[PATCH] D52812: Change the warning message for -warn-ifunc-textrel.

[Rui Ueyama via Phabricator via llvm-commits]

ruiu updated this revision to Diff 168180.
ruiu added a comment.

- update the warning message


https://reviews.llvm.org/D52812

Files:
  lld/ELF/Relocations.cpp
  lld/docs/ld.lld.1
  lld/test/ELF/textrel.s


Index: lld/test/ELF/textrel.s
===================================================================
--- lld/test/ELF/textrel.s
+++ lld/test/ELF/textrel.s
@@ -6,12 +6,7 @@
 
 # With --warn-text-ifunc, lld should run with warnings:
 # RUN: ld.lld --warn-ifunc-textrel -z notext %t.o -o /dev/null 2>&1 | FileCheck %s
-# CHECK: using ifunc symbols when text relocations are allowed may produce
-# CHECK-SAME: a binary that will segfault, if the object file is linked with
-# CHECK-SAME: old version of glibc (glibc 2.28 and earlier). If this applies to
-# CHECK-SAME: you, consider recompiling the object files without -fPIC and
-# CHECK-SAME: without -Wl,-z,notext option. Use -no-warn-ifunc-textrel to
-# CHECK-SAME: turn off this warning.
+# CHECK: We detected that your program uses both ifunc symbols and
 # CHECK: >>> defined in {{.*}}
 # CHECK: >>> referenced by {{.*}}:(.text+0x8)
 
Index: lld/docs/ld.lld.1
===================================================================
--- lld/docs/ld.lld.1
+++ lld/docs/ld.lld.1
@@ -447,16 +447,9 @@
 .It Fl -warn-common
 Warn about duplicate common symbols.
 .It Fl -warn-ifunc-textrel
-Warn about using ifunc symbols in conjunction with text relocations.
-Older versions of glibc library (2.28 and earlier) has a bug that causes
-the segment that includes ifunc symbols to be marked as not executable when
-they are relocated. As a result, although the program compiles and links
-successfully, it gives segmentation fault when the instruction pointer reaches
-an ifunc symbol. Use -warn-ifunc-textrel to let lld give a warning, if the
-code may include ifunc symbols, may do text relocations and be linked with
-an older glibc version. Otherwise, there is no need to use it, as the default
-value does not give a warning. This flag has been introduced in late 2018,
-has no counter part in ld and gold linkers, and may be removed in the future.
+Warn if both ifunc symbols and text relocations are used. glibc
+released in 2018 or earlier (version 2.28 or earlier) has a bug that
+causes programs to crash on startup if both features are used.
 .It Fl -warn-unresolved-symbols
 Report unresolved symbols as warnings.
 .It Fl -whole-archive
Index: lld/ELF/Relocations.cpp
===================================================================
--- lld/ELF/Relocations.cpp
+++ lld/ELF/Relocations.cpp
@@ -982,12 +982,13 @@
   // is always at the beginning of a search list. We can leverage that fact.
   if (Sym.isGnuIFunc()) {
     if (!Config->ZText && Config->WarnIfuncTextrel) {
-      warn("using ifunc symbols when text relocations are allowed may produce "
-           "a binary that will segfault, if the object file is linked with "
-           "old version of glibc (glibc 2.28 and earlier). If this applies to "
-           "you, consider recompiling the object files without -fPIC and "
-           "without -Wl,-z,notext option. Use -no-warn-ifunc-textrel to "
-           "turn off this warning." +
+      warn("We detected that your program uses both ifunc symbols and text "
+           "relocations, which is not compatible with glibc released in 2018 "
+           "or earlier (version 2.28 or earlier) due to a bug in glibc. As a "
+           "result, your program may crash on startup on a system that uses "
+           "glibc as a libc (i.e. most Linux systems). If this applies to you, "
+           "consider recompiling with `-fPIC` or link your program without "
+           "`-z notext`. Use `-no-warn-ifunc-textrel` to disable this warning." +
            getLocation(Sec, Sym, Offset));
     }
     Expr = toPlt(Expr);


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