Re: [PATCH v3 0/9] RISC-V: Implement TLS Descriptors.

[Fangrui Song <i@maskray.me>]

On Tue, Dec 5, 2023 at 4:33 PM Nelson Chu <nelson@rivosinc.com> wrote:
>
> Sorry that I don't familiar with the TLS stuff and TLS descriptor, so I will need more time to figure these out if other maintainers are all busy.  Since there are other patches which are also being reviewed, if someone thinks this is an urgent matter, please feel free to let us know, so we can switch to see these first.

I know that Android wants TLSDESC and having TLSDESC in gcc/binutils
helps check LLVM feature parity...
If we have TLSDESC earlier, an OS with a new RISC-V port can make
TLSDESC part of the baseline ABI...

> On Wed, Dec 6, 2023 at 12:44 AM Tatsuyuki Ishi <ishitatsuyuki@gmail.com> wrote:
>>
>> > On Nov 28, 2023, at 17:51, Tatsuyuki Ishi <ishitatsuyuki@gmail.com> wrote:
>> >
>> > This patchset implements TLS Descriptors (TLSDESC) for RISC-V targets, per
>> > the specification (merged) at [1].
>> >
>> > Tested on rv64gc for:
>> > - No regression (& passing new tests) in binutils
>> > - No regression in gcc
>> > - No regression in glibc for subdirs=elf
>> > With both -mtls-dialect=desc and trad.
>> >
>> > This contribution is made on behalf of Blue Whale Systems, which has
>> > copyright assignment on file with the FSF.
>> >
>> > [1]: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/373
>> >
>> > v2: Add changelogs and tests. Minor fixes described in patch messages.
>> > v3: Add relaxation support. This fixes tst-tls1-static in glibc.
>>
>> Would anyone like to review this?  This is a prerequisite for the GCC-side
>> implementation to be useful (especially the gas part).
>
>
>  For these huge features, gcc/binutils/glibc should be reviewed at the same time, since all the stuff should be bound and tested together, so "prerequisite" shouldn't apply here ;)
>
> Thanks
> Nelson

Agreed. I wonder whether Wei can find someone to test
gcc/binutils/glibc patches... and some packages using TLS (e.g.
https://codesearch.debian.net/search?q=__thread&literal=1).

>>
>>
>> I can split up the series into bug fix / refactors and actual changes if
>> desired.
>>
>> > Tatsuyuki Ishi (9):
>> >  RISC-V: Fix local GOT and reloc size calculation for TLS.
>> >  RISC-V: Add TLSDESC reloc definitions.
>> >  RISC-V: Add assembly support for TLSDESC.
>> >  RISC-V: Define and use GOT entry size constants for TLS.
>> >  RISC-V: Initial ld.bfd support for TLSDESC.
>> >  RISC-V: Move STATIC_TLS handling into record_tls_type.
>> >  RISC-V: Unify TLS handling in check_relocs.
>> >  RISC-V: Add elf_link_hash_entry to relax_func args.
>> >  RISC-V: Introduce TLSDESC relaxation.
>> >
>> > bfd/bfd-in2.h                              |   4 +
>> > bfd/elfnn-riscv.c                          | 341 ++++++++++++++++++---
>> > bfd/elfxx-riscv.c                          | 130 +++++++-
>> > bfd/libbfd.h                               |   4 +
>> > bfd/reloc.c                                |   8 +
>> > gas/config/tc-riscv.c                      |  18 +-
>> > gas/testsuite/gas/riscv/tlsdesc.d          |  22 ++
>> > gas/testsuite/gas/riscv/tlsdesc.s          |  24 ++
>> > include/elf/riscv.h                        |  21 +-
>> > include/opcode/riscv.h                     |   1 +
>> > ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp |   8 +
>> > ld/testsuite/ld-riscv-elf/tls.d            |  17 +
>> > ld/testsuite/ld-riscv-elf/tls.s            |  42 +++
>> > ld/testsuite/ld-riscv-elf/tlsbin.d         |   7 +
>> > ld/testsuite/ld-riscv-elf/tlslib.s         |   6 +
>> > opcodes/riscv-opc.c                        |   1 +
>> > 16 files changed, 601 insertions(+), 53 deletions(-)
>> > create mode 100644 gas/testsuite/gas/riscv/tlsdesc.d
>> > create mode 100644 gas/testsuite/gas/riscv/tlsdesc.s
>> > create mode 100644 ld/testsuite/ld-riscv-elf/tls.d
>> > create mode 100644 ld/testsuite/ld-riscv-elf/tls.s
>> > create mode 100644 ld/testsuite/ld-riscv-elf/tlsbin.d
>> > create mode 100644 ld/testsuite/ld-riscv-elf/tlslib.s
>> >
>> > --
>> > 2.43.0
>> >
>>