Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 21 May 2015 17:38:02 -0700 | Subject | Re: [PATCH] x86: Stop relying on magic jmp behavior for early_idt_handlers |
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On Thu, May 21, 2015 at 5:32 PM, H. Peter Anvin <hpa@zytor.com> wrote: > On 05/21/2015 05:17 PM, Andy Lutomirski wrote: >> >> diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h >> index 5a9856eb12ba..4bbe0eb24d7e 100644 >> --- a/arch/x86/include/asm/segment.h >> +++ b/arch/x86/include/asm/segment.h >> @@ -231,12 +231,21 @@ >> #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) >> >> #ifdef __KERNEL__ >> -#ifndef __ASSEMBLY__ >> >> -extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5]; >> +/* >> + * early_idt_handlers is an array of entry points. For simplicity, it's >> + * a real array. We allocate nine bytes for each entry: two one-byte >> + * push instructions and a five-byte jump in the worst case. >> + */ >> +#define EARLY_IDT_HANDLER_STRIDE 9 >> +#ifndef __ASSEMBLY__ >> +extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_STRIDE]; >> #ifdef CONFIG_TRACING >> # define trace_early_idt_handlers early_idt_handlers >> #endif >> +#endif >> + >> +#ifndef __ASSEMBLY__ >> > > Please get rid of the unnecessary #ifndef/#endif pair.
I did it to preserve logical nesting. I didn't want the pile of early_idt_handlers declarations and comments to have the side affect of starting an #ifdef block.
If you still think I should change it, I'll change it.
> >> +/* Build the early_idt_handlers array */ >> __INIT >> .globl early_idt_handlers > > Let's use ENTRY(early_idt_handlers) for consistency.
Will do.
--Andy
> > Otherwise it looks good. I like the use of .fill better than moving ., > it seems more robust to me. > > Conditionally-Acked-by: H. Peter Anvin <hpa@linux.intel.com> >
-- Andy Lutomirski AMA Capital Management, LLC
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