Re: [PATCH 1/2] perf: Move task_pt_regs sampling into arch code

2015-01-05 Thread Andy Lutomirski
On Mon, Jan 5, 2015 at 8:44 AM, Peter Zijlstra wrote: > On Mon, Jan 05, 2015 at 08:13:49AM -0800, Andy Lutomirski wrote: >> > Just wondering how bad it would be to fill out the actual pt_regs that >> > was previously partially initialized? >> >> Bad, for at least two reasons. >> >> One is that we

Re: [PATCH 1/2] perf: Move task_pt_regs sampling into arch code

2015-01-05 Thread Peter Zijlstra
On Mon, Jan 05, 2015 at 08:13:49AM -0800, Andy Lutomirski wrote: > > Just wondering how bad it would be to fill out the actual pt_regs that > > was previously partially initialized? > > Bad, for at least two reasons. > > One is that we don't actually know which regs are initialized. bx, > bp, r1

Re: [PATCH 1/2] perf: Move task_pt_regs sampling into arch code

2015-01-05 Thread Andy Lutomirski
n Jan 5, 2015 6:08 AM, "Peter Zijlstra" wrote: > > On Sun, Jan 04, 2015 at 10:36:19AM -0800, Andy Lutomirski wrote: > > On x86_64, at least, task_pt_regs may be only partially initialized > > in many contexts, so x86_64 should not use it without extra care > > from interrupt context, let alone NMI

Re: [PATCH 1/2] perf: Move task_pt_regs sampling into arch code

2015-01-05 Thread Peter Zijlstra
On Sun, Jan 04, 2015 at 10:36:19AM -0800, Andy Lutomirski wrote: > On x86_64, at least, task_pt_regs may be only partially initialized > in many contexts, so x86_64 should not use it without extra care > from interrupt context, let alone NMI context. > > This will allow x86_64 to override the logi