499 lines
14 KiB
C++
499 lines
14 KiB
C++
// Functions for Exception Support for Java.
|
||
|
||
/* Copyright (C) 1998, 1999, 2001, 2002, 2006 Free Software Foundation
|
||
|
||
This file is part of libgcj.
|
||
|
||
This software is copyrighted work licensed under the terms of the
|
||
Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
|
||
details. */
|
||
|
||
#include <config.h>
|
||
|
||
#include <stddef.h>
|
||
#include <stdlib.h>
|
||
|
||
#include <java/lang/Class.h>
|
||
#include <java/lang/NullPointerException.h>
|
||
#include <gnu/gcj/RawData.h>
|
||
#include <gcj/cni.h>
|
||
#include <jvm.h>
|
||
|
||
// unwind-pe.h uses std::abort(), but sometimes we compile libjava
|
||
// without libstdc++-v3. The following hack forces it to use
|
||
// stdlib.h's abort().
|
||
namespace std
|
||
{
|
||
static __attribute__ ((__noreturn__)) void
|
||
abort ()
|
||
{
|
||
::abort ();
|
||
}
|
||
}
|
||
#include "unwind.h"
|
||
|
||
struct alignment_test_struct
|
||
{
|
||
char space;
|
||
char end[0] __attribute__((aligned));
|
||
};
|
||
|
||
struct java_exception_header
|
||
{
|
||
/* Cache handler details between Phase 1 and Phase 2. */
|
||
_Unwind_Ptr landingPad;
|
||
int handlerSwitchValue;
|
||
|
||
/* The object being thrown. Compiled code expects this to be immediately
|
||
before the generic exception header. Which is complicated by the fact
|
||
that _Unwind_Exception is ((aligned)). */
|
||
|
||
char pad[sizeof(jthrowable) < sizeof(alignment_test_struct)
|
||
? sizeof(alignment_test_struct) - sizeof(jthrowable) : 0]
|
||
__attribute__((aligned));
|
||
|
||
jthrowable value;
|
||
|
||
/* The generic exception header. */
|
||
_Unwind_Exception unwindHeader;
|
||
};
|
||
|
||
#ifdef __ARM_EABI_UNWINDER__
|
||
// This is the exception class we report -- "GNUCJAVA".
|
||
|
||
const _Unwind_Exception_Class __gcj_exception_class
|
||
= {'G', 'N', 'U', 'C', 'J', 'A', 'V', 'A'};
|
||
|
||
static inline java_exception_header *
|
||
get_exception_header_from_ue (_Unwind_Exception *exc)
|
||
{
|
||
return reinterpret_cast<java_exception_header *>(exc + 1) - 1;
|
||
}
|
||
|
||
extern "C" void __cxa_begin_cleanup (_Unwind_Exception*);
|
||
|
||
#else // !__ARM_EABI_UNWINDER__
|
||
// This is the exception class we report -- "GNUCJAVA".
|
||
const _Unwind_Exception_Class __gcj_exception_class
|
||
= ((((((((_Unwind_Exception_Class) 'G'
|
||
<< 8 | (_Unwind_Exception_Class) 'N')
|
||
<< 8 | (_Unwind_Exception_Class) 'U')
|
||
<< 8 | (_Unwind_Exception_Class) 'C')
|
||
<< 8 | (_Unwind_Exception_Class) 'J')
|
||
<< 8 | (_Unwind_Exception_Class) 'A')
|
||
<< 8 | (_Unwind_Exception_Class) 'V')
|
||
<< 8 | (_Unwind_Exception_Class) 'A');
|
||
|
||
|
||
static inline java_exception_header *
|
||
get_exception_header_from_ue (_Unwind_Exception *exc)
|
||
{
|
||
return reinterpret_cast<java_exception_header *>(exc + 1) - 1;
|
||
}
|
||
#endif // !__ARM_EABI_UNWINDER__
|
||
|
||
/* Perform a throw, Java style. Throw will unwind through this call,
|
||
so there better not be any handlers or exception thrown here. */
|
||
|
||
extern "C" void
|
||
_Jv_Throw (jthrowable value)
|
||
{
|
||
java_exception_header *xh
|
||
= static_cast<java_exception_header *>(_Jv_AllocRawObj (sizeof (*xh)));
|
||
|
||
if (value == NULL)
|
||
value = new java::lang::NullPointerException ();
|
||
xh->value = value;
|
||
|
||
memcpy (&xh->unwindHeader.exception_class, &__gcj_exception_class,
|
||
sizeof xh->unwindHeader.exception_class);
|
||
xh->unwindHeader.exception_cleanup = NULL;
|
||
|
||
/* We're happy with setjmp/longjmp exceptions or region-based
|
||
exception handlers: entry points are provided here for both. */
|
||
_Unwind_Reason_Code code;
|
||
#ifdef SJLJ_EXCEPTIONS
|
||
code = _Unwind_SjLj_RaiseException (&xh->unwindHeader);
|
||
#else
|
||
code = _Unwind_RaiseException (&xh->unwindHeader);
|
||
#endif
|
||
|
||
/* If code == _URC_END_OF_STACK, then we reached top of stack without
|
||
finding a handler for the exception. Since each thread is run in
|
||
a try/catch, this oughtn't happen. If code is something else, we
|
||
encountered some sort of heinous lossage from which we could not
|
||
recover. As is the way of such things, almost certainly we will have
|
||
crashed before now, rather than actually being able to diagnose the
|
||
problem. */
|
||
abort();
|
||
}
|
||
|
||
|
||
#include "unwind-pe.h"
|
||
|
||
struct lsda_header_info
|
||
{
|
||
_Unwind_Ptr Start;
|
||
_Unwind_Ptr LPStart;
|
||
const unsigned char *TType;
|
||
const unsigned char *action_table;
|
||
unsigned char ttype_encoding;
|
||
unsigned char call_site_encoding;
|
||
};
|
||
|
||
static const unsigned char *
|
||
parse_lsda_header (_Unwind_Context *context, const unsigned char *p,
|
||
lsda_header_info *info)
|
||
{
|
||
_uleb128_t tmp;
|
||
unsigned char lpstart_encoding;
|
||
|
||
info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
|
||
|
||
// Find @LPStart, the base to which landing pad offsets are relative.
|
||
lpstart_encoding = *p++;
|
||
if (lpstart_encoding != DW_EH_PE_omit)
|
||
p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
|
||
else
|
||
info->LPStart = info->Start;
|
||
|
||
// Find @TType, the base of the handler and exception spec type data.
|
||
info->ttype_encoding = *p++;
|
||
if (info->ttype_encoding != DW_EH_PE_omit)
|
||
{
|
||
p = read_uleb128 (p, &tmp);
|
||
info->TType = p + tmp;
|
||
}
|
||
else
|
||
info->TType = 0;
|
||
|
||
// The encoding and length of the call-site table; the action table
|
||
// immediately follows.
|
||
info->call_site_encoding = *p++;
|
||
p = read_uleb128 (p, &tmp);
|
||
info->action_table = p + tmp;
|
||
|
||
return p;
|
||
}
|
||
|
||
#ifdef __ARM_EABI_UNWINDER__
|
||
|
||
static void **
|
||
get_ttype_entry(_Unwind_Context *, lsda_header_info* info, _uleb128_t i)
|
||
{
|
||
_Unwind_Ptr ptr;
|
||
|
||
ptr = (_Unwind_Ptr) (info->TType - (i * 4));
|
||
ptr = _Unwind_decode_target2(ptr);
|
||
|
||
return reinterpret_cast<void **>(ptr);
|
||
}
|
||
|
||
#else
|
||
|
||
static void **
|
||
get_ttype_entry (_Unwind_Context *context, lsda_header_info *info, long i)
|
||
{
|
||
_Unwind_Ptr ptr;
|
||
|
||
i *= size_of_encoded_value (info->ttype_encoding);
|
||
read_encoded_value (context, info->ttype_encoding, info->TType - i, &ptr);
|
||
|
||
return reinterpret_cast<void **>(ptr);
|
||
}
|
||
|
||
#endif
|
||
|
||
// Using a different personality function name causes link failures
|
||
// when trying to mix code using different exception handling models.
|
||
#ifdef SJLJ_EXCEPTIONS
|
||
#define PERSONALITY_FUNCTION __gcj_personality_sj0
|
||
#define __builtin_eh_return_data_regno(x) x
|
||
#else
|
||
#define PERSONALITY_FUNCTION __gcj_personality_v0
|
||
#endif
|
||
|
||
#ifdef __ARM_EABI_UNWINDER__
|
||
|
||
#define CONTINUE_UNWINDING \
|
||
do \
|
||
{ \
|
||
if (__gnu_unwind_frame(ue_header, context) != _URC_OK) \
|
||
return _URC_FAILURE; \
|
||
return _URC_CONTINUE_UNWIND; \
|
||
} \
|
||
while (0)
|
||
|
||
extern "C" _Unwind_Reason_Code
|
||
PERSONALITY_FUNCTION (_Unwind_State state,
|
||
struct _Unwind_Exception* ue_header,
|
||
struct _Unwind_Context* context)
|
||
#else
|
||
|
||
#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
|
||
|
||
extern "C" _Unwind_Reason_Code
|
||
PERSONALITY_FUNCTION (int version,
|
||
_Unwind_Action actions,
|
||
_Unwind_Exception_Class exception_class,
|
||
struct _Unwind_Exception *ue_header,
|
||
struct _Unwind_Context *context)
|
||
|
||
#endif
|
||
{
|
||
java_exception_header *xh = get_exception_header_from_ue (ue_header);
|
||
|
||
lsda_header_info info;
|
||
const unsigned char *language_specific_data;
|
||
const unsigned char *action_record;
|
||
const unsigned char *p;
|
||
_Unwind_Ptr landing_pad, ip;
|
||
int handler_switch_value;
|
||
bool saw_cleanup;
|
||
bool saw_handler;
|
||
bool foreign_exception;
|
||
int ip_before_insn = 0;
|
||
|
||
#ifdef __ARM_EABI_UNWINDER__
|
||
_Unwind_Action actions;
|
||
|
||
switch (state & _US_ACTION_MASK)
|
||
{
|
||
case _US_VIRTUAL_UNWIND_FRAME:
|
||
actions = _UA_SEARCH_PHASE;
|
||
break;
|
||
|
||
case _US_UNWIND_FRAME_STARTING:
|
||
actions = _UA_CLEANUP_PHASE;
|
||
if (!(state & _US_FORCE_UNWIND)
|
||
&& ue_header->barrier_cache.sp == _Unwind_GetGR(context, 13))
|
||
actions |= _UA_HANDLER_FRAME;
|
||
break;
|
||
|
||
case _US_UNWIND_FRAME_RESUME:
|
||
CONTINUE_UNWINDING;
|
||
break;
|
||
|
||
default:
|
||
std::abort();
|
||
}
|
||
actions |= state & _US_FORCE_UNWIND;
|
||
|
||
// We don't know which runtime we're working with, so can't check this.
|
||
// However the ABI routines hide this from us, and we don't actually need
|
||
// to know.
|
||
foreign_exception = false;
|
||
|
||
// The dwarf unwinder assumes the context structure holds things like the
|
||
// function and LSDA pointers. The ARM implementation caches these in
|
||
// the exception header (UCB). To avoid rewriting everything we make the
|
||
// virtual IP register point at the UCB.
|
||
ip = (_Unwind_Ptr) ue_header;
|
||
_Unwind_SetGR(context, 12, ip);
|
||
|
||
#else
|
||
// Interface version check.
|
||
if (version != 1)
|
||
return _URC_FATAL_PHASE1_ERROR;
|
||
foreign_exception = exception_class != __gcj_exception_class;
|
||
#endif
|
||
|
||
// Shortcut for phase 2 found handler for domestic exception.
|
||
if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)
|
||
&& !foreign_exception)
|
||
{
|
||
handler_switch_value = xh->handlerSwitchValue;
|
||
landing_pad = xh->landingPad;
|
||
goto install_context;
|
||
}
|
||
|
||
// FIXME: In Phase 1, record _Unwind_GetIPInfo in xh->obj as a part of
|
||
// the stack trace for this exception. This will only collect Java
|
||
// frames, but perhaps that is acceptable.
|
||
// FIXME2: _Unwind_GetIPInfo is nonsensical for SJLJ, being a call-site
|
||
// index instead of a PC value. We could perhaps arrange for
|
||
// _Unwind_GetRegionStart to return context->fc->jbuf[1], which
|
||
// is the address of the handler label for __builtin_longjmp, but
|
||
// there is no solution for DONT_USE_BUILTIN_SETJMP.
|
||
|
||
language_specific_data = (const unsigned char *)
|
||
_Unwind_GetLanguageSpecificData (context);
|
||
|
||
// If no LSDA, then there are no handlers or cleanups.
|
||
if (! language_specific_data)
|
||
CONTINUE_UNWINDING;
|
||
|
||
// Parse the LSDA header.
|
||
p = parse_lsda_header (context, language_specific_data, &info);
|
||
#ifdef HAVE_GETIPINFO
|
||
ip = _Unwind_GetIPInfo (context, &ip_before_insn);
|
||
#else
|
||
ip = _Unwind_GetIP (context);
|
||
#endif
|
||
if (! ip_before_insn)
|
||
--ip;
|
||
landing_pad = 0;
|
||
action_record = 0;
|
||
handler_switch_value = 0;
|
||
|
||
#ifdef SJLJ_EXCEPTIONS
|
||
// The given "IP" is an index into the call-site table, with two
|
||
// exceptions -- -1 means no-action, and 0 means terminate. But
|
||
// since we're using uleb128 values, we've not got random access
|
||
// to the array.
|
||
if ((int) ip <= 0)
|
||
return _URC_CONTINUE_UNWIND;
|
||
else
|
||
{
|
||
_uleb128_t cs_lp, cs_action;
|
||
do
|
||
{
|
||
p = read_uleb128 (p, &cs_lp);
|
||
p = read_uleb128 (p, &cs_action);
|
||
}
|
||
while (--ip);
|
||
|
||
// Can never have null landing pad for sjlj -- that would have
|
||
// been indicated by a -1 call site index.
|
||
landing_pad = cs_lp + 1;
|
||
if (cs_action)
|
||
action_record = info.action_table + cs_action - 1;
|
||
goto found_something;
|
||
}
|
||
#else
|
||
// Search the call-site table for the action associated with this IP.
|
||
while (p < info.action_table)
|
||
{
|
||
_Unwind_Ptr cs_start, cs_len, cs_lp;
|
||
_uleb128_t cs_action;
|
||
|
||
// Note that all call-site encodings are "absolute" displacements.
|
||
p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
|
||
p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
|
||
p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
|
||
p = read_uleb128 (p, &cs_action);
|
||
|
||
// The table is sorted, so if we've passed the ip, stop.
|
||
if (ip < info.Start + cs_start)
|
||
p = info.action_table;
|
||
else if (ip < info.Start + cs_start + cs_len)
|
||
{
|
||
if (cs_lp)
|
||
landing_pad = info.LPStart + cs_lp;
|
||
if (cs_action)
|
||
action_record = info.action_table + cs_action - 1;
|
||
goto found_something;
|
||
}
|
||
}
|
||
#endif // SJLJ_EXCEPTIONS
|
||
|
||
// If ip is not present in the table, C++ would call terminate.
|
||
// ??? It is perhaps better to tweek the LSDA so that no-action
|
||
// is mapped to no-entry for Java.
|
||
CONTINUE_UNWINDING;
|
||
|
||
found_something:
|
||
saw_cleanup = false;
|
||
saw_handler = false;
|
||
|
||
if (landing_pad == 0)
|
||
{
|
||
// If ip is present, and has a null landing pad, there are
|
||
// no cleanups or handlers to be run.
|
||
}
|
||
else if (action_record == 0)
|
||
{
|
||
// If ip is present, has a non-null landing pad, and a null
|
||
// action table offset, then there are only cleanups present.
|
||
// Cleanups use a zero switch value, as set above.
|
||
saw_cleanup = true;
|
||
}
|
||
else
|
||
{
|
||
// Otherwise we have a catch handler.
|
||
_sleb128_t ar_filter, ar_disp;
|
||
|
||
while (1)
|
||
{
|
||
p = action_record;
|
||
p = read_sleb128 (p, &ar_filter);
|
||
read_sleb128 (p, &ar_disp);
|
||
|
||
if (ar_filter == 0)
|
||
{
|
||
// Zero filter values are cleanups.
|
||
saw_cleanup = true;
|
||
}
|
||
|
||
// During forced unwinding, we only run cleanups. With a
|
||
// foreign exception class, we have no class info to match.
|
||
else if ((actions & _UA_FORCE_UNWIND)
|
||
|| foreign_exception)
|
||
;
|
||
|
||
else if (ar_filter > 0)
|
||
{
|
||
// Positive filter values are handlers.
|
||
|
||
void **catch_word = get_ttype_entry (context, &info, ar_filter);
|
||
jclass catch_type = (jclass)*catch_word;
|
||
|
||
// FIXME: This line is a kludge to work around exception
|
||
// handlers written in C++, which don't yet use indirect
|
||
// dispatch.
|
||
if (catch_type == *(void **)&java::lang::Class::class$)
|
||
catch_type = (jclass)catch_word;
|
||
|
||
if (_Jv_IsInstanceOf (xh->value, catch_type))
|
||
{
|
||
handler_switch_value = ar_filter;
|
||
saw_handler = true;
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
// Negative filter values are exception specifications,
|
||
// which Java does not use.
|
||
// ??? Perhaps better to make them an index into a table
|
||
// of null-terminated strings instead of playing games
|
||
// with Utf8Const+1 as above.
|
||
abort ();
|
||
}
|
||
|
||
if (ar_disp == 0)
|
||
break;
|
||
action_record = p + ar_disp;
|
||
}
|
||
}
|
||
|
||
if (! saw_handler && ! saw_cleanup)
|
||
CONTINUE_UNWINDING;
|
||
|
||
if (actions & _UA_SEARCH_PHASE)
|
||
{
|
||
if (! saw_handler)
|
||
CONTINUE_UNWINDING;
|
||
|
||
// For domestic exceptions, we cache data from phase 1 for phase 2.
|
||
if (! foreign_exception)
|
||
{
|
||
xh->handlerSwitchValue = handler_switch_value;
|
||
xh->landingPad = landing_pad;
|
||
}
|
||
return _URC_HANDLER_FOUND;
|
||
}
|
||
|
||
install_context:
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
|
||
(_Unwind_Ptr) &xh->unwindHeader);
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
|
||
handler_switch_value);
|
||
_Unwind_SetIP (context, landing_pad);
|
||
#ifdef __ARM_EABI_UNWINDER__
|
||
if (saw_cleanup)
|
||
__cxa_begin_cleanup(ue_header);
|
||
#endif
|
||
return _URC_INSTALL_CONTEXT;
|
||
}
|