On Wed, 2015-07-22 at 00:46 -0400, David Long wrote:

On 06/29/15 23:29, Michael Ellerman wrote:

quoted

On Wed, 2015-06-17 at 14:30 -0400, David Long wrote:

quoted

On 06/16/15 09:17, Rob Herring wrote:

quoted

On Mon, Jun 15, 2015 at 11:42 AM, David Long [off-list ref] wrote:

quoted

   #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 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.

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