Lina 2023-03-09 14:16 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 07/18] rust: drm: mm: Add DRM MM Range Allocator abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-06 14:15 ` Daniel Vetter 2023-04-06 14:15 ` Daniel Vetter 2023-04-06 15:28 ` Miguel Ojeda 2023-04-06 15:28 ` Miguel Ojeda 2023-04-06 15:45 ` Daniel Vetter 2023-04-06 15:45 ` Daniel Vetter 2023-04-06 17:19 ` Miguel Ojeda 2023-04-06 17:19 ` Miguel Ojeda 2023-04-06 15:53 ` Asahi Lina 2023-04-06 16:13 ` [Linaro-mm-sig] " Daniel Vetter 2023-04-06 16:13 ` Daniel Vetter 2023-04-06 16:39 ` Asahi Lina 2023-04-06 16:39 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 08/18] rust: dma_fence: Add DMA Fence abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 11:10 ` Daniel Vetter 2023-04-05 11:10 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 09/18] rust: drm: syncobj: Add DRM Sync Object abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 12:33 ` Daniel Vetter 2023-04-05 12:33 ` Daniel Vetter 2023-04-06 16:04 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 10/18] drm/scheduler: Add can_run_job callback Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-08 8:46 ` Christian König 2023-03-08 8:46 ` Christian König 2023-03-08 9:41 ` Asahi Lina 2023-03-08 9:41 ` Asahi Lina 2023-03-08 10:00 ` Christian König 2023-03-08 10:00 ` Christian König 2023-03-08 14:53 ` Asahi Lina 2023-03-08 14:53 ` Asahi Lina 2023-03-08 15:30 ` Christian König 2023-03-08 15:30 ` Christian König 2023-03-08 16:44 ` Asahi Lina 2023-03-08 16:44 ` Asahi Lina 2023-03-08 17:57 ` Christian König 2023-03-08 17:57 ` Christian König 2023-03-08 19:05 ` Asahi Lina 2023-03-08 19:05 ` Asahi Lina 2023-03-08 19:12 ` Christian König 2023-03-08 19:12 ` Christian König 2023-03-08 19:45 ` Asahi Lina 2023-03-08 19:45 ` Asahi Lina 2023-03-08 20:14 ` Christian König 2023-03-08 20:14 ` Christian König 2023-03-09 6:30 ` Asahi Lina 2023-03-09 6:30 ` Asahi Lina 2023-03-09 8:05 ` Christian König 2023-03-09 8:05 ` Christian König 2023-03-09 9:14 ` Asahi Lina 2023-03-09 9:14 ` Asahi Lina 2023-03-09 18:50 ` Faith Ekstrand 2023-03-09 18:50 ` Faith Ekstrand 2023-03-10 9:16 ` Asahi Lina 2023-03-10 9:16 ` Asahi Lina 2023-03-08 12:39 ` Karol Herbst 2023-03-08 12:39 ` Karol Herbst 2023-03-08 13:47 ` Christian König 2023-03-08 13:47 ` Christian König 2023-03-08 14:43 ` Karol Herbst 2023-03-08 14:43 ` Karol Herbst 2023-03-08 15:02 ` Christian König 2023-03-08 15:02 ` Christian König 2023-03-08 15:19 ` Karol Herbst 2023-03-08 15:19 ` Karol Herbst 2023-03-16 13:40 ` Daniel Vetter 2023-03-16 13:40 ` Daniel Vetter 2023-04-05 13:40 ` Daniel Vetter 2023-04-05 13:40 ` Daniel Vetter 2023-04-05 14:14 ` Christian König 2023-04-05 14:21 ` Daniel Vetter 2023-04-05 14:21 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 11/18] drm/scheduler: Clean up jobs when the scheduler is torn down Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-08 9:57 ` Maarten Lankhorst 2023-03-08 9:57 ` Maarten Lankhorst 2023-03-08 10:03 ` Christian König 2023-03-08 10:03 ` Christian König 2023-03-08 15:18 ` Asahi Lina 2023-03-08 15:18 ` Asahi Lina 2023-03-08 15:42 ` Christian König 2023-03-08 15:42 ` Christian König 2023-03-08 17:32 ` Asahi Lina 2023-03-08 17:32 ` Asahi Lina 2023-03-08 18:12 ` Christian König 2023-03-08 18:12 ` Christian König 2023-03-08 19:37 ` Asahi Lina 2023-03-08 19:37 ` Asahi Lina 2023-03-09 8:42 ` Christian König 2023-03-09 8:42 ` Christian König 2023-03-09 9:43 ` Asahi Lina 2023-03-09 9:43 ` Asahi Lina 2023-03-09 11:47 ` Christian König 2023-03-09 11:47 ` Christian König 2023-03-09 13:48 ` Asahi Lina 2023-03-09 13:48 ` Asahi Lina 2023-03-09 19:59 ` Faith Ekstrand 2023-03-09 19:59 ` Faith Ekstrand 2023-03-10 9:58 ` Asahi Lina 2023-03-10 9:58 ` Asahi Lina 2023-03-13 20:11 ` Faith Ekstrand 2023-03-13 20:11 ` Faith Ekstrand 2023-03-08 17:39 ` alyssa 2023-03-08 17:39 ` alyssa 2023-03-08 17:44 ` Asahi Lina 2023-03-08 17:44 ` Asahi Lina 2023-03-08 18:13 ` Christian König 2023-03-08 18:13 ` Christian König 2023-04-05 13:52 ` Daniel Vetter 2023-04-05 13:52 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 12/18] rust: drm: sched: Add GPU scheduler abstraction Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 15:43 ` Daniel Vetter 2023-04-05 15:43 ` Daniel Vetter 2023-04-05 19:29 ` Daniel Vetter 2023-04-18 8:45 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 13/18] drm/gem: Add a flag to control whether objects can be exported Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 14:55 ` Daniel Vetter 2023-04-05 14:55 ` Daniel Vetter 2023-03-07 14:25 ` [PATCH RFC 14/18] rust: drm: gem: Add set_exportable() method Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 15/18] drm/asahi: Add the Asahi driver UAPI [DO NOT MERGE] Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 15:28 ` Karol Herbst 2023-03-07 15:28 ` Karol Herbst 2023-03-07 14:25 ` [PATCH RFC 16/18] rust: bindings: Bind the Asahi DRM UAPI Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 17/18] rust: macros: Add versions macro Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-03-07 14:25 ` [PATCH RFC 18/18] drm/asahi: Add the Asahi driver for Apple AGX GPUs Asahi Lina 2023-03-07 14:25 ` Asahi Lina 2023-04-05 14:37 ` Daniel Vetter 2023-04-05 14:37 ` Daniel Vetter 2023-04-06 4:44 ` Asahi Lina 2023-04-06 4:44 ` Asahi Lina 2023-04-06 5:09 ` Asahi Lina 2023-04-06 5:09 ` Asahi Lina 2023-04-06 11:26 ` Daniel Vetter 2023-04-06 11:26 ` Daniel Vetter 2023-04-06 10:42 ` [Linaro-mm-sig] " Daniel Vetter 2023-04-06 10:42 ` Daniel Vetter 2023-04-06 11:55 ` Daniel Vetter 2023-04-06 11:55 ` Daniel Vetter 2023-04-06 13:15 ` Asahi Lina 2023-04-06 13:15 ` Asahi Lina 2023-04-06 13:48 ` Daniel Vetter 2023-04-06 13:48 ` Daniel Vetter 2023-04-06 15:19 ` Asahi Lina 2023-04-06 15:19 ` Asahi Lina 2023-04-05 14:44 ` Daniel Vetter 2023-04-05 14:44 ` Daniel Vetter 2023-04-06 5:02 ` Asahi Lina 2023-04-06 5:02 ` Asahi Lina 2023-04-06 5:09 ` Asahi Lina 2023-04-06 5:09 ` Asahi Lina 2023-04-06 11:25 ` [Linaro-mm-sig] " Daniel Vetter 2023-04-06 11:25 ` Daniel Vetter 2023-04-06 13:32 ` Asahi Lina 2023-04-06 13:32 ` Asahi Lina 2023-04-06 13:54 ` Daniel Vetter 2023-04-06 13:54 ` Daniel Vetter 2023-03-07 16:17 ` [PATCH RFC 00/18] Rust DRM subsystem abstractions (& preview AGX driver) Asahi Lina 2023-03-07 16:17 ` Asahi Lina
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