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Groups > linux.kernel > #1589387
| From | Abel Vesa <abelvesa@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS |
| Date | 2017-02-28 13:00 +0100 |
| Message-ID | <tfOBI-3VC-3@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <tfvSq-7FO-17@gated-at.bofh.it> <tfEiZ-576-13@gated-at.bofh.it> <tfNPj-3Bl-13@gated-at.bofh.it> <tfO8G-3IX-13@gated-at.bofh.it> <tfOBI-3VC-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Feb 28, 2017 at 11:46:38AM +0000, Russell King - ARM Linux wrote: > On Tue, Feb 28, 2017 at 11:22:27AM +0000, Abel Vesa wrote: > > On Tue, Feb 28, 2017 at 11:58:49AM +0100, Nicolai Stange wrote: > > > Hi Abel, > > > > > > On Tue, Feb 28 2017, Abel Vesa wrote: > > > > > > > On Mon, Feb 27, 2017 at 04:52:06PM +0100, Nicolai Stange wrote: > > > >> On Fri, Feb 24 2017, Abel Vesa wrote: > > > >> Wouldn't it be better (and more consistent with other archs) to have > > > >> > > > >> pt_regs->ARM_lr = original lr > > > >> pt_refs->ARM_pc = current lr > > > >> > > > >> instead? > > > > > > The stack would look like this then > > > > > > @ ... | ARM_ip | ARM_sp | ARM_lr | ARM_pc | ... | > > > @ 0 4 48 52 56 60 64 68 72 > > > @ R0 | R1 | ... | LR | SP + 4 | original LR | original PC | PSR | OLD_R0 | original LR | > > > > > > I.e. the pt_regs would capture almost the full context of the > > > instrumented function (except for ip). > > > > > So basicly what you are saying is: > > - instead of current LR save original LR (previous one saved in instrumented function epilog) > > - instead of current PC save original PC (previous one saved in instrumented function epilog) > > > > I still don't see the point of saving the actual value of PC since nobody will ever > > restore it. In case of livepatch it will get overwritten anyway. As for LR, I agree, > > it could be the original one in pt_regs. > > > > I'll look into this sometime today or tomorrow and get back with updates. > > Which is exactly what I proposed, with code, on one of the previous > iterations of this patch... Fair enough. I probably missunderstood your comments then. Thanks. > > -- > RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up > according to speedtest.net.
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[PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Abel Vesa <abelvesa@linux.com> - 2017-02-25 00:00 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Nicolai Stange <nicstange@gmail.com> - 2017-02-27 17:00 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Abel Vesa <abelvesa@gmail.com> - 2017-02-28 02:00 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Nicolai Stange <nicstange@gmail.com> - 2017-02-28 12:10 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Abel Vesa <abelvesa@gmail.com> - 2017-02-28 12:30 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Abel Vesa <abelvesa@gmail.com> - 2017-02-28 13:00 +0100
Re: [PATCHv4] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-02-28 13:10 +0100
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