Handle GOTTPOFF relocations in delocate.go
These relocations can be emitted for thread-local data. BoringSSL itself
doesn't include any thread-local variables that need linker support, but
ASAN and MSAN may inject these references in order to handle their own
bookkeeping.
Change-Id: I0c6e61d244be84d6bee5ccbf7c4ff4ea0f0b90fd
Reviewed-on: https://boringssl-review.googlesource.com/15147
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/fipsmodule/delocate.go b/crypto/fipsmodule/delocate.go
index 12100dc..36f6c67 100644
--- a/crypto/fipsmodule/delocate.go
+++ b/crypto/fipsmodule/delocate.go
@@ -125,6 +125,13 @@
return i == len(line) || line[i] == '+' || line[i] == '('
}
+// threadLocalOffsetFunc describes a function that fetches the offset to symbol
+// in the thread-local space and writes it to the given target register.
+type threadLocalOffsetFunc struct {
+ target string
+ symbol string
+}
+
// transform performs a number of transformations on the given assembly code.
// See FIPS.md in the current directory for an overview.
func transform(lines []string, symbols map[string]bool) (ret []string) {
@@ -148,6 +155,10 @@
// accessor functions need to be emitted outside of the module.
var bssAccessorsNeeded []string
+ // threadLocalOffsets records the accessor functions needed for getting
+ // offsets in the thread-local storage.
+ threadLocalOffsets := make(map[string]threadLocalOffsetFunc)
+
for lineNo, line := range lines {
if referencesIA32CapDirectly(line) {
panic("reference to OPENSSL_ia32cap_P needs to be changed to indirect via OPENSSL_ia32cap_addr")
@@ -218,6 +229,30 @@
ret = append(ret, line)
continue
+ case "movq":
+ if !strings.Contains(line, "@GOTTPOFF(%rip)") {
+ ret = append(ret, line)
+ continue
+ }
+
+ // GOTTPOFF are offsets into the thread-local storage
+ // that are stored in the GOT. We have to move these
+ // relocations out of the module, but do not know
+ // whether rax is live at this point. Thus a normal
+ // function call might clobber a register and so we
+ // synthesize different functions for writing to each
+ // target register.
+ //
+ // (BoringSSL itself does not use __thread variables,
+ // but ASAN and MSAN may add these references for their
+ // bookkeeping.)
+ targetRegister := parts[2][1:]
+ symbol := strings.SplitN(parts[1], "@", 2)[0]
+ functionName := fmt.Sprintf("BORINGSSL_bcm_tpoff_to_%s_for_%s", targetRegister, symbol)
+ threadLocalOffsets[functionName] = threadLocalOffsetFunc{target: targetRegister, symbol: symbol}
+ ret = append(ret, "\tcallq "+functionName+"\n")
+ continue
+
case ".file":
// Do not reorder .file directives. These define
// numbered files which are referenced by other debug
@@ -320,6 +355,22 @@
ret = append(ret, "\t.quad OPENSSL_ia32cap_P")
}
+ // Emit accessors for thread-local offsets.
+ var threadAccessorNames []string
+ for name := range threadLocalOffsets {
+ threadAccessorNames = append(threadAccessorNames, name)
+ }
+ sort.Strings(threadAccessorNames)
+
+ for _, name := range threadAccessorNames {
+ f := threadLocalOffsets[name]
+
+ ret = append(ret, ".type "+name+",@function")
+ ret = append(ret, name+":")
+ ret = append(ret, "\tmovq "+f.symbol+"@GOTTPOFF(%rip), %"+f.target)
+ ret = append(ret, "\tret")
+ }
+
// Emit an array for storing the module hash.
ret = append(ret, ".type BORINGSSL_bcm_text_hash,@object")
ret = append(ret, ".size OPENSSL_ia32cap_addr,32")
