/* Copyright (C) 2009-2024 Free Software Foundation, Inc.
Contributed by ARM Ltd.
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
. */
/* Always include AArch64 unwinder header file. */
#include "config/aarch64/aarch64-unwind.h"
#ifndef inhibit_libc
#include
#include
#include
/* Since insns are always stored LE, on a BE system the opcodes will
be loaded byte-reversed. Therefore, define two sets of opcodes,
one for LE and one for BE. */
#if __AARCH64EB__
#define MOVZ_X8_8B 0x681180d2
#define SVC_0 0x010000d4
#else
#define MOVZ_X8_8B 0xd2801168
#define SVC_0 0xd4000001
#endif
#define MD_FALLBACK_FRAME_STATE_FOR aarch64_fallback_frame_state
#ifndef FPSIMD_MAGIC
#define FPSIMD_MAGIC 0x46508001
#endif
#ifndef TPIDR2_MAGIC
#define TPIDR2_MAGIC 0x54504902
#endif
#ifndef ZA_MAGIC
#define ZA_MAGIC 0x54366345
#endif
#ifndef EXTRA_MAGIC
#define EXTRA_MAGIC 0x45585401
#endif
static _Unwind_Reason_Code
aarch64_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState * fs)
{
/* The kernel creates an rt_sigframe on the stack immediately prior
to delivering a signal.
This structure must have the same shape as the linux kernel
equivalent. */
struct rt_sigframe
{
siginfo_t info;
ucontext_t uc;
};
struct tpidr2_block
{
uint64_t za_save_buffer;
uint16_t num_za_save_slices;
uint8_t reserved[6];
};
struct za_block
{
struct _aarch64_ctx head;
uint16_t vl;
uint16_t reserved[3];
uint64_t data;
};
struct rt_sigframe *rt_;
_Unwind_Ptr new_cfa;
unsigned *pc = context->ra;
struct sigcontext *sc;
struct _aarch64_ctx *extension_marker;
int i;
/* A signal frame will have a return address pointing to
__default_sa_restorer. This code is hardwired as:
0xd2801168 movz x8, #0x8b
0xd4000001 svc 0x0
*/
if (pc[0] != MOVZ_X8_8B || pc[1] != SVC_0)
{
return _URC_END_OF_STACK;
}
rt_ = context->cfa;
/* Historically, the uc_mcontext member was of type struct sigcontext, but
glibc uses a different type now with member names in the implementation
namespace. */
sc = (struct sigcontext *) &rt_->uc.uc_mcontext;
/* This define duplicates the definition in aarch64.md */
#define SP_REGNUM 31
new_cfa = (_Unwind_Ptr) sc;
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
for (i = 0; i < AARCH64_DWARF_NUMBER_R; i++)
{
fs->regs.how[AARCH64_DWARF_R0 + i] = REG_SAVED_OFFSET;
fs->regs.reg[AARCH64_DWARF_R0 + i].loc.offset =
(_Unwind_Ptr) & (sc->regs[i]) - new_cfa;
}
/* The core context may be extended with an arbitrary set of
additional contexts appended sequentially. Each additional
context contains a magic identifier and size in bytes. The size
field can be used to skip over unrecognized context extensions.
The end of the context sequence is marked by a context with magic
0 or size 0. */
struct tpidr2_block *tpidr2 = 0;
struct za_block *za_ctx = 0;
for (extension_marker = (struct _aarch64_ctx *) &sc->__reserved;
extension_marker->magic;
extension_marker = (struct _aarch64_ctx *)
((unsigned char *) extension_marker + extension_marker->size))
{
restart:
if (extension_marker->magic == FPSIMD_MAGIC)
{
struct fpsimd_context *ctx =
(struct fpsimd_context *) extension_marker;
int i;
for (i = 0; i < AARCH64_DWARF_NUMBER_V; i++)
{
_Unwind_Sword offset;
fs->regs.how[AARCH64_DWARF_V0 + i] = REG_SAVED_OFFSET;
/* sigcontext contains 32 128bit registers for V0 to
V31. The kernel will have saved the contents of the
V registers. We want to unwind the callee save D
registers. Each D register comprises the least
significant half of the corresponding V register. We
need to offset into the saved V register dependent on
our endianness to find the saved D register. */
offset = (_Unwind_Ptr) & (ctx->vregs[i]) - new_cfa;
/* The endianness adjustment code below expects that a
saved V register is 16 bytes. */
gcc_assert (sizeof (ctx->vregs[0]) == 16);
#if defined (__AARCH64EB__)
offset = offset + 8;
#endif
fs->regs.reg[AARCH64_DWARF_V0 + i].loc.offset = offset;
}
}
else if (extension_marker->magic == TPIDR2_MAGIC)
{
/* A TPIDR2 context.
All the casting is to support big-endian ILP32. We could read
directly into TPIDR2 otherwise. */
struct { struct _aarch64_ctx h; uint64_t tpidr2; } *ctx
= (void *)extension_marker;
#if defined (__ILP32__)
tpidr2 = (struct tpidr2_block *) (uintptr_t) ctx->tpidr2;
#else
tpidr2 = (struct tpidr2_block *) ctx->tpidr2;
#endif
}
else if (extension_marker->magic == ZA_MAGIC)
/* A ZA context. We interpret this later. */
za_ctx = (void *)extension_marker;
else if (extension_marker->magic == EXTRA_MAGIC)
{
/* Extra context. The ABI guarantees that the next _aarch64_ctx
in the current list will be the zero terminator, so we can simply
switch to the new list and continue from there. The new list is
also zero-terminated.
As above, the casting is to support big-endian ILP32. */
struct { struct _aarch64_ctx h; uint64_t next; } *ctx
= (void *)extension_marker;
#if defined (__ILP32__)
extension_marker = (struct _aarch64_ctx *) (uintptr_t) ctx->next;
#else
extension_marker = (struct _aarch64_ctx *) ctx->next;
#endif
goto restart;
}
else
{
/* There is context provided that we do not recognize! */
}
}
/* Signal handlers are entered with ZA in the off state (TPIDR2_ELO==0 and
PSTATE.ZA==0). The normal process when transitioning from ZA being
dormant to ZA being off is to commit the lazy save; see the AAPCS64
for details. However, this is not done when entering a signal handler.
Instead, linux saves the old contents of ZA and TPIDR2_EL0 to the
sigcontext without interpreting them further.
Therefore, if a signal handler throws an exception to code outside the
signal handler, the unwinder must commit the lazy save after the fact.
Committing a lazy save means:
(1) Storing the contents of ZA into the buffer provided by TPIDR2_EL0.
(2) Setting TPIDR2_EL0 to zero.
(3) Turning ZA off.
(2) and (3) have already been done by the call to __libgcc_arm_za_disable.
(1) involves copying data from the ZA sigcontext entry to the
corresponding lazy save buffer. */
if (tpidr2 && za_ctx && tpidr2->za_save_buffer)
{
/* There is a 16-bit vector length (measured in bytes) at ZA_CTX + 8.
The data itself starts at ZA_CTX + 16.
As above, the casting is to support big-endian ILP32. */
uint16_t vl = za_ctx->vl;
#if defined (__ILP32__)
void *save_buffer = (void *) (uintptr_t) tpidr2->za_save_buffer;
const void *za_buffer = (void *) (uintptr_t) &za_ctx->data;
#else
void *save_buffer = (void *) tpidr2->za_save_buffer;
const void *za_buffer = (void *) &za_ctx->data;
#endif
uint64_t num_slices = tpidr2->num_za_save_slices;
if (num_slices > vl)
num_slices = vl;
memcpy (save_buffer, za_buffer, num_slices * vl);
}
fs->regs.how[31] = REG_SAVED_OFFSET;
fs->regs.reg[31].loc.offset = (_Unwind_Ptr) & (sc->sp) - new_cfa;
fs->signal_frame = 1;
fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__] =
REG_SAVED_VAL_OFFSET;
fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset =
(_Unwind_Ptr) (sc->pc) - new_cfa;
fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
return _URC_NO_REASON;
}
#endif