From: Ian Lance Taylor Date: Thu, 18 Jun 2015 01:28:50 +0000 (-0700) Subject: debug/elf: change R_ARM_REL32 to R_ARM_ABS32 in applyRelocationsARM X-Git-Tag: go1.5beta1~106 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=61cd48b1ce95d518dc80d6344c1d84bbb55af5c3;p=gostls13.git debug/elf: change R_ARM_REL32 to R_ARM_ABS32 in applyRelocationsARM The original version of applyRelocationsARM was added in http://golang.org/cl/7266. It was added to fix the ARM build, which had been broken by http://golang.org/cl/6780. Before CL 6780, there was no relocation processing for ARM. CL 6780 changed the code to require relocation processing for every supported target. CL 7266 fixed the ARM build by adding a relocation processing function, but in fact no actual processing was done. The code only looked for REL32 relocations, but ARM debug info has no such relocations. The test case added in CL 7266 doesn't have any either. This didn't matter because no relocation processing was required on ARM, at least not for GCC-generated debug info. GCC generates ABS32 relocations, but only against section symbols which have the value 0. Therefore, the addition done by correct handling of ABS32 doesn't change anything. Clang, however, generates ABS32 relocations against local symbols, some of which have non-zero values. For those, we need to handle ABS32 relocations. This patch corrects the CL 7266 to look for ABS32 relocations instead of REL32 relocations. The code was already written to correctly handle ABS32 relocations, it just mistakenly said REL32. This is the ARM equivalent of https://golang.org/cl/96680045, which fixed the same problem in the same way for clang on 386. With this patch, clang-3.5 can be used to build Go on ARM GNU/Linux. Fixes #8980. Change-Id: I0c2d72eadfe6373bde99cd03eee40de6a582dda1 Reviewed-on: https://go-review.googlesource.com/11222 Reviewed-by: Russ Cox Run-TryBot: Ian Lance Taylor --- diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go index 8e02c8bbd5..40625435fd 100644 --- a/src/debug/elf/file.go +++ b/src/debug/elf/file.go @@ -653,7 +653,7 @@ func (f *File) applyRelocationsARM(dst []byte, rels []byte) error { sym := &symbols[symNo-1] switch t { - case R_ARM_REL32: + case R_ARM_ABS32: if rel.Off+4 >= uint32(len(dst)) { continue } diff --git a/src/debug/elf/file_test.go b/src/debug/elf/file_test.go index 48fe9d26e1..1ad43146ac 100644 --- a/src/debug/elf/file_test.go +++ b/src/debug/elf/file_test.go @@ -272,6 +272,12 @@ var relocationTests = []relocationTest{ {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{{Attr: dwarf.AttrProducer, Val: "GNU C 4.9.2 20141224 (prerelease) -march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16 -mtls-dialect=gnu -g", Class: dwarf.ClassString}, {Attr: dwarf.AttrLanguage, Val: int64(1), Class: dwarf.ClassConstant}, {Attr: dwarf.AttrName, Val: "go-relocation-test-gcc492.c", Class: dwarf.ClassString}, {Attr: dwarf.AttrCompDir, Val: "/root/go/src/debug/elf/testdata", Class: dwarf.ClassString}, {Attr: dwarf.AttrLowpc, Val: uint64(0x0), Class: dwarf.ClassAddress}, {Attr: dwarf.AttrHighpc, Val: int64(0x28), Class: dwarf.ClassConstant}, {Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr}}}}, }, }, + { + "testdata/go-relocation-test-clang-arm.obj", + []relocationTestEntry{ + {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{dwarf.Field{Attr: dwarf.AttrProducer, Val: "Debian clang version 3.5.0-10 (tags/RELEASE_350/final) (based on LLVM 3.5.0)", Class: dwarf.ClassString}, dwarf.Field{Attr: dwarf.AttrLanguage, Val: int64(12), Class: dwarf.ClassConstant}, dwarf.Field{Attr: dwarf.AttrName, Val: "hello.c", Class: dwarf.ClassString}, dwarf.Field{Attr: dwarf.AttrStmtList, Val: int64(0x0), Class: dwarf.ClassLinePtr}, dwarf.Field{Attr: dwarf.AttrCompDir, Val: "/tmp", Class: dwarf.ClassString}, dwarf.Field{Attr: dwarf.AttrLowpc, Val: uint64(0x0), Class: dwarf.ClassAddress}, dwarf.Field{Attr: dwarf.AttrHighpc, Val: int64(48), Class: dwarf.ClassConstant}}}}, + }, + }, { "testdata/go-relocation-test-gcc5-ppc.obj", []relocationTestEntry{ diff --git a/src/debug/elf/testdata/go-relocation-test-clang-arm.obj b/src/debug/elf/testdata/go-relocation-test-clang-arm.obj new file mode 100644 index 0000000000..1cc7e4b111 Binary files /dev/null and b/src/debug/elf/testdata/go-relocation-test-clang-arm.obj differ