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- // Copyright (c) 2015 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "ppapi/tests/test_nacl_irt_stack_alignment.h"
- #include <stddef.h>
- #include "ppapi/c/pp_var.h"
- #include "ppapi/c/ppb_var.h"
- #include "ppapi/cpp/instance.h"
- #include "ppapi/cpp/module.h"
- #include "ppapi/cpp/var.h"
- #include "ppapi/tests/testing_instance.h"
- // This whole test is really only meant for x86-32 NaCl (not PNaCl).
- //
- // This is a regression test for the IRT code being sensitive to stack
- // alignment. The de jure ABI is that the stack should be aligned to
- // 16 bytes at call sites. However, the de facto ABI is that the IRT
- // worked in the past when called with misaligned stack. NaCl code is
- // now compiled to expect the proper 16-byte alignment, but the IRT
- // code must remain compatible with old binaries that failed to do so.
- #if defined(__i386__)
- REGISTER_TEST_CASE(NaClIRTStackAlignment);
- bool TestNaClIRTStackAlignment::Init() {
- var_interface_ = static_cast<const PPB_Var*>(
- pp::Module::Get()->GetBrowserInterface(PPB_VAR_INTERFACE));
- return var_interface_ && CheckTestingInterface();
- }
- void TestNaClIRTStackAlignment::RunTests(const std::string& filter) {
- RUN_TEST(MisalignedCallVarAddRef, filter);
- }
- // This calls the given function with the stack explicitly misaligned.
- // If the function (in the IRT) was compiled wrongly, it will crash.
- void MisalignedCall(void (*func)(PP_Var), const PP_Var* arg)
- asm("MisalignedCall") __attribute__((regparm(2)));
- // regparm(2) means: First argument in %eax, second argument in %edx.
- // Writing this with an inline asm would require explaining all the
- // call-clobbers register behavior in the asm clobber list, which is a
- // lot with all the SSE and FPU state. It's far simpler just to make
- // it a function call the compiler knows is a function call, and then
- // write the function itself in pure assembly.
- asm("MisalignedCall:\n"
- // Use an SSE register to copy the 16 bytes of memory.
- // Note this instruction does not care about alignment.
- // The pointer is not necessarily aligned to 16 bytes.
- "movups (%edx), %xmm0\n"
- // Set up a frame so we can recover the stack pointer after alignment.
- "push %ebp\n"
- "mov %esp, %ebp\n"
- // Align the stack properly to 16 bytes.
- "andl $-16, %esp\n"
- // Now make space for the 16 bytes of argument data,
- // plus another 4 bytes so the stack pointer is misaligned.
- "subl $20, %esp\n"
- // Copy the argument onto the (misaligned) top of stack.
- "movups %xmm0, (%esp)\n"
- // Now call into the IRT, and hilarity ensues.
- "naclcall %eax\n"
- // Standard epilogue.
- "mov %ebp, %esp\n"
- "pop %ebp\n"
- "naclret");
- std::string TestNaClIRTStackAlignment::TestMisalignedCallVarAddRef() {
- PP_Var var;
- var.type = PP_VARTYPE_INT32;
- var.padding = 0;
- var.value.as_int = 23;
- ASSERT_EQ(sizeof(var), static_cast<size_t>(16));
- // This will crash if the test fails.
- MisalignedCall(var_interface_->AddRef, &var);
- MisalignedCall(var_interface_->Release, &var);
- PASS();
- }
- #endif // defined(__i386__)
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