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2306 discussions

Intel's Memory Protection Keys
by Sid Agrawal 31 Jan '22

31 Jan '22

Hi, I want to use Intel's MPK in my project with Genode. A grep of the source code did not yield anything obvious. >From what I know about Intel's MPKs, I should be able to piggyback on the kernel's capability to manipulate the page table. The "keys" reside in the top 4 bits of the translation in the PTE. So maybe I do not need any special support from Genode or seL4, for that matter. But I just wanted to run it by the group to see if I missed something. Or if someone has tried this before. Best, Sidhartha Agrawal sid-agrawal.ca

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how to allow execution of bash scripts inside genode
by Alexander Tormasov 14 Jan '22

14 Jan '22

based on combination of tool_chain_auto.run and ssh.run I am able to run an instance with toolchain and login into it I am able to create file using vim with some commands, like this: echo ok if I try to execute it inside genode bash (eg in /home/build) - I do receive the following: in ssh client : bash-4.4# vim c bash-4.4# ls -la total 1 -rwx------ 1 root 0 1004 Jan 1 2022 c drwx------ 1 root 0 144 Jan 1 1970 depot bash-4.4# ./c bash: ./c: No such file or directory bash-4.4# bash -c ./c bash: ./c: No such file or directory bash-4.4# bash -c c bash: c: command not found or, if I add this to beginning #!/bin/sh echo ok bash: ./c: /bin/bash: bad interpreter: No such file or directory in log: [init -> /bin/bash -> 12] Error: ROM-session creation failed (ram_quota=6144, cap_quota=3, label="/home/build/c") [init -> /bin/bash -> 12] Error: Could not open ROM session for "/home/build/c" [init -> /bin/bash -> 12] Warning: execve: executable binary inaccessible as ROM module I suspect that I need to allow execution via dynamic run file. or may be I need to add some attributes in run file for this dir? Sincerely, Alexander

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lwext4_fs test fail on ftruncate()
by Alexander Tormasov 13 Jan '22

13 Jan '22

I am trying to run lwext4_fs.run from world repo it gives the following error on linux/x86_64 ... [init -> test-libc_vfs] calling open(file_name4, O_CREAT | O_WRONLY) file_name=test4.tst [init -> test-libc_vfs] open(file_name4, O_CREAT | O_WRONLY) succeeded [init -> test-libc_vfs] calling ftruncate(fd, 100) [init -> test-libc_vfs] ftruncate(fd, 100) succeeded [init -> test-libc_vfs] calling close(fd) [init -> test-libc_vfs] close(fd) succeeded [init -> test-libc_vfs] calling stat(file_name4, &stat_buf) file_name=test4.tst [init -> test-libc_vfs] stat(file_name4, &stat_buf) failed, ret=0, errno=2 [init -> test-libc_vfs] Error: Uncaught exception of type 'Test_failed' [init -> test-libc_vfs] Warning: abort called - thread: ep ^Cmake: *** [Makefile:396: run/lwext4_fs] Error 130 can this error could be ignored? is lwext4 port somhow usable in general on 21.11? can I utilise it as a main fs inside genode to store compilation results in rw mode? Sincerely, Alexander

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native gcc and external image mount example
by Alexander Tormasov 13 Jan '22

13 Jan '22

Hi! I am considering native (not cross compilation) support of golang inside genode. I made two first steps - port golang runtime using cross compilation via genode toolchain and check it with tcp support inside qemu x86_64/arm64. Now I want to run gccgo and related binutils (files from gcc like gccgo/go1/as/ld/etc) natively inside genode using qemu. do anyone have an example to run gcc inside genode? I remember that sometimes ago it was mentioned, while I did not find any test in repos/ I can build it using "make noux/gcc_x86» - but any examples how to utilise it inside genode image? like to compile and run «helloworld.c» inside? Also I need a persistent partition (eg linux loopback image) to be mounted via qemu. Do we have any examples how I can create such image, attach it to qemu, mount/umount it inside? I need this to keep compiled code inside qemu. preferably with file system with journalling support if any (ext3/4? not talking about btrfs) Alexander

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Questions about Address Space, Scheduling and CSpace
by Sid Agrawal 12 Jan '22

12 Jan '22

Hi, I am using Genode with the seL4 backend for my research and have questions about some of the core's services. Address Space: -------------------- 1. Referring to section 3.4.4 from the Genode foundation's book. I am not sure I follow how using a different RM for the stack segment helps us provide buffers in between stacks of different threads in a PD. 2. A PD is defined as Address Space and CSpace. I wondered if it is possible to have multiple address spaces inside a PD. The RM for each of these different Address spaces would still be separate capabilities in the singular CSpace for that PD. This way, a thread can potentially jump across different address spaces like [1, 2]. Or multiple threads can have slightly different address spaces. 3. Where am I going with this? I am trying to implement a new type of thread. In this thread(let's call it thread-stack), each thread's stack will be completely isolated from the other threads. That is, threads will not have access to each other's stacks. They will still share the code-section, library, and heap sections. This is a toy idea, so I can get my hand dirty with the Genode basics. I think everything I need to implement is already there in Genode but wanted to get your opinion. 4. Are they any helper functions to clone an entire address space? Replicate the page table hierarchy with the same underlying page frames. Scheduling: --------------- Since scheduling is done inside the kernel in seL4, I think we might be limited to the options exposed by the kernel, but I still wanted to run it by you guys to see if I am missing anything. 1. Using the notion of Affinity, I can restrict a thread to run on a particular CPU, but is there a way to restrict other threads from running on a given CPU. I am exploring isolating two threads by ensuring that they run on separate cores. 2. Is there a way to restrict the time slices given to a particular thread. I am thinking of something like cgroups. I see that seL4 has the MCS kernel, which shares some of the motivations. But I think Genode does not support the MCS sel4 kernel. Debugging Capability Spaces: --------------------------------------- 1. Is the CSpace for a PD the same as CSpace in seL4, or is there a different notion of Cspace in Genode? 2. Is there an easy way to print the entire CSpace for debugging purposes? Thanks a lot. Sid sid-agrawal.ca [1] Light-Weight Contexts: An OS Abstraction for Safety and Performance | USENIX [2] SpaceJMP: Programming with Multiple Virtual Address Space | ACM SIGPLAN

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sel4 and compilation with/without optimisation
by Alexander Tormasov 05 Jan '22

05 Jan '22

found «interesting» problem with compilation of genode: compilation of sel4 failed due to optimisation flag. I already reported this around 2 years ago [3] in short, during compilation of sel4 library in the build/x86_64/var/libcache/kernel-sel4-pc it generates «on the fly» file kernel_final.c which should generate kernel_final.s file. what’s happens: kernel_final.c do contains something similar to below (take a look to x86_flush_rsb() in original code [2], simplify here): typedef unsigned long word_t; static inline void x86_flush_rsb(void) { word_t iter = 32; __asm__ volatile( "pause\n" : [iter]"+r"(iter) : [stack_amount]"i"(sizeof(word_t) * iter) : "cc" ); } void c_handle_vmexit() { if (1) { x86_flush_rsb(); } } code like this works perfectly ok genode-x86-gcc -S -O1 -o kernel_final.s t.c while code genode-x86-gcc -S -o kernel_final.s t.c or genode-x86-gcc -S -O0 -o kernel_final.s t.c does not! t.c: In function ‘x86_flush_rsb’: t.c:7:5: warning: ‘asm’ operand 1 probably does not match constraints 7 | __asm__ volatile( | ^~~~~~~ t.c:7:5: error: impossible constraint in ‘asm’ What’s happens: asm code inside function do have this kind of input parameters : [stack_amount]"i"(sizeof(word_t) * iter) IMHO (I am not sure for 100%) «i» mean immediate constant which should be known in advance while «iter» above is a variable updated in output! as stated in [1]: ‘i’ An immediate integer operand (one with constant value) is allowed. This includes symbolic constants whose values will be known only at assembly time or later. Gcc with any optimisation level do drop this code because original function which call x86_flush_rsb (c_handle_vmexit) does not used at all and being removed during optimisation. So, if you during debug add something like CFLAGS= as an env or make variable with -O0 - you are doomed! this is true for current 10.3 and previous 9 gcc compilers… This is not a part of genode code while problem happens in port sources [2]. I am not even sure how I can post an issue. [1] https://gcc.gnu.org/onlinedocs/gcc/Simple-Constraints.html#Simple-Constrain… [2] contrib/sel4-9ab19376285d865052c2b5021560306306bf19a8/src/kernel/sel4/include/arch/x86/arch/machine.h [3] https://lists.genode.org/pipermail/users/2020-August/007193.html Alexander

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now you can run http web server based on golang in genode 21.11
by Alexander Tormasov 23 Dec '21

23 Dec '21

I have a progress in porting of golang from gcc 10.3 to genode 21.11. Seems that now it suitable for external testing. More details in https://github.com/tor-m6/genode-world/blob/21.11/src/test/go_app/README.go… In particular, it is possible to run most of the golang programs, including tcp network (http server from net/http package) in SMP mode (tested on 4 cpu) on genode for nova, foc and linux, run inside qemu (or on linux), for x86_64. May be some other platforms works as well (except sel4- see below). To run you need 2 repos: https://github.com/tor-m6/genode.git Need to checkout 21.11 branch - while it have only one commit introducing .go as a target for compilation. support code is in repos/world (don’t forget to uncomment it) https://github.com/tor-m6/genode-world.git (Need to checkout 21.11 branch) I successfully run some tests with channels/async goroutines - some of them (Like Hanoi towers or barber serving) inside https://github.com/tor-m6/genode-world/blob/21.11/src/test/go_app/main.go also you can run network code like this: package main import ( "fmt" "log" "net/http" ) func main() { http.HandleFunc("/", HelloServer) fmt.Println("Server started at port 80") log.Fatal(http.ListenAndServe(":80", nil)) } func HelloServer(w http.ResponseWriter, r *http.Request) { fmt.Fprintf(w, "Hello, %s!\n", r.URL.Path[1:]) } Future plan: - add arm64 support - check sel4 problem - add automated generation of part of run file (all shared libs/binaries need to appears in appropriate places to unwind process works correctly) - check performance problems on sel4 and foc (probably timeouts/timer, waits too long in the very beginning) - try to integrate it in native mode to create workable «go build» code inside genode as native compilation. Note1: currently it can’t run on x86_64 sel4 because during initial golang stack unwind process it touch stack guard page, deeply inside _Unwind_Backtrace libgcc function (not sure why - probably this is compiler flags/optimisation issue). Once I have workable version with different debug options… Note2: May be it worth to add patch below permanently to main genode? diff --git a/repos/base/mk/generic.mk b/repos/base/mk/generic.mk index 66e5c309c..aea75e342 100644 --- a/repos/base/mk/generic.mk +++ b/repos/base/mk/generic.mk @@ -7,7 +7,7 @@ # Collect object files and avoid duplicates (by using 'sort') # SRC_O += $(addprefix binary_,$(addsuffix .o,$(notdir $(SRC_BIN)))) -SRC = $(sort $(SRC_C) $(SRC_CC) $(SRC_ADB) $(SRC_ADS) $(SRC_RS) $(SRC_S) $(SRC_O)) +SRC = $(sort $(SRC_C) $(SRC_CC) $(SRC_ADB) $(SRC_ADS) $(SRC_RS) $(SRC_S) $(SRC_O) $(SRC_GO)) OBJECTS = $(addsuffix .o,$(basename $(SRC))) # @@ -69,6 +69,16 @@ endif $(MSG_ASSEM)$@ $(VERBOSE)$(CC) $(CC_DEF) $(CC_C_OPT) $(INCLUDES) -c $< -o $@ +# +# Compiling Go sources +# +%.o: %.go + $(MSG_COMP)$@ + $(VERBOSE)$(GOLANG) $(CUSTOM_GO_FLAGS) -c -o $@ $< + +CUSTOM_GO ?= $(CROSS_DEV_PREFIX)gccgo +GOLANG = $(CUSTOM_GO) + # # Compiling Ada source codes #

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Genode and sign-conversion warnings.
by Piotr Tworek 21 Dec '21

21 Dec '21

Hello, Since Wconversion got enabled on Genode master branch I'm wondering if there are any plans WRT Wsign-conversion warnings? I presonally find it a bit strange GCC Wconversion does not also enable Wsign-conversion. IMO implicit conversions between signed and unsigned types are as often as bad as implicit conversion between types of different size. /ptw

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CBE key encryption
by Stefan Thöni 19 Dec '21

19 Dec '21

Hello Genodians, we are still working to add hardware-based encryption to CBE. To this end, we have implemented a custom trust anchor and crypto engine. Generating a key, encrypting this key on behalf of cbe_init and decrypting it again on behalf of the vfs_cbe plugin works fine. But then the vfs_cbe requests to have a all zero key encrypted which due to the ICV added by hardware black key handling fails. We cannot seam to find out where the request originates or why vfs_cbe would ever encrypt any key, let alone a key of all zeros. Any pointer or idea would by very welcome. Kind regards Stefan

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Silly Sculpt Build Problem
by John J. Karcher 16 Dec '21

16 Dec '21

Hello, Recent updates to Debian Unstable seem to be causing a few minor build problems in Genode. Automake being updated from 1.15 to 1.16 was simple to solve, but I have another problem that I'm not sure how to solve. Depending of whether I'm building a disk image or an ISO, I get one of the following errors: Error: 'e2mkdir' command could be not found. or: Error: 'xorriso' command could be not found. But both of those commands are available, and worked up until recently. Does anyone have any thoughts on what might cause this? Thanks! -- John J. Karcher devuser(a)alternateapproach.com

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