| Message ID | 1389868125-7349-1-git-send-email-will.newton@linaro.org |
|---|---|
| State | Accepted |
| Headers | show |
On 16 January 2014 10:28, Will Newton <will.newton@linaro.org> wrote: > I'm not sure what the implications of this patch are, so I thought I would > post it here in the hope that someone can explain what might break. > > The issue comes from a report that Qt does not work correctly on ARM when > built with -Bsymbolic: > > http://lists.linaro.org/pipermail/linaro-toolchain/2014-January/003942.html > > Unless point_equality_needed is set then set st_value to be zero > for undefined symbols. > > bfd/ChangeLog: > > 2014-01-10 Will Newton <will.newton@linaro.org> > > * elf32-arm.c (elf32_arm_check_relocs): Set > pointer_equality_needed for absolute references within > executable links. > (elf32_arm_finish_dynamic_symbol): Set st_value to zero > unless pointer_equality_needed is set. > > ld/testsuite/ChangeLog: > > 2014-01-10 Will Newton <will.newton@linaro.org> > > * ld-arm/ifunc-14.rd: Update symbol values. > --- > bfd/elf32-arm.c | 7 ++++++- > ld/testsuite/ld-arm/ifunc-14.rd | 4 ++-- > 2 files changed, 8 insertions(+), 3 deletions(-) Ping?
On 24 January 2014 04:17, Alan Modra <amodra@gmail.com> wrote: > On Thu, Jan 23, 2014 at 03:22:21PM +0000, Will Newton wrote: >> On 16 January 2014 10:28, Will Newton <will.newton@linaro.org> wrote: >> > I'm not sure what the implications of this patch are, so I thought I would >> > post it here in the hope that someone can explain what might break. > > You're probably being a bit too honest here. :) > > The patch looks OK to me as far as it goes, but I count myself > unqualified to ack it. I don't know enough about ARM to say whether > you've set pointer_equality_needed for all the relocs types you > should. It needs to be set whenever you might be taking the address > of a function in non-PIC code or data. Thanks, I wasn't sure of the semantics of pointer_equality_needed. I'll investigate and post an updated patch.
On 24 January 2014 10:11, Will Newton <will.newton@linaro.org> wrote: > On 24 January 2014 04:17, Alan Modra <amodra@gmail.com> wrote: >> On Thu, Jan 23, 2014 at 03:22:21PM +0000, Will Newton wrote: >>> On 16 January 2014 10:28, Will Newton <will.newton@linaro.org> wrote: >>> > I'm not sure what the implications of this patch are, so I thought I would >>> > post it here in the hope that someone can explain what might break. >> >> You're probably being a bit too honest here. :) >> >> The patch looks OK to me as far as it goes, but I count myself >> unqualified to ack it. I don't know enough about ARM to say whether >> you've set pointer_equality_needed for all the relocs types you >> should. It needs to be set whenever you might be taking the address >> of a function in non-PIC code or data. > > Thanks, I wasn't sure of the semantics of pointer_equality_needed. > I'll investigate and post an updated patch. After investigating the relocs involved I believe the original patch is correct from that point of view. Richard, have you got any opinion on the patch? Thanks,
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c index 7216244..a999b64 100644 --- a/bfd/elf32-arm.c +++ b/bfd/elf32-arm.c @@ -12681,6 +12681,11 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, /* Fall through. */ case R_ARM_ABS32: case R_ARM_ABS32_NOI: + if (h != NULL && info->executable) + { + h->pointer_equality_needed = 1; + } + /* Fall through. */ case R_ARM_REL32: case R_ARM_REL32_NOI: case R_ARM_MOVW_PREL_NC: @@ -14046,7 +14051,7 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, Otherwise, the PLT entry would provide a definition for the symbol even if the symbol wasn't defined anywhere, and so the symbol would never be NULL. */ - if (!h->ref_regular_nonweak) + if (!h->ref_regular_nonweak || !h->pointer_equality_needed) sym->st_value = 0; } else if (eh->is_iplt && eh->plt.noncall_refcount != 0) diff --git a/ld/testsuite/ld-arm/ifunc-14.rd b/ld/testsuite/ld-arm/ifunc-14.rd index 59ea29b..9c44092 100644 --- a/ld/testsuite/ld-arm/ifunc-14.rd +++ b/ld/testsuite/ld-arm/ifunc-14.rd @@ -8,5 +8,5 @@ Relocation section '\.rel\.dyn' at offset 0x8000 contains 4 entries: Relocation section '\.rel\.plt' at offset 0x8020 contains 2 entries: Offset Info Type Sym\.Value Sym\. Name -0001100c ......16 R_ARM_JUMP_SLOT 00009014 f2t -00011010 ......16 R_ARM_JUMP_SLOT 00009020 f2 +0001100c ......16 R_ARM_JUMP_SLOT 00000000 f2t +00011010 ......16 R_ARM_JUMP_SLOT 00000000 f2