Messages in this thread | | | Date | Mon, 22 Nov 2021 16:17:56 +0000 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH] ARM: ptrace: Use bitfield helpers |
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On Mon, Nov 22, 2021 at 04:53:41PM +0100, Geert Uytterhoeven wrote: > The isa_mode() macro extracts two fields, and recombines them into a > single value. The shift value of the J-bit may look off-by-one to the > casual reader, as it is the net result of the extraction and > recombination steps.
I'd recommend avoiding the suggestion that the explicit "- 1" could be misinterpreted as an off-by-one error.
> #define isa_mode(regs) \ > - ((((regs)->ARM_cpsr & PSR_J_BIT) >> (__ffs(PSR_J_BIT) - 1)) | \ > - (((regs)->ARM_cpsr & PSR_T_BIT) >> (__ffs(PSR_T_BIT)))) > + ((FIELD_GET(PSR_J_BIT, (regs)->ARM_cpsr) << 1) | \
I'd suggest getting rid of the extra unnecessary parens there. Too many parens leads to a decrease in readability.
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