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# HG changeset patch
# User Lars T Hansen <lhansen@mozilla.com>
# Date 1521449886 -3600
# Node ID 903a79a1efff18fc7cc50db09a3fe5d768adc9a8
# Parent 4d2955a9ca7e30ca4c3af9c214ccc77fb2fe7fb8
Bug 1445907 - Save x28 before clobbering it in the regex compiler. r=sstangl
Origin: upstream
Applied-upstream: 61, commit: https://hg.mozilla.org/mozilla-central/rev/903a79a1efff
---
diff --git a/js/src/irregexp/NativeRegExpMacroAssembler.cpp b/js/src/irregexp/NativeRegExpMacroAssembler.cpp
--- a/js/src/irregexp/NativeRegExpMacroAssembler.cpp
+++ b/js/src/irregexp/NativeRegExpMacroAssembler.cpp
@@ -118,17 +118,25 @@ NativeRegExpMacroAssembler::GenerateCode
Label return_temp0;
// Finalize code - write the entry point code now we know how many
// registers we need.
masm.bind(&entry_label_);
#ifdef JS_CODEGEN_ARM64
- // ARM64 communicates stack address via sp, but uses a pseudo-sp for addressing.
+ // ARM64 communicates stack address via SP, but uses a pseudo-sp (PSP) for
+ // addressing. The register we use for PSP may however also be used by
+ // calling code, and it is nonvolatile, so save it. Do this as a special
+ // case first because the generic save/restore code needs the PSP to be
+ // initialized already.
+ MOZ_ASSERT(PseudoStackPointer64.Is(masm.GetStackPointer64()));
+ masm.Str(PseudoStackPointer64, vixl::MemOperand(sp, -16, vixl::PreIndex));
+
+ // Initialize the PSP from the SP.
masm.initStackPtr();
#endif
// Push non-volatile registers which might be modified by jitcode.
size_t pushedNonVolatileRegisters = 0;
for (GeneralRegisterForwardIterator iter(savedNonVolatileRegisters); iter.more(); ++iter) {
masm.Push(*iter);
pushedNonVolatileRegisters++;
@@ -416,17 +424,32 @@ NativeRegExpMacroAssembler::GenerateCode
masm.pop(temp0);
masm.movePtr(temp0, StackPointer);
#endif
// Restore non-volatile registers which were saved on entry.
for (GeneralRegisterBackwardIterator iter(savedNonVolatileRegisters); iter.more(); ++iter)
masm.Pop(*iter);
+#ifdef JS_CODEGEN_ARM64
+ // Now restore the value that was in the PSP register on entry, and return.
+
+ // Obtain the correct SP from the PSP.
+ masm.Mov(sp, PseudoStackPointer64);
+
+ // Restore the saved value of the PSP register, this value is whatever the
+ // caller had saved in it, not any actual SP value, and it must not be
+ // overwritten subsequently.
+ masm.Ldr(PseudoStackPointer64, vixl::MemOperand(sp, 16, vixl::PostIndex));
+
+ // Perform a plain Ret(), as abiret() will move SP <- PSP and that is wrong.
+ masm.Ret(vixl::lr);
+#else
masm.abiret();
+#endif
// Backtrack code (branch target for conditional backtracks).
if (backtrack_label_.used()) {
masm.bind(&backtrack_label_);
Backtrack();
}
// Backtrack stack overflow code.
diff --git a/js/src/jit-test/tests/regexp/bug1445907.js b/js/src/jit-test/tests/regexp/bug1445907.js
new file mode 100644
--- /dev/null
+++ b/js/src/jit-test/tests/regexp/bug1445907.js
@@ -0,0 +1,15 @@
+// On ARM64, we failed to save x28 properly when generating code for the regexp
+// matcher.
+//
+// There's wasm and Debugger code here because the combination forces the use of
+// x28 and exposes the bug when running on the simulator.
+
+if (!wasmIsSupported())
+ quit();
+
+var g = newGlobal('');
+var dbg = new Debugger(g);
+g.eval(`var m = new WebAssembly.Instance(new WebAssembly.Module(wasmTextToBinary('(module (func (export "test")))')))`);
+var re = /./;
+dbg.onEnterFrame = function(frame) { re.exec("x") };
+result = g.eval("m.exports.test()");
--
2.21.0
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