November 2017 - kernelnewbies@kernelnewbies.org

Why replacing running executable file is forbidden, but overwriting of memory mapped shared object is allowed ?
by Lev Olshvang Nov. 14, 2017

Nov. 14, 2017

Hi list The reason for my question is mainly security context. Here the story If you ever tried to replace executable file by new image the message executable is busy appeared and operation fails. But the attempt to replace shared object library succeeded, and I do not understand the logic of this decision. Besides to be security hole, I do not see any legitimate use except of live patching of shared object. I do not know whether production or mission critical system may take a risk of live patching, but development system would do a library update by stopping dependent application first. I saw in kernel archives that some years ago the decision was made to withdraw restriction on shared object live replacement and I would like to know the what what were the reasons because I want to patch my kernel to forbid shared objects live replacement. ( as I said I worry about security issue) Regards, Lev

5 9

Re: git pull
by Greg Kroah-Hartman Nov. 14, 2017

Nov. 14, 2017

On Tue, Nov 14, 2017 at 01:00:14PM +0100, Ulf Hansson wrote: > [...] > > > > > An example pull request of mine might look like: > > Char/Misc patches for 4.15-rc1 > > > > Here is the big char/misc patch set for the 4.15-rc1 merge > > window. Contained in here is the normal set of new functions > > added to all of these crazy drivers, as well as the following > > brand new subsystems: > > - time_travel_controller: Finally a set of drivers for > > the latest time travel bus architecture that provides > > i/o to the CPU before it asked for it, allowing > > uninterrupted processing > > - relativity_shifters: due to the affect that the > > time_travel_controllers have on the overall system, > > there was a need for a new set of relativity shifter > > drivers to accommodate the newly formed black holes > > that would threaten to suck CPUs into them. This > > subsystem handles this in a way to successfully > > neutralize the problems. There is a Kconfig option to > > force these to be enabled when needed, so problems > > should not occur. > > > > All of these patches have been successfully tested in the latest > > linux-next releases, and the original problems that it found > > have all been resolved (apologies to anyone living near Canberra > > for the lack of the Kconfig options in the earlier versions of > > the linux-next tree creations.) > > > > Signed-off-by: Your-name-here <your_email@domain> > > > > > > The tag message format is just like a git commit id. One line at the > > top for a "summary subject" and be sure to sign-off at the bottom. > > I don't add my s-o-b to signed tags for pull requests, but perhaps I should. > > However, I think most maintainers don't use it, and neither does it > seems like Linus is preserving the tag when he does the pull. The text of the tag is in the merge commit, but you are right, the signed-off-by doesn't seem to be in the merge commit, I guess Linus's workflow removes them. I know I keep them in there if present for pull requests that people send to me. thanks, greg k-h

1 0

What's the exact difference between make silentoldconfig and oldconfig?
by Shiyao MA Nov. 10, 2017

Nov. 10, 2017

Hi, The man help says, silentoldconfig is like oldconfig, but quietly and additionally updates dependencies. 1. What does it mean by "quietly"? 2. What dependency that silentoldconfig updates but oldconfig does not? Looking at http://elixir.free-electrons.com/linux/latest/source/scripts/kconfig/conf.c… seems there must be some logic difference between oldconfig and silentoldconfig, but currently it's a mess for me and can't tell the difference. -- Best, Shiyao

2 2

How inode of /proc. /sys keep the same number on a given system
by Lev Olshvang Nov. 8, 2017

Nov. 8, 2017

Hello all, I observe that between reboot inode of files in /proc and /sys filesystem keep the same number. I need to know whether I can rely on this in my program, and under what conditions this assumption became incorrect? Would inode number be the same on another system burned from the same image ? I mean when I create 10 of embedded devices, will the inode /proc of same files same between all devices? Best regards, Lev

2 1

Linux generic irq handling
by Shrikant Dharwadkar Nov. 6, 2017

Nov. 6, 2017

*Register an linux generic interrupt handler using an virtual irq which maps to the actual hwirq of domain to handle interrupts.* I'm having issues in handling interrupts. So far I have registered an interrupt handler based on the following kernel docuentation IRQ-domain.txt <https://www.kernel.org/doc/Documentation/IRQ-domain.txt>, by setting the ops and creating mapping between domain and hwirq. But unable to receive interrupts on the newly registered virtual interrupt line. So my question's are: 1. Am I doing something wrong in the mapping because I am not seeing any interrupts getting handled in cat /proc/interrupts. 2. Should the request_thereaded_irq() consist of the actual hwirq and later handled in the threaded handler on virq as done in arizona. *code:* static struct irq_chip irq_chip = { .name = "CHIP-IRQ", .irq_disable = noop, .irq_enable = noop, }; static int irq_map(struct irq_domain *h, unsigned int virq, irq_hw_number_t hw) { struct chipdata *data = h->host_data; irq_set_chip_and_handler(virq, &irq_chip, handle_simple_irq); irq_set_chip_data(virq, data); irq_set_noprobe(virq); return 0; } static const struct irq_domain_ops irq_domain_ops = { .map = irq_map, .xlate = irq_domain_xlate_twocell, }; /* Register an interrupt domain */ ` chipdata.irq_domain = irq_domain_create_linear( fwn, 20, &irq_domain_ops, ebus); if (!chipdata.irq_domain) { dev_err(ebus->bus.dev, "Failed to add core IRQ domain\n"); } /* Create mapping between domain and hwirq*/ virq = irq_create_mapping( chipdata.irq_domain, hwirq); ret = request_threaded_irq( virq, interrupt, threaded_interrupt, IRQF_SHARED, KBUILD_MODNAME, ebus); if (ret) { dev_err(bus->dev, "unable to grab IRQ %d, disabling device\n", virq); return ret; }

1 0

Ask for the linux memory managment mailing list
by VOID 001 Nov. 5, 2017

Nov. 5, 2017

Hi, I am looking for the way to subscribe to linux-mm mailing list, but when I refer to http://vger.kernel.org/vger-lists.html I can not found the mailing list named linux-mm, could anyone please point it out for me? Thanks in advance.

2 1

Non-web based LXR
by Tobin C. Harding Nov. 2, 2017

Nov. 2, 2017

CC'd Thomas because I read online recently him commenting on web based cross reference tools. Hi, Does any one use a terminal based source code cross referencer to search the kernel tree? thanks, Tobin.

6 7

Mentors and Archives?
by leam hall Nov. 1, 2017

Nov. 1, 2017

Newly back to the list. Is there a way to see if the idea of Kernel-Mentors has been talked about recently besides pulling the zip files and grep'ing? if no one recalls any discussion; up for it? :) Thanks! Leam

3 2