l4-hackers June 2017

l4-hackers@os.inf.tu-dresden.de

12 participants
24 discussions

Re: Fiasco.OC: null-pointer dereference?
by Leslie Zhai 08 Jun '17

08 Jun '17

Hi Matthias, Thank you so much for your pretty cool 0001-Fix-invalid-initialization-in-new.patch http://os.inf.tu-dresden.de/pipermail/l4-hackers/2017/008005.html Jean taught me about how to debug L4Re using jdb in qemu http://os.inf.tu-dresden.de/pipermail/l4-hackers/2017/008038.html it used a on purpose bug (null ptr deref) to crash Ned, then L4Re thrown: unhandled write page fault at 0x0 pc=0x100398d, and addr2line ... -e ned -a 100398d to indicate the root cause line. But how to find out the root cause if unclear that which components bring in the issue? just like Jean investigated why framebuffer-example-x86 failed to work, actually it is not init process issue, but Fiasco `_quota` member of a thread is not correctly initialized. 0001-Fix-invalid-initialization-in-new.patch is awesome! how to debug deepinto it? it might be easy to a maintainer of Fiasco kernel, but it is really magic to me :) The same story is how to debug L4Linux? http://os.inf.tu-dresden.de/pipermail/l4-hackers/2017/008047.html please give me some advice, thanks a lot! -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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Re: About l4linux debug method
by Leslie Zhai 07 Jun '17

07 Jun '17

Hi L4 hackers, But how to debug L4Linux in qemu by jdb? please give me some hints, thanks a lot! fiasco r72 applied 0001-Fix-invalid-initialization-in-new.patch http://os.inf.tu-dresden.de/pipermail/l4-hackers/2017/008005.html l4re r72 and l4linux r54 is not able to work https://pbs.twimg.com/media/DBtVv8zXoAAelwt.png -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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Re: Graphical desktop, l4con, mag
by Leslie Zhai 07 Jun '17

07 Jun '17

Hi Jean, Happy holiday :) 在 2017年06月05日 23:43, Jean Wolter 写道: > Hello Leslie, > > today are public holidays in Germany, so I will try to follow up on > the issue tomorrow. I downloaded your binaries and am able to > reproduce the problem. It appears to be a problem with the fiasco > build. When I use my fiasco image build with gcc 4.9 l4/build/.config GCCDIR=/usr/lib/gcc/x86_64-redhat-linux/6.3.1 ... > the systems boots. When I use your fiasco image it triggers the > pagefault shown in your screen shots. > > There are some warnings in the boot sequence with your kernel: > "Warning: Buddy::alloc: Size mismatch: e58 v 1000" ... fiasco/build/globalconfig.out # CONFIG_AMD64_K8 is not set # CONFIG_AMD64_CORE2 is not set CONFIG_AMD64_CORE_I=y l4/build/.config CONFIG_BUILD_ARCH="amd64" CONFIG_BUILD_ARCH_amd64=y CONFIG_CPU="K8" CONFIG_CPU_X86_K8=y does it mean this mismatch? but when I rebuilt fiasco with CONFIG_AMD64_K8=y # CONFIG_AMD64_CORE2 is not set # CONFIG_AMD64_CORE_I is not set the same story so I need to go deeper into fiasco/kern/buddy_alloc.cpp > > > regards, > > Jean > > -- Regards, Leslie Zhai - a LLVM hackerhttps://reviews.llvm.org/p/xiangzhai/

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Re: clang-5.0 is not supported. Please use one of the following versions
by Leslie Zhai 06 Jun '17

06 Jun '17

Dear Rui, ご回答有難うございます！ > I believe the LLD's linker script is now fairly decent that you can expect it should work in most cases. -- Regards, Leslie Zhai https://reviews.llvm.org/p/xiangzhai/

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Re: clang-5.0 is not supported. Please use one of the following versions
by Leslie Zhai 05 Jun '17

05 Jun '17

Hi Adam, Thanks for your reply! > we tend to defer to enable versions until they're actually released. Please remove 5.0 :) And what about LLVM's lld? I found it is only for ld https://svn.l4re.org/repos/oc/l4re/trunk/kernel/fiasco/src/kernel.amd64.ld correct? -- Regards, Leslie Zhai https://reviews.llvm.org/p/xiangzhai/

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Re: Graphical desktop, l4con, mag
by Leslie Zhai 05 Jun '17

05 Jun '17

在 2017年06月03日 04:56, Jean Wolter 写道: > Hello Leslie, > > On 02/06/17 11:33, Jean Wolter wrote: >> I replaced my "ned" binary with yours and the system boots up fine. >> >> Now I wonder how I could reproduce your problem. It looks like I >> >> * either need all binaries or >> * need to build them the same way you are building them. I used a >> fresh checkout from the svn repositories and use gcc version >> 4.9.2 (Debian 4.9.2-10) to build the components. >> > > Since I neither have your binaries nor know how you build them https://drive.google.com/open?id=0ByE8c-y74l_uLUdKWG9NWndnSUk and https://drive.google.com/open?id=0ByE8c-y74l_udUtJOTZvc3BycG8 > I thought about how you could diagnose the problem further. To > demonstrate how to do this I intentionally added a null pointer > dereference to ned and would like to discuss how I would diagnose this. > > --- ned/server/src/main.cc (revision 72) > +++ ned/server/src/main.cc (working copy) > @@ -35,6 +35,8 @@ > Dbg::set_level(Dbg::Warn); > info.printf("Hello from Ned\n"); > > + *(int *)0 = 0; > + > boot_info.printf("cmdline: "); > for (int i = 0; i < argc; ++i) > boot_info.cprintf("%s ", argv[i]); > > 1. Add -serial_esc -wait to kernel options in conf/modules.list > > --- modules.list (revision 72) > +++ modules.list (working copy) > @@ -80,6 +80,7 @@ > module libuc_c.so > > entry framebuffer-example-x86 > +kernel fiasco -serial_esc -wait > roottask moe rom/x86-fb.cfg > module x86-fb.cfg > module l4re > > If you boot this the kernel will enter the kernel debugger before > doing anything else. Enter the following commands: > > * P+ /* show every pagefault before forwarding it to the pager */ > * Prx0<space>100<space> /* restrict pagefault logging to pagefaults > between [0-100] */. > * g /* go */ > > The kernel should stop when the access to 0x18 happens, then you can > enter the kernel debugger using 'i' and can check who is responsible > and maybe get a correct instruction pointer. If I do this here it > looks like follows (I added -serial stdio to the qemu options): > > qemu-system-x86_64 -kernel > /home/jw5/build/tmp/l4re/bin/amd64_K8/bootstrap -append "bootstrap > -modaddr 0x01100000" -serial stdio -initrd > "/home/jw5/build/tmp/fiasco//fiasco -serial_esc > -wait,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/sigma0 > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe > rom/x86-fb.cfg,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.cfg > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/l4re > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ned > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/io > ,/home/jw5/src/l4resvn/src/l4/pkg/io/io/config//x86-legacy.devs > ,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.io > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/fb-drv > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/mag > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ex_fb_spectrum_cc " > ... > Freeing init code/data: 49152 bytes (12 pages) > > Calibrating timer loop... done. > > --------------------------------------------------------------------- > CPU 0 [fffffffff003df99]: Wait > jdb: P+ > PF logging enabled > jdb: Pr restrict to addr in [0-100] /* pressed > Prx0<space>100<space> */ > PF logging enabled, restricted to 0000000000000000 <= pfa <= > 0000000000000100 > jdb: g /* g does no show up in output */ > ... > MOE: cmdline: /home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe rom/x86-fb.cfg > MOE: Starting: rom/ned rom/x86-fb.cfg > MOE: loading 'rom/ned' > pf: 0022 pfa=0000000000000000 ip=00000000010038a2 (w-) > spc=0xffffffff807c3dd8 > /* press i */ > --------------------------------------------------------------------- > CPU 0 [fffffffff0062116]: LOG > jdb: > > Now you can use the kernel debugger to inspect the current state of > the system. Here I simply use addr2line to find the error: > > addr2line -p -i -e bin/amd64_K8/l4f/ned -a 10038a2 > 0x00000000010038a2: > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:38 > (inlined by) > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:77 > > > Line 38 is the line with the null pointer dereference. > > I hope this helps, > Jean > > > -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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Re: Graphical desktop, l4con, mag
by Leslie Zhai 05 Jun '17

05 Jun '17

在 2017年06月03日 04:56, Jean Wolter 写道: > Hello Leslie, > > On 02/06/17 11:33, Jean Wolter wrote: >> I replaced my "ned" binary with yours and the system boots up fine. >> >> Now I wonder how I could reproduce your problem. It looks like I >> >> * either need all binaries or >> * need to build them the same way you are building them. I used a >> fresh checkout from the svn repositories and use gcc version >> 4.9.2 (Debian 4.9.2-10) to build the components. >> > > Since I neither have your binaries nor know how you build them I > thought about how you could diagnose the problem further. To > demonstrate how to do this I intentionally added a null pointer > dereference to ned and would like to discuss how I would diagnose this. > > --- ned/server/src/main.cc (revision 72) > +++ ned/server/src/main.cc (working copy) > @@ -35,6 +35,8 @@ > Dbg::set_level(Dbg::Warn); > info.printf("Hello from Ned\n"); > > + *(int *)0 = 0; > + > boot_info.printf("cmdline: "); > for (int i = 0; i < argc; ++i) > boot_info.cprintf("%s ", argv[i]); > > 1. Add -serial_esc -wait to kernel options in conf/modules.list > > --- modules.list (revision 72) > +++ modules.list (working copy) > @@ -80,6 +80,7 @@ > module libuc_c.so > > entry framebuffer-example-x86 > +kernel fiasco -serial_esc -wait > roottask moe rom/x86-fb.cfg > module x86-fb.cfg > module l4re > > If you boot this the kernel will enter the kernel debugger before > doing anything else. Enter the following commands: > > * P+ /* show every pagefault before forwarding it to the pager */ > * Prx0<space>100<space> /* restrict pagefault logging to pagefaults > between [0-100] */. > * g /* go */ > > The kernel should stop when the access to 0x18 happens, then you can > enter the kernel debugger using 'i' and can check who is responsible > and maybe get a correct instruction pointer. If I do this here it > looks like follows (I added -serial stdio to the qemu options): > > qemu-system-x86_64 -kernel > /home/jw5/build/tmp/l4re/bin/amd64_K8/bootstrap -append "bootstrap > -modaddr 0x01100000" -serial stdio -initrd > "/home/jw5/build/tmp/fiasco//fiasco -serial_esc > -wait,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/sigma0 > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe > rom/x86-fb.cfg,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.cfg > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/l4re > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ned > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/io > ,/home/jw5/src/l4resvn/src/l4/pkg/io/io/config//x86-legacy.devs > ,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.io > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/fb-drv > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/mag > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ex_fb_spectrum_cc " > ... > Freeing init code/data: 49152 bytes (12 pages) > > Calibrating timer loop... done. > > --------------------------------------------------------------------- > CPU 0 [fffffffff003df99]: Wait > jdb: P+ > PF logging enabled > jdb: Pr restrict to addr in [0-100] /* pressed > Prx0<space>100<space> */ > PF logging enabled, restricted to 0000000000000000 <= pfa <= > 0000000000000100 > jdb: g /* g does no show up in output */ > ... > MOE: cmdline: /home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe rom/x86-fb.cfg > MOE: Starting: rom/ned rom/x86-fb.cfg > MOE: loading 'rom/ned' > pf: 0022 pfa=0000000000000000 ip=00000000010038a2 (w-) > spc=0xffffffff807c3dd8 > /* press i */ > --------------------------------------------------------------------- > CPU 0 [fffffffff0062116]: LOG > jdb: > > Now you can use the kernel debugger to inspect the current state of > the system. Here I simply use addr2line to find the error: > > addr2line -p -i -e bin/amd64_K8/l4f/ned -a 10038a2 > 0x00000000010038a2: > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:38 > (inlined by) > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:77 > > > Line 38 is the line with the null pointer dereference. Thanks for your help! worked :) addr2line -p -i -e bin/amd64_K8/l4f/ned -a 100398d 0x000000000100398d: /home/zhaixiang/project/l4re/l4/pkg/l4re-core/ned/server/src/main.cc:38 (inlined by) /home/zhaixiang/project/l4re/l4/pkg/l4re-core/ned/server/src/main.cc:77 and I need to carefully read JDB manual. > > I hope this helps, > Jean > > > -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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Re: Graphical desktop, l4con, mag
by Leslie Zhai 04 Jun '17

04 Jun '17

Hi Jean, Thanks for your help! 在 2017年06月03日 04:56, Jean Wolter 写道: > Hello Leslie, > > On 02/06/17 11:33, Jean Wolter wrote: >> I replaced my "ned" binary with yours and the system boots up fine. >> >> Now I wonder how I could reproduce your problem. It looks like I >> >> * either need all binaries or >> * need to build them the same way you are building them. I used a >> fresh checkout from the svn repositories and use gcc version >> 4.9.2 (Debian 4.9.2-10) to build the components. >> > > Since I neither have your binaries nor know how you build them I follow the http://os.inf.tu-dresden.de/fiasco/build.html and http://l4re.org/build.html and my environment is Fedora 24, gcc 6.3.1, qemu 2.6.2 and clang-5.0svn. hello example is able to work :) > I thought about how you could diagnose the problem further. To > demonstrate how to do this I intentionally added a null pointer > dereference to ned and would like to discuss how I would diagnose this. > > --- ned/server/src/main.cc (revision 72) > +++ ned/server/src/main.cc (working copy) > @@ -35,6 +35,8 @@ > Dbg::set_level(Dbg::Warn); > info.printf("Hello from Ned\n"); > > + *(int *)0 = 0; > + > boot_info.printf("cmdline: "); > for (int i = 0; i < argc; ++i) > boot_info.cprintf("%s ", argv[i]); > > 1. Add -serial_esc -wait to kernel options in conf/modules.list > > --- modules.list (revision 72) > +++ modules.list (working copy) > @@ -80,6 +80,7 @@ > module libuc_c.so > > entry framebuffer-example-x86 > +kernel fiasco -serial_esc -wait > roottask moe rom/x86-fb.cfg > module x86-fb.cfg > module l4re > > If you boot this the kernel will enter the kernel debugger before > doing anything else. Enter the following commands: > > * P+ /* show every pagefault before forwarding it to the pager */ > * Prx0<space>100<space> /* restrict pagefault logging to pagefaults > between [0-100] */. > * g /* go */ > > The kernel should stop when the access to 0x18 happens, then you can > enter the kernel debugger using 'i' and can check who is responsible > and maybe get a correct instruction pointer. If I do this here it > looks like follows (I added -serial stdio to the qemu options): > > qemu-system-x86_64 -kernel > /home/jw5/build/tmp/l4re/bin/amd64_K8/bootstrap -append "bootstrap > -modaddr 0x01100000" -serial stdio -initrd > "/home/jw5/build/tmp/fiasco//fiasco -serial_esc > -wait,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/sigma0 > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe > rom/x86-fb.cfg,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.cfg > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/l4re > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ned > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/io > ,/home/jw5/src/l4resvn/src/l4/pkg/io/io/config//x86-legacy.devs > ,/home/jw5/src/l4resvn/src/l4/conf/examples//x86-fb.io > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/fb-drv > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/mag > ,/home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/ex_fb_spectrum_cc " > ... > Freeing init code/data: 49152 bytes (12 pages) > > Calibrating timer loop... done. > > --------------------------------------------------------------------- > CPU 0 [fffffffff003df99]: Wait > jdb: P+ when I input p+ then pressed Enter, but jdb did not print out "PF logging enabled" to me https://pbs.twimg.com/media/DBcu1DUUwAAkiDl.png > PF logging enabled > jdb: Pr restrict to addr in [0-100] /* pressed > Prx0<space>100<space> */ > PF logging enabled, restricted to 0000000000000000 <= pfa <= > 0000000000000100 > jdb: g /* g does no show up in output */ but input g then pressed Enter will continue to go https://pbs.twimg.com/media/DBc0XlWUAAAmgSN.png sorry I am not familiar with jdb, but have some experience with gdb. > ... > MOE: cmdline: /home/jw5/build/tmp/l4re/bin/amd64_K8/l4f/moe rom/x86-fb.cfg > MOE: Starting: rom/ned rom/x86-fb.cfg > MOE: loading 'rom/ned' > pf: 0022 pfa=0000000000000000 ip=00000000010038a2 (w-) > spc=0xffffffff807c3dd8 > /* press i */ > --------------------------------------------------------------------- > CPU 0 [fffffffff0062116]: LOG > jdb: > > Now you can use the kernel debugger to inspect the current state of > the system. Here I simply use addr2line to find the error: so I failed to debug the on purpose null ptr dereference issue *(int *)0 = 0; in your patch via jdb. > addr2line -p -i -e bin/amd64_K8/l4f/ned -a 10038a2 > 0x00000000010038a2: > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:38 > (inlined by) > /home/jw5/src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:77 > > > Line 38 is the line with the null pointer dereference. > > I hope this helps, > Jean > > > -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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Re: Graphical desktop, l4con, mag
by Leslie Zhai 02 Jun '17

02 Jun '17

在 2017年06月02日 15:34, Jean Wolter 写道: > > Hello Leslie, > > On 02/06/17 05:52, Leslie Zhai wrote: >> Thanks for your reply! but I met the same story for L4Linux >> https://pbs.twimg.com/media/DBSQtoNUIAEE2HY.png > It looks like the very same error, an unhandled read page-fault at > address 0x18 triggered by an instruction at 0x102d72a. > >> > Maybe you could use addr2line/objdump >> > to figure out, what happens at address 0x102d72a in ned. >> >> cd /home/zhaixiang/project/l4re/l4/build >> addr2line -p -e bin/amd64_K8/l4f/ned 0x102d72a >> >> but there is no output easy to read for humans, I am not familiar >> with addr2line, please give me some advice, thanks a lot! > If I try it with an instruction pointer somewhere in the main function > it looks like follows: > > ~/build/tmp/l4re/bin/amd64_K8/l4f$ addr2line -p -i -e ned -a 10038b3 > 0x00000000010038b3: > /home/.../src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:39 > (inlined by) > /home/.../src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:75 > > >> objdump -D bin/amd64_K8/l4f/ned > ned.S >> > If you use -lSd you should see line number information in the > disassembled output, e.g: > > /home/.../src/l4resvn/src/l4/pkg/l4re-core/ned/server/src/main.cc:39 > for (int i = 0; i < argc; ++i) > 10038b3: 85 db test %ebx,%ebx > > >> 102d72a: 66 0f 12 05 9e 7b 02 movlpd 0x27b9e(%rip),%xmm0 # >> 10552d0 <_ZL7HOOKKEY+0x 8> >> is it enough to figure out what happened? if not, I will upload the >> disassemble to my Google drive. > This looks strange. There is nothing looking like an access to 0x18. > Could send me your ned binary? https://drive.google.com/open?id=0ByE8c-y74l_uVlB6cnJBdWV1VzA > > regards, > Jean > -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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xorriso : FAILURE : Not a known command
by Leslie Zhai 02 Jun '17

02 Jun '17

Hi L4 hackers, When I Running hello.iso http://os.inf.tu-dresden.de/fiasco/build.html via *make grub2iso E=hello MODULE_SEARCH_PATH=/path/to/fiasco-build-dir *it failed to generate ISO, xorriso thrown such error: xorriso : FAILURE : Not a known command: '-f' xorriso : aborting : -abort_on 'FAILURE' encountered 'FAILURE' Failed to create ISO at tool/lib/L4/Grub.pm line 123. Makefile:598: recipe for target 'grub2iso' failed so I simply changed the option: Index: tool/lib/L4/Grub.pm =================================================================== --- tool/lib/L4/Grub.pm (revision 72) +++ tool/lib/L4/Grub.pm (working copy) @@ -116,7 +116,7 @@ close A; }; my $cmd = "$mkr --output=\"$isofilename\" $dir ". - join(' ', @morefiles)." --$opt -f"; + join(' ', @morefiles)." --$opt -follow default"; system("$cmd"); die "Failed to create ISO" if $?; # grub-mkrescue does not propagate internal tool errors please review my patch, thanks a lot! -- Regards, Leslie Zhai - a LLVM hacker https://reviews.llvm.org/p/xiangzhai/

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l4-hackers June 2017