cmd/compile,runtime: race support for riscv64

mauri870 commented 1 year ago

There was a previous issue requesting support for riscv64 (https://github.com/golang/go/issues/58739), but it was closed because upstream support in LLVM was lacking.

On Oct 6 support for riscv64 was finally merged into the LLVM tree.

I propose we reconsider adding race detector support to Risc-V. From the top of my head this would require:

Update the compiler to recognize -race on linux/riscv64
clone llvm and compile a race_linux_riscv64.syso file, push the necessary changes upstream
linux-riscv64-race builder?
Add a new platform to x/build/cmd/racebuild to build syso files for riscv64
Add race instrumentation (race_riscv64.s) to runtime
Document support on https://go.dev/doc/articles/race_detector
freebsd/riscv64 support is possible in the future?

Happy to work on this for the early stage of Go 1.23.

cc @golang/runtime @golang/riscv64

mengzhuo commented 1 year ago

I can setup a linux-riscv64-race builder(LUCI) for you.

mauri870 commented 1 year ago

Thanks @mengzhuo, appreciate if you could handle that 🙏

mauri870 commented 12 months ago

@mengzhuo I tried compiling the syso file for riscv64 with CC=clang and got stuck in this part:

runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LBB438_37 (type=291 (R_RISCV_ADD32) stype=1 (STEXT))
runtime/race(.rodata): unexpected relocation type 295 (R_RISCV_SUB32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LJTI438_0 (type=295 (R_RISCV_SUB32) stype=9 (SRODATA))runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LBB438_169 (type=291 (R_RISCV_ADD32) stype=1 (STEXT))
runtime/race(.rodata): unexpected relocation type 295 (R_RISCV_SUB32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LJTI438_0 (type=295 (R_RISCV_SUB32) stype=9 (SRODATA))runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LBB438_169 (type=291 (R_RISCV_ADD32) stype=1 (STEXT))
runtime/race(.rodata): unexpected relocation type 295 (R_RISCV_SUB32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LJTI438_0 (type=295 (R_RISCV_SUB32) stype=9 (SRODATA))runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LBB438_169 (type=291 (R_RISCV_ADD32) stype=1 (STEXT))
runtime/race(.rodata): unexpected relocation type 295 (R_RISCV_SUB32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LJTI438_0 (type=295 (R_RISCV_SUB32) stype=9 (SRODATA))runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LBB438_169 (type=291 (R_RISCV_ADD32) stype=1 (STEXT))
runtime/race(.rodata): unexpected relocation type 295 (R_RISCV_SUB32)
runtime/race(.rodata): unsupported dynamic relocation for symbol .LJTI438_0 (type=295 (R_RISCV_SUB32) stype=9 (SRODATA))runtime/race(.rodata): unexpected relocation type 291 (R_RISCV_ADD32)
/home/ubuntu/git/go/pkg/tool/linux_riscv64/link: too many errors

Maybe I have to use some specific compiler flag? I see that these relocations are currently supported in the go linker

mengzhuo commented 10 months ago

CC @4a6f656c @mauri870 builder is up, I had same issue like yours.

4a6f656c commented 7 months ago

@mauri870 that looks like the riscv64 linker is missing handling for some relocation types - do you have a branch handy that I can build/test from?

mauri870 commented 7 months ago

@4a6f656c I have some changes in one of my branches, hopefully you can still build from it, if not then let me know:

https://github.com/golang/go/compare/master...mauri870:go:feature/race-riscv64?expand=1

Edit: If you wanna compile the syso file yourself, then you have to get a hold of a llvm copy and then cd compiler-rt/lib/tsan/go && CC=clang ./buildgo.sh

4a6f656c commented 6 months ago

@mauri870 I've added the missing relocation handling to the internal linker and fixed up some other aspects of the riscv64 race code:

https://github.com/4a6f656c/go/tree/riscv64-race

We can now call into the TSAN code, however it fails on the call to __tsan_map_shadow with:

==2568052==ERROR: ThreadSanitizer failed to allocate 0x1f10000 (32571392) bytes at address 200000660000 (errno: 12)

At a first guess, this looks like it is using the 48-bit VMA mapping even though it is running on a 39-bit VMA platform.

mauri870 commented 6 months ago

@4a6f656c Error 12 is ENOMEM, perhaps you are running out of memory on this machine?

https://github.com/torvalds/linux/blob/6f52b16c5b29b89d92c0e7236f4655dc8491ad70/include/uapi/asm-generic/errno-base.h#L16

Looking at the riscv64 tsan commit in llvm the 1000 0000 00 - 4000 0000 00 range seems to be correct for shadow memory on a 39-bit VMA.

golang / go

cmd/compile,runtime: race support for riscv64 #64345