April 2013 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

still confused by kernel compile msg, "sizeof(struct x86cpu_device_id)=12 ..."
by Robert P. J. Day April 28, 2013

April 28, 2013

i'm just getting back to trying to figure out what's happening with a simple kernel configure and build on my 64-bit ubuntu system, and can't believe no one else is running into this issue. with the current "git pull" of linus' tree, and a really boring configuration, the build eventually fails trying to build a module as follows: FATAL: arch/x86/crypto/ghash-clmulni-intel: sizeof(struct x86cpu_device_id)=12 is not a modulo of the size of section __mod_x86cpu_device_table=32. Fix definition of struct x86cpu_device_id in mod_devicetable.h make[2]: *** [__modpost] Error 1 make[1]: *** [modules] Error 2 make: *** [sub-make] Error 2 one solution is to simply select that feature as built-in rather than modular. at that point, i get another similar error elsewhere: FATAL: arch/x86/kvm/kvm-intel: sizeof(struct x86cpu_device_id)=12 is not a modulo of the size of section __mod_x86cpu_device_table=32. Fix definition of struct x86cpu_device_id in mod_devicetable.h make[2]: *** [__modpost] Error 1 make[1]: *** [modules] Error 2 make: *** [sub-make] Error 2 fine, so make *that* built-in, only to get: FATAL: drivers/ata/acard-ahci: sizeof(struct pci_device_id)=28 is not a modulo of the size of section __mod_pci_device_table=64. Fix definition of struct pci_device_id in mod_devicetable.h make[2]: *** [__modpost] Error 1 make[1]: *** [modules] Error 2 make: *** [sub-make] Error 2 what's going on here? it's been a couple releases since i built a kernel for this box, and i've never seen this before. it looks like a structure packing issue. my gcc version is: $ gcc --version gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

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oops in a kernel module
by Kevin Wilson April 28, 2013

April 28, 2013

Hello, I have written a short kernel module which should zero a network SNMP mib. I have OOPs. My idea was to take an existing macro that adds an integer to a network SNMP mib and to change it so that it would zero that counter. So I tool the TCP_ADD_STATS() macro - see in the comments of the module below. I tried both with xor and with subtracting the value of the SNMP mib from itself. In both cases it fails with the same OOPS. I will appreciate if someone could advice/suggest alternative methods. Following is my module and the OOPs i get: #include <linux/module.h> #include <linux/slab.h> #include <linux/types.h> #include <linux/string.h> #include <linux/errno.h> #include <linux/skbuff.h> #include <linux/cgroup.h> #include <linux/rcupdate.h> #include <linux/atomic.h> #include <net/rtnetlink.h> #include <net/pkt_cls.h> #include <net/sock.h> #include <net/snmp.h> #include <net/net_namespace.h> static int __init init_zeromib(void) { int ret = 0; printk("in %s\n",__func__); //#define SNMP_ADD_STATS(mib, field, addend) this_cpu_add(mib[0]->mibs[field], addend) //#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) // TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, // tcp_skb_pcount(skb)); #define SNMP_ZERO_STATS(mib, field) this_cpu_add(mib[0]->mibs[field], -(mib[0]->mibs[field])) #define TCP_ZERO_STATS(net, field) SNMP_ZERO_STATS((net)->mib.tcp_statistics, field) TCP_ZERO_STATS(&init_net, ICMP_MIB_OUTMSGS); return ret; } static void __exit exit_zeromib(void) { printk("in %s\n",__func__); } module_init(init_zeromib); module_exit(exit_zeromib); MODULE_LICENSE("GPL v2"); The oops when insmoding the moudle is: Apr 27 19:27:36 amd kernel: [ 2683.611903] in init_zeromib Apr 27 19:27:36 amd kernel: [ 2683.611929] BUG: unable to handle kernel paging request at 0000000000017fe0 Apr 27 19:27:36 amd kernel: [ 2683.612017] IP: [<ffffffffa0005020>] init_zeromib+0x20/0x1000 [zeromib] Apr 27 19:27:36 amd kernel: [ 2683.612017] PGD 3b9eb067 PUD 3c514067 PMD 0 Apr 27 19:27:36 amd kernel: [ 2683.612017] Oops: 0000 [#1] SMP Apr 27 19:27:36 amd kernel: [ 2683.612017] Modules linked in: zeromib(+) edac_core edac_mce_amd k8temp nv_tco i2c_nforce2 i2c_core 8139too r8169 8139cp mii ata_generic sata_nv pata_acpi pata_amd Apr 27 19:27:36 amd kernel: [ 2683.612017] CPU 1 Apr 27 19:27:36 amd kernel: [ 2683.612017] Pid: 5620, comm: insmod Not tainted 3.9.0-rc1+ #56 /KN9(NF-MCP55 series) Apr 27 19:27:36 amd kernel: [ 2683.612017] RIP: 0010:[<ffffffffa0005020>] [<ffffffffa0005020>] init_zeromib+0x20/0x1000 [zeromib] Apr 27 19:27:36 amd kernel: [ 2683.612017] RSP: 0018:ffff88003c4e1d48 EFLAGS: 00010292 Apr 27 19:27:36 amd kernel: [ 2683.612017] RAX: 0000000000017f70 RBX: ffff88003c4e1ee8 RCX: ffff88003fd0fa68 Apr 27 19:27:36 amd kernel: [ 2683.612017] RDX: 0000000000000000 RSI: ffff88003fd0ded8 RDI: 0000000000000246 Apr 27 19:27:36 amd kernel: [ 2683.612017] RBP: ffff88003c4e1d48 R08: 000000000000000a R09: 00000000000016f6 Apr 27 19:27:36 amd kernel: [ 2683.612017] R10: 0000000000000000 R11: 00000000000016f5 R12: ffffffffa0005000 Apr 27 19:27:36 amd kernel: [ 2683.612017] R13: 0000000000000000 R14: ffffffffa004b000 R15: ffff88003c5ec8a0 Apr 27 19:27:36 amd kernel: [ 2683.612017] FS: 00007f0990404700(0000) GS:ffff88003fd00000(0000) knlGS:0000000000000000 Apr 27 19:27:36 amd kernel: [ 2683.612017] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Apr 27 19:27:36 amd kernel: [ 2683.612017] CR2: 0000000000017fe0 CR3: 000000003bab6000 CR4: 00000000000007e0 Apr 27 19:27:36 amd kernel: [ 2683.612017] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Apr 27 19:27:36 amd kernel: [ 2683.612017] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Apr 27 19:27:36 amd kernel: [ 2683.612017] Process insmod (pid: 5620, threadinfo ffff88003c4e0000, task ffff88003be5ae80) Apr 27 19:27:36 amd kernel: [ 2683.612017] Stack: Apr 27 19:27:36 amd kernel: [ 2683.612017] ffff88003c4e1d78 ffffffff8100215a ffff88003c4e1ee8 ffffffffa004b018 Apr 27 19:27:36 amd kernel: [ 2683.612017] ffffffffa004b050 ffffffffa004b000 ffff88003c4e1ed8 ffffffff810c2276 Apr 27 19:27:36 amd kernel: [ 2683.612017] ffffffff81328240 ffffffff81a0cc98 ffff88003c4e1ef8 ffff880000000000 Apr 27 19:27:36 amd kernel: [ 2683.612017] Call Trace: Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff8100215a>] do_one_initcall+0x12a/0x180 Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff810c2276>] load_module+0x1c16/0x27a0 Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff81328240>] ? ddebug_proc_open+0xc0/0xc0 Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff8115c162>] ? insert_vmalloc_vmlist+0x22/0x80 Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff810c2eae>] sys_init_module+0xae/0x110 Apr 27 19:27:36 amd kernel: [ 2683.612017] [<ffffffff8159c659>] system_call_fastpath+0x16/0x1b Apr 27 19:27:36 amd kernel: [ 2683.612017] Code: <48> 8b 50 70 48 f7 da 65 48 01 50 70 31 c0 5d c3 00 00 00 00 00 00 Apr 27 19:27:36 amd kernel: [ 2683.612017] RIP [<ffffffffa0005020>] init_zeromib+0x20/0x1000 [zeromib] Apr 27 19:27:36 amd kernel: [ 2683.612017] RSP <ffff88003c4e1d48> Apr 27 19:27:36 amd kernel: [ 2683.612017] CR2: 0000000000017fe0 Apr 27 19:27:36 amd kernel: [ 2683.638099] ---[ end trace 95e77c0f2eeae8bc ]-- rgs, Kevin

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Invitation to connect on LinkedIn
by Ashish Anand via LinkedIn April 27, 2013

April 27, 2013

LinkedIn ------------ Ashish Anand requested to add you as a connection on LinkedIn: ------------------------------------------ Deepak, I'd like to add you to my professional network on LinkedIn. - Ashish Accept invitation from Ashish Anand http://www.linkedin.com/e/8z2206-hg0nolw3-3d/L90NvsYL3GREvJdnM0f-HnfkWNbSD_… View profile of Ashish Anand http://www.linkedin.com/e/8z2206-hg0nolw3-3d/rso/165943060/0fsy/name/494894… ------------------------------------------ You are receiving Invitation emails. This email was intended for Deepak Shah. Learn why this is included: http://www.linkedin.com/e/8z2206-hg0nolw3-3d/plh/http%3A%2F%2Fhelp%2Elinked… (c) 2012, LinkedIn Corporation. 2029 Stierlin Ct, Mountain View, CA 94043, USA.

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Compile multiple modules with a single makefile
by Henrique Rodrigues April 26, 2013

April 26, 2013

Hi all, I have the one .c source file that I want to create multiple kernel modules out of it by setting macros using the makefile. The idea is that if -DMODULE1 is set, I'll build module1.ko and if -DMODULE2 is set, I'll build module 2. Does anyone know how to do this? I created the following makefile: ... module1: override obj-m := module1.o module1: EXTRA_CFLAGS += -DMODULE1 module1: $(MAKE) -C $(KDIR) M=$(PWD) modules module2: override obj-m := module2.o module2: EXTRA_CFLAGS += -DMODULE2 module2: $(MAKE) -C $(KDIR) M=$(PWD) modules ... But it isn't working as I expected. Anyone with kernel build system experience knows the answer for that? Thanks, -- Henrique Rodrigues

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ucontext in signal handler
by Warlich, Christof April 26, 2013

April 26, 2013

Hi, I'm porting a MIPS-based realtime control system that runs directly on top of the MIPS hardware (i.e. no dedicated operating systen inbetween) to x86 Linux. The systen is open to execute user code, and it catches floating point exceptions (e.g. underflow and overflow) by replacing out of range numbers with "sensible" values. To remain compatible whith the old system, I somehow need to do the same under Linux. I started out quite cheerfully whith some initial test code by registering a signal handler for floation point exceptions that just skips across any floating point instruction that causes an exception. (Note that the function instructionSize() calculates the length of the assembler instruction pointed to by ist argument): void fpeHandler(int, siginfo_t *info, void *context) { int size = instructionSize((unsigned char *) info->si_addr); ((ucontext_t *) context)->uc_mcontext.gregs[REG_EIP] += size; } This works great so far: When the signal handler returns, my program resumes right _after_ the instruction that caused the exception. But there is (much) more to do: To start with, the exception flags need to be cleared, otherwise any following floation point instructions would throw the exception again, even if they would not normally cause one. Initially, this seemed to be an easy task again, as the floating point registers are as well available in ucontext_t. So I looked at the source code of glibc to see the implementation of feclearexcept() to learn how to clear exception flags: Int feclearexcept (int excepts) { fenv_t temp; unsigned int mxcsr; /* Mask out unsupported bits/exceptions. */ excepts &= FE_ALL_EXCEPT; /* Bah, we have to clear selected exceptions. Since there is no `fldsw' instruction we have to do it the hard way. */ __asm__ ("fnstenv %0" : "=m" (*&temp)); /* Clear the relevant bits. */ temp.__status_word &= excepts ^ FE_ALL_EXCEPT; /* Put the new data in effect. */ __asm__ ("fldenv %0" : : "m" (*&temp)); /* And the same procedure for SSE. */ __asm__ ("stmxcsr %0" : "=m" (*&mxcsr)); /* Clear the relevant bits. */ mxcsr &= ~excepts; /* And put them into effect. */ __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr)); /* Success. */ return 0; } So I need to clear the relevant bits in the processor's floating point status word and in the mxcsr register. Looks easy. But ... 1) While ucontext_t _does_ have the status register, e.g.: ((ucontext_t *) context)->uc_mcontext.fpregs->status &= FE_ALL_EXCEPT ^ FE_ALL_EXCEPT; , the register mxcsr is _not_ part of ucontext_t. 2) Even worse, the following link suggests that only the general purpose registers are restored from ucontext_t, while the floating point registers in ucontext_t are ignored: http://valgrind.10908.n7.nabble.com/need-FPU-and-SSE-state-in-sigcontext-uc… As everything is so nicely available for general purpose registers, why are things not done in the same way for floating point registers? Is there any other way to achive my goal? If not, are there any realistic chances (for a kernel newbie) to fix this in the kernel? I already looked at arch/x86/kernel/signal.c, but it looks difficult to get on track. Thanks for any help, Chris

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[HELP] Documentation on CPU:/sys/devices/system/cpu/cpuX/cache/indexX/shared_cpu_map
by Ren Zhen April 25, 2013

April 25, 2013

Hi all: Can anybody help me to understand the usage of 'shared_cpu_map' in /sys/devices/system/cpu/cpuX/cache/indexX/. when I execute the cmd--'#cat shared_cpu_map', it retures '05'. And my computer use Ubuntu12.04,Intel core i3 CPU. I have read one email in LKML,it says: "The patch also adds a bunch of interfaces under /sys/devices/system/cpu/cpuX/cache, showing various information about the caches. Most useful field being shared_cpu_map, which says what caches are shared among which logical cpus. " But I still cannot catch the meaning of 'which says what caches are shared among which logical cpus'. Thanks. -- Sincerely, Ren Zhen

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［OT] How to use relative path in gdb macro
by hz hanks April 24, 2013

April 24, 2013

Hi, All I'm using gdb macro (.gdb files) in gdb to achieve complex process. And my .gdb files will use command "source" to include the python files to do the actual work. The problem is that the .gdb files only know the relative path of .py files. Does anyone know how to write that kind of source command? Thanks! Best, Hanks

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Re: Dynamic Sysfs Attribute Files
by Matt Davis April 24, 2013

April 24, 2013

> Date: Wed, 24 Apr 2013 15:39:42 +0200 > From: Tobias Boege <tobias(a)gambas-buch.de> > > On Wed, 24 Apr 2013, Matt Davis wrote: >> Hello, >> I want my kernel module to dynamically add sysfs files for its >> corresponding device. Without going into detail, the attribute file >> will be named something like: /sys/class/myclass/mydev0/fileX where >> 'X' is an integer ranging from 1-256. I did not see anything in the >> api to allow this. I suppose I could just dynamically allocate an >> attribute, give it the unique name by tacking on my own integer, and >> pass that off to device_create_file(). However, I have not seen >> anywhere in the codebase where another module does this; I assume it >> is not allowed (or there is a better solution). >> >> The other solution (instead of sysfs) would be to add an ioctl, but >> this means the userland application must know the specific 'file' id >> to query. In the sysfs version above, the userland application can >> just grab the directory listing of /sys/class/myclaass/mydev0/ and see >> how many 'file' instances exist. >> >> -Matt > > Hmm, the following led some places on my system: > > $ shopt -s extglob > $ find /sys/!(module|kernel) -name "*[0-9]" > ... > /sys/firmware/acpi/interrupts/gpe00 > /sys/firmware/acpi/interrupts/gpe01 > /sys/firmware/acpi/interrupts/gpe02 > /sys/firmware/acpi/interrupts/gpe03 > /sys/firmware/acpi/interrupts/gpe04 > /sys/firmware/acpi/interrupts/gpe05 > ... > > >From a quick grep, the source _may_ be somewhere around > > drivers/acpi/sysfs.c: > 658 sprintf(buffer, "gpe%02X", i); > > Hope this helps you further. Tobi, That is exactly what I am looking for; that and the fact no one explicitly flamed me for my idea. -Matt

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anyone else getting "sizeof(struct x86cpu_device_id)" errors compiling kernel?
by Robert P. J. Day April 24, 2013

April 24, 2013

for the first time in a while, i'm compiling the current git pull of the kernel source on my ubuntu system and, for a number of modules, i'm getting: Building modules, stage 2. MODPOST 1943 modules FATAL: arch/x86/kvm/kvm-amd: sizeof(struct x86cpu_device_id)=12 is not a modulo of the size of section __mod_x86cpu_device_table=32. Fix definition of struct x86cpu_device_id in mod_devicetable.h make[2]: *** [__modpost] Error 1 make[1]: *** [modules] Error 2 make: *** [sub-make] Error 2 i already deselected a couple of crypto modules that produced that but it's clear there are a number of modules that are going to cause this grief. i've never seen this before and i'm about to dig into it, but anyone else tripped over this and know the workaround? this is on a 64-bit ubuntu system, with: $ gcc --version gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 ... it looks like something related to packed structures but that's just a guess right now. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

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[HELP]CPU in SYSFS:/sys/devices/system/cpu/cpu0/microcode
by Ren Zhen April 24, 2013

April 24, 2013

Hi all: Can anyone help me to understand the usage of 'microcode' in /sys/devices/system/cpu/cpu0/. ------------------------------------------------------------------------------------- mysystem: /sys/devices/system/cpu/cpu0/ #ls processor_flags reload version ------------------------------------------------------------------------------------- What are the usages of 'processor_flags', 'reload' and 'version'? I have searched in the Documentation and LKML,but failed to find helpful information. Can Anyone who know those give me some more information about this? Any help will be appreciated! -- Sincerely, Ren Zhen

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