From: rostedt at goodmis.org (Steven Rostedt) Subject: [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member Date: Sun, 28 Apr 2019 13:51:43 -0400 [thread overview] Message-ID: <20190428135143.09d35bb6@oasis.local.home> (raw) In-Reply-To: <F6268634-96D3-4267-B739-6D375FAB26A8@amacapital.net> On Sun, 28 Apr 2019 10:41:10 -0700 Andy Lutomirski <luto at amacapital.net> wrote: > > Note that at any given point > > in time, there can be at most four such call insn emulations pending: > > namely at most one per "process", "irq", "softirq" and "nmi" context. > > > > That’s quite an assumption. I think your list should also contain > exception, exceptions nested inside that exception, and machine > check, at the very least. I’m also wondering why irq and softirq are > treated separately. 4 has usually been the context count we choose. But I guess in theory, if we get exceptions then I could potentially be more. As for irq vs softirq, an interrupt can preempt a softirq. Interrupts are enabled while softirqs are running. When sofirqs run, softirqs are disabled to prevent nested softirqs. But interrupts are enabled again, and another interrupt may come in while a softirq is executing. > > All this makes me think that one of the other solutions we came up > with last time we discussed this might be better. +100 Perhaps adding another slot into pt_regs that gets used by int3 to store a slot to emulate a call on return? -- Steve
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From: rostedt@goodmis.org (Steven Rostedt) Subject: [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member Date: Sun, 28 Apr 2019 13:51:43 -0400 [thread overview] Message-ID: <20190428135143.09d35bb6@oasis.local.home> (raw) Message-ID: <20190428175143.FDJbfbtv0_j1a3ywAKvQEAOIX5t8Oq4A3uRkgsG0sAQ@z> (raw) In-Reply-To: <F6268634-96D3-4267-B739-6D375FAB26A8@amacapital.net> On Sun, 28 Apr 2019 10:41:10 -0700 Andy Lutomirski <luto@amacapital.net> wrote: > > Note that at any given point > > in time, there can be at most four such call insn emulations pending: > > namely at most one per "process", "irq", "softirq" and "nmi" context. > > > > That’s quite an assumption. I think your list should also contain > exception, exceptions nested inside that exception, and machine > check, at the very least. I’m also wondering why irq and softirq are > treated separately. 4 has usually been the context count we choose. But I guess in theory, if we get exceptions then I could potentially be more. As for irq vs softirq, an interrupt can preempt a softirq. Interrupts are enabled while softirqs are running. When sofirqs run, softirqs are disabled to prevent nested softirqs. But interrupts are enabled again, and another interrupt may come in while a softirq is executing. > > All this makes me think that one of the other solutions we came up > with last time we discussed this might be better. +100 Perhaps adding another slot into pt_regs that gets used by int3 to store a slot to emulate a call on return? -- Steve
next prev parent reply other threads:[~2019-04-28 17:51 UTC|newest] Thread overview: 128+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-27 10:06 [PATCH 0/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange 2019-04-27 10:06 ` Nicolai Stange 2019-04-27 10:06 ` [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member nstange 2019-04-27 10:06 ` Nicolai Stange 2019-04-28 17:41 ` luto 2019-04-28 17:41 ` Andy Lutomirski 2019-04-28 17:51 ` rostedt [this message] 2019-04-28 17:51 ` Steven Rostedt 2019-04-28 18:08 ` luto 2019-04-28 18:08 ` Andy Lutomirski 2019-04-28 19:43 ` rostedt 2019-04-28 19:43 ` Steven Rostedt 2019-04-28 20:56 ` luto 2019-04-28 20:56 ` Andy Lutomirski 2019-04-28 21:22 ` nstange 2019-04-28 21:22 ` Nicolai Stange 2019-04-28 23:27 ` luto 2019-04-28 23:27 ` Andy Lutomirski 2019-04-27 10:06 ` [PATCH 2/4] ftrace: drop 'static' qualifier from ftrace_ops_list_func() nstange 2019-04-27 10:06 ` Nicolai Stange 2019-04-27 10:06 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange 2019-04-27 10:06 ` Nicolai Stange 2019-04-27 10:26 ` peterz 2019-04-27 10:26 ` Peter Zijlstra 2019-04-28 17:38 ` rostedt 2019-04-28 17:38 ` Steven Rostedt 2019-04-29 18:06 ` torvalds 2019-04-29 18:06 ` Linus Torvalds 2019-04-29 18:22 ` torvalds 2019-04-29 18:22 ` Linus Torvalds 2019-04-29 18:42 ` luto 2019-04-29 18:42 ` Andy Lutomirski [not found] ` <CAHk-=whtt4K2f0KPtG-4Pykh3FK8UBOjD8jhXCUKB5nWDj_YRA@mail.gmail.com> 2019-04-29 18:56 ` luto 2019-04-29 18:56 ` Andy Lutomirski [not found] ` <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com> [not found] ` <CAHk-=whay7eN6+2gZjY-ybRbkbcqAmgrLwwszzHx8ws3c=S-MA@mail.gmail.com> 2019-04-29 19:24 ` luto 2019-04-29 19:24 ` Andy Lutomirski 2019-04-29 20:07 ` torvalds 2019-04-29 20:07 ` Linus Torvalds 2019-04-30 13:56 ` peterz 2019-04-30 13:56 ` Peter Zijlstra 2019-04-30 16:06 ` torvalds 2019-04-30 16:06 ` Linus Torvalds 2019-04-30 16:33 ` luto 2019-04-30 16:33 ` Andy Lutomirski 2019-04-30 17:03 ` rostedt 2019-04-30 17:03 ` Steven Rostedt 2019-04-30 17:20 ` rostedt 2019-04-30 17:20 ` Steven Rostedt 2019-04-30 17:49 ` [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler rostedt 2019-04-30 17:49 ` Steven Rostedt 2019-04-30 18:33 ` torvalds 2019-04-30 18:33 ` Linus Torvalds 2019-04-30 19:00 ` rostedt 2019-04-30 19:00 ` Steven Rostedt 2019-04-30 21:08 ` rostedt 2019-04-30 21:08 ` Steven Rostedt 2019-05-01 13:11 ` peterz 2019-05-01 13:11 ` Peter Zijlstra 2019-05-01 18:58 ` rostedt 2019-05-01 18:58 ` Steven Rostedt 2019-05-01 19:03 ` peterz 2019-05-01 19:03 ` Peter Zijlstra 2019-05-01 19:03 ` torvalds 2019-05-01 19:03 ` Linus Torvalds 2019-05-01 19:13 ` peterz 2019-05-01 19:13 ` Peter Zijlstra 2019-05-01 19:13 ` rostedt 2019-05-01 19:13 ` Steven Rostedt 2019-05-01 19:33 ` jikos 2019-05-01 19:33 ` Jiri Kosina 2019-05-01 19:41 ` peterz 2019-05-01 19:41 ` Peter Zijlstra 2019-04-30 21:53 ` [RFC][PATCH v2] " rostedt 2019-04-30 21:53 ` Steven Rostedt 2019-05-01 1:35 ` rostedt 2019-05-01 1:35 ` Steven Rostedt 2019-05-01 1:58 ` torvalds 2019-05-01 1:58 ` Linus Torvalds 2019-05-01 8:26 ` nstange 2019-05-01 8:26 ` Nicolai Stange 2019-05-01 13:22 ` rostedt 2019-05-01 13:22 ` Steven Rostedt 2019-04-29 20:16 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation torvalds 2019-04-29 20:16 ` Linus Torvalds 2019-04-29 22:08 ` sean.j.christopherson 2019-04-29 22:08 ` Sean Christopherson 2019-04-29 22:22 ` torvalds 2019-04-29 22:22 ` Linus Torvalds 2019-04-30 0:08 ` sean.j.christopherson 2019-04-30 0:08 ` Sean Christopherson 2019-04-30 0:45 ` sean.j.christopherson 2019-04-30 0:45 ` Sean Christopherson 2019-04-30 2:26 ` torvalds 2019-04-30 2:26 ` Linus Torvalds 2019-04-30 10:40 ` peterz 2019-04-30 10:40 ` Peter Zijlstra 2019-04-30 11:17 ` jikos 2019-04-30 11:17 ` Jiri Kosina 2019-04-29 22:06 ` torvalds 2019-04-29 22:06 ` Linus Torvalds 2019-04-30 11:18 ` peterz 2019-04-30 11:18 ` Peter Zijlstra 2019-04-29 18:52 ` rostedt 2019-04-29 18:52 ` Steven Rostedt [not found] ` <CAHk-=wjm93jLtVxTX4HZs6K4k1Wqh3ujjmapqaYtcibVk_YnzQ@mail.gmail.com> 2019-04-29 19:07 ` rostedt 2019-04-29 19:07 ` Steven Rostedt 2019-04-29 20:06 ` torvalds 2019-04-29 20:06 ` Linus Torvalds 2019-04-29 20:20 ` torvalds 2019-04-29 20:20 ` Linus Torvalds 2019-04-29 20:30 ` rostedt 2019-04-29 20:30 ` Steven Rostedt 2019-04-29 21:38 ` torvalds 2019-04-29 21:38 ` Linus Torvalds 2019-04-29 22:07 ` rostedt 2019-04-29 22:07 ` Steven Rostedt 2019-04-30 9:24 ` nstange 2019-04-30 9:24 ` Nicolai Stange 2019-04-30 10:46 ` peterz 2019-04-30 10:46 ` Peter Zijlstra 2019-04-30 13:44 ` rostedt 2019-04-30 13:44 ` Steven Rostedt 2019-04-30 14:20 ` peterz 2019-04-30 14:20 ` Peter Zijlstra 2019-04-30 14:36 ` rostedt 2019-04-30 14:36 ` Steven Rostedt 2019-04-27 10:06 ` [PATCH 4/4] selftests/livepatch: add "ftrace a live patched function" test nstange 2019-04-27 10:06 ` Nicolai Stange
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