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/* C6X ABI compliant unwinding routines
Copyright (C) 2011-2022 Free Software Foundation, Inc.
This file is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
This file 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 for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "unwind.h"
/* We add a prototype for abort here to avoid creating a dependency on
target headers. */
extern void abort (void);
typedef struct _ZSt9type_info type_info; /* This names C++ type_info type */
/* Misc constants. */
#define R_A0 0
#define R_A1 1
#define R_A2 2
#define R_A3 3
#define R_A4 4
#define R_A5 5
#define R_A6 6
#define R_A7 7
#define R_A8 8
#define R_A9 9
#define R_A10 10
#define R_A11 11
#define R_A12 12
#define R_A13 13
#define R_A14 14
#define R_A15 15
#define R_B0 16
#define R_B1 17
#define R_B2 18
#define R_B3 19
#define R_B4 20
#define R_B5 21
#define R_B6 22
#define R_B7 23
#define R_B8 24
#define R_B9 25
#define R_B10 26
#define R_B11 27
#define R_B12 28
#define R_B13 29
#define R_B14 30
#define R_B15 31
#define R_SP R_B15
#define R_PC 33
#define uint32_highbit (((_uw) 1) << 31)
void __attribute__((weak)) __cxa_call_unexpected(_Unwind_Control_Block *ucbp);
/* Unwind descriptors. */
typedef struct
{
_uw16 length;
_uw16 offset;
} EHT16;
typedef struct
{
_uw length;
_uw offset;
} EHT32;
/* Calculate the address encoded by a 31-bit self-relative offset at address
P. Copy of routine in unwind-arm.c. */
static inline _uw
selfrel_offset31 (const _uw *p)
{
_uw offset;
offset = *p;
/* Sign extend to 32 bits. */
if (offset & (1 << 30))
offset |= 1u << 31;
return offset + (_uw) p;
}
/* Personality routine helper functions. */
#define CODE_FINISH (0xe7)
/* Return the next byte of unwinding information, or CODE_FINISH if there is
no data remaining. */
static inline _uw8
next_unwind_byte (__gnu_unwind_state * uws)
{
_uw8 b;
if (uws->bytes_left == 0)
{
/* Load another word */
if (uws->words_left == 0)
return CODE_FINISH; /* Nothing left. */
uws->words_left--;
uws->data = *(uws->next++);
uws->bytes_left = 3;
}
else
uws->bytes_left--;
/* Extract the most significant byte. */
b = (uws->data >> 24) & 0xff;
uws->data <<= 8;
return b;
}
static void
unwind_restore_pair (_Unwind_Context * context, int reg, _uw *ptr)
{
#ifdef _BIG_ENDIAN
_Unwind_VRS_Set (context, _UVRSC_CORE, reg, _UVRSD_UINT32, ptr + 1);
_Unwind_VRS_Set (context, _UVRSC_CORE, reg + 1, _UVRSD_UINT32, ptr);
#else
_Unwind_VRS_Set (context, _UVRSC_CORE, reg, _UVRSD_UINT32, ptr);
_Unwind_VRS_Set (context, _UVRSC_CORE, reg + 1, _UVRSD_UINT32, ptr + 1);
#endif
}
static const int
unwind_frame_regs[13] =
{
R_A15, R_B15, R_B14, R_B13, R_B12, R_B11, R_B10, R_B3,
R_A14, R_A13, R_A12, R_A11, R_A10
};
static void
pop_compact_frame (_Unwind_Context * context, _uw mask, _uw *ptr, int inc_sp)
{
int size;
_uw test;
int i, regno, nregs;
size = 0;
nregs = __builtin_popcount (mask);
for (i = 0; i < 13; i++)
{
test = 1 << i;
if ((mask & test) == 0)
continue;
regno = unwind_frame_regs[12 - i];
if (i < 12 && nregs > 2
&& (mask & (test << 1)) != 0
&& unwind_frame_regs[11 - i] == regno + 1
&& (regno & 1) == 0)
{
i++;
nregs--;
}
nregs--;
size += 2;
}
if (!inc_sp)
ptr -= size;
/* SP points just past the end of the stack. */
ptr += 2;
nregs = __builtin_popcount (mask);
for (i = 0; i < 13; i++)
{
test = 1 << i;
if ((mask & test) == 0)
continue;
regno = unwind_frame_regs[12 - i];
if (i < 12 && nregs > 2
&& (mask & (test << 1)) != 0
&& unwind_frame_regs[11 - i] == regno + 1
&& (regno & 1) == 0)
{
/* Register pair. */
unwind_restore_pair (context, regno, ptr);
i++;
nregs--;
}
else
{
/* Single register with padding. */
_Unwind_VRS_Set (context, _UVRSC_CORE, regno, _UVRSD_UINT32, ptr);
}
nregs--;
ptr += 2;
}
ptr -= 2;
if ((mask & (1 << 11)) == 0)
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
}
static void
pop_frame (_Unwind_Context * context, _uw mask, _uw *ptr, int inc_sp)
{
int i;
int regno;
int nregs;
nregs = __builtin_popcount (mask);
if (!inc_sp)
ptr -= nregs;
else if (nregs & 1)
ptr++;
ptr++;
for (i = 0; i < 13; i++)
{
if ((mask & (1 << i)) == 0)
continue;
regno = unwind_frame_regs[12 - i];
if (i < 12 && unwind_frame_regs[11 - i] == (regno + 1)
&& (mask & (1 << (i + 1))) != 0
&& (((_uw)ptr) & 4) == 0
&& (regno & 1) == 0)
{
unwind_restore_pair (context, regno, ptr);
i++;
ptr += 2;
}
else
{
_Unwind_VRS_Set (context, _UVRSC_CORE, regno, _UVRSD_UINT32,
ptr);
ptr++;
}
}
ptr--;
if ((mask & (1 << 11)) == 0)
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
}
/* Unwind a 24-bit encoded frame. */
_Unwind_Reason_Code
__gnu_unwind_24bit (_Unwind_Context * context, _uw data, int compact)
{
_uw offset;
_uw mask;
_uw *ptr;
_uw tmp;
int ret_reg = unwind_frame_regs[data & 0xf];
if (ret_reg != R_B3)
{
_Unwind_VRS_Get (context, _UVRSC_CORE, unwind_frame_regs[data & 0xf],
_UVRSD_UINT32, &tmp);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, &tmp);
}
mask = (data >> 4) & 0x1fff;
offset = (data >> 17) & 0x7f;
if (offset == 0x7f)
_Unwind_VRS_Get (context, _UVRSC_CORE, R_A15, _UVRSD_UINT32, &ptr);
else
{
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
ptr += offset * 2;
}
if (compact)
pop_compact_frame (context, mask, ptr, offset != 0x7f);
else
pop_frame (context, mask, ptr, offset != 0x7f);
_Unwind_VRS_Get (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, &tmp);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_PC, _UVRSD_UINT32, &tmp);
return _URC_OK;
}
static void
unwind_pop_rts (_Unwind_Context * context)
{
_uw *ptr;
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
#ifdef _BIG_ENDIAN
_Unwind_VRS_Set (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, ptr + 1);
#else
_Unwind_VRS_Set (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, ptr + 2);
#endif
ptr += 3;
unwind_restore_pair (context, R_A10, ptr);
ptr += 2;
unwind_restore_pair (context, R_B10, ptr);
ptr += 2;
unwind_restore_pair (context, R_A12, ptr);
ptr += 2;
unwind_restore_pair (context, R_B12, ptr);
ptr += 2;
unwind_restore_pair (context, R_A14, ptr);
ptr += 2;
_Unwind_VRS_Set (context, _UVRSC_CORE, R_B14, _UVRSD_UINT32, ptr);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
/* PC will be set by implicit RETURN opcode. */
}
/* Execute the unwinding instructions described by UWS. */
_Unwind_Reason_Code
__gnu_unwind_execute (_Unwind_Context * context, __gnu_unwind_state * uws)
{
_uw op;
int inc_sp;
_uw reg;
_uw *ptr;
inc_sp = 1;
for (;;)
{
op = next_unwind_byte (uws);
if (op == CODE_FINISH)
{
/* Drop out of the loop. */
break;
}
if ((op & 0xc0) == 0)
{
/* sp += (imm6 << 3) + 8. */
_uw offset;
offset = ((op & 0x3f) << 3) + 8;
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &reg);
reg += offset;
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &reg);
continue;
}
if (op == 0xd2)
{
/* vsp = vsp + 0x204 + (uleb128 << 2). */
int shift;
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &reg);
op = next_unwind_byte (uws);
shift = 3;
while (op & 0x80)
{
reg += ((op & 0x7f) << shift);
shift += 7;
op = next_unwind_byte (uws);
}
reg += ((op & 0x7f) << shift) + 0x408;
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &reg);
continue;
}
if ((op & 0xe0) == 0x80)
{
/* POP bitmask */
_uw mask = ((op & 0x1f) << 8) | next_unwind_byte (uws);
if (mask == 0)
{
/* CANTUNWIND */
return _URC_FAILURE;
}
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
pop_frame (context, mask, ptr, inc_sp);
continue;
}
if ((op & 0xe0) == 0xa0)
{
/* POP bitmask (compact) */
_uw mask = ((op & 0x1f) << 8) | next_unwind_byte (uws);
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
pop_compact_frame (context, mask, ptr, inc_sp);
continue;
}
if ((op & 0xf0) == 0xc0)
{
/* POP registers */
int nregs = op & 0xf;
_Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &ptr);
while (nregs > 0)
{
op = next_unwind_byte (uws);
if ((op >> 4) != 0xf)
{
reg = unwind_frame_regs[op >> 4];
_Unwind_VRS_Set (context, _UVRSC_CORE, reg, _UVRSD_UINT32,
ptr);
nregs--;
}
ptr--;
if ((op & 0xf) != 0xf)
{
reg = unwind_frame_regs[op & 0xf];
_Unwind_VRS_Set (context, _UVRSC_CORE, reg, _UVRSD_UINT32,
ptr);
nregs--;
}
ptr--;
}
continue;
}
if (op == 0xd0)
{
/* MV FP, SP */
inc_sp = 0;
_Unwind_VRS_Get (context, _UVRSC_CORE, R_A15, _UVRSD_UINT32, &reg);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &reg);
continue;
}
if (op == 0xd1)
{
/* __cx6abi_pop_rts */
unwind_pop_rts (context);
break;
}
if ((op & 0xf0) == 0xe0)
{
/* B3 = reg. RETURN case already handled above. */
int regno = unwind_frame_regs[op & 0xf];
_Unwind_VRS_Get (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &reg);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, &reg);
continue;
}
/* Reserved. */
return _URC_FAILURE;
}
/* Implicit RETURN. */
_Unwind_VRS_Get (context, _UVRSC_CORE, R_B3, _UVRSD_UINT32, &reg);
_Unwind_VRS_Set (context, _UVRSC_CORE, R_PC, _UVRSD_UINT32, &reg);
return _URC_OK;
}
/* Execute the unwinding instructions associated with a frame. UCBP and
CONTEXT are the current exception object and virtual CPU state
respectively. */
_Unwind_Reason_Code
__gnu_unwind_frame (_Unwind_Control_Block * ucbp, _Unwind_Context * context)
{
_uw *ptr;
__gnu_unwind_state uws;
ptr = (_uw *) ucbp->pr_cache.ehtp;
/* Skip over the personality routine address. */
ptr++;
/* Setup the unwinder state. */
uws.data = (*ptr) << 8;
uws.next = ptr + 1;
uws.bytes_left = 3;
uws.words_left = ((*ptr) >> 24) & 0xff;
return __gnu_unwind_execute (context, &uws);
}
/* Data segment base pointer corresponding to the function catching
the exception. */
_Unwind_Ptr
_Unwind_GetDataRelBase (_Unwind_Context *context)
{
return _Unwind_GetGR (context, R_B14);
}
/* This should never be used. */
_Unwind_Ptr
_Unwind_GetTextRelBase (_Unwind_Context *context __attribute__ ((unused)))
{
abort ();
}
/* Only used by gcc personality routines, so can rely on a value they hid
there earlier. */
_Unwind_Ptr
_Unwind_GetRegionStart (_Unwind_Context *context)
{
_Unwind_Control_Block *ucbp;
ucbp = (_Unwind_Control_Block *) _Unwind_GetGR (context, UNWIND_POINTER_REG);
return (_Unwind_Ptr) ucbp->pr_cache.fnstart;
}
void *
_Unwind_GetLanguageSpecificData (_Unwind_Context *context)
{
_Unwind_Control_Block *ucbp;
_uw *ptr;
ucbp = (_Unwind_Control_Block *) _Unwind_GetGR (context, UNWIND_POINTER_REG);
ptr = (_uw *) ucbp->pr_cache.ehtp;
/* Skip the personality routine address. */
ptr++;
/* Skip the unwind opcodes. */
ptr += (((*ptr) >> 24) & 0xff) + 1;
return ptr;
}