[PATCH] gold: Add -z noreloc-overflow option

[Hang Deng (handeng)]

HJ, Cary,

Thanks, we tried your patch for X86_64, it works well.

And the patch below also works with arm64,  but I am not familiar with  the test case and review/commit process, can you please help to commit this patch as well?

Thanks,
Hunter

diff --git a/gold/aarch64.cc b/gold/aarch64.cc
index b207dcdc..29da1e35 100644
--- a/gold/aarch64.cc
+++ b/gold/aarch64.cc
@@ -5972,7 +5972,6 @@ Target_aarch64<size, big_endian>::Scan::local(
     case elfcpp::R_AARCH64_NONE:
       break;
 
-    case elfcpp::R_AARCH64_ABS32:
     case elfcpp::R_AARCH64_ABS16:
       if (parameters->options().output_is_position_independent())
        {
@@ -5981,6 +5980,13 @@ Target_aarch64<size, big_endian>::Scan::local(
        }
       break;
 
+    case elfcpp::R_AARCH64_ABS32:
+      if ( parameters->options().output_is_position_independent() &&
+          !parameters->options().noreloc_overflow()) {
+              gold_error(_("%s: unsupported reloc %u in pos independent link."),
+                       object->name().c_str(), r_type);
+           break;
+       }
     case elfcpp::R_AARCH64_ABS64:
       // If building a shared library or pie, we need to mark this as a dynmic
       // reloction, so that the dynamic loader can relocate it.


On 2020/11/3, 2:53 AM, "H.J. Lu" <hjl.tools@gmail.com> wrote:

    On Mon, Nov 2, 2020 at 10:05 AM Cary Coutant <ccoutant@gmail.com> wrote:
    >
    > > +    case elfcpp::R_X86_64_32S:
    > > +      // -z noreloc-overflow
    > > +      if (parameters->options().noreloc_overflow())
    > > +       return;
    > > +      // Fall through.
    > > +
    > >      default:
    > >        // This prevents us from issuing more than one error per reloc
    > >        // section.  But we can still wind up issuing more than one
    >
    > This will issue the wrong error message in the normal (check overflow)
    > case, won't it? You'll get "requires unsupported dynamic reloc"
    > instead of "requires R_X86_64_32S reloc which may overflow at
    > runtime".

    Since R_X86_64_32S is handled by the default label, the error
    message without -z noreloc-overflow is unchanged.

    > Also, shouldn't -z noreloc-overflow turn off link-time overflow
    > checking? All this patch does is disable the warning about a possible
    > overflow at runtime. If that's all you want, I think the option is
    > misnamed.
    >

    This patch disables overflow checks for R_X86_64_32S and
    R_X86_64_32 as the tests show.

    -- 
    H.J.