Messages in this thread | | | Subject | Re: [patch 15/14] x86/dumpstack/64: Speedup in_exception_stack() | From | Andy Lutomirski <> | Date | Tue, 2 Apr 2019 10:11:19 -0600 |
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> On Apr 2, 2019, at 9:48 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > >> On Tue, 2 Apr 2019, Josh Poimboeuf wrote: >>> On Tue, Apr 02, 2019 at 12:19:46PM +0200, Thomas Gleixner wrote: >>> +/* >>> + * Array of exception stack page descriptors. If the stack is larger than >>> + * PAGE_SIZE, all pages covering a particular stack will have the same >>> + * info. >>> + */ >>> +static const struct estack_pages estack_pages[ESTACK_PAGES] ____cacheline_aligned = { >>> + [CONDRANGE(DF)] = ESTACK_PAGE(DOUBLEFAULT_IST, DF), >>> + [CONDRANGE(NMI)] = ESTACK_PAGE(NMI_IST, NMI), >>> + [PAGERANGE(DB)] = ESTACK_PAGE(DEBUG_IST, DB), >>> + [CONDRANGE(MCE)] = ESTACK_PAGE(MCE_IST, MCE), >> >> It would be nice if the *_IST macro naming aligned with the struct >> cea_exception_stacks field naming. Then you could just do, e.g. >> ESTACKPAGE(DF). > > Yes, lemme fix that up. > >> Also it's a bit unfortunate that some of the stack size knowledge is >> hard-coded here, i.e #DB always being > 1 page and non-#DB being >> sometimes 1 page. > > The problem is that there is no way to make this macro maze conditional on > sizeof(). But my macro foo is rusty.
How about a much better fix: make the DB stack be the same size as all the others and just have 4 of them (DB0, DB1, DB2, and DB3. After all, overflowing from one debug stack into another is just as much of a bug as overflowing into a different IST stack.
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