* arm64 uprobes support showing signs of life @ 2015-01-05 16:06 William Cohen 2015-01-05 16:12 ` [fedora-arm] " Peter Robinson 2015-01-07 12:07 ` Pratyush Anand 0 siblings, 2 replies; 5+ messages in thread From: William Cohen @ 2015-01-05 16:06 UTC (permalink / raw) To: systemtap, Pratyush Anand, arm Hi All, Pratyush has been implementing uprobes support for aarch64 and has posted a set of patches (http://comments.gmane.org/gmane.linux.ports.arm.kernel/382237) for review. The really new Linux kernels requires a patch to the systemtap runtime because the f_dentry macro has been removed. With the patched systemtap I was able to run the systemtap testsuite and get some test results exercising the uprobes support: https://web.elastic.org/~dejazilla/viewsummary.php?summary=%3D%27%3C54A9E21C.2080504%40redhat.com%3E%27 There looked to be a localized fixes for plt support to eliminate the unsupported systemtap.base/list.exp plt-* tests. A number of the tests appear to fail because of userspace arguments cannot be found for sdt probes. The uprobe patches still need some refinement. On a number of systemtap "make installcheck" runs the kernel would get stuck spewing out: Unexpected kernel single-step exception at EL1 However, things are looking better for user-space probing on arm64. -Will ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [fedora-arm] arm64 uprobes support showing signs of life 2015-01-05 16:06 arm64 uprobes support showing signs of life William Cohen @ 2015-01-05 16:12 ` Peter Robinson 2015-01-07 12:07 ` Pratyush Anand 1 sibling, 0 replies; 5+ messages in thread From: Peter Robinson @ 2015-01-05 16:12 UTC (permalink / raw) To: William Cohen; +Cc: systemtap, Pratyush Anand, arm On Mon, Jan 5, 2015 at 4:06 PM, William Cohen <wcohen@redhat.com> wrote: > Hi All, > > Pratyush has been implementing uprobes support for aarch64 and has > posted a set of patches > (http://comments.gmane.org/gmane.linux.ports.arm.kernel/382237) for > review. The really new Linux kernels requires a patch to the > systemtap runtime because the f_dentry macro has been removed. With > the patched systemtap I was able to run the systemtap testsuite and > get some test results exercising the uprobes support: > > https://web.elastic.org/~dejazilla/viewsummary.php?summary=%3D%27%3C54A9E21C.2080504%40redhat.com%3E%27 > > There looked to be a localized fixes for plt support to eliminate the > unsupported systemtap.base/list.exp plt-* tests. > > A number of the tests appear to fail because of userspace arguments > cannot be found for sdt probes. > > The uprobe patches still need some refinement. On a number of > systemtap "make installcheck" runs the kernel would get stuck spewing > out: > > Unexpected kernel single-step exception at EL1 > > However, things are looking better for user-space probing on arm64. good news, thanks for the update. Peter ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arm64 uprobes support showing signs of life 2015-01-05 16:06 arm64 uprobes support showing signs of life William Cohen 2015-01-05 16:12 ` [fedora-arm] " Peter Robinson @ 2015-01-07 12:07 ` Pratyush Anand 2015-01-07 13:10 ` William Cohen 1 sibling, 1 reply; 5+ messages in thread From: Pratyush Anand @ 2015-01-07 12:07 UTC (permalink / raw) To: William Cohen, systemtap, arm Hi Will, On Monday 05 January 2015 09:36 PM, William Cohen wrote: > Hi All, > > Pratyush has been implementing uprobes support for aarch64 and has > posted a set of patches > (http://comments.gmane.org/gmane.linux.ports.arm.kernel/382237) for > review. The really new Linux kernels requires a patch to the > systemtap runtime because the f_dentry macro has been removed. With > the patched systemtap I was able to run the systemtap testsuite and > get some test results exercising the uprobes support: > > https://web.elastic.org/~dejazilla/viewsummary.php?summary=%3D%27%3C54A9E21C.2080504%40redhat.com%3E%27 > > There looked to be a localized fixes for plt support to eliminate the > unsupported systemtap.base/list.exp plt-* tests. > > A number of the tests appear to fail because of userspace arguments > cannot be found for sdt probes. > > The uprobe patches still need some refinement. On a number of > systemtap "make installcheck" runs the kernel would get stuck spewing > out: > > Unexpected kernel single-step exception at EL1 There are at least two functions of arm64/uprobe implementation uprobe_breakpoint_handler and uprobe_single_step_handler, where a kprobe insertion might be causing above issue. Currently I have qualified these functions with __kprobe, so that one can not insert a kprobe there. With this you should not be able to see the above message. However, I am still investigating if a kprobe insertion be allowed to these functions or any other function which is called directly from debug exception handler (do_debug_exception) Update code is here: https://github.com/pratyushanand/linux.git : ml_arm64_uprobe_devel_v2 ~Pratyush > > However, things are looking better for user-space probing on arm64. > > -Will > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arm64 uprobes support showing signs of life 2015-01-07 12:07 ` Pratyush Anand @ 2015-01-07 13:10 ` William Cohen 2015-01-07 13:34 ` Pratyush Anand 0 siblings, 1 reply; 5+ messages in thread From: William Cohen @ 2015-01-07 13:10 UTC (permalink / raw) To: Pratyush Anand, systemtap, arm On 01/07/2015 07:07 AM, Pratyush Anand wrote: > Hi Will, > > > On Monday 05 January 2015 09:36 PM, William Cohen wrote: >> Hi All, >> >> Pratyush has been implementing uprobes support for aarch64 and has >> posted a set of patches >> (http://comments.gmane.org/gmane.linux.ports.arm.kernel/382237) for >> review. The really new Linux kernels requires a patch to the >> systemtap runtime because the f_dentry macro has been removed. With >> the patched systemtap I was able to run the systemtap testsuite and >> get some test results exercising the uprobes support: >> >> https://web.elastic.org/~dejazilla/viewsummary.php?summary=%3D%27%3C54A9E21C.2080504%40redhat.com%3E%27 >> >> There looked to be a localized fixes for plt support to eliminate the >> unsupported systemtap.base/list.exp plt-* tests. >> >> A number of the tests appear to fail because of userspace arguments >> cannot be found for sdt probes. >> >> The uprobe patches still need some refinement. On a number of >> systemtap "make installcheck" runs the kernel would get stuck spewing >> out: >> >> Unexpected kernel single-step exception at EL1 > > There are at least two functions of arm64/uprobe implementation uprobe_breakpoint_handler and uprobe_single_step_handler, where a kprobe insertion might be causing above issue. Currently I have qualified these functions with __kprobe, so that one can not insert a kprobe there. With this you should not be able to see the above message. > > However, I am still investigating if a kprobe insertion be allowed to these functions or any other function which is called directly from debug exception handler (do_debug_exception) > Hi Pratyush, Are there any other places that need to be protected from kprobe probing in the arm64 code? > Update code is here: > > https://github.com/pratyushanand/linux.git : ml_arm64_uprobe_devel_v2 > > ~Pratyush I will give the new kernel a try. -Will > >> >> However, things are looking better for user-space probing on arm64. >> >> -Will >> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arm64 uprobes support showing signs of life 2015-01-07 13:10 ` William Cohen @ 2015-01-07 13:34 ` Pratyush Anand 0 siblings, 0 replies; 5+ messages in thread From: Pratyush Anand @ 2015-01-07 13:34 UTC (permalink / raw) To: William Cohen, systemtap, arm On Wednesday 07 January 2015 06:40 PM, William Cohen wrote: > On 01/07/2015 07:07 AM, Pratyush Anand wrote: >> Hi Will, >> >> >> On Monday 05 January 2015 09:36 PM, William Cohen wrote: >>> Hi All, >>> >>> Pratyush has been implementing uprobes support for aarch64 and has >>> posted a set of patches >>> (http://comments.gmane.org/gmane.linux.ports.arm.kernel/382237) for >>> review. The really new Linux kernels requires a patch to the >>> systemtap runtime because the f_dentry macro has been removed. With >>> the patched systemtap I was able to run the systemtap testsuite and >>> get some test results exercising the uprobes support: >>> >>> https://web.elastic.org/~dejazilla/viewsummary.php?summary=%3D%27%3C54A9E21C.2080504%40redhat.com%3E%27 >>> >>> There looked to be a localized fixes for plt support to eliminate the >>> unsupported systemtap.base/list.exp plt-* tests. >>> >>> A number of the tests appear to fail because of userspace arguments >>> cannot be found for sdt probes. >>> >>> The uprobe patches still need some refinement. On a number of >>> systemtap "make installcheck" runs the kernel would get stuck spewing >>> out: >>> >>> Unexpected kernel single-step exception at EL1 >> >> There are at least two functions of arm64/uprobe implementation uprobe_breakpoint_handler and uprobe_single_step_handler, where a kprobe insertion might be causing above issue. Currently I have qualified these functions with __kprobe, so that one can not insert a kprobe there. With this you should not be able to see the above message. >> >> However, I am still investigating if a kprobe insertion be allowed to these functions or any other function which is called directly from debug exception handler (do_debug_exception) >> > > Hi Pratyush, > > Are there any other places that need to be protected from kprobe probing in the arm64 code? yes, I tried inserting kprobe in arch/arm64/kernel/debug-monitors.c:brk_handler and it failed. So, I think as of now, we can not probe any function which comes in the path of do_debug_exception. Looking into kprobe code, it seems that it allows REENTER, so it should have worked. Do not have much idea at present. Still, studying these part of code. ~Pratyush > >> Update code is here: >> >> https://github.com/pratyushanand/linux.git : ml_arm64_uprobe_devel_v2 >> >> ~Pratyush > > I will give the new kernel a try. > > -Will > >> >>> >>> However, things are looking better for user-space probing on arm64. >>> >>> -Will >>> > ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-01-07 13:34 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-01-05 16:06 arm64 uprobes support showing signs of life William Cohen 2015-01-05 16:12 ` [fedora-arm] " Peter Robinson 2015-01-07 12:07 ` Pratyush Anand 2015-01-07 13:10 ` William Cohen 2015-01-07 13:34 ` Pratyush Anand
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