linker: update section names to be unambiguous

[fabiobaltieri]

Recently 0ae0c3d allowed for three digit priorities, this resulted in objects potentially matching multiple sections, for example:

.z_init_PRE_KERNEL_2_0_0_
.z_init_PRE_KERNEL_2_?_*
.z_init_PRE_KERNEL_2_???_*

This does not seem to be detected by ld, but the IAR linker emits a warning.

Add some extra qualifiers in the object section name to make it unambiguous, this has the extra value of making it easier to interpret, for example going from:

.z_init_POST_KERNEL_90_00012_

to

.z_init_POST_KERNEL_P_90_SUB_00012_

[fabiobaltieri]

cc @dewitt-garmin @GoranWall, would this fix the issue detected in #86999 (comment)?

[RobinKastberg]

@fabiobaltieri the IAR linker doesn't complain with this.

[dewitt-garmin]

Good catch. Another option might be to use a character class, [0-9], instead of ?

[fabiobaltieri]

Good catch. Another option might be to use a character class, [0-9], instead of ?

Interesting, did not realize the linker supported it, not sure why that hasn't been used in the first place but I feel like it may not be supported by some old release or something like that, though it's used in include/zephyr/linker/common-rom/common-rom-kernel-devices.ld so I think it should work?

I think it's worth a try, but maybe let's merge this now to remove the ambiguity issue and consider that for a followup, and then we can revert it separately if something breaks.

I like the new symbols names anyway, makes them way more understandable.

[fabiobaltieri]

Tagging has hotfix, strictly speaking it does not break the CI, but one may argue that it should.

[pdgendt]

Good catch. Another option might be to use a character class, [0-9], instead of ?

Interesting, did not realize the linker supported it, not sure why that hasn't been used in the first place but I feel like it may not be supported by some old release or something like that, though it's used in include/zephyr/linker/common-rom/common-rom-kernel-devices.ld so I think it should work?

There were issues with using [0-9] as this wasn't supported by all tools in the field.

[fabiobaltieri]

There were issues with using [0-9] as this wasn't supported by all tools in the field.

@pdgendt it's used in here though:

zephyr/include/zephyr/linker/common-rom/common-rom-kernel-devices.ld

Line 70 in d19abff

KEEP(*(SORT(.z_init_[_A-Z0-9]*)))

Do you happen to remember the specific issue?

[dewitt-garmin]

Good catch. Another option might be to use a character class, [0-9], instead of ?

Interesting, did not realize the linker supported it, not sure why that hasn't been used in the first place but I feel like it may not be supported by some old release or something like that, though it's used in include/zephyr/linker/common-rom/common-rom-kernel-devices.ld so I think it should work?

There were issues with using [0-9] as this wasn't supported by all tools in the field.

Do you know what tools could not support this? I just tried [0-9] and all of the ones that twister builds seemed to pass but as we have just seen that apparently is not sufficient. Maybe IAR is also the limitation here?

[RobinKastberg]

Yeah.. These linker wildcards are NOT regexps, even though it seems ld supports a little bit more than we (IAR do)
This is IAR documentation:
From https://wwwfiles.iar.com/arm/webic/doc/EWARM_DevelopmentGuide.ENU.pdf

section section-name Only sections whose names match the section-name
                     will be selected. Two wildcards are allowed: 
                     ? matches any single character
                     * matches zero or more characters

Note: A section selector with narrower scope has higher priority than a more generic 
section selector. If more than one section selector matches for the same purpose, one of 
them must be more specific. A section selector is more specific than another one if in 
priority order:
* It specifies a public symbol name with no wildcards and the other one does not.
* It specifies a section name or object name with no wildcards and the other one does 
not
* It specifies a section type and the other one does not
* There could be sections that match the other selector that also match this one, 
however, the reverse is not true.

[LoveKarlsson]

There were issues with using [0-9] as this wasn't supported by all tools in the field.

@pdgendt it's used in here though:

zephyr/include/zephyr/linker/common-rom/common-rom-kernel-devices.ld

Line 70 in d19abff

KEEP(*(SORT(.z_init_[_A-Z0-9]*)))

Do you happen to remember the specific issue?

I have a PR to remove that regular expression, as the IAR linker does not support regular expressions.

#87112