Sometimes, R_RISCV_CHERIOT_COMPARTMENT_HI relocations are broken during compartment linking #108
Description
Building this example fails, specifically in linking the firmware image with all of the demo code in the same compartment.
Specifically, in the set_secret function, prior to linking the compartment (in secret.cc.o), we see this:
00000022 <.LBB0_4>:
22: 17 05 00 00 auipcc ca0, 0
00000022: R_RISCV_CHERIOT_COMPARTMENT_HI template parameter object for (anonymous namespace)::DebugContext<23u>{char [23]{(char)74, (char)97, (char)118, (char)97, (char)83, (char)99, (char)114, (char)105, (char)112, (char)116, (char)32, (char)99, (char)111, (char)109, (char)112, (char)97, (char)114, (char)116, (char)109, (char)101, (char)110, (char)116}}
00000022: R_RISCV_RELAX *ABS*
26: 5b 15 05 00 cincoffset ca0, ca0, 0
00000026: R_RISCV_CHERIOT_COMPARTMENT_LO_I .LBB0_4
00000026: R_RISCV_RELAX *ABS*
2a: 5b 25 05 00 csetbounds ca0, ca0, 0
0000002a: R_RISCV_CHERIOT_COMPARTMENT_SIZE template parameter object for (anonymous namespace)::DebugContext<23u>{char [23]{(char)74, (char)97, (char)118, (char)97, (char)83, (char)99, (char)114, (char)105, (char)112, (char)116, (char)32, (char)99, (char)111, (char)109, (char)112, (char)97, (char)114, (char)116, (char)109, (char)101, (char)110, (char)116}}
But in the insecure_js.compartment file, we see this:
000013ac <.LBB0_4>:
; .LBB0_4():
; debug_log_message_write(
13ac: 17 05 00 00 auipcc ca0, 0
000013ac: R_RISCV_CHERIOT_COMPARTMENT_HI *ABS*
000013ac: R_RISCV_RELAX *ABS*
13b0: 5b 15 05 00 cincoffset ca0, ca0, 0
000013b0: R_RISCV_CHERIOT_COMPARTMENT_LO_I .LBB0_4
000013b0: R_RISCV_RELAX *ABS*
13b4: 5b 25 05 00 csetbounds ca0, ca0, 0
000013b4: R_RISCV_CHERIOT_COMPARTMENT_SIZE *ABS*
Note that the R_RISCV_CHERIOT_COMPARTMENT_HI relocation has been replaced. I have a couple of guesses about why this may happen, both may be wrong:
- Something in GC is deleting the string from the template parameter and so the relocation becomes dangling.
- The linker is determining that the string is <4 KiB away and so processing the relocation.
Unfortunately, RISC-V relocations that use AUIPC expect to find the address of the symbol when via the HI reloc when processing the LO one (so the reloc on the cincoffset is pointing at .LBB0_4 to find the symbol in the reloc for that instruction).