[DTrace probe] is there a [portable] way to add section to elf executable?

[welkam]

On Wednesday, 23 October 2019 at 15:24:13 UTC, drug wrote:
> I'd like to add (and modify) section to ELF executable to 
> implement DTrace probes. DTrace does it in probe assembly:
> ```
> __asm__ __volatile__ (
> 	"990: nop
> 	.pushsection .note.stapsdt,\"?\",\"note\"
> 	.balign 4
> 	.4byte 992f-991f, 994f-993f, 3
> 	991: .asciz \"stapsdt\"
> 	992: .balign 4
> 	993: .8byte 990b
> 	.8byte _.stapsdt.base
> 	.8byte 0
> 	.asciz \"myapp\"
> 	.asciz \"func_call\"
> 	.asciz \"%n[_SDT_S1]@%[_SDT_A1] %n[_SDT_S2]@%[_SDT_A2]\"
> 	994: .balign 4
> 	.popsection"
> 	:: [_SDT_S1] "n" (SNIPPED_ONE),
> 	   [_SDT_A1] "nor" ((a)),
> 	   [_SDT_S2] "n" (SNIPPED_TWO),
> 	   [_SDT_A2] "nor" ((b))
> );
> ```
>
> So I need a way to add no op operation and define some data in 
> `.note.stapsdt` section. This page 
> https://dlang.org/spec/iasm.html does not contain any 
> information about sections

I hope you are not mixing up D SCRIPTING language that is used by 
Dtrace and D PROGRAMMING language.

Second thing is that ELF format is used by Linux and other 
operating systems use different executable formats (mach-0 for 
macOs and PE for windows). So by definition its not portable.

D's inline asm does not provide a way to modify *.obj files. It 
just insert your asm at that place.