Hi Arnd, Russell, Linus, Can we ensure the arm32 kprobes fix I submitted gets upstream before 5.0 final ? It takes care of an illegal instruction issue with optimized kprobes on arm32. Here is the current state of default kprobes configuration on arm32: using them will trigger illegal instruction OOPS on v5.0-rc7, 4.19.24, v4.14.102. My fix is in "accepted" state in the arm patch tracking system: https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8834/1 Should I send it directly to Linus as well ? Thanks, Mathieu ----- On Feb 18, 2019, at 9:55 AM, Mathieu Desnoyers mathieu.desnoyers@xxxxxxxxxxxx wrote: > ----- On Feb 18, 2019, at 7:26 AM, Greg Kroah-Hartman gregkh@xxxxxxxxxxxxxxxxxxx > wrote: > >> On Wed, Feb 06, 2019 at 01:41:15PM +0900, Masami Hiramatsu wrote: >>> On Tue, 5 Feb 2019 15:06:10 +0000 >>> Kees Cook <keescook@xxxxxxxxxxxx> wrote: >>> >>> > On Mon, Feb 4, 2019 at 7:15 PM Mathieu Desnoyers >>> > <mathieu.desnoyers@xxxxxxxxxxxx> wrote: >>> > > >>> > > Hi, >>> > > >>> > > I notice this commit as a possible culprit of the illegal instructions my lttng >>> > > users are noticing on arm32 when using kprobes on a v4.19.13 Linux kernel >>> > > in a Yocto environment [1]. They were able to reproduce the issue with perf >>> > > as well. >>> > > >>> > > commit e46daee53bb50bde38805f1823a182979724c229 >>> > > Author: Kees Cook <keescook@xxxxxxxxxxxx> >>> > > Date: Tue Oct 30 22:12:56 2018 +0100 >>> > > >>> > > ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE >>> > > >>> > > I *think* the intent there was to do >>> > > >>> > > - memcpy(code, &optprobe_template_entry, >>> > > + memcpy(code, (unsigned long *)&optprobe_template_entry, >>> > > >>> > > But if you look at the commit, the "&" seems to have been stripped away, >>> > > which happens to change the behavior significantly. >>> > >>> > Yeah, this was a typo on my part. :( >>> >>> Ah, I thought it had been fixed as same as x86. >>> On x86, all optprobe_template_* are defined as kprobe_opcode_t [], >>> but on arm, it still be kprobe_opcode_t. >>> >>> Hmm, but I think we should use kprobe_opcode_t [] or char[] as asm/sections.h >>> does. >>> OK, I'll prepare for the change. >> >> Did this ever get fixed in Linus's tree? If so, what is the git commit >> id, I can't seem to find anything... > > It seems to still be in the arm patch tracking system: > > https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8834/1 > > If I understand its status correctly, it is applied to the arm tree, but > perhaps it has not been pulled by Linus yet ? The code is still broken > in Linus' master. > > It would be important to get this arm kprobes fix upstream before 5.0 > final. > > Thanks, > > Mathieu > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
