/* * Copyright (c) 2008, 2025, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "asm/assembler.inline.hpp" #include "classfile/vmSymbols.hpp" #include "code/vtableStubs.hpp" #include "interpreter/interpreter.hpp" #include "jvm.h" #include "memory/allocation.inline.hpp" #include "nativeInst_arm.hpp" #include "os_linux.hpp" #include "os_posix.hpp" #include "prims/jniFastGetField.hpp" #include "prims/jvm_misc.hpp" #include "runtime/arguments.hpp" #include "runtime/frame.inline.hpp" #include "runtime/interfaceSupport.inline.hpp" #include "runtime/java.hpp" #include "runtime/javaCalls.hpp" #include "runtime/mutexLocker.hpp" #include "runtime/osThread.hpp" #include "runtime/safepointMechanism.hpp" #include "runtime/sharedRuntime.hpp" #include "runtime/stubRoutines.hpp" #include "runtime/threads.hpp" #include "runtime/timer.hpp" #include "signals_posix.hpp" #include "utilities/debug.hpp" #include "utilities/events.hpp" #include "utilities/vmError.hpp" // put OS-includes here # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include # include #define SPELL_REG_SP "sp" #ifndef __thumb__ enum { // Offset to add to frame::_fp when dealing with non-thumb C frames C_frame_offset = -1, }; #endif // Don't #define SPELL_REG_FP for thumb because it is not safe to use, so this makes sure we never fetch it. #ifndef __thumb__ #define SPELL_REG_FP "fp" #endif address os::current_stack_pointer() { register address sp __asm__ (SPELL_REG_SP); return sp; } char* os::non_memory_address_word() { // Must never look like an address returned by reserve_memory return (char*) -1; } #if NGREG == 16 // These definitions are based on the observation that until // the certain version of GCC mcontext_t was defined as // a structure containing gregs[NGREG] array with 16 elements. // In later GCC versions mcontext_t was redefined as struct sigcontext, // along with NGREG constant changed to 18. #define arm_pc gregs[15] #define arm_sp gregs[13] #define arm_fp gregs[11] #define arm_r0 gregs[0] #endif #define ARM_REGS_IN_CONTEXT 16 address os::Posix::ucontext_get_pc(const ucontext_t* uc) { return (address)uc->uc_mcontext.arm_pc; } void os::Posix::ucontext_set_pc(ucontext_t* uc, address pc) { uc->uc_mcontext.arm_pc = (uintx)pc; } intptr_t* os::Linux::ucontext_get_sp(const ucontext_t* uc) { return (intptr_t*)uc->uc_mcontext.arm_sp; } intptr_t* os::Linux::ucontext_get_fp(const ucontext_t* uc) { return (intptr_t*)uc->uc_mcontext.arm_fp; } bool is_safe_for_fp(address pc) { #ifdef __thumb__ if (CodeCache::find_blob(pc) != nullptr) { return true; } // For thumb C frames, given an fp we have no idea how to access the frame contents. return false; #else // Calling os::address_is_in_vm() here leads to a dladdr call. Calling any libc // function during os::get_native_stack() can result in a deadlock if JFR is // enabled. For now, be more lenient and allow all pc's. There are other // frame sanity checks in shared code, and to date they have been sufficient // for other platforms. //return os::address_is_in_vm(pc); return true; #endif } address os::fetch_frame_from_context(const void* ucVoid, intptr_t** ret_sp, intptr_t** ret_fp) { address epc; const ucontext_t* uc = (const ucontext_t*)ucVoid; if (uc != nullptr) { epc = os::Posix::ucontext_get_pc(uc); if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc); if (ret_fp) { intptr_t* fp = os::Linux::ucontext_get_fp(uc); #ifndef __thumb__ if (CodeCache::find_blob(epc) == nullptr) { // It's a C frame. We need to adjust the fp. fp += C_frame_offset; } #endif // Clear FP when stack walking is dangerous so that // the frame created will not be walked. // However, ensure FP is set correctly when reliable and // potentially necessary. if (!is_safe_for_fp(epc)) { // FP unreliable fp = (intptr_t *)nullptr; } *ret_fp = fp; } } else { epc = nullptr; if (ret_sp) *ret_sp = (intptr_t *)nullptr; if (ret_fp) *ret_fp = (intptr_t *)nullptr; } return epc; } frame os::fetch_frame_from_context(const void* ucVoid) { intptr_t* sp; intptr_t* fp; address epc = fetch_frame_from_context(ucVoid, &sp, &fp); if (!is_readable_pointer(epc)) { // Try to recover from calling into bad memory // Assume new frame has not been set up, the same as // compiled frame stack bang return fetch_compiled_frame_from_context(ucVoid); } return frame(sp, fp, epc); } frame os::fetch_compiled_frame_from_context(const void* ucVoid) { const ucontext_t* uc = (const ucontext_t*)ucVoid; // In compiled code, the stack banging is performed before LR // has been saved in the frame. LR is live, and SP and FP // belong to the caller. intptr_t* fp = os::Linux::ucontext_get_fp(uc); intptr_t* sp = os::Linux::ucontext_get_sp(uc); address pc = (address)(uc->uc_mcontext.arm_lr - NativeInstruction::instruction_size); return frame(sp, fp, pc); } intptr_t* os::fetch_bcp_from_context(const void* ucVoid) { assert(ucVoid != nullptr, "invariant"); const ucontext_t* uc = (const ucontext_t*)ucVoid; assert(os::Posix::ucontext_is_interpreter(uc), "invariant"); #if (FP_REG_NUM == 11) assert(Rbcp == R7, "expected FP=R11, Rbcp=R7"); return (intptr_t*)uc->uc_mcontext.arm_r7; #else assert(Rbcp == R11, "expected FP=R7, Rbcp=R11"); return (intptr_t*)uc->uc_mcontext.arm_fp; // r11 #endif } frame os::get_sender_for_C_frame(frame* fr) { #ifdef __thumb__ // We can't reliably get anything from a thumb C frame. return frame(); #else address pc = fr->sender_pc(); if (! is_safe_for_fp(pc)) { return frame(fr->sender_sp(), (intptr_t *)nullptr, pc); } else { return frame(fr->sender_sp(), fr->link() + C_frame_offset, pc); } #endif } // // This actually returns two frames up. It does not return os::current_frame(), // which is the actual current frame. Nor does it return os::get_native_stack(), // which is the caller. It returns whoever called os::get_native_stack(). Not // very intuitive, but consistent with how this API is implemented on other // platforms. // frame os::current_frame() { #ifdef __thumb__ // We can't reliably get anything from a thumb C frame. return frame(); #else register intptr_t* fp __asm__ (SPELL_REG_FP); // fp is for os::current_frame. We want the fp for our caller. frame myframe((intptr_t*)os::current_stack_pointer(), fp + C_frame_offset, CAST_FROM_FN_PTR(address, os::current_frame)); frame caller_frame = os::get_sender_for_C_frame(&myframe); if (os::is_first_C_frame(&caller_frame)) { // stack is not walkable // Assert below was added because it does not seem like this can ever happen. // How can this frame ever be the first C frame since it is called from C code? // If it does ever happen, undo the assert and comment here on when/why it happens. assert(false, "this should never happen"); return frame(); } // return frame for our caller's caller return os::get_sender_for_C_frame(&caller_frame); #endif } extern "C" address check_vfp_fault_instr; extern "C" address check_vfp3_32_fault_instr; extern "C" address check_simd_fault_instr; extern "C" address check_mp_ext_fault_instr; address check_vfp_fault_instr = nullptr; address check_vfp3_32_fault_instr = nullptr; address check_simd_fault_instr = nullptr; address check_mp_ext_fault_instr = nullptr; bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info, ucontext_t* uc, JavaThread* thread) { if (sig == SIGILL && ((info->si_addr == (caddr_t)check_simd_fault_instr) || info->si_addr == (caddr_t)check_vfp_fault_instr || info->si_addr == (caddr_t)check_vfp3_32_fault_instr || info->si_addr == (caddr_t)check_mp_ext_fault_instr)) { // skip faulty instruction + instruction that sets return value to // success and set return value to failure. os::Posix::ucontext_set_pc(uc, (address)info->si_addr + 8); uc->uc_mcontext.arm_r0 = 0; return true; } address stub = nullptr; address pc = nullptr; bool unsafe_access = false; if (info != nullptr && uc != nullptr && thread != nullptr) { pc = (address) os::Posix::ucontext_get_pc(uc); // Handle ALL stack overflow variations here if (sig == SIGSEGV) { address addr = (address) info->si_addr; // check if fault address is within thread stack if (thread->is_in_full_stack(addr)) { // stack overflow StackOverflow* overflow_state = thread->stack_overflow_state(); if (overflow_state->in_stack_yellow_reserved_zone(addr)) { overflow_state->disable_stack_yellow_reserved_zone(); if (thread->thread_state() == _thread_in_Java) { // Throw a stack overflow exception. Guard pages will be re-enabled // while unwinding the stack. stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); } else { // Thread was in the vm or native code. Return and try to finish. return true; } } else if (overflow_state->in_stack_red_zone(addr)) { // Fatal red zone violation. Disable the guard pages and fall through // to the exception handling code below. overflow_state->disable_stack_red_zone(); tty->print_raw_cr("An irrecoverable stack overflow has occurred."); } else { // Accessing stack address below sp may cause SEGV if current // thread has MAP_GROWSDOWN stack. This should only happen when // current thread was created by user code with MAP_GROWSDOWN flag // and then attached to VM. See notes in os_linux.cpp. if (thread->osthread()->expanding_stack() == 0) { thread->osthread()->set_expanding_stack(); if (os::Linux::manually_expand_stack(thread, addr)) { thread->osthread()->clear_expanding_stack(); return true; } thread->osthread()->clear_expanding_stack(); } else { fatal("recursive segv. expanding stack."); } } } } if (thread->thread_state() == _thread_in_Java) { // Java thread running in Java code => find exception handler if any // a fault inside compiled code, the interpreter, or a stub if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) { stub = SharedRuntime::get_poll_stub(pc); } else if (sig == SIGBUS) { // BugId 4454115: A read from a MappedByteBuffer can fault // here if the underlying file has been truncated. // Do not crash the VM in such a case. CodeBlob* cb = CodeCache::find_blob(pc); nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr; if ((nm != nullptr && nm->has_unsafe_access()) || (thread->doing_unsafe_access() && UnsafeMemoryAccess::contains_pc(pc))) { unsafe_access = true; } } else if (sig == SIGSEGV && MacroAssembler::uses_implicit_null_check(info->si_addr)) { // Determination of interpreter/vtable stub/compiled code null exception CodeBlob* cb = CodeCache::find_blob(pc); if (cb != nullptr) { stub = SharedRuntime::continuation_for_implicit_exception( thread, pc, SharedRuntime::IMPLICIT_NULL); } } } else if ((thread->thread_state() == _thread_in_vm || thread->thread_state() == _thread_in_native) && sig == SIGBUS && thread->doing_unsafe_access()) { unsafe_access = true; } // jni_fast_GetField can trap at certain pc's if a GC kicks in // and the heap gets shrunk before the field access. if (sig == SIGSEGV || sig == SIGBUS) { address addr = JNI_FastGetField::find_slowcase_pc(pc); if (addr != (address)-1) { stub = addr; } } } if (unsafe_access && stub == nullptr) { // it can be an unsafe access and we haven't found // any other suitable exception reason, // so assume it is an unsafe access. address next_pc = pc + Assembler::InstructionSize; if (UnsafeMemoryAccess::contains_pc(pc)) { next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc); } #ifdef __thumb__ if (uc->uc_mcontext.arm_cpsr & PSR_T_BIT) { next_pc = (address)((intptr_t)next_pc | 0x1); } #endif stub = SharedRuntime::handle_unsafe_access(thread, next_pc); } if (stub != nullptr) { #ifdef __thumb__ if (uc->uc_mcontext.arm_cpsr & PSR_T_BIT) { intptr_t p = (intptr_t)pc | 0x1; pc = (address)p; // Clear Thumb mode bit if we're redirected into the ARM ISA based code if (((intptr_t)stub & 0x1) == 0) { uc->uc_mcontext.arm_cpsr &= ~PSR_T_BIT; } } else { // No Thumb2 compiled stubs are triggered from ARM ISA compiled JIT'd code today. // The support needs to be added if that changes assert((((intptr_t)stub & 0x1) == 0), "can't return to Thumb code"); } #endif // save all thread context in case we need to restore it if (thread != nullptr) thread->set_saved_exception_pc(pc); os::Posix::ucontext_set_pc(uc, stub); return true; } return false; } void os::Linux::init_thread_fpu_state(void) { os::setup_fpu(); } int os::Linux::get_fpu_control_word(void) { return 0; } void os::Linux::set_fpu_control_word(int fpu_control) { // Nothing to do } void os::setup_fpu() { #if !defined(__SOFTFP__) && defined(__VFP_FP__) // Turn on IEEE-754 compliant VFP mode __asm__ volatile ( "mov %%r0, #0;" "fmxr fpscr, %%r0" : /* no output */ : /* no input */ : "r0" ); #endif } //////////////////////////////////////////////////////////////////////////////// // thread stack // Minimum usable stack sizes required to get to user code. Space for // HotSpot guard pages is added later. size_t os::_compiler_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 4)) * K; size_t os::_java_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 4)) * K; size_t os::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K; // return default stack size for thr_type size_t os::Posix::default_stack_size(os::ThreadType thr_type) { // default stack size (compiler thread needs larger stack) size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K); return s; } ///////////////////////////////////////////////////////////////////////////// // helper functions for fatal error handler void os::print_context(outputStream *st, const void *context) { if (context == nullptr) return; const ucontext_t *uc = (const ucontext_t*)context; st->print_cr("Registers:"); intx* reg_area = (intx*)&uc->uc_mcontext.arm_r0; for (int r = 0; r < ARM_REGS_IN_CONTEXT; r++) { st->print_cr(" %-3s = " INTPTR_FORMAT, as_Register(r)->name(), reg_area[r]); } #define U64_FORMAT "0x%016llx" // now print flag register uint32_t cpsr = uc->uc_mcontext.arm_cpsr; st->print_cr(" %-4s = 0x%08x", "cpsr", cpsr); // print out instruction set state st->print("isetstate: "); const int isetstate = ((cpsr & (1 << 5)) ? 1 : 0) | // T ((cpsr & (1 << 24)) ? 2 : 0); // J switch (isetstate) { case 0: st->print_cr("ARM"); break; case 1: st->print_cr("Thumb"); break; case 2: st->print_cr("Jazelle"); break; case 3: st->print_cr("ThumbEE"); break; default: ShouldNotReachHere(); }; st->cr(); } void os::print_register_info(outputStream *st, const void *context, int& continuation) { const int register_count = ARM_REGS_IN_CONTEXT; int n = continuation; assert(n >= 0 && n <= register_count, "Invalid continuation value"); if (context == nullptr || n == register_count) { return; } const ucontext_t *uc = (const ucontext_t*)context; intx* reg_area = (intx*)&uc->uc_mcontext.arm_r0; while (n < register_count) { // Update continuation with next index before printing location continuation = n + 1; st->print(" %-3s = ", as_Register(n)->name()); print_location(st, reg_area[n]); ++n; } } ARMAtomicFuncs::cmpxchg_long_func_t ARMAtomicFuncs::_cmpxchg_long_func = ARMAtomicFuncs::cmpxchg_long_bootstrap; ARMAtomicFuncs::load_long_func_t ARMAtomicFuncs::_load_long_func = ARMAtomicFuncs::load_long_bootstrap; ARMAtomicFuncs::store_long_func_t ARMAtomicFuncs::_store_long_func = ARMAtomicFuncs::store_long_bootstrap; ARMAtomicFuncs::atomic_add_func_t ARMAtomicFuncs::_add_func = ARMAtomicFuncs::add_bootstrap; ARMAtomicFuncs::atomic_xchg_func_t ARMAtomicFuncs::_xchg_func = ARMAtomicFuncs::xchg_bootstrap; ARMAtomicFuncs::cmpxchg_func_t ARMAtomicFuncs::_cmpxchg_func = ARMAtomicFuncs::cmpxchg_bootstrap; int64_t ARMAtomicFuncs::cmpxchg_long_bootstrap(int64_t compare_value, int64_t exchange_value, volatile int64_t* dest) { // try to use the stub: cmpxchg_long_func_t func = CAST_TO_FN_PTR(cmpxchg_long_func_t, StubRoutines::atomic_cmpxchg_long_entry()); if (func != nullptr) { _cmpxchg_long_func = func; return (*func)(compare_value, exchange_value, dest); } assert(Threads::number_of_threads() == 0, "for bootstrap only"); int64_t old_value = *dest; if (old_value == compare_value) *dest = exchange_value; return old_value; } int64_t ARMAtomicFuncs::load_long_bootstrap(const volatile int64_t* src) { // try to use the stub: load_long_func_t func = CAST_TO_FN_PTR(load_long_func_t, StubRoutines::Arm::atomic_load_long_entry()); if (func != nullptr) { _load_long_func = func; return (*func)(src); } assert(Threads::number_of_threads() == 0, "for bootstrap only"); int64_t old_value = *src; return old_value; } void ARMAtomicFuncs::store_long_bootstrap(int64_t val, volatile int64_t* dest) { // try to use the stub: store_long_func_t func = CAST_TO_FN_PTR(store_long_func_t, StubRoutines::Arm::atomic_store_long_entry()); if (func != nullptr) { _store_long_func = func; return (*func)(val, dest); } assert(Threads::number_of_threads() == 0, "for bootstrap only"); *dest = val; } int32_t ARMAtomicFuncs::add_bootstrap(int32_t add_value, volatile int32_t *dest) { atomic_add_func_t func = CAST_TO_FN_PTR(atomic_add_func_t, StubRoutines::atomic_add_entry()); if (func != nullptr) { _add_func = func; return (*func)(add_value, dest); } int32_t old_value = *dest; *dest = old_value + add_value; return (old_value + add_value); } int32_t ARMAtomicFuncs::xchg_bootstrap(int32_t exchange_value, volatile int32_t *dest) { atomic_xchg_func_t func = CAST_TO_FN_PTR(atomic_xchg_func_t, StubRoutines::atomic_xchg_entry()); if (func != nullptr) { _xchg_func = func; return (*func)(exchange_value, dest); } int32_t old_value = *dest; *dest = exchange_value; return (old_value); } int32_t ARMAtomicFuncs::cmpxchg_bootstrap(int32_t compare_value, int32_t exchange_value, volatile int32_t* dest) { // try to use the stub: cmpxchg_func_t func = CAST_TO_FN_PTR(cmpxchg_func_t, StubRoutines::atomic_cmpxchg_entry()); if (func != nullptr) { _cmpxchg_func = func; return (*func)(compare_value, exchange_value, dest); } assert(Threads::number_of_threads() == 0, "for bootstrap only"); int32_t old_value = *dest; if (old_value == compare_value) *dest = exchange_value; return old_value; } #ifndef PRODUCT void os::verify_stack_alignment() { } #endif int os::extra_bang_size_in_bytes() { // ARM does not require an additional stack bang. return 0; }