Messages in this thread Patch in this message | | | Date | Fri, 5 Nov 2021 21:26:08 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 07/22] x86,extable: Extend extable functionality |
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On Fri, Nov 05, 2021 at 09:15:57PM +0100, Peter Zijlstra wrote:
> That's really unfortunate that is... 6.4.4.1 item 5 of the C99 spec > covers this gem :-( I suppose I'll go stick that (int) cast in the > EX_IMM_MASK definition or something.
--- a/arch/x86/include/asm/extable_fixup_types.h +++ b/arch/x86/include/asm/extable_fixup_types.h @@ -2,10 +2,15 @@ #ifndef _ASM_X86_EXTABLE_FIXUP_TYPES_H #define _ASM_X86_EXTABLE_FIXUP_TYPES_H +/* + * Our IMM is signed, as such it must live at the top end of the word. Also, + * since C99 hex constants are of ambigious type, force cast the mask to 'int' + * so that FIELD_GET() will DTRT and sign extend the value when it extracts it. + */ #define EX_DATA_TYPE_MASK 0x000000FF #define EX_DATA_REG_MASK 0x00000F00 #define EX_DATA_FLAG_MASK 0x0000F000 -#define EX_DATA_IMM_MASK 0xFFFF0000 +#define EX_DATA_IMM_MASK ((int)0xFFFF0000) #define EX_DATA_REG_SHIFT 8 #define EX_DATA_FLAG_SHIFT 12
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