OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
037586ddda
gcc/libgo/runtime/go-unwind.c
Ian Lance Taylor 772455c964 libgo: fix for unaligned read in go-unwind.c's read_encoded_value() 
Change code to work properly reading unaligned data on architectures
    that don't support unaliged reads. This fixes a regression (broke
    Solaris/sparc) introduced in https://golang.org/cl/90235.
    
    Reviewed-on: https://go-review.googlesource.com/111296

From-SVN: r259935
2018-05-04 14:29:05 +00:00

566 lines
15 KiB
C
Raw Blame History

/* go-unwind.c -- unwind the stack for panic/recover.
Copyright 2010 The Go 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 "config.h"
#include <stdlib.h>
#include <unistd.h>
#include "unwind.h"
#include "runtime.h"
/* These constants are documented here:
https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA/dwarfext.html
*/
#define DW_EH_PE_omit 0xff
#define DW_EH_PE_absptr 0x00
#define DW_EH_PE_uleb128 0x01
#define DW_EH_PE_udata2 0x02
#define DW_EH_PE_udata4 0x03
#define DW_EH_PE_udata8 0x04
#define DW_EH_PE_sleb128 0x09
#define DW_EH_PE_sdata2 0x0A
#define DW_EH_PE_sdata4 0x0B
#define DW_EH_PE_sdata8 0x0C
#define DW_EH_PE_pcrel 0x10
#define DW_EH_PE_textrel 0x20
#define DW_EH_PE_datarel 0x30
#define DW_EH_PE_funcrel 0x40
#define DW_EH_PE_aligned 0x50
#define DW_EH_PE_indirect 0x80
/* The code for a Go exception. */
#ifdef __ARM_EABI_UNWINDER__
static const _Unwind_Exception_Class __go_exception_class =
{ 'G', 'N', 'U', 'C', 'G', 'O', '\0', '\0' };
#else
static const _Unwind_Exception_Class __go_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) 'G')
<< 8 | (_Unwind_Exception_Class) 'O')
<< 8 | (_Unwind_Exception_Class) '\0')
<< 8 | (_Unwind_Exception_Class) '\0');
#endif
/* Rethrow an exception. */
void rethrowException (void) __asm__(GOSYM_PREFIX "runtime.rethrowException");
void
rethrowException ()
{
struct _Unwind_Exception *hdr;
hdr = (struct _Unwind_Exception *) runtime_g()->exception;
#ifdef __USING_SJLJ_EXCEPTIONS__
_Unwind_SjLj_Resume_or_Rethrow (hdr);
#else
#if defined(_LIBUNWIND_STD_ABI)
_Unwind_RaiseException (hdr);
#else
_Unwind_Resume_or_Rethrow (hdr);
#endif
#endif
/* Rethrowing the exception should not return. */
abort();
}
/* Return the size of the type that holds an exception header, so that
it can be allocated by Go code. */
uintptr unwindExceptionSize(void)
__asm__ (GOSYM_PREFIX "runtime.unwindExceptionSize");
uintptr
unwindExceptionSize ()
{
uintptr ret, align;
ret = sizeof (struct _Unwind_Exception);
/* Adjust the size fo make sure that we can get an aligned value. */
align = __alignof__ (struct _Unwind_Exception);
if (align > __alignof__ (uintptr))
ret += align - __alignof__ (uintptr);
return ret;
}
/* Throw an exception. This is called with g->exception pointing to
an uninitialized _Unwind_Exception instance. */
void throwException (void) __asm__(GOSYM_PREFIX "runtime.throwException");
void
throwException ()
{
struct _Unwind_Exception *hdr;
uintptr align;
hdr = (struct _Unwind_Exception *)runtime_g ()->exception;
/* Make sure the value is correctly aligned. It will be large
enough, because of unwindExceptionSize. */
align = __alignof__ (struct _Unwind_Exception);
hdr = ((struct _Unwind_Exception *)
(((uintptr) hdr + align - 1) &~ (align - 1)));
__builtin_memcpy (&hdr->exception_class, &__go_exception_class,
sizeof hdr->exception_class);
hdr->exception_cleanup = NULL;
#ifdef __USING_SJLJ_EXCEPTIONS__
_Unwind_SjLj_RaiseException (hdr);
#else
_Unwind_RaiseException (hdr);
#endif
/* Raising an exception should not return. */
abort ();
}
static inline _Unwind_Ptr
encoded_value_base (uint8_t encoding, struct _Unwind_Context *context)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return 0;
case DW_EH_PE_textrel:
return _Unwind_GetTextRelBase(context);
case DW_EH_PE_datarel:
return _Unwind_GetDataRelBase(context);
case DW_EH_PE_funcrel:
return _Unwind_GetRegionStart(context);
}
abort ();
}
/* Read an unsigned leb128 value. */
static inline const uint8_t *
read_uleb128 (const uint8_t *p, _uleb128_t *val)
{
unsigned int shift = 0;
_uleb128_t result = 0;
uint8_t byte;
do
{
byte = *p++;
result |= ((_uleb128_t)byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
*val = result;
return p;
}
/* Similar, but read a signed leb128 value. */
static inline const uint8_t *
read_sleb128 (const uint8_t *p, _sleb128_t *val)
{
unsigned int shift = 0;
_uleb128_t result = 0;
uint8_t byte;
do
{
byte = *p++;
result |= ((_uleb128_t)byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
/* sign extension */
if (shift < (8 * sizeof(result)) && (byte & 0x40) != 0)
result |= (((_uleb128_t)~0) << shift);
*val = (_sleb128_t)result;
return p;
}
#define ROUND_UP_TO_PVB(x) (x + sizeof(void *) - 1) &- sizeof(void *)
static inline const uint8_t *
read_encoded_value (struct _Unwind_Context *context, uint8_t encoding,
const uint8_t *p, _Unwind_Ptr *val)
{
_Unwind_Ptr base = encoded_value_base (encoding, context);
_Unwind_Internal_Ptr decoded = 0;
const uint8_t *origp = p;
if (encoding == DW_EH_PE_aligned)
{
_Unwind_Internal_Ptr uip = (_Unwind_Internal_Ptr)p;
uip = ROUND_UP_TO_PVB (uip);
decoded = *(_Unwind_Internal_Ptr *)uip;
p = (const uint8_t *)(uip + sizeof(void *));
}
else
{
switch (encoding & 0x0f)
{
case DW_EH_PE_sdata2:
{
int16_t result;
__builtin_memcpy (&result, p, sizeof(int16_t));
decoded = result;
p += sizeof(int16_t);
break;
}
case DW_EH_PE_udata2:
{
uint16_t result;
__builtin_memcpy (&result, p, sizeof(uint16_t));
decoded = result;
p += sizeof(uint16_t);
break;
}
case DW_EH_PE_sdata4:
{
int32_t result;
__builtin_memcpy (&result, p, sizeof(int32_t));
decoded = result;
p += sizeof(int32_t);
break;
}
case DW_EH_PE_udata4:
{
uint32_t result;
__builtin_memcpy (&result, p, sizeof(uint32_t));
decoded = result;
p += sizeof(uint32_t);
break;
}
case DW_EH_PE_sdata8:
{
int64_t result;
__builtin_memcpy (&result, p, sizeof(int64_t));
decoded = result;
p += sizeof(int64_t);
break;
}
case DW_EH_PE_udata8:
{
uint64_t result;
__builtin_memcpy (&result, p, sizeof(uint64_t));
decoded = result;
p += sizeof(uint64_t);
break;
}
case DW_EH_PE_uleb128:
{
_uleb128_t value;
p = read_uleb128 (p, &value);
decoded = (_Unwind_Internal_Ptr)value;
break;
}
case DW_EH_PE_sleb128:
{
_sleb128_t value;
p = read_sleb128 (p, &value);
decoded = (_Unwind_Internal_Ptr)value;
break;
}
case DW_EH_PE_absptr:
__builtin_memcpy (&decoded, (const void *)p, sizeof(const void*));
p += sizeof(void *);
break;
default:
abort ();
}
if (decoded == 0)
{
*val = decoded;
return p;
}
if ((encoding & 0x70) == DW_EH_PE_pcrel)
decoded += ((_Unwind_Internal_Ptr)origp);
else
decoded += base;
if ((encoding & DW_EH_PE_indirect) != 0)
decoded = *(_Unwind_Internal_Ptr *)decoded;
}
*val = decoded;
return p;
}
/* The rest of this code is really similar to gcc/unwind-c.c and
libjava/exception.cc. */
typedef struct
{
_Unwind_Ptr Start;
_Unwind_Ptr LPStart;
_Unwind_Ptr ttype_base;
const unsigned char *TType;
const unsigned char *action_table;
unsigned char ttype_encoding;
unsigned char call_site_encoding;
} lsda_header_info;
static const unsigned char *
parse_lsda_header (struct _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;
}
/* The personality function is invoked when unwinding the stack due to
a panic. Its job is to find the cleanup and exception handlers to
run. We can't split the stack here, because we won't be able to
unwind from that split. */
#ifdef __ARM_EABI_UNWINDER__
/* ARM EABI personality routines must also unwind the stack. */
#define CONTINUE_UNWINDING \
do \
{ \
if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \
return _URC_FAILURE; \
return _URC_CONTINUE_UNWIND; \
} \
while (0)
#else
#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
#endif
#ifdef __USING_SJLJ_EXCEPTIONS__
#define PERSONALITY_FUNCTION __gccgo_personality_sj0
#define __builtin_eh_return_data_regno(x) x
#else
#define PERSONALITY_FUNCTION __gccgo_personality_v0
#endif
#ifdef __ARM_EABI_UNWINDER__
_Unwind_Reason_Code
PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *,
struct _Unwind_Context *)
__attribute__ ((no_split_stack, flatten));
_Unwind_Reason_Code
PERSONALITY_FUNCTION (_Unwind_State state,
struct _Unwind_Exception * ue_header,
struct _Unwind_Context * context)
#else
_Unwind_Reason_Code
PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,
struct _Unwind_Exception *, struct _Unwind_Context *)
__attribute__ ((no_split_stack, flatten));
_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
{
lsda_header_info info;
const unsigned char *language_specific_data, *p, *action_record;
_Unwind_Ptr landing_pad, ip;
int ip_before_insn = 0;
_Bool is_foreign;
G *g;
#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:
abort();
}
actions |= state & _US_FORCE_UNWIND;
is_foreign = 0;
/* 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
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
is_foreign = exception_class != __go_exception_class;
#endif
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 = NULL;
#ifdef __USING_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 = (_Unwind_Ptr)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
/* IP is not in table. No associated cleanups. */
CONTINUE_UNWINDING;
found_something:
if (landing_pad == 0)
{
/* IP is present, but has a null landing pad.
No handler to be run. */
CONTINUE_UNWINDING;
}
if (actions & _UA_SEARCH_PHASE)
{
if (action_record == 0)
{
/* This indicates a cleanup rather than an exception
handler. */
CONTINUE_UNWINDING;
}
return _URC_HANDLER_FOUND;
}
/* It's possible for g to be NULL here for an exception thrown by a
language other than Go. */
g = runtime_g ();
if (g == NULL)
{
if (!is_foreign)
abort ();
}
else
{
g->exception = ue_header;
g->isforeign = is_foreign;
}
_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
(_Unwind_Ptr) ue_header);
_Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);
_Unwind_SetIP (context, landing_pad);
return _URC_INSTALL_CONTEXT;
}
Reference in New Issue View Git Blame Copy Permalink