linux-kernel - [PATCH] ppc: add "-z notext" flag to disable diagnostic

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Message-Id: <20210812204951.1551782-1-morbo@google.com>
Date:   Thu, 12 Aug 2021 13:49:51 -0700
From:   Bill Wendling <morbo@...gle.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Cc:     Bill Wendling <morbo@...gle.com>
Subject: [PATCH] ppc: add "-z notext" flag to disable diagnostic

The "-z notext" flag disables reporting an error if DT_TEXTREL is set on
PPC with CONFIG=kdump:

  ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 against
    local symbol in readonly segment; recompile object files with -fPIC
    or pass '-Wl,-z,notext' to allow text relocations in the output
  >>> defined in built-in.a(arch/powerpc/kernel/misc.o)
  >>> referenced by arch/powerpc/kernel/misc.o:(.text+0x20) in archive
      built-in.a

The BFD linker disables this by default (though it's configurable in
current versions). LLD enables this by default. So we add the flag to
keep LLD from emitting the error.

Signed-off-by: Bill Wendling <morbo@...gle.com>

---
The output of the "get_maintainer.pl" run just in case no one believes me. :-)

$ ./scripts/get_maintainer.pl arch/powerpc/Makefile
Michael Ellerman <mpe@...erman.id.au> (supporter:LINUX FOR POWERPC (32-BIT AND 64-BIT))
Benjamin Herrenschmidt <benh@...nel.crashing.org> (reviewer:LINUX FOR POWERPC (32-BIT AND 64-BIT))
Paul Mackerras <paulus@...ba.org> (reviewer:LINUX FOR POWERPC (32-BIT AND 64-BIT))
Nathan Chancellor <nathan@...nel.org> (supporter:CLANG/LLVM BUILD SUPPORT)
Nick Desaulniers <ndesaulniers@...gle.com> (supporter:CLANG/LLVM BUILD SUPPORT)
linuxppc-dev@...ts.ozlabs.org (open list:LINUX FOR POWERPC (32-BIT AND 64-BIT))
linux-kernel@...r.kernel.org (open list)
clang-built-linux@...glegroups.com (open list:CLANG/LLVM BUILD SUPPORT)
---
 arch/powerpc/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 6505d66f1193..17a9fbf9b789 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -122,6 +122,7 @@ endif
 
 LDFLAGS_vmlinux-y := -Bstatic
 LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
+LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) += -z notext
 LDFLAGS_vmlinux	:= $(LDFLAGS_vmlinux-y)
 
 ifdef CONFIG_PPC64
-- 
2.33.0.rc1.237.g0d66db33f3-goog