Messages in this thread | | | Date | Wed, 22 Jul 2015 09:30:59 -0400 | From | David Long <> | Subject | Re: [PATCH 1/2] Move the pt_regs_offset struct definition from arch to common include file |
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On 07/22/15 01:11, Michael Ellerman wrote: > On Wed, 2015-07-22 at 00:46 -0400, David Long wrote: >> On 06/29/15 23:29, Michael Ellerman wrote: >>> On Wed, 2015-06-17 at 14:30 -0400, David Long wrote: >>>> On 06/16/15 09:17, Rob Herring wrote: >>>>> On Mon, Jun 15, 2015 at 11:42 AM, David Long <dave.long@linaro.org> wrote: >>>>>> >>>>>> #define REG_OFFSET_NAME(r) \ >>>>>> {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)} >>>>>> #define REG_OFFSET_END {.name = NULL, .offset = 0} >>>>> >>>>> Can't you also move these? ARM is complicated with the "ARM_" >>>>> prefixing, but the others appear to be the same. Maybe you can remove >>>>> the prefix or redefine the macro for ARM. >>>> >>>> That would mandate that all the architecture-specific pt_regs structures >>>> would have to use a top-level named field for each named register. >>> >>> Why does it mandate that? >>> >>> See eg. powerpc where we use REG_OFFSET_NAME for the top-level named fields and >>> then a different macro for the array elements: >>> >>> #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)} >>> #define GPR_OFFSET_NAME(num) \ >>> {.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])} >>> >>> static const struct pt_regs_offset regoffset_table[] = { >>> GPR_OFFSET_NAME(0), >>> GPR_OFFSET_NAME(1), >>> GPR_OFFSET_NAME(2), >>> GPR_OFFSET_NAME(3), >>> ... >>> REG_OFFSET_NAME(nip), >>> REG_OFFSET_NAME(msr), >>> >>> >>> So I don't see why REG_OFFSET_NAME couldn't be common. >>> >> >> Sorry for the delay in responding to this. >> >> OK, so you're saying architectures that don't want this constraint can >> make their own macro. Seems to make this whole exercise slightly less >> useful, but whatever. > > Well yeah. > > In fact of the 4 arches that use REG_OFFSET_NAME, 2 already have another macro > for specially named registers (powerpc & sh). > >> I see three ways to go here: >> >> 1) Leave it as is. >> 2) Force all architectures to use a common definition. >> 3) Provide a common definition that all architectures (except "arm") >> currently using this functionality will use. >> >> I have a v2 patch to implement #3, ready to post. Do we think this is >> the way to go? > > Yeah I think it is. How are you making it conditional? Just #ifndef REG_OFFSET_NAME? >
I'm just defining a new macro for arm. The macro is only invoked in one arm file. Then the REG_OFFSET_NAME macro goes unused for this architecture.
>> I don't like #2 because I really don't want to rename all >> uses of the current register fields for arm since this is >> architecture-specific code to begin with and since it affects code in 39 >> arm source files. > > I guess you're talking about renaming all the ARM_x regs to x. That would > likely cause problems because they're implemented as #defines, > eg. #define r0 uregs[0] would probably confuse your assembler. >
Yeah, and I had not looked further to the implications of doing that but I see you've found where it is a genuine problem.
> The clean thing to do would be to have the in-kernel struct pt_regs have actual > named members, but that would still be an intrusive change. > > cheers > >
Thanks, -dl
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