I have a side question related to the same code. Currently __STACK_LIMIT is constant, but I would like the preamble to verify stack overflow for multithreaded context, i.e. __STACK_LIMIT will depend on the current running thread. Is there any reason, why it's not a function? Any objections if I do some refactoring and make it a function? For a simple case that could be a weak symbol that returns a constant.
On Tue, Apr 22, 2014 at 9:00 AM, Alex Crichton <a...@crichton.co> wrote: > I agree with Corey, it's much better to send it upstream first. I'd be > more than willing to help you out with writing tests or taking a peek > at the patch if you want! I'm acrichto on IRC > > On Tue, Apr 22, 2014 at 12:43 AM, Vladimir Pouzanov <farcal...@gmail.com> > wrote: > > The problem is that mrc is generated unless target is thumb1, but > cortex-m3 > > is thumb2 that still doesn't support mrc: > > > http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka398.html > , > > so an additional check to ST->TargetTriple.Data is required to verify > it's > > not thumbv7m. > > > > Do I need to submit patch against https://github.com/rust-lang/llvm or > send > > it to upstream? > > > > > > On Mon, Apr 21, 2014 at 6:34 PM, Vladimir Pouzanov <farcal...@gmail.com> > > wrote: > >> > >> Hm, it seems to have precautions to stop mrc from materializing on > Thumb1. > >> I guess I need to take a better look into what's going wrong on my side. > >> I'll see what I can do with that. > >> > >> > >> On Mon, Apr 21, 2014 at 5:23 PM, Alex Crichton <a...@crichton.co> > wrote: > >>> > >>> The split stack patches for ARM were recently upstreamed, and they > >>> were modified when being upstreamed as well. Primarily the location of > >>> the split stack is no longer at a magic address for thumb, but rather > >>> it uses the same instruction as ARM (some thumb processors do indeed > >>> have the coprocessor). More information is in the long thread starting > >>> at the initial attempt to upstream [1]. > >>> > >>> For now you'll have to use no_split_stack because the thumb split > >>> stack will always use a coprocessor, but I'm sure that the upstream > >>> LLVM devs would be quite welcoming to tweaks to the slit-stack support > >>> (I'd also be willing to help). You can find the initial commit for > >>> support at rust-lang/llvm [2]. > >>> > >>> [1] - > >>> > http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140224/205968.html > >>> [2] - https://github.com/rust-lang/llvm/pull/4 > >>> > >>> On Mon, Apr 21, 2014 at 6:50 AM, Vladimir Pouzanov < > farcal...@gmail.com> > >>> wrote: > >>> > Starting recently (no more than two weeks), rustc is generating a > >>> > broken > >>> > prologue for arm. Here's the sample assembly: > >>> > 0x00000f44 <+0>: push {r4, r5} > >>> > => 0x00000f46 <+2>: mrc 15, 0, r4, cr13, cr0, {3} > >>> > 0x00000f4a <+6>: mov r5, sp > >>> > 0x00000f4c <+8>: b.n 0xa78 <main+2616> > >>> > 0x00000f4e <+10>: ands r4, r0 > >>> > 0x00000f50 <+12>: cmp r4, r5 > >>> > 0x00000f52 <+14>: bcc.n 0xf66 > >>> > > >>> > > <_ZN7drivers3lcd6c1233244C12332$LT$$x27a$C$$x20S$C$$x20T$GT$.lcd..LCD5flush20h76589116290686712394v0.0E+34> > >>> > 0x00000f54 <+16>: movs r4, #16 > >>> > 0x00000f56 <+18>: movs r5, #0 > >>> > 0x00000f58 <+20>: push {lr} > >>> > 0x00000f5a <+22>: bl 0x19d8 <__morestack> > >>> > 0x00000f5e <+26>: ldr.w lr, [sp], #4 > >>> > 0x00000f62 <+30>: pop {r4, r5} > >>> > 0x00000f64 <+32>: bx lr > >>> > > >>> > The problem is at 0x00000f46, where code tries to read from > coprocessor > >>> > 15 > >>> > register 13, which is "process id register". Well, coprocessor 15 > >>> > (actually, > >>> > all of the coprocessors) are missing from my target > thumbv7m-linux-eabi > >>> > (with added flavour of -Ctarget-cpu=cortex-m3, which should be > >>> > redundant > >>> > anyway), so I'm getting hardfaults in every function that rust > doesn't > >>> > inline. > >>> > > >>> > Any ideas on what might be going wrong? I assume that this is > actually > >>> > llvm's fault, as llvm should not materialize machine code which is > not > >>> > available for target anyway. > >>> > > >>> > Wrapping everything in #[no_split_stack] is a temporary workaround > and > >>> > surely not a long-term strategy. > >>> > > >>> > -- > >>> > Sincerely, > >>> > Vladimir "Farcaller" Pouzanov > >>> > http://farcaller.net/ > >>> > > >>> > _______________________________________________ > >>> > Rust-dev mailing list > >>> > Rust-dev@mozilla.org > >>> > https://mail.mozilla.org/listinfo/rust-dev > >>> > > >> > >> > >> > >> > >> -- > >> Sincerely, > >> Vladimir "Farcaller" Pouzanov > >> http://farcaller.net/ > > > > > > > > > > -- > > Sincerely, > > Vladimir "Farcaller" Pouzanov > > http://farcaller.net/ > -- Sincerely, Vladimir "Farcaller" Pouzanov http://farcaller.net/
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