Rust for linux arm 32bit #2

TheSven73 · 2021-04-14T01:20:20Z

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This is simply based on output from: $ rustc +nightly -Z unstable-options \ --target=arm-unknown-linux-gnueabi \ --print target-spec-json Changes made: - removed "unsupported-abis" (does not build) - added "function-sections": false (all kernel functions should go in the .text section) - added "relocation-model": "static" (kernel does not support .data.rel.ro sections) Signed-off-by: Sven Van Asbroeck <[email protected]>

The bug which this guard protects against (rust-lang/rust-bindgen#1671) was fixed upstream as of rust-bindgen v0.53: rust-lang/rust-bindgen#1688 d650823839f7 ("Remove size_t to usize conversion") The current recommended rust-bindgen version for building the Linux kernel is v0.56, so the guard can be safely dropped. Signed-off-by: Sven Van Asbroeck <[email protected]>

Add panic handlers for the following 32-bit arm intrinsics: - __aeabi_ul2f, __aeabi_ul2d : floating-point operations - __aeabi_uldivmod, __mulodi4 : 64-bit division Neither floating point operations, nor native 64-bit division are supported inside the kernel, so we can safely implement these with a panic handler. Signed-off-by: Sven Van Asbroeck <[email protected]>

Remove the assumption that c_types::c_ulong is u64. This is true only on 64-bit cpu architectures. Signed-off-by: Sven Van Asbroeck <[email protected]>

Everything is now in place to enable Rust support on 32-bit arm. Signed-off-by: Sven Van Asbroeck <[email protected]>

qemu emulates the virt machine running a cortex-a7. kernel-arm-release.config corresponds to: - arch/arm/configs/multi_v7_defconfig (includes cortex-a7 virt support) - enable rust support, enable rust samples (as modules) - enable android/binder rust support Signed-off-by: Sven Van Asbroeck <[email protected]>

Merge branch 'mlxsw-fixes' Ido Schimmel says: ==================== mlxsw: Thermal and qdisc fixes Patches #1-#2 fix wrong validation of burst size in qdisc code and a user triggerable WARN_ON(). Patch #3 fixes a regression in thermal monitoring of transceiver modules and gearboxes. ==================== Signed-off-by: David S. Miller <[email protected]>

When user space brings PKRU into init state, then the kernel handling is broken: T1 user space xsave(state) state.header.xfeatures &= ~XFEATURE_MASK_PKRU; xrstor(state) T1 -> kernel schedule() XSAVE(S) -> T1->xsave.header.xfeatures[PKRU] == 0 T1->flags |= TIF_NEED_FPU_LOAD; wrpkru(); schedule() ... pk = get_xsave_addr(&T1->fpu->state.xsave, XFEATURE_PKRU); if (pk) wrpkru(pk->pkru); else wrpkru(DEFAULT_PKRU); Because the xfeatures bit is 0 and therefore the value in the xsave storage is not valid, get_xsave_addr() returns NULL and switch_to() writes the default PKRU. -> FAIL #1! So that wrecks any copy_to/from_user() on the way back to user space which hits memory which is protected by the default PKRU value. Assumed that this does not fail (pure luck) then T1 goes back to user space and because TIF_NEED_FPU_LOAD is set it ends up in switch_fpu_return() __fpregs_load_activate() if (!fpregs_state_valid()) { load_XSTATE_from_task(); } But if nothing touched the FPU between T1 scheduling out and back in, then the fpregs_state is still valid which means switch_fpu_return() does nothing and just clears TIF_NEED_FPU_LOAD. Back to user space with DEFAULT_PKRU loaded. -> FAIL #2! The fix is simple: if get_xsave_addr() returns NULL then set the PKRU value to 0 instead of the restrictive default PKRU value in init_pkru_value. [ bp: Massage in minor nitpicks from folks. ] Fixes: 0cecca9 ("x86/fpu: Eager switch PKRU state") Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Dave Hansen <[email protected]> Acked-by: Rik van Riel <[email protected]> Tested-by: Babu Moger <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected]

ASan reported a memory leak of BPF-related ksymbols map and dso. The leak is caused by refount never reaching 0, due to missing __put calls in the function machine__process_ksymbol_register. Once the dso is inserted in the map, dso__put() should be called (map__new2() increases the refcount to 2). The same thing applies for the map when it's inserted into maps (maps__insert() increases the refcount to 2). $ sudo ./perf record -- sleep 5 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.025 MB perf.data (8 samples) ] ================================================================= ==297735==ERROR: LeakSanitizer: detected memory leaks Direct leak of 6992 byte(s) in 19 object(s) allocated from: #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7) #1 0x8e4e53 in map__new2 /home/user/linux/tools/perf/util/map.c:216:20 #2 0x8cf68c in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:778:10 [...] Indirect leak of 8702 byte(s) in 19 object(s) allocated from: #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7) #1 0x8728d7 in dso__new_id /home/user/linux/tools/perf/util/dso.c:1256:20 #2 0x872015 in dso__new /home/user/linux/tools/perf/util/dso.c:1295:9 #3 0x8cf623 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:774:21 [...] Indirect leak of 1520 byte(s) in 19 object(s) allocated from: #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7) #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23 #2 0x888954 in map__process_kallsym_symbol /home/user/linux/tools/perf/util/symbol.c:710:8 [...] Indirect leak of 1406 byte(s) in 19 object(s) allocated from: #0 0x4f43c7 in calloc (/home/user/linux/tools/perf/perf+0x4f43c7) #1 0x87b3da in symbol__new /home/user/linux/tools/perf/util/symbol.c:269:23 #2 0x8cfbd8 in machine__process_ksymbol_register /home/user/linux/tools/perf/util/machine.c:803:8 [...] Signed-off-by: Riccardo Mancini <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Ian Rogers <[email protected]> Cc: Jiapeng Chong <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Tommi Rantala <[email protected]> Link: http://lore.kernel.org/lkml/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

This reverts commit 1815d9c. Unfortunately this inverts the locking hierarchy, so back to the drawing board. Full lockdep splat below: ====================================================== WARNING: possible circular locking dependency detected 5.13.0-rc7-CI-CI_DRM_10254+ #1 Not tainted ------------------------------------------------------ kms_frontbuffer/1087 is trying to acquire lock: ffff88810dcd01a8 (&dev->master_mutex){+.+.}-{3:3}, at: drm_is_current_master+0x1b/0x40 but task is already holding lock: ffff88810dcd0488 (&dev->mode_config.mutex){+.+.}-{3:3}, at: drm_mode_getconnector+0x1c6/0x4a0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&dev->mode_config.mutex){+.+.}-{3:3}: __mutex_lock+0xab/0x970 drm_client_modeset_probe+0x22e/0xca0 __drm_fb_helper_initial_config_and_unlock+0x42/0x540 intel_fbdev_initial_config+0xf/0x20 [i915] async_run_entry_fn+0x28/0x130 process_one_work+0x26d/0x5c0 worker_thread+0x37/0x380 kthread+0x144/0x170 ret_from_fork+0x1f/0x30 -> #1 (&client->modeset_mutex){+.+.}-{3:3}: __mutex_lock+0xab/0x970 drm_client_modeset_commit_locked+0x1c/0x180 drm_client_modeset_commit+0x1c/0x40 __drm_fb_helper_restore_fbdev_mode_unlocked+0x88/0xb0 drm_fb_helper_set_par+0x34/0x40 intel_fbdev_set_par+0x11/0x40 [i915] fbcon_init+0x270/0x4f0 visual_init+0xc6/0x130 do_bind_con_driver+0x1e5/0x2d0 do_take_over_console+0x10e/0x180 do_fbcon_takeover+0x53/0xb0 register_framebuffer+0x22d/0x310 __drm_fb_helper_initial_config_and_unlock+0x36c/0x540 intel_fbdev_initial_config+0xf/0x20 [i915] async_run_entry_fn+0x28/0x130 process_one_work+0x26d/0x5c0 worker_thread+0x37/0x380 kthread+0x144/0x170 ret_from_fork+0x1f/0x30 -> #0 (&dev->master_mutex){+.+.}-{3:3}: __lock_acquire+0x151e/0x2590 lock_acquire+0xd1/0x3d0 __mutex_lock+0xab/0x970 drm_is_current_master+0x1b/0x40 drm_mode_getconnector+0x37e/0x4a0 drm_ioctl_kernel+0xa8/0xf0 drm_ioctl+0x1e8/0x390 __x64_sys_ioctl+0x6a/0xa0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: &dev->master_mutex --> &client->modeset_mutex --> &dev->mode_config.mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&dev->mode_config.mutex); lock(&client->modeset_mutex); lock(&dev->mode_config.mutex); lock(&dev->master_mutex); *** DEADLOCK *** 1 lock held by kms_frontbuffer/1087: #0: ffff88810dcd0488 (&dev->mode_config.mutex){+.+.}-{3:3}, at: drm_mode_getconnector+0x1c6/0x4a0 stack backtrace: CPU: 7 PID: 1087 Comm: kms_frontbuffer Not tainted 5.13.0-rc7-CI-CI_DRM_10254+ #1 Hardware name: Intel Corporation Ice Lake Client Platform/IceLake U DDR4 SODIMM PD RVP TLC, BIOS ICLSFWR1.R00.3234.A01.1906141750 06/14/2019 Call Trace: dump_stack+0x7f/0xad check_noncircular+0x12e/0x150 __lock_acquire+0x151e/0x2590 lock_acquire+0xd1/0x3d0 __mutex_lock+0xab/0x970 drm_is_current_master+0x1b/0x40 drm_mode_getconnector+0x37e/0x4a0 drm_ioctl_kernel+0xa8/0xf0 drm_ioctl+0x1e8/0x390 __x64_sys_ioctl+0x6a/0xa0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Note that this broke the intel-gfx CI pretty much across the board because it has to reboot machines after it hits a lockdep splat. Testcase: igt/debugfs_test/read_all_entries Acked-by: Petri Latvala <[email protected]> Fixes: 1815d9c ("drm: add a locked version of drm_is_current_master") Cc: Desmond Cheong Zhi Xi <[email protected]> Cc: Emil Velikov <[email protected]> Cc: [email protected] Signed-off-by: Daniel Vetter <[email protected]> Cc: Maarten Lankhorst <[email protected]> Cc: Maxime Ripard <[email protected]> Cc: Thomas Zimmermann <[email protected]> Cc: David Airlie <[email protected]> Cc: Daniel Vetter <[email protected]> Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

The XSAVE init code initializes all enabled and supported components with XRSTOR(S) to init state. Then it XSAVEs the state of the components back into init_fpstate which is used in several places to fill in the init state of components. This works correctly with XSAVE, but not with XSAVEOPT and XSAVES because those use the init optimization and skip writing state of components which are in init state. So init_fpstate.xsave still contains all zeroes after this operation. There are two ways to solve that: 1) Use XSAVE unconditionally, but that requires to reshuffle the buffer when XSAVES is enabled because XSAVES uses compacted format. 2) Save the components which are known to have a non-zero init state by other means. Looking deeper, #2 is the right thing to do because all components the kernel supports have all-zeroes init state except the legacy features (FP, SSE). Those cannot be hard coded because the states are not identical on all CPUs, but they can be saved with FXSAVE which avoids all conditionals. Use FXSAVE to save the legacy FP/SSE components in init_fpstate along with a BUILD_BUG_ON() which reminds developers to validate that a newly added component has all zeroes init state. As a bonus remove the now unused copy_xregs_to_kernel_booting() crutch. The XSAVE and reshuffle method can still be implemented in the unlikely case that components are added which have a non-zero init state and no other means to save them. For now, FXSAVE is just simple and good enough. [ bp: Fix a typo or two in the text. ] Fixes: 6bad06b ("x86, xsave: Use xsaveopt in context-switch path when supported") Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected]

Sven Van Asbroeck added 3 commits April 13, 2021 20:43

TheSven73 force-pushed the rust-for-linux-arm-32bit branch 15 times, most recently from 0362cbd to 49ad371 Compare April 14, 2021 18:51

Sven Van Asbroeck added 2 commits April 14, 2021 16:18

rust/binder: remove dependency on 64-bit cpu architectures

e3d296e

Remove the assumption that c_types::c_ulong is u64. This is true only on 64-bit cpu architectures. Signed-off-by: Sven Van Asbroeck <[email protected]>

rust: enable for 32-bit arm

725f5c5

Everything is now in place to enable Rust support on 32-bit arm. Signed-off-by: Sven Van Asbroeck <[email protected]>

TheSven73 force-pushed the rust-for-linux-arm-32bit branch 5 times, most recently from a85d1cb to 882f378 Compare April 14, 2021 21:46

TheSven73 force-pushed the rust-for-linux-arm-32bit branch from 882f378 to 6b11d96 Compare April 14, 2021 21:47

TheSven73 closed this Apr 14, 2021

TheSven73 deleted the rust-for-linux-arm-32bit branch April 14, 2021 23:44

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Rust for linux arm 32bit #2

Rust for linux arm 32bit #2

TheSven73 commented Apr 14, 2021

Rust for linux arm 32bit #2

Rust for linux arm 32bit #2

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TheSven73 commented Apr 14, 2021