Messages in this thread | | | Date | Fri, 25 Feb 2005 01:04:20 +0100 | From | Jordi Brínquez <> | Subject | Re: Possible bug on signal.h |
| |
I'm trying to modify UML so I'm using kernel headers
but anyway there is a problem on sigaction definition on signal.h
Jordi
linux-os wrote:
> On Thu, 24 Feb 2005, Jordi Brinquez wrote: > >> Hi, >> >> I think I found a possible bug on file signal.h. >> >> The problem comes when you define a struct sigaction on a user program >> and then you use the function sigaction to remap a signal handler (in >> my case a page_fault) for my own function, this system call is >> compiled as __NR_sigaction system call (by default this routine is >> managed by sys_sigaction routine) and if the architecture defines >> __ARCH_WANT_SYS_RT_SIGACTION kernel uses the routine sys_rt_sigaction >> on the file kernel/signal.c that instead of copying the fields from >> one structure to the other it just uses copy_from_user and >> copy_to_user with the consequent mess with the fields. >> > > You NEVER use kernel headers for user code.... EVER. If you > are making something strange, like as you said a page-fault > handler, then you make an in-kernel driver (module). > > FYI, no page-fault handler could ever work in user-mode > anyway. A page-fault occurs because the user accesses some > page it doesn't own (probably because it isn't in memory). > The kernel page-fault handler checks to see if the page was > promised. If not, it terminates the user-mode task with > a signal. If so, it finds some free page or makes one > available and maps it into the user's address-space before > returning control to the user. Since the user doesn't own > any free pages, it can't map in any. > > > [SNIPPED...] > > > Cheers, > Dick Johnson > Penguin : Linux version 2.6.10 on an i686 machine (5537.79 BogoMips). > Notice : All mail here is now cached for review by Dictator Bush. > 98.36% of all statistics are fiction. > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |