Messages in this thread | | | Date | Sun, 3 Aug 2008 23:24:21 -0400 | From | "Mike Frysinger" <> | Subject | Re: [PATCH 2/3] binfmt_elf_fdpic: Convert initial stack alignment to arch_align_stack(). |
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On Fri, Aug 1, 2008 at 5:44 PM, Paul Mundt wrote: > On Fri, Aug 01, 2008 at 03:01:19PM +0100, David Howells wrote: >> Paul Mundt <lethal@linux-sh.org> wrote: >> > + * In some cases (e.g. Hyper-Threading), we want to avoid L1 >> > + * evictions by the processes running on the same package. One >> > + * thing we can do is to shuffle the initial stack for them, so >> > + * we give the architecture an opportunity to do so here. >> > + */ >> > #ifdef CONFIG_MMU >> > - sp = bprm->p; >> > + sp = arch_align_stack(bprm->p); >> > #else >> > - sp = mm->start_stack; >> > + sp = arch_align_stack(mm->start_stack); >> >> Ummm... You're calling arch_align_stack() under NOMMU... Is that really a >> good idea? > > Not particularly, no. > >> You can't necessarily move the stack pointer without exiting the allocated >> region or shrinking the amount of stack space the executable asked for. If >> you want to do this sort of thing, you need to tell the memory allocator what >> you're up to - or at the very least allocate some slack. > > Yes, that's a good point, and one that probably ought to be documented > alongside the initial alignment. I'll send an updated patch.
fs/binfmt_elf_fdpic.c: In function 'create_elf_fdpic_tables': fs/binfmt_elf_fdpic.c:497: error: implicit declaration of function 'arch_align_stack' make[1]: *** [fs/binfmt_elf_fdpic.o] Error 1 make: *** [fs] Error 2
Blackfin lacks a arch_align_stack(x) in asm-blackfin/system.h ... i imagine a stub will work for us like every other arch though
feel like doing that Bryan ? i'm guessing Paul doesnt want to ... ;) -mike
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