Re: [PATCH] ld/ARM: Fix IFUNC and TLS descriptors in the same shared object

[Will Newton <will dot newton at linaro dot org>]

On 23 May 2014 15:13, Will Newton <will.newton@linaro.org> wrote:
> Combining TLS descriptors and GNU indirect functions in the same
> object could lead to assertions or multiple dynamic relocations
> for the same GOT slot. Fix the bookkeeping so this doesn't happen.
>
> This allows building and make checking glibc with -mtls-dialect=gnu2.
>
> bfd/ChangeLog:
>
> 2014-05-21  Will Newton  <will.newton@linaro.org>
>
>         * elf32-arm.c (elf32_arm_allocate_plt_entry): Increment
>         htab->next_tls_desc_index in the non-IPLT case.
>         Calculate GOT offset correctly for the non-IPLT case.
>         (allocate_dynrelocs_for_symbol): Don't increment
>         htab->next_tls_desc_index here.
>
> ld/testsuite/ChangeLog:
>
> 2014-05-21  Will Newton  <will.newton@linaro.org>
>
>         * ld-arm/arm-elf.exp: Add ifunc-gdesc test.
>         * ld-arm/ifunc-gdesc.r: New file.
>         * ld-arm/ifunc-gdesc.s: Likewise.
>         * ld-arm/ifunc-gdesc.ver: Likewise.
> ---
>  bfd/elf32-arm.c                     |  9 ++++++---
>  ld/testsuite/ld-arm/arm-elf.exp     |  3 +++
>  ld/testsuite/ld-arm/ifunc-gdesc.r   |  6 ++++++
>  ld/testsuite/ld-arm/ifunc-gdesc.s   | 29 +++++++++++++++++++++++++++++
>  ld/testsuite/ld-arm/ifunc-gdesc.ver |  4 ++++
>  5 files changed, 48 insertions(+), 3 deletions(-)
>  create mode 100644 ld/testsuite/ld-arm/ifunc-gdesc.r
>  create mode 100644 ld/testsuite/ld-arm/ifunc-gdesc.s
>  create mode 100644 ld/testsuite/ld-arm/ifunc-gdesc.ver

Ping?

> diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
> index 526d4f8..6a20baf 100644
> --- a/bfd/elf32-arm.c
> +++ b/bfd/elf32-arm.c
> @@ -7521,6 +7521,8 @@ elf32_arm_allocate_plt_entry (struct bfd_link_info *info,
>          first entry.  */
>        if (splt->size == 0)
>         splt->size += htab->plt_header_size;
> +
> +      htab->next_tls_desc_index++;
>      }
>
>    /* Allocate the PLT entry itself, including any leading Thumb stub.  */
> @@ -7533,7 +7535,10 @@ elf32_arm_allocate_plt_entry (struct bfd_link_info *info,
>      {
>        /* We also need to make an entry in the .got.plt section, which
>          will be placed in the .got section by the linker script.  */
> -      arm_plt->got_offset = sgotplt->size - 8 * htab->num_tls_desc;
> +      if (is_iplt_entry)
> +       arm_plt->got_offset = sgotplt->size;
> +      else
> +       arm_plt->got_offset = sgotplt->size - 8 * htab->num_tls_desc;
>        sgotplt->size += 4;
>      }
>  }
> @@ -13359,8 +13364,6 @@ allocate_dynrelocs_for_symbol (struct elf_link_hash_entry *h, void * inf)
>               h->target_internal = ST_BRANCH_TO_ARM;
>             }
>
> -         htab->next_tls_desc_index++;
> -
>           /* VxWorks executables have a second set of relocations for
>              each PLT entry.  They go in a separate relocation section,
>              which is processed by the kernel loader.  */
> diff --git a/ld/testsuite/ld-arm/arm-elf.exp b/ld/testsuite/ld-arm/arm-elf.exp
> index c255587..2e7e164 100644
> --- a/ld/testsuite/ld-arm/arm-elf.exp
> +++ b/ld/testsuite/ld-arm/arm-elf.exp
> @@ -460,6 +460,9 @@ set armelftests_nonacl {
>       "" {long-plt-format.s}
>       {{objdump "-d -j .plt" long-plt-format.d}}
>       "long-plt-format"}
> +    {"IFUNC and TLS descriptor shared library" "-shared -T arm-lib.ld --version-script=ifunc-gdesc.ver" "" "" {ifunc-gdesc.s}
> +     {{objdump "-Rw" ifunc-gdesc.r}}
> +     "ifunc-gdesc.so"}
>  }
>
>  run_ld_link_tests $armelftests_common
> diff --git a/ld/testsuite/ld-arm/ifunc-gdesc.r b/ld/testsuite/ld-arm/ifunc-gdesc.r
> new file mode 100644
> index 0000000..a49dd2b
> --- /dev/null
> +++ b/ld/testsuite/ld-arm/ifunc-gdesc.r
> @@ -0,0 +1,6 @@
> +tmpdir/ifunc-gdesc.so:     file format elf32-(big|little)arm
> +DYNAMIC RELOCATION RECORDS
> +OFFSET   TYPE              VALUE
> +0000825c R_ARM_IRELATIVE   \*ABS\*
> +00008248 R_ARM_TLS_DESC    \*ABS\*
> +00008250 R_ARM_TLS_DESC    \*ABS\*
> diff --git a/ld/testsuite/ld-arm/ifunc-gdesc.s b/ld/testsuite/ld-arm/ifunc-gdesc.s
> new file mode 100644
> index 0000000..a07a5d5
> --- /dev/null
> +++ b/ld/testsuite/ld-arm/ifunc-gdesc.s
> @@ -0,0 +1,29 @@
> +
> +       .arm
> +
> +foo:
> +       bl      ifunc1(PLT)
> +       ldr     r0,1f
> +2:     bl      loc1(tlscall)
> +       nop
> +1:     .word   loc1(tlsdesc) + (. - 2b)
> +
> +       ldr     r0,1f
> +2:     bl      loc2(tlscall)
> +       nop
> +1:     .word   loc2(tlsdesc) + (. - 2b)
> +
> +       .type   ifunc1,%gnu_indirect_function
> +       .global ifunc1
> +ifunc1:
> +       mov     pc,lr
> +       .size   ifunc1,.-ifunc1
> +
> +
> +       .section        .tdata,"awT",%progbits
> +       .space  8
> +       .type   loc1, %object
> +loc1:  .space  4
> +       .type   loc2, %object
> +loc2:  .space  4
> +
> diff --git a/ld/testsuite/ld-arm/ifunc-gdesc.ver b/ld/testsuite/ld-arm/ifunc-gdesc.ver
> new file mode 100644
> index 0000000..a82ffc4
> --- /dev/null
> +++ b/ld/testsuite/ld-arm/ifunc-gdesc.ver
> @@ -0,0 +1,4 @@
> +{
> +global: foo;
> +local: *;
> +};
> \ No newline at end of file
> --
> 1.9.0
>



-- 
Will Newton
Toolchain Working Group, Linaro