PING: [PATCH v8 0/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers

[H.J. Lu]

On Fri, Feb 16, 2024 at 7:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Changes in v8:
>
> 1. Remove malloc-for-test.c and move malloc to tst-gnu2-tls2.c.
> 2. Add malloc_counter to verify malloc in tst-gnu2-tls2.c is called for
> TLSDESC call.
> 3. Add BEFORE_TLSDESC_CALL and AFTER_TLSDESC_CALL.
> 4. Use /* ... */ in assembly code comments.
>
> Changes in v7:
>
> 1. Generate malloc-for-test.map at build time to get the correct version
> map for malloc.
>
> Changes in v6:
>
> 1. Drop Tile registers.
>
> Changes in v5:
>
> 1. Also preserve Tile registers.
> 2. Add an error check in i386 dl-tlsdesc-dynamic.h.
>
> Changes in v4:
>
> 1.  Add APX registers to STATE_SAVE_MASK so that APX registers are saved
> in ld.so trampoline.
> 2. Also save x87 FPU stack registers for TLSDESC_CALL and TLS_DESC_CALL.
> 3. Change i386 _dl_tlsdesc_dynamic to IFUNC.
> 4. Rename GLRO(dl_x86_64_tlsdesc_dynamic) to GLRO(dl_x86_tlsdesc_dynamic)
> for both i386 and x86-64.
> 5. Update the testcase for i386 with a simple malloc interceptor.
>
> Changes in v3:
>
> 1. Don't add GLRO(dl_x86_64_tlsdesc_dynamic) to libc.a.
>
> Changes in v2:
>
> 1.  Add GLRO(dl_x86_64_runtime_resolve) to optimize
> elf_machine_runtime_setup.
> ---
> Add APX registers to STATE_SAVE_MASK so that APX registers are saved in
> ld.so trampoline.  This fixes BZ #31371.
>
> Compiler generates the following instruction sequence for GNU2 dynamic
> TLS access:
>
>         leaq    tls_var@TLSDESC(%rip), %rax
>         call    *tls_var@TLSCALL(%rax)
>
> or
>
>         leal    tls_var@TLSDESC(%ebx), %eax
>         call    *tls_var@TLSCALL(%eax)
>
> CALL instruction is transparent to compiler which assumes all registers,
> except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> path.  __tls_get_addr is a normal function which doesn't preserve any
> caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> caller-saved registers, but didn't preserve any other caller-saved
> registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> fixes BZ #31372.
>
> Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> to optimize elf_machine_runtime_setup.
>
> H.J. Lu (2):
>   x86-64: Save APX registers in ld.so trampoline
>   x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers
>
>  elf/Makefile                                 |  14 ++
>  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
>  elf/tst-gnu2-tls2.h                          |  36 ++++
>  elf/tst-gnu2-tls2mod0.c                      |  31 +++
>  elf/tst-gnu2-tls2mod1.c                      |  31 +++
>  elf/tst-gnu2-tls2mod2.c                      |  31 +++
>  sysdeps/i386/dl-machine.h                    |   2 +-
>  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
>  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
>  sysdeps/x86/Makefile                         |   7 +-
>  sysdeps/x86/cpu-features.c                   |  56 +++++-
>  sysdeps/x86/dl-procinfo.c                    |  16 ++
>  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
>  sysdeps/x86/sysdep.h                         |  56 +++++-
>  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
>  sysdeps/x86_64/Makefile                      |   2 +-
>  sysdeps/x86_64/dl-machine.h                  |  19 +-
>  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
>  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
>  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
>  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
>  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
>  sysdeps/x86_64/dl-trampoline.S               |  20 +-
>  sysdeps/x86_64/dl-trampoline.h               |  34 +---
>  24 files changed, 959 insertions(+), 218 deletions(-)
>  create mode 100644 elf/tst-gnu2-tls2.c
>  create mode 100644 elf/tst-gnu2-tls2.h
>  create mode 100644 elf/tst-gnu2-tls2mod0.c
>  create mode 100644 elf/tst-gnu2-tls2mod1.c
>  create mode 100644 elf/tst-gnu2-tls2mod2.c
>  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
>  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
>  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
>  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
>
> --
> 2.43.0
>

PING.

-- 
H.J.