From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: build scripts for the WIP xenomai porting to kernel 5.4 References: <20201014132459.GB24671@linux.intel.com> <8e59bc35-84ae-78be-8296-4f2367e8e844@siemens.com> <20201016033638.GB5581@linux.intel.com> <0ba45dfa-4755-c627-e1fd-9f2c32ea8b8a@siemens.com> <9153481d-6df6-314f-c2c0-f413a34fb815@siemens.com> <20201021114329.GA4344@linux.intel.com> <88232cd0-0713-4e45-bad2-e22acdeb7632@siemens.com> From: Jan Kiszka Message-ID: <3a85c6c8-6792-40d1-5ef2-6ee634fc3c91@siemens.com> Date: Thu, 22 Oct 2020 09:26:59 +0200 MIME-Version: 1.0 In-Reply-To: <88232cd0-0713-4e45-bad2-e22acdeb7632@siemens.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fino Meng Cc: xenomai@xenomai.org On 22.10.20 08:27, Jan Kiszka via Xenomai wrote: > On 21.10.20 13:43, Fino Meng wrote: >> On Wed, Oct 21, 2020 at 08:36:04AM +0200, Jan Kiszka wrote: >>> On 18.10.20 23:41, Jan Kiszka via Xenomai wrote: >>>> On 16.10.20 05:36, Fino Meng wrote: >>>>> On Thu, Oct 15, 2020 at 04:20:11PM +0200, Jan Kiszka wrote: >>>>>> On 14.10.20 15:25, Fino Meng wrote: >>>>>>> hi team, >>>>>>> >>>>>>> I just updated the scripts to build the WIP version xenomai porting to >>>>>>> kernel 5.4, just follow the steps: >>>>>>> >>>>>>> git clone https://github.com/finomeng/xenomai-mirror.git /tmp/xenomai-mirror.next-5.4 >>>>>>> cd /tmp/xenomai-mirror.next-5.4 >>>>>>> git checkout -t origin/wip/next-5.4-porting >>>>>>> >>>>>>> git clone https://github.com/intel/linux-stable-xenomai /tmp/kernel >>>>>>> cd /tmp/kernel >>>>>>> git checkout -t review/5.4.59/stable/ipipe-x86 >>>>>>> >>>>>>> ./patching-xenomai2kernel.sh >>>>>>> >>>>>>> cp config_xenomai.kernel_debug .config >>>>>>> make olddefconfig >>>>>>> ./build-debpkg.sh >>>>>>> >>>>>>> >>>>>>> I didn't put it togethter with ISAR/Debian yet. I test it with a PC with Debian 10 installed. >>>>>>> >>>>>>> if no error, linux-image-*.deb and linux-headers-*.deb should generated outside kernel folder, >>>>>>> copy them to your target test device with already installed a Debian/Ubuntu, >>>>>>> install the deb with "dpkg -i", update-grub should be called during install linux-image-*.deb >>>>>>> reboot and select to boot the new kernel in grub's menu >>>>>>> >>>>>>> the build steps also written in patching-xenomai2kernel.sh and build-debpkg.sh >>>>>>> >>>>>>> switchtest will fail in current version, for example: "./switchtest rtk_fp_ufpp0" >>>>>>> will print: >>>>>>> >>>>>>> r0: 2147483648 != 1000 >>>>>>> r1: 2147483648 != 1000 >>>>>>> r2: 2147483648 != 1000 >>>>>>> r3: 2147483648 != 1000 >>>>>>> r4: 2147483648 != 1000 >>>>>>> r5: 2147483648 != 1000 >>>>>>> r6: 2147483648 != 1000 >>>>>>> r7: 2147483648 != 1000 >>>>>>> ymm0: 2676586395008836901/0 != 1000/1000 >>>>>>> ymm1: 71776119061217280/0 != 1000/1000 >>>>>>> ymm2: 0/0 != 1000/1000 >>>>>>> ymm3: 1000/0 != 1000/1000 >>>>>>> ymm4: 1000/0 != 1000/1000 >>>>>>> ymm5: 1000/0 != 1000/1000 >>>>>>> ymm6: 1000/0 != 1000/1000 >>>>>>> ymm7: 1000/0 != 1000/1000 >>>>>>> Error after context switch from task 1(rtk_fp_ufpp0-1) to task 0(sleeper_ufps0-0), >>>>>>> FPU registers were set to 0 (maybe task sleeper_ufps0-0) >>>>>>> >>>>>>> if meet more questions just write to me, thanks! >>>>>>> >>>>>>> BR fino >>>>>>> >>>>>> >>>>>> I can reproduce in KVM and poked around a bit, though without finding >>>>>> the needle yet. Likely, there are multiple aspects. The change in >>>>>> upstream to FPU switching on user-return is a hot lead, but it takes a >>>>>> bit to fully grasp that and map it on our scenarios with Xenomai. >>>>>> >>>>>> Jan >>>>> >>>>> it seems that, switch_fpu_prepare() and switch_fpu_finish() are >>>>> for kernel thread context switch (in __switch_to() )and switch_fpu_return() is needed >>>>> before return to userspace( in prepare_exit_to_usermode()). >>>>> >>>> >>>> Yes, we need explicit switch_fpu_return() (likely open-coded, to skip >>>> the PF_KTHREAD check) at the end of xnarch_switch_to, at least as long >>>> as we do not add that to all fast (primary-mode) return-to-user paths. >>>> >>>> But it's more complex. The removal of fpu_initialized changed the >>>> condition under which __switch_to() does FPU saving and restoring: All >>>> kernel threads, also ours, are excluded. That needs to be compensated. >>>> >>>> But I'm still facing corruptions - continuing to debug. >>>> >>> >>> Quick update: >>> >>> I made some progress with changes like below, but I'm still facing >>> issues, not with weird AVX register corruptions. They confuse me because >>> classic FPU registers are updated and saved/restored the same way, but >>> they are currently unaffected. >>> >>> Jan >> >> in my current understand, >> a userspace Xenomai/Cobalt process's context switch always need FPU >> state save/restore; but how about the other case? >> >> in vanilla kernel, I see if a pure kernel thread want to use FPU, need >> manually call kernel_fpu_begin() and kernel_fpu_end(), like a critical >> area. > > Xenomai kernel threads can use the FPU, and that without > kernel_fpu_begin/end. That this works is also tested by switchtest, and > there were several issues, possibly there are still more. > > One step further: My weird avx register corruption is understand. It was > the local instrumentation. xnftrace_printf likely uses xmm regs > internally, and I had such an output after setting up the test pattern. > Fixing that, I still have a corruption, but not a "normal one" again, > ie. of the legacy FPU regs. > > Jan > Got it working: diff --git a/kernel/cobalt/arch/x86/thread.c b/kernel/cobalt/arch/x86/thread.c index aa7b5d19d8..9a014818ef 100644 --- a/kernel/cobalt/arch/x86/thread.c +++ b/kernel/cobalt/arch/x86/thread.c @@ -215,6 +215,15 @@ void xnarch_switch_to(struct xnthread *out, struct xnthread *in) */ clts(); #endif /* ! IPIPE_X86_FPU_EAGER */ + if (!xnthread_test_state(out, XNROOT | XNUSER) && + !test_thread_flag(TIF_NEED_FPU_LOAD)) { + struct fpu *prev_fpu = &prev->thread.fpu; + + if (!copy_fpregs_to_fpstate(prev_fpu)) + prev_fpu->last_cpu = -1; + else + prev_fpu->last_cpu = smp_processor_id(); + } next = in_tcb->core.host_task; #ifndef IPIPE_X86_FPU_EAGER @@ -260,6 +269,19 @@ void xnarch_switch_to(struct xnthread *out, struct xnthread *in) #ifndef IPIPE_X86_FPU_EAGER stts(); #endif /* ! IPIPE_X86_FPU_EAGER */ + if (xnthread_current() && + !xnthread_test_state(xnthread_current(), XNROOT) && + test_thread_flag(TIF_NEED_FPU_LOAD)) { + struct fpu *fpu = ¤t->thread.fpu; + int cpu = smp_processor_id(); + + if (!fpregs_state_valid(fpu, cpu)) { + copy_kernel_to_fpregs(&fpu->state); + fpregs_activate(fpu); + fpu->last_cpu = cpu; + } + clear_thread_flag(TIF_NEED_FPU_LOAD); + } } #ifndef IPIPE_X86_FPU_EAGER @@ -488,6 +510,7 @@ void xnarch_switch_fpu(struct xnthread *from, struct xnthread *to) return; copy_kernel_to_fpregs(&to_tcb->kfpu->state); + __cpu_invalidate_fpregs_state(); kernel_fpu_disable(); } #endif /* ! IPIPE_X86_FPU_EAGER */ @@ -541,7 +564,8 @@ void xnarch_init_shadow_tcb(struct xnthread *thread) #if LINUX_VERSION_CODE < KERNEL_VERSION(4,14,0) fpu__activate_fpstate_read(&p->thread.fpu); #else - fpu__clear(&p->thread.fpu); + set_thread_flag(TIF_NEED_FPU_LOAD); + fpstate_init(&p->thread.fpu.state); #endif #endif /* ! IPIPE_X86_FPU_EAGER */ } This still requires proper wrapping for the different kernel versions and some comments. But maybe you can continue testing from there. BTW, there are more to-dos: [ 0.182466] Freeing SMP alternatives memory: 44K [ 0.182656] ------------[ cut here ]------------ [ 0.183038] WARNING: CPU: 0 PID: 0 at ../kernel/ipipe/core.c:1968 __ipipe_spin_unlock_debug+0x14/0x20 [ 0.183600] Modules linked in: [ 0.183600] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.59-xenomai+ #64 [ 0.183600] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 0.183600] I-pipe domain: Linux [ 0.183600] RIP: 0010:__ipipe_spin_unlock_debug+0x14/0x20 [ 0.183600] Code: 8b 07 5b e9 0e d5 c7 00 5b c3 66 66 2e 0f 1f 84 00 00 00 00 00 90 e8 bb de a7 00 f7 c7 00 02 00 00 74 09 9c 58 f6 c4 02 75 02 <0f> 0b c3 66 0f 1f 84 00 00 00 00 00 e8 9b de a7 00 41 54 55 53 9c [ 0.183600] RSP: 0000:ffffffff82403d68 EFLAGS: 00010046 [ 0.183600] RAX: 0000000000000006 RBX: b74e512d1320154d RCX: ffff88803e6f2cc0 [ 0.183600] RDX: 0000000000000001 RSI: ffffffff810c1c9e RDI: 0000000000000200 [ 0.183600] RBP: ffff88803ea3afe4 R08: 0000000000000000 R09: ffff88803dd0e540 [ 0.183600] R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000200 [ 0.183600] R13: ffff88803dd0da00 R14: ffffffff82403eb0 R15: 0000000000000000 [ 0.183600] FS: 0000000000000000(0000) GS:ffff88803ea00000(0000) knlGS:0000000000000000 [ 0.183600] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.183600] CR2: ffff888003201000 CR3: 000000000240a001 CR4: 0000000000360ef0 [ 0.183600] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 0.183600] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 0.183600] Call Trace: [ 0.183600] get_random_u64+0x68/0x80 [ 0.183600] copy_process+0x37e/0x1ae0 [ 0.183600] _do_fork+0x92/0x340 [ 0.183600] ? acpi_hw_register_read+0x93/0x123 [ 0.183600] kernel_thread+0x55/0x70 [ 0.183600] ? rest_init+0xc0/0xc0 [ 0.183600] rest_init+0x1e/0xc0 [ 0.183600] start_kernel+0x4d4/0x4f9 [ 0.183600] secondary_startup_64+0xa4/0xb0 [ 0.183600] ---[ end trace 9d5e39ac2de18173 ]--- This is with I-pipe debugging enabled. Could you have a look? Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux