Relocations in .text on arm #16369
Description
It looks like AOT compiler produces shared libraries on XA/arm, which contains relocations in .text section.
Discussed it with @vargaz on slack and he thinks it was introduced recently by 9ff3b0d65ee4
I have tried older XA d16.1 and it indeed didn't contain relocations in .text, while current XA with mono-2019-06 does.
d16.1:
arm-linux-androideabi-readelf -a /Users/rodo/git/monodroid-samples/android5.0/Topeka/Topeka/obj/Release/aot/armeabi-v7a/libaot-Topeka.dll.so |grep TEXT
Relevant part of source
.text 1
.align 3
method_addresses:
.local method_addresses
.type method_addresses,#function
bl .Lm_0
bl .Lm_1
bl .Lm_2
...
No relocations in .text:
Section Headers:
...
[ 5] .text PROGBITS 00000240 000240 022a30 00 AX 0 0 16
...
Relocation section '.rel.dyn' at offset 0x178 contains 24 entries:
Offset Info Type Sym.Value Sym. Name
00024008 00000017 R_ARM_RELATIVE
0002401c 00000017 R_ARM_RELATIVE
00024020 00000017 R_ARM_RELATIVE
00024024 00000017 R_ARM_RELATIVE
00024028 00000017 R_ARM_RELATIVE
0002402c 00000017 R_ARM_RELATIVE
00024030 00000017 R_ARM_RELATIVE
00024034 00000017 R_ARM_RELATIVE
00024038 00000017 R_ARM_RELATIVE
0002403c 00000017 R_ARM_RELATIVE
00024040 00000017 R_ARM_RELATIVE
00024044 00000017 R_ARM_RELATIVE
0002404c 00000017 R_ARM_RELATIVE
00024050 00000017 R_ARM_RELATIVE
00024054 00000017 R_ARM_RELATIVE
00024058 00000017 R_ARM_RELATIVE
0002405c 00000017 R_ARM_RELATIVE
0002407c 00000017 R_ARM_RELATIVE
00024080 00000017 R_ARM_RELATIVE
00024084 00000017 R_ARM_RELATIVE
00024088 00000017 R_ARM_RELATIVE
0002408c 00000017 R_ARM_RELATIVE
00024090 00000017 R_ARM_RELATIVE
00024094 00000017 R_ARM_RELATIVE
master (which uses mono-2019-06):
arm-linux-androideabi-readelf -a /Users/rodo/git/monodroid-samples/android5.0/Topeka/Topeka/obj/Release-master/aot/armeabi-v7a/libaot-Topeka.dll.so |grep TEXT
0x00000016 (TEXTREL) 0x0
0x0000001e (FLAGS) TEXTREL
Relevant part of source:
.text 1
.align 3
method_addresses:
.local method_addresses
.type method_addresses,#function
ldr pc,=.Lm_0
.ltorg
ldr pc,=.Lm_1
.ltorg
ldr pc,=.Lm_2
Relocations in .text
Section Headers:
...
[ 5] .text PROGBITS 00001580 001580 022e78 00 AX 0 0 16
...
Relocation section '.rel.dyn' at offset 0x178 contains 640 entries:
Offset Info Type Sym.Value Sym. Name
00020fe4 00000017 R_ARM_RELATIVE
00020fec 00000017 R_ARM_RELATIVE
00020ff4 00000017 R_ARM_RELATIVE
00020ffc 00000017 R_ARM_RELATIVE
...
This probably affects the performance and will potentially cause problems on Android as the shared libs should not contain .text relocations on API >= 23. (https://android-developers.googleblog.com/2016/06/android-changes-for-ndk-developers.html)