armstub7: Also reset CNTVOFF #113
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Currently only one free instruction for GIC code below 0x100 so move it above 0x100 live armstub8
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Unfortunately i'm not that assembler / ARM expert, but from my limited PoV this looks like the requested ones. The timer frequency is already been set. Maybe @vianpl wants to take a look. |
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Like @lategoodbye I'm not an expert in such low level matters. That said, it looks correct to me. We could go ahead and drop "arm,cpu-registers-not-fw-configured" altogether, but I guess we'd have to time it with a firmware release. Let me do some extra research/testing to really validate this. As for raspberrypi/linux#3579, FYI, it's still being looked at and I doubt this will fix the underlying issue (albeit probably mask it): |
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The DT property "arm,cpu-registers-not-fw-configured" is really ugly and now hard to remove. Maybe in mainline we should do this (first) only for RPi 4 because of the few users. I agree regarding raspberrypi/linux#3579 because this is an orthogonal issue. |
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Am I right in thinking that "armstub7: Increase GIC version to 0x200" is required in order for "armstub7: Also reset CNTVOFF" to fit? We might get some complaints from users of other OSs expecting to be able to put their DTB at 0x100, but some headroom would be nice. |
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Yes, currently one free word is available for armstub8-32-gic.bin. |
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I suppose the GIC / noddy-DTB-handling intersection is probably vanishingly small. |
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Yes - I made sure non-GIC code wasn't increased. |
- The bootstub has been completely rewritten taking advantage of the Thumb-2 instruction set, which results in major space gains - Res0 bits of NSACR are no longer set (supersedes #85) - CNTVOFF is set to zero, now consistent with armstub8 (supersedes #113) - SMC instructions are now disabled, now consistent with armstub8 - ACTLR is now configured to allow Non-secure access to several CPU configuration registers (CPUACTLR/CPUECTLR/L2CTLR/L2ECTLR/L2ACTLR), which makes it possible to e.g. enable Spectre v4 mitigations directly in the kernel without needing a separate bootstub variant (potentially supersedes #115) Free space in each affected bootstub after this commit: armstub7.bin: 108 bytes armstub8-32.bin: 104 bytes armstub8-32-gic.bin: 44 bytes (!)
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This fix was included in #117 |
See: raspberrypi/linux#3579 (comment)
Ping @lategoodbye - is this what was wanted?