Use a linker script for host bionic embedded linker sections
Use an implicit linker script instead of flags in a file to specify
the locations of the host bionic embedded linker and to prevent it
from being stripped.
Test: build and run host bionic binary
Change-Id: I64e12118d33c67bab5e657cbc3ea8cde8f0fd7e6
diff --git a/Android.bp b/Android.bp
index 8f7f3e2..45e661e 100644
--- a/Android.bp
+++ b/Android.bp
@@ -92,7 +92,7 @@
}
cc_genrule {
- name: "host_bionic_linker_flags",
+ name: "host_bionic_linker_script",
host_supported: true,
device_supported: false,
target: {
@@ -107,9 +107,9 @@
},
},
tools: ["extract_linker"],
- cmd: "$(location) -f $(out) $(in)",
+ cmd: "$(location) -T $(out) $(in)",
srcs: [":linker"],
- out: ["linker.flags"],
+ out: ["linker.script"],
}
// Instantiate the dex_bootjars singleton module.
diff --git a/cc/binary.go b/cc/binary.go
index 201fdcc..3aa3fdf 100644
--- a/cc/binary.go
+++ b/cc/binary.go
@@ -178,7 +178,7 @@
// the kernel before jumping to the embedded linker.
if ctx.Os() == android.LinuxBionic && !binary.static() {
deps.DynamicLinker = "linker"
- deps.LinkerFlagsFile = "host_bionic_linker_flags"
+ deps.CrtBegin = append(deps.CrtBegin, "host_bionic_linker_script")
}
}
@@ -345,12 +345,6 @@
var linkerDeps android.Paths
- // Add flags from linker flags file.
- if deps.LinkerFlagsFile.Valid() {
- flags.Local.LdFlags = append(flags.Local.LdFlags, "$$(cat "+deps.LinkerFlagsFile.String()+")")
- linkerDeps = append(linkerDeps, deps.LinkerFlagsFile.Path())
- }
-
if flags.DynamicLinker != "" {
flags.Local.LdFlags = append(flags.Local.LdFlags, "-Wl,-dynamic-linker,"+flags.DynamicLinker)
} else if ctx.toolchain().Bionic() && !binary.static() {
diff --git a/cc/cc.go b/cc/cc.go
index ef503af..6e9518d 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -129,8 +129,7 @@
CrtBegin, CrtEnd []string
// Used for host bionic
- LinkerFlagsFile string
- DynamicLinker string
+ DynamicLinker string
// List of libs that need to be excluded for APEX variant
ExcludeLibsForApex []string
@@ -179,9 +178,6 @@
// Paths to crt*.o files
CrtBegin, CrtEnd android.Paths
- // Path to the file container flags to use with the linker
- LinkerFlagsFile android.OptionalPath
-
// Path to the dynamic linker binary
DynamicLinker android.OptionalPath
}
@@ -717,7 +713,6 @@
genHeaderDepTag = dependencyTag{name: "gen header"}
genHeaderExportDepTag = dependencyTag{name: "gen header export"}
objDepTag = dependencyTag{name: "obj"}
- linkerFlagsDepTag = dependencyTag{name: "linker flags file"}
dynamicLinkerDepTag = installDependencyTag{name: "dynamic linker"}
reuseObjTag = dependencyTag{name: "reuse objects"}
staticVariantTag = dependencyTag{name: "static variant"}
@@ -2254,9 +2249,6 @@
actx.AddVariationDependencies(crtVariations, CrtEndDepTag,
RewriteSnapshotLib(crt, GetSnapshot(c, &snapshotInfo, actx).Objects))
}
- if deps.LinkerFlagsFile != "" {
- actx.AddDependency(c, linkerFlagsDepTag, deps.LinkerFlagsFile)
- }
if deps.DynamicLinker != "" {
actx.AddDependency(c, dynamicLinkerDepTag, deps.DynamicLinker)
}
@@ -2555,17 +2547,6 @@
} else {
ctx.ModuleErrorf("module %q is not a genrule", depName)
}
- case linkerFlagsDepTag:
- if genRule, ok := dep.(genrule.SourceFileGenerator); ok {
- files := genRule.GeneratedSourceFiles()
- if len(files) == 1 {
- depPaths.LinkerFlagsFile = android.OptionalPathForPath(files[0])
- } else if len(files) > 1 {
- ctx.ModuleErrorf("module %q can only generate a single file if used for a linker flag file", depName)
- }
- } else {
- ctx.ModuleErrorf("module %q is not a genrule", depName)
- }
case CrtBeginDepTag:
depPaths.CrtBegin = append(depPaths.CrtBegin, android.OutputFileForModule(ctx, dep, ""))
case CrtEndDepTag:
diff --git a/cc/testing.go b/cc/testing.go
index f5c5ec5..bee170f 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -490,7 +490,7 @@
}
cc_genrule {
- name: "host_bionic_linker_flags",
+ name: "host_bionic_linker_script",
host_supported: true,
device_supported: false,
target: {
@@ -501,7 +501,7 @@
enabled: true,
},
},
- out: ["linker.flags"],
+ out: ["linker.script"],
}
cc_defaults {
diff --git a/cmd/extract_linker/main.go b/cmd/extract_linker/main.go
index d62dea1..2dcb894 100644
--- a/cmd/extract_linker/main.go
+++ b/cmd/extract_linker/main.go
@@ -13,7 +13,7 @@
// limitations under the License.
// This tool extracts ELF LOAD segments from our linker binary, and produces an
-// assembly file and linker flags which will embed those segments as sections
+// assembly file and linker script which will embed those segments as sections
// in another binary.
package main
@@ -31,10 +31,10 @@
func main() {
var asmPath string
- var flagsPath string
+ var scriptPath string
flag.StringVar(&asmPath, "s", "", "Path to save the assembly file")
- flag.StringVar(&flagsPath, "f", "", "Path to save the linker flags")
+ flag.StringVar(&scriptPath, "T", "", "Path to save the linker script")
flag.Parse()
f, err := os.Open(flag.Arg(0))
@@ -49,13 +49,16 @@
}
asm := &bytes.Buffer{}
+ script := &bytes.Buffer{}
baseLoadAddr := uint64(0x1000)
load := 0
- linkFlags := []string{}
fmt.Fprintln(asm, ".globl __dlwrap_linker_offset")
fmt.Fprintf(asm, ".set __dlwrap_linker_offset, 0x%x\n", baseLoadAddr)
+ fmt.Fprintln(script, "ENTRY(__dlwrap__start)")
+ fmt.Fprintln(script, "SECTIONS {")
+
for _, prog := range ef.Progs {
if prog.Type != elf.PT_LOAD {
continue
@@ -82,10 +85,9 @@
fmt.Fprintf(asm, ".globl %s\n%s:\n\n", symName, symName)
- linkFlags = append(linkFlags,
- fmt.Sprintf("-Wl,--undefined=%s", symName),
- fmt.Sprintf("-Wl,--section-start=%s=0x%x",
- sectionName, baseLoadAddr+prog.Vaddr))
+ fmt.Fprintf(script, " %s %d : {\n", sectionName, baseLoadAddr+prog.Vaddr)
+ fmt.Fprintf(script, " KEEP(*(%s));\n", sectionName)
+ fmt.Fprintln(script, " }")
buffer, _ := ioutil.ReadAll(prog.Open())
bytesToAsm(asm, buffer)
@@ -104,16 +106,18 @@
load += 1
}
+ fmt.Fprintln(script, "}")
+ fmt.Fprintln(script, "INSERT BEFORE .note.android.ident;")
+
if asmPath != "" {
if err := ioutil.WriteFile(asmPath, asm.Bytes(), 0777); err != nil {
log.Fatalf("Unable to write %q: %v", asmPath, err)
}
}
- if flagsPath != "" {
- flags := strings.Join(linkFlags, " ")
- if err := ioutil.WriteFile(flagsPath, []byte(flags), 0777); err != nil {
- log.Fatalf("Unable to write %q: %v", flagsPath, err)
+ if scriptPath != "" {
+ if err := ioutil.WriteFile(scriptPath, script.Bytes(), 0777); err != nil {
+ log.Fatalf("Unable to write %q: %v", scriptPath, err)
}
}
}