Arm64 support

[amckinstry]

Hi Greg

I have a wishlist bug in Debian (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=871696) where someone would like arm64 support.
I see that it would require a port of src/cov_i386.C to src/cov_arm.C ; how much work do you think this would be? Any good sources you'd recommend on ISA details relevant to the problem?

Best regards
Alastair

[gnb]

G'day, Almost all of ggcov's functionality is processor independent. The code in cov_i386.C only supports the calltree feature, and ggcov is still useful without it. So I think it would be entirely sensible to disable that feature and unit test using some kind of autoconf magic on arm64 and declare ggcov "mostly" supported. If however you want to pursue a full port, and you have access to an arm64 development environment and hardware, then you should start by picking apart the assembler output from gcc -S test/test033/foo.c to see how the platform implements function calls between functions in the same object file, then tweak the scan_statics() code to look for that byte signature. I would expect that function calls between object files would still be detectable using relocs, same as i386.

On Wed, Aug 30, 2017 at 03:13 Alastair McKinstry ***@***.***> wrote: Hi Greg I have a wishlist bug in Debian ( https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=871696) where someone would like arm64 support. I see that it would require a port of src/cov_i386.C to src/cov_arm.C ; how much work do you think this would be? Any good sources you'd recommend on ISA details relevant to the problem? Best regards Alastair — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjCYG7AURKKQPiWv55vZj7cr78fiFZ4ks5sdTXcgaJpZM4PHKhp> .

-- Greg.

[amckinstry]

Hi Greg,

I've a patch working now on Debian to disable calltree (and test033) on non-x86 archs. It appears to work fine.
I'll upload to github ASAP.
Working on a full arm patch is a bit beyond the time i've got; a fair amount of research into Arm ISAs is needed.

Best regards
Alastair

[gnb]

Ok, cool.

…

On 18 September 2017 at 06:06, Alastair McKinstry ***@***.***> wrote: Hi Greg, I've a patch working now on Debian to disable calltree (and test033) on non-x86 archs. It appears to work fine. I'll upload to github ASAP. Working on a full arm patch is a bit beyond the time i've got; a fair amount of research into Arm ISAs is needed. Best regards Alastair — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjCYJnLbbOBirj6s6vSRFQ27zqYXY6Rks5sjmq6gaJpZM4PHKhp> .

-- Greg.

[gnb]

To clarify the scope: this ticket is for adding a new ARM64-specific subclass of cov_call_scanner_t which understands just enough about the ARM instruction set to be able to reliably extract callsites to fixed functions (i.e. not through function pointers) from an instruction stream in an ARM64 ELF+DWARF object file.