Devel May 2018

devel@sel4.systems

9 participants
11 discussions

Questions about Memory Management in seL4
by Daniel Wang 19 May '23

19 May '23

Hi all, Sorry to bother, I have some basic questions about seL4 memory management. Can someone help me? 1. where is the kernel’s address space? I know there are basically three methods: a) separate virtual address space, e.g. through changing page tables on entry into privileged mode to access b) physical space, e.g. through disable automatic hardware translation of virtual addresses on entry into privilege mode c) privilege region in each process’s virtual address space, e.g. through page table to map kernel address into use-mode process. My question is which of this is being used by seL4 microkernel? 2. Objects like CSpace, VSpace, CNode, TCB, Endpoint, etc. are called kernel objects, but it seems all dynamically allocated in thread running/creating time. Are those objects (e.g. Figure 3.3 in seL4 manual) in kernel space or in user space? 3. I read that after the kernel boot up, it passes all resources, untyped memory to the first thread. Are those untyped memory physical memory or virtual memory in a single page? The reason I ask is I’m learning the code of the UNSW AOS project (two of the assignment projects are implementing frame and papers). I’m confused that before the implementation of frames and pages what kind of memory is passed to the the first thread? I saw int AOS project, it uses ut_table_init(), ut_steal_mem(), I wonder what kind of memory it operates on? Thanks -Dan

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Questions on U-boot Verified Boot with CAmkES-ARM-VM
by Daniel Wang 10 Jul '18

10 Jul '18

Hi all, I’m trying to test secure boot with the CAmkES-arm-vm. I found that U-boot has its implementation of secure boot called verified boot, but it seems only support FIT image format. I’m wondering is there a way to convert the final ELF image to an FIT image? I’m studying the details of different booting image format. I’m not sure how it would work with seL4 camkes demo specifically, since there are so many binary files and cpio archives packed in the final ELF image. Would love to hear your opinions. Thank you very much! Best Regards -Daniel Wang

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sel4 qemu x86 runtime error
by Thad Seeberger 10 Jul '18

10 Jul '18

Compile now no problem however I'm getting error when running. I believe its an invalid opcode exception. I think my build not matching the qemu but I've tried diff machines and they do the same. I also get this warning during build, not sure if this relevant: Warning: Installation path /home/maddthad/camkes-tutorials-manifest/projects/capdl/capDL-tool not found on the PATH environment variable. make: Leaving directory `/home/maddthad/camkes-tutorials-manifest/projects/capdl/capDL-tool' Qemu commanr, lines with ????? suspect: qemu-system-i386 -nographic -m 512 -kernel images/kernel-ia32-pc99 -initrd images/capdl-loader-experimental-image-ia32-pc99 (process:98550): GLib-WARNING **: gmem.c:483: custom memory allocation vtable not supported Boot config: parsing cmdline 'images/kernel-ia32-pc99 ' Boot config: console_port = 0x3f8 Boot config: debug_port = 0x3f8 Boot config: disable_iommu = false ???? Warning: Your kernel was not compiled for the current microarchitecture. Parsing GRUB physical memory map Physical Memory Region from 0 size 9fc00 type 1 Physical Memory Region from 9fc00 size 400 type 2 Physical Memory Region from f0000 size 10000 type 2 Physical Memory Region from 100000 size 1fefe000 type 1 Adding physical memory region 0x100000-0x1f800000 Physical Memory Region from 1fffe000 size 2000 type 2 Physical Memory Region from fffc0000 size 40000 type 2 Multiboot gave us no video information Kernel loaded to: start=0x100000 end=0x160000 size=0x60000 entry=0x10005e ACPI: RSDP paddr=0xf7180 ACPI: RSDP vaddr=0xdfcf7180 ACPI: RSDT paddr=0x1ffffbc1 ACPI: RSDT vaddr=0xdffffbc1 ACPI: FADT paddr=0x1ffff1c0 ACPI: FADT vaddr=0xdffff1c0 ACPI: FADT flags=0x80a5 ACPI: 0 IOMMUs detected ACPI: MADT paddr=0x1ffffb11 ACPI: MADT vaddr=0xdffffb11 ACPI: MADT apic_addr=0xfee00000 ACPI: MADT flags=0x1 ACPI: MADT_APIC apic_id=0x0 ACPI: MADT_IOAPIC ioapic_id=0 ioapic_addr=0xfec00000 gsib=0 ACPI: MADT_ISO bus=0 source=0 gsi=2 flags=0x0 ACPI: MADT_ISO bus=0 source=5 gsi=5 flags=0xd ACPI: MADT_ISO bus=0 source=9 gsi=9 flags=0xd ACPI: MADT_ISO bus=0 source=10 gsi=10 flags=0xd ACPI: MADT_ISO bus=0 source=11 gsi=11 flags=0xd ACPI: 1 CPU(s) detected Detected 1 IOAPICs, but configured to use PIC instead Detected 1 boot module(s): module #0: start=0x161000 end=0x25aed0 size=0xf9ed0 name='images/capdl-loader-experimental-image-ia32-pc99' ELF-loading userland images from boot modules: size=0x189000 v_entry=0x804f544 v_start=0x8048000 v_end=0x81d1000 p_start=0x25b000 p_end=0x3e4000 Moving loaded userland images to final location: from=0x25b000 to=0x160000 size=0x189000 Starting node #0 with APIC ID 0 Booting all finished, dropped to user space Caught cap fault in send phase at address 0x0 while trying to handle: ?????? user exception 0x6 code 0x0 in thread 0xff3f5d00 "rootserver" at address 0x805130e With stack: 0x80cfda0: 0x0 0x80cfda4: 0x0 0x80cfda8: 0x0 0x80cfdac: 0x0 0x80cfdb0: 0x0 0x80cfdb4: 0x0 0x80cfdb8: 0x0 0x80cfdbc: 0x0 0x80cfdc0: 0x0 0x80cfdc4: 0x0 0x80cfdc8: 0x0 0x80cfdcc: 0x0 0x80cfdd0: 0x0 0x80cfdd4: 0x0 0x80cfdd8: 0x0 0x80cfddc: 0x0 QEMU: Terminated Have a great day.

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ARM Vchan Error
by Daniel Wang 10 Jul '18

10 Jul '18

Hi all, I’m trying to make Vchan work on camkes-arm-vm in the process I encountered a couple problems. Hope you can give me some advice. I knew that Vchan is out dated and never finished on ARM. But it seems the only option for now (please correct me if I’m wrong). Here is what I did so far: 1. modified tk1_vmlinux.c by adding the virtual device and fault handler and installed it to guest linux with vm_add_device(vm, &vchan_dev); --------------------------------------------------- vchan_device_fault_handler(struct device* d UNUSED, vm_t* vm, fault_t* fault){ //uint32_t data = fault_get_data(fault); uint32_t data = fault_get_ctx(fault)->r1; vchan_entry_point(vm, data); // fflush(stdout); advance_fault(fault); return 0; } struct device vchan_dev = { .devid = DEV_CUSTOM, .name = "vchan-driver", .pstart = 0x2040000, .size = 0x1000, .handle_page_fault = &vchan_device_fault_handler, .priv = NULL, }; --------------------------------------------------- 2. compiled linux-tegra using buildroot (by the way the current linux-tegra is 4.9.0 which is not supported by buildroot-2016, the earliest version works for me is buildroot-2017-2), added a vmm-manager kernel driver similar to the one in camkes-x86-vm. But I changed the call_into_hypervisor() to the following: --------------------------------------------------- int call_into_hypervisor(int cmd, void *data, size_t sz, vmcall_args_t *vmcall) { int res = 0; int err; unsigned phys_ptr = virt_to_phys(vmcall); vmcall->data = data; vmcall->cmd = cmd; vmcall->phys_data = virt_to_phys(data); vmcall->size = sz; down(&hyp_sem); /* Set up arguments for the ARM hyp call */ asm volatile ("mov r0, %0; mov r1, %1" : : "r" (VMM_MANAGER_TOKEN), "r" (phys_ptr): "%r0", "%r1"); asm volatile (".arch_extension virt\n\t” "hvc #0"); asm volatile ("mov %0, r0" : "=r" (res) : : ); err = vargs->err; up(&hyp_sem); return err; } --------------------------------------------------- The kernel built and run correctly. But when I try to install the kernel driver. It crashed with following information. --------------------------------------------------- # modprobe driver.ko [81.826621] driver: loading out-of-tree module taints kernel Bad sys call from [Linux]: scone 0 at PC: 0xbf000214 Assertion failed” !err (/camkes-arm-vm/libs/libsel4arm-vmm/src/vm.c: vm_event: 407) ————————————————————————— I’m not sure if this error is triggered by the modified call_into_hypervisor() or by event_thread_run()->eventfd_signal(). Any help would be appreciated! Thanks in advance. Best Regards -Daniel Wang

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IPC
by tj5527 04 Jul '18

04 Jul '18

Searching on the sel4 repository, I find there is a manual talking about IPC (https://github.com/seL4/seL4/blob/9dba8e67ccb54e207bbec22e25f21c65e5c6a45f/…) In addition to this material, where - particularly source code - would be a good start point to look into IPC design and implementation? Thanks

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seL4_Wait crash if kernel is compiled with -O0 (qemu, pc99, gcc 4.8.2)
by Fabrizio Bertocci 25 May '18

25 May '18

Hi, After hours of debugging I have discovered a quite nasty issue where seL4_Wait() crash if I build the kernel without optimization (gcc option -O0) on a pc99 tested with qemu. How to reproduce: Just create an endpoint (from a vka) and call seL4_Wait(). The simplest reproducer can be obtained from the hello-2 tutorial: - Copy the main.c from the solution directory in the apps/hello-2/src/main.c - Add the following codes right after the creation of vka (TASK 5, approx line 150): { printf("WAITING----------------------------------------------\n"); seL4_Word myBadge; vka_object_t ep_object = {0}; error = vka_alloc_endpoint(&vka, &ep_object); ZF_LOGF_IFERR(error, "Failed to allocate new endpoint object.\n"); seL4_Wait(ep_object.cptr, &myBadge); printf("---------------------------------------------- DONE!!\n"); } Essentially the added code, creates an endpoint using vka and calls seL4_Wait() on it... I expect the code to block forever since there are no other threads that can unblock it... - Build it and run it with: make pc99_hello-2_defconfig make make simulate Expected output: Booting all finished, dropped to user space 4 untypeds of size 12 4 untypeds of size 13 [...] 6 untypeds of size 29 WAITING---------------------------------------------- - Now change the configuration using 'make menuconfig' and select: seL4 Kernel -> Build Options -> Compiler optimisation flag (-O2) and change it to -O0, save the new configuration. - Rebuild and run: make simulate Now you get a kernel exception: [...] 6 untypeds of size 29 WAITING---------------------------------------------- ========== KERNEL EXCEPTION ========== Vector: 0xd ErrCode: 0xa658 IP: 0xe0118ce5 SP: 0xffaf7e28 FLAGS: 0x86 CR0: 0x8001003b CR2: 0x0 (page-fault address) CR3: 0x142000 (page-directory physical address) CR4: 0x100290 Stack Dump: *0xffaf7e28 == 0xe011a658 *0xffaf7e2c == 0x0 *0xffaf7e30 == 0x0 *0xffaf7e34 == 0xe011a658 *0xffaf7e38 == 0x8 *0xffaf7e3c == 0x202 *0xffaf7e40 == 0x0 *0xffaf7e44 == 0x0 *0xffaf7e48 == 0x10 *0xffaf7e4c == 0x7 *0xffaf7e50 == 0x0 *0xffaf7e54 == 0x0 *0xffaf7e58 == 0x0 *0xffaf7e5c == 0x0 *0xffaf7e60 == 0x0 *0xffaf7e64 == 0x0 *0xffaf7e68 == 0x0 *0xffaf7e6c == 0x0 *0xffaf7e70 == 0x0 *0xffaf7e74 == 0x0 Halting... halting... Kernel entry via Interrupt, irq 157 Version info: - gcc: gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11) - qemu: QEMU emulator version 2.0.0, Copyright (c) 2003-2008 Fabrice Bellard - Build environment: CentOS Linux release 7.3.1611 (Core) Other info: - gcc 4.8.5 doesn't seem to support the 'Nehalem' x86 microarchitecture, so I am selecting the 'Generic' microarchitecture (Toolchain Options -> X86 microarchitecture) - Even the tutorial 'hello-timer' fails exactly with the same exception without any modifications if you build the kernel with -O0. - Tested on a Beaglebone black: no problems compiling kernel with -O0 Regards, Fabrizio Bertocci Real-Time Innovations, Inc.

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Tutorials broken?
by Fabrizio Bertocci 22 May '18

22 May '18

Hi all, I was going through the tutorials, unfortunately I've been finding very challenging to follow the instructions as I keep encountering issues after issue. First, the repo command seems to be incorrect. In document: https://docs.sel4.systems/Tutorials/ it says: repo init -u https://github.com/SEL4PROJ/sel4-tutorials-manifest -m sel4-tutorials.xml but the manifest file 'sel4-tutorials.xml' does not exist on the git repository (of the sel4-tutorial-manifest). What is the correct manifest file to use? There are two manifests (in any branch and tag): master.xml and default.xml. default.xml seems to use the 'new' format of identifying the individual versions of the libraries (through the hash). Let's assume the correct manifest to use is the 'default.xml' from the 'sel4-tutorials' branch and initialize the workspace with: repo init -u https://github.com/SEL4PROJ/sel4-tutorials-manifest -b sel4-tutorials repo sync So, now: first tutorial, ok (but this tutorial does very little). Second tutorial (hello-2), not so good... to avoid mistake, I am copying directly the solution into the app area: cp projects/sel4-tutorials/solutions/hello-2/src/main.c apps/hello-2/src/main.c make pc99_hello-2_defconfig make ... and the build fails with: [...]/workspaces/sel4-tutorials-2/stage/x86/pc99/lib/libsel4allocman.a(virtual_pool.o): In function `_add_page': [...]/workspaces/sel4-tutorials-2/libs/libsel4allocman/src/mspace/virtual_pool.c:52: undefined reference to `vspace_get_map_obj' The missing function appears to be part of libsel4vspace, that is missing from the library dependency list. Let's add it to add it to the apps/hello-2/Makefile: diff --git a/exercises/hello-2/Makefile b/exercises/hello-2/Makefile index 25c0b35..97a4fc6 100644 --- a/exercises/hello-2/Makefile +++ b/exercises/hello-2/Makefile @@ -28,6 +28,7 @@ ASMFILES += $(patsubst $(SOURCE_DIR)/%,%,$(wildcard $(SOURCE_DIR)/src/plat/${PLA # Libraries required to build the target LIBS = c sel4 sel4muslcsys \ sel4simple sel4vka sel4allocman \ + sel4vspace \ sel4platsupport platsupport \ utils sel4simple-default sel4utils sel4debug Now it builds successfully, unfortunately when running, the child thread doesn't appear to run at all. This is the output of qemu running 'make simulate': Booting all finished, dropped to user space 4 untypeds of size 12 5 untypeds of size 13 5 untypeds of size 14 4 untypeds of size 15 4 untypeds of size 16 4 untypeds of size 17 4 untypeds of size 18 5 untypeds of size 19 5 untypeds of size 20 2 untypeds of size 21 4 untypeds of size 22 4 untypeds of size 23 2 untypeds of size 24 3 untypeds of size 25 3 untypeds of size 26 3 untypeds of size 27 1 untypeds of size 28 6 untypeds of size 29 main: hello world I would have expected seeing on the output the string 'thread_2: hallo wereld' somewhere... Why the thread 2 does not run? This code was working last time I checked (version 5.2). I tried then to continue testing the tutorials, and I went to the hello-3. Hello-3 is based on the Hello-2 but adds an endpoint for IPC between the main thread and the child thread. Surprisingly, this app not only builds out of the box without errors (apparently libsel4vspace was already added to its Makefile), but even running it, works as expected: Booting all finished, dropped to user space 3 untypeds of size 12 5 untypeds of size 13 5 untypeds of size 14 4 untypeds of size 15 4 untypeds of size 16 4 untypeds of size 17 4 untypeds of size 18 5 untypeds of size 19 5 untypeds of size 20 2 untypeds of size 21 4 untypeds of size 22 4 untypeds of size 23 2 untypeds of size 24 3 untypeds of size 25 3 untypeds of size 26 3 untypeds of size 27 1 untypeds of size 28 6 untypeds of size 29 main: hello world thread_2: hallo wereld thread_2: got a message 0x6161 from 0x61 main: got a reply: 0xffff9e9e Right now I suspect that seL4_TCB_Configure() does not work correctly if we don't provide an endpoint (because that's essentially the main difference between the two tests). Can somebody try to run the tutorials and perhaps confirm the problem? Regards, Fabrizio Bertocci Real-Time Innovations, Inc. Sunnyvale, CA

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docker build error
by Paolo Crisafulli 18 May '18

18 May '18

Hi all, I'm using the docker build environment provided by https://github.com/SEL4PROJ/seL4-CAmkES-L4v-dockerfiles Currently, "make sel4" fails with this message: E: Package 'ncurses-dev' has no installation candidate Anyone experimenting the same behaviour? Cheers, Paolo

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Help with Isabelle/AutoCorres
by Burkhart Wolff 18 May '18

18 May '18

Dear all, I stumbled into some problems with AutoCorres and would be grateful if someone could help me. I used the recent version autocorres1.4 under Isabelle2017. A) Running under MacOS, cpp is apparently not running inside install_C_file (yes, I installed the cpp wrapper: >>>>>>>>>>>>>>>>>>>>>> !/bin/bash # Wrapper for clang C preprocessor on MacOS export L4CPP="-DTARGET=ARM -DTARGET_ARM -DPLATFORM=Sabre -DPLATFORM_Sabre" llvm-gcc -Wno-invalid-pp-token -E -x c $@ <<<<<<<<<<<<<<<<<<<<<< and made sure that it is in the path of the shell in which I started Isabelle.) Does anyone know a cause for this behaviour or a feasible workaround ? (besides doing the expansions by hand) Is there an explicit Isabelle shell variable where the path to cpp must be set ? B) I get a weird crash of AutoCorres without a clue what might cause it: I have a T4.h file with >>>>>>>>>>>>>>>>>>>>>>> #define N_TEETH ( 100 * MODULO ) // shaft encoder's number of teeth per turn #define SIZE_OF_SPEED_FIFO 10 // number of samples to compute average speed extern const char *InputField[]; enum State { S1=1, S2, S3, S4, S5, S6, SFail=0 }; enum Status { FAIL, SUCCESS }; enum InputPatterns { Ph1 = 1, Ph2 = 5, Ph3 = 4, Ph4 = 6, Ph5 = 2, Ph6 = 3 }; struct OBits { int C1 ; int C2 ; int C3 ; } Obits; /********* Output data *****************/ extern enum Status O_Position_Valid; extern unsigned int O_Position_Count; extern unsigned int Relative_Position; extern int Instantaneous_Speed; extern int Mean_Speed; <<<<<<<<<<<<<<<<<<<<<<<<<<<<< and a T4.c file with: >>>>>>>>>>>>>>>>>>>>>>>>>>>>> #include "T4_AlgoODO.h" enum Status O_P_V = SUCCESS; unsigned int O_P_C = 0; unsigned int Relative_Position = 0; int I_Speed = 0; int Mean_Speed = 0; int Acceleration = 0; int scale = 1000; int PI_approx = 3141; struct OBits Input; enum State OState; const unsigned int Radius = 500; const unsigned int Sampling_Rate = 400; unsigned int F_O_P_C = 0; int Speed_FIFO[10 /*SIZE_OF_SPEED_FIFO*/]; int FIFO_pointer = 0; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< Loading this in Isabelle/AutoCorres with: >>>>>>>>>>>>>>>>>>>>>>>>> install_C_file "code/c/T4.c” <<<<<<<<<<<<<<<<<<<<<<<<< results in the following AutoCorres crash: … exception Fail raised (line 175 of "~/codebox/odo_new/odo/autocorres-1.4/c-parser/calculate_state.ML"): translate_inttype: incomplete array! Can anybody tell me what this means and propose a workaround ? Best regards B. Wolff

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Untyped Retype destination not empty?
by Richard Clark 18 May '18

18 May '18

Hi! I could use a clue as to the cause of this problem. The program has its free slots start index set correctly. It is trying to allocate a dma buffer. (4k with a known physical address). The vspace has been properly set up and knows the phys addresses of its free memory. This used to work fine in a different process, but I can't find anything I've done different/wrong in this one... I've added some extra printfs, and some debug code (in kernel/src/object/untyped.c). /* Ensure that the destination slots are all empty. */ slots.cnode = CTE_PTR(cap_cnode_cap_get_capCNodePtr(nodeCap)); slots.offset = nodeOffset; slots.length = nodeWindow; for (i = nodeOffset; i < nodeOffset + nodeWindow; i++) { status = ensureEmptySlot(slots.cnode + i); if (status != EXCEPTION_NONE) { userError("Untyped Retype: Slot #%d from %p in destination window non-empty.", (int)i, (void *)slots.cnode); userError("Untyped Retype: At offset #%d length %d.", (int)nodeOffset, (int)nodeWindow); int j = 0; for(j=0;j<2048;j++){ status = ensureEmptySlot(slots.cnode + (i + j)); if (status == EXCEPTION_NONE) { userError("Next Free Slot at #%d from %p.", (int)(i+j), (void *)slots.cnode); status = EXCEPTION_SYSCALL_ERROR; break; } } return status; } } And finally, here is the output from the console: <<seL4(CPU 0) [decodeCNodeInvocation/94 T0xffffff8001a25400 "Lockmaproc" @4196e8]: CNode Copy/Mint/Move/Mutate: Destination not empty.>> <<seL4(CPU 0) [decodeUntypedInvocation/166 T0xffffff8001a25400 "Lockmaproc" @420f2c]: Untyped Retype: Slot #196 from 0xffffff807f000000 in destination window non-empty.>> <<seL4(CPU 0) [decodeUntypedInvocation/167 T0xffffff8001a25400 "Lockmaproc" @420f2c]: Untyped Retype: At offset #196 length 1.>> <<seL4(CPU 0) [decodeUntypedInvocation/172 T0xffffff8001a25400 "Lockmaproc" @420f2c]: Next Free Slot at #197 from 0xffffff807f000000.>> _refill_pool@split.c:187 Failed to retype untyped, error 8 vka_alloc_object_at_maybe_dev@object.h:59 Failed to allocate object of size 4096, error 1 dma_alloc@page_dma.c:92 Failed to allocate untyped of size 12 I need a hint... help? Thanks! Richard ________________________________ This message and all attachments are PRIVATE, and contain information that is PROPRIETARY to Intelligent Automation, Inc. You are not authorized to transmit or otherwise disclose this message or any attachments to any third party whatsoever without the express written consent of Intelligent Automation, Inc. If you received this message in error or you are not willing to view this message or any attachments on a confidential basis, please immediately delete this email and any attachments and notify Intelligent Automation, Inc.

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