From mboxrd@z Thu Jan 1 00:00:00 1970 From: mhiramat at kernel.org (Masami Hiramatsu) Date: Wed, 8 May 2019 02:15:51 +0900 Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions In-Reply-To: <20190507231340.92b1b0665d1110f90929d878@kernel.org> References: <20190502181811.GY2623@hirez.programming.kicks-ass.net> <20190502195052.0af473cf@gandalf.local.home> <20190503092959.GB2623@hirez.programming.kicks-ass.net> <20190503092247.20cc1ff0@gandalf.local.home> <2045370D-38D8-406C-9E94-C1D483E232C9@amacapital.net> <20190506081951.GJ2606@hirez.programming.kicks-ass.net> <20190506095631.6f71ad7c@gandalf.local.home> <20190506130643.62c35eeb@gandalf.local.home> <20190506145745.17c59596@gandalf.local.home> <20190506162915.380993f9@gandalf.local.home> <20190506174511.2f8b696b@gandalf.local.home> <20190507231340.92b1b0665d1110f90929d878@kernel.org> Message-ID: <20190508021551.ca791c725cbddc2db541273f@kernel.org> On Tue, 7 May 2019 23:13:40 +0900 Masami Hiramatsu wrote: > On Mon, 6 May 2019 17:45:11 -0400 > Steven Rostedt wrote: > > > If we go with Peter's patch, I can make this code much more sane, and > > not have to worry about having ®s->sp be at the top of the stack. I > > could simply, just push everything in the order of pt_regs and call the > > handler. > > Hi Steve, I need to catch up with the origin of this series, but it seems > also good to optprobe which is doing similar trick on pt_regs. If we can > assume that int3 pt_regs can have a gap, optprobe can also make a gap, and > it can be also used for storing destination address. Sorry, I misunderstood. I see the issue ( https://lkml.org/lkml/2019/5/1/497 ) and solutions on the thread. If we really need to fix this trace-livepatch combination issue, it may be good to backport to stable trees. >>From this viewpoint, Linus's suggestion (no pt_reg changes on x86-32) seems to have a point. BTW, even though I think Peter's patch (unifying pt_regs behavior) will also be good for us for more general reason (not only for fixing actual issue). Thank you, -- Masami Hiramatsu From mboxrd@z Thu Jan 1 00:00:00 1970 From: mhiramat@kernel.org (Masami Hiramatsu) Date: Wed, 8 May 2019 02:15:51 +0900 Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions In-Reply-To: <20190507231340.92b1b0665d1110f90929d878@kernel.org> References: <20190502181811.GY2623@hirez.programming.kicks-ass.net> <20190502195052.0af473cf@gandalf.local.home> <20190503092959.GB2623@hirez.programming.kicks-ass.net> <20190503092247.20cc1ff0@gandalf.local.home> <2045370D-38D8-406C-9E94-C1D483E232C9@amacapital.net> <20190506081951.GJ2606@hirez.programming.kicks-ass.net> <20190506095631.6f71ad7c@gandalf.local.home> <20190506130643.62c35eeb@gandalf.local.home> <20190506145745.17c59596@gandalf.local.home> <20190506162915.380993f9@gandalf.local.home> <20190506174511.2f8b696b@gandalf.local.home> <20190507231340.92b1b0665d1110f90929d878@kernel.org> Message-ID: <20190508021551.ca791c725cbddc2db541273f@kernel.org> Content-Type: text/plain; charset="UTF-8" Message-ID: <20190507171551.9w33o_99wqTiWSfd8PJzGt7nP0h4P_3aj7u3TlEGJ-I@z> On Tue, 7 May 2019 23:13:40 +0900 Masami Hiramatsu wrote: > On Mon, 6 May 2019 17:45:11 -0400 > Steven Rostedt wrote: > > > If we go with Peter's patch, I can make this code much more sane, and > > not have to worry about having ®s->sp be at the top of the stack. I > > could simply, just push everything in the order of pt_regs and call the > > handler. > > Hi Steve, I need to catch up with the origin of this series, but it seems > also good to optprobe which is doing similar trick on pt_regs. If we can > assume that int3 pt_regs can have a gap, optprobe can also make a gap, and > it can be also used for storing destination address. Sorry, I misunderstood. I see the issue ( https://lkml.org/lkml/2019/5/1/497 ) and solutions on the thread. If we really need to fix this trace-livepatch combination issue, it may be good to backport to stable trees. >>From this viewpoint, Linus's suggestion (no pt_reg changes on x86-32) seems to have a point. BTW, even though I think Peter's patch (unifying pt_regs behavior) will also be good for us for more general reason (not only for fixing actual issue). Thank you, -- Masami Hiramatsu