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binutils-gdb/gdb/ppc-netbsd-tdep.c
Simon Marchi a2e3cce344 gdb/solib: C++ify solib_ops 
Convert solib_ops into an abstract base class (with abstract methods,
some of them with default implementations) and convert all the existing
solib_ops instances to solib_ops derived classes / implementations.

Prior to this patch, solib_ops is a structure holding function pointers,
of which there are only a handful of global instances (in the
`solib-*.c` files).  When passing an `solib_ops *` around, it's a
pointer to one of these instances.  After this patch, there are no more
global solib_ops instances.  Instances are created as needed and stored
in struct program_space.  These instances could eventually be made to
contain the program space-specific data, which is currently kept in
per-program space registries (I have some pending patches for that).

Prior to this patch, `gdbarch_so_ops` is a gdbarch method that returns a
pointer to the appropriate solib_ops implementation for the gdbarch.
This is replaced with the `gdbarch_make_solib_ops` method, which returns
a new instance of the appropriate solib_ops implementation for this
gdbarch.  This requires introducing some factory functions for the
various solib_ops implementation, to be used as `gdbarch_make_solib_ops`
callbacks.  For instance:

    solib_ops_up
    make_linux_ilp32_svr4_solib_ops ()
    {
      return std::make_unique<linux_ilp32_svr4_solib_ops> ();
    }

The previous code is full of cases of tdep files copying some base
solib_ops implementation, and overriding one or more function pointer
(see ppc_linux_init_abi, for instance).  I tried to convert all of this
is a class hierarchy.  I like that it's now possible to get a good
static view of all the existing solib_ops variants.  The hierarchy looks
like this:

    solib_ops
    ├── aix_solib_ops
    ├── darwin_solib_ops
    ├── dsbt_solib_ops
    ├── frv_solib_ops
    ├── rocm_solib_ops
    ├── svr4_solib_ops
    │   ├── ilp32_svr4_solib_ops
    │   ├── lp64_svr4_solib_ops
    │   ├── linux_ilp32_svr4_solib_ops
    │   │   ├── mips_linux_ilp32_svr4_solib_ops
    │   │   └── ppc_linux_ilp32_svr4_solib_ops
    │   ├── linux_lp64_svr4_solib_ops
    │   │   └── mips_linux_lp64_svr4_solib_ops
    │   ├── mips_nbsd_ilp32_svr4_solib_ops
    │   ├── mips_nbsd_lp64_svr4_solib_ops
    │   ├── mips_fbsd_ilp32_svr4_solib_ops
    │   └── mips_fbsd_lp64_svr4_solib_ops
    └── target_solib_ops
        └── windows_solib_ops

The solib-svr4 code has per-arch specialization to provide a
link_map_offsets, containing the offsets of the interesting fields in
`struct link_map` on that particular architecture.  Prior to this patch,
arches would set a callback returning the appropriate link_map_offsets
by calling `set_solib_svr4_fetch_link_map_offsets`, which also happened
to set the gdbarch's so_ops to `&svr_so_ops`.  I converted this to an
abstract virtual method of `struct svr4_solib_ops`, meaning that all
classes deriving from svr4_solib_ops must provide a method returning the
appropriate link_map_offsets for the architecture.  I renamed
`set_solib_svr4_fetch_link_map_offsets` to `set_solib_svr4_ops`.  This
function is still necessary because it also calls
set_gdbarch_iterate_over_objfiles_in_search_order, but if it was not for
that, we could get rid of it.

There is an instance of CRTP in mips-linux-tdep.c, because both
mips_linux_ilp32_svr4_solib_ops and mips_linux_lp64_svr4_solib_ops need
to derive from different SVR4 base classes (linux_ilp32_svr4_solib_ops
and linux_lp64_svr4_solib_ops), but they both want to override the
in_dynsym_resolve_code method with the same implementation.

The solib_ops::supports_namespaces method is new: the support for
namespaces was previously predicated by the presence or absence of a
find_solib_ns method.  It now needs to be explicit.

There is a new progspace::release_solib_ops method, which is only needed
for rocm_solib_ops.  For the moment, rocm_solib_ops replaces and wraps
the existing svr4_solib_ops instance, in order to combine the results of
the two.  The plan is to have a subsequent patch to allow program spaces to have
multiple solib_ops, removing the need for release_solib_ops.

Speaking of rocm_solib_ops: it previously overrode only a few methods by
copying svr4_solib_ops and overwriting some function pointers.  Now, it
needs to implement all the methods that svr4_solib_ops implements, in
order to forward the call.  Otherwise, the default solib_ops method
would be called, hiding the svr4_solib_ops implementation.  Again, this
can be removed once we have support for multiple solib_ops in a
program_space.

There is also a small change in how rocm_solib_ops is activated.  Prior
to this patch, it's done at the end of rocm_update_solib_list.  Since it
overrides the function pointer in the static svr4_solib_ops, and then
overwrites the host gdbarch, so_ops field, it's something that happens
only once.  After the patch though, we need to set rocm_solib_ops in all
the program spaces that appear.  We do this in
rocm_solib_target_inferior_created and in the new
rocm_solib_target_inferior_execd.  After this, I will explore doing a
change where rocm_solib_ops is only set when we detect the ROCm runtime
is loaded.

Change-Id: I5896b5bcbf8bdb024d67980380feba1ffefaa4c9
Approved-By: Pedro Alves <pedro@palves.net>
2025-06-26 14:08:31 -04:00

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/* Target-dependent code for NetBSD/powerpc.
Copyright (C) 2002-2025 Free Software Foundation, Inc.
Contributed by Wasabi Systems, Inc.
This file is part of GDB.
This program 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 of the License, or
(at your option) any later version.
This program 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.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "gdbtypes.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "trad-frame.h"
#include "tramp-frame.h"
#include "ppc-tdep.h"
#include "netbsd-tdep.h"
#include "solib-svr4.h"
/* Register offsets from <machine/reg.h>. */
static ppc_reg_offsets ppcnbsd_reg_offsets;
/* Core file support. */
/* NetBSD/powerpc register sets. */
const struct regset ppcnbsd_gregset =
{
&ppcnbsd_reg_offsets,
ppc_supply_gregset
};
const struct regset ppcnbsd_fpregset =
{
&ppcnbsd_reg_offsets,
ppc_supply_fpregset
};
/* Iterate over core file register note sections. */
static void
ppcnbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
cb (".reg", 148, 148, &ppcnbsd_gregset, NULL, cb_data);
cb (".reg2", 264, 264, &ppcnbsd_fpregset, NULL, cb_data);
}
/* NetBSD is confused. It appears that 1.5 was using the correct SVR4
convention but, 1.6 switched to the below broken convention. For
the moment use the broken convention. Ulgh! */
static enum return_value_convention
ppcnbsd_return_value (struct gdbarch *gdbarch, struct value *function,
struct type *valtype, struct regcache *regcache,
gdb_byte *readbuf, const gdb_byte *writebuf)
{
#if 0
if ((valtype->code () == TYPE_CODE_STRUCT
|| valtype->code () == TYPE_CODE_UNION)
&& !((valtype->length () == 16 || valtype->length () == 8)
&& valtype->is_vector ())
&& !(valtype->length () == 1
|| valtype->length () == 2
|| valtype->length () == 4
|| valtype->length () == 8))
return RETURN_VALUE_STRUCT_CONVENTION;
else
#endif
return ppc_sysv_abi_broken_return_value (gdbarch, function, valtype,
regcache, readbuf, writebuf);
}
/* Signal trampolines. */
extern const struct tramp_frame ppcnbsd2_sigtramp;
static void
ppcnbsd_sigtramp_cache_init (const struct tramp_frame *self,
const frame_info_ptr &this_frame,
struct trad_frame_cache *this_cache,
CORE_ADDR func)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
ppc_gdbarch_tdep *tdep = gdbarch_tdep<ppc_gdbarch_tdep> (gdbarch);
CORE_ADDR addr, base;
int i;
base = get_frame_register_unsigned (this_frame,
gdbarch_sp_regnum (gdbarch));
if (self == &ppcnbsd2_sigtramp)
addr = base + 0x10 + 2 * tdep->wordsize;
else
addr = base + 0x18 + 2 * tdep->wordsize;
for (i = 0; i < ppc_num_gprs; i++, addr += tdep->wordsize)
{
int regnum = i + tdep->ppc_gp0_regnum;
trad_frame_set_reg_addr (this_cache, regnum, addr);
}
trad_frame_set_reg_addr (this_cache, tdep->ppc_lr_regnum, addr);
addr += tdep->wordsize;
trad_frame_set_reg_addr (this_cache, tdep->ppc_cr_regnum, addr);
addr += tdep->wordsize;
trad_frame_set_reg_addr (this_cache, tdep->ppc_xer_regnum, addr);
addr += tdep->wordsize;
trad_frame_set_reg_addr (this_cache, tdep->ppc_ctr_regnum, addr);
addr += tdep->wordsize;
trad_frame_set_reg_addr (this_cache, gdbarch_pc_regnum (gdbarch),
addr); /* SRR0? */
addr += tdep->wordsize;
/* Construct the frame ID using the function start. */
trad_frame_set_id (this_cache, frame_id_build (base, func));
}
static const struct tramp_frame ppcnbsd_sigtramp =
{
SIGTRAMP_FRAME,
4,
{
{ 0x3821fff0, ULONGEST_MAX }, /* add r1,r1,-16 */
{ 0x4e800021, ULONGEST_MAX }, /* blrl */
{ 0x38610018, ULONGEST_MAX }, /* addi r3,r1,24 */
{ 0x38000127, ULONGEST_MAX }, /* li r0,295 */
{ 0x44000002, ULONGEST_MAX }, /* sc */
{ 0x38000001, ULONGEST_MAX }, /* li r0,1 */
{ 0x44000002, ULONGEST_MAX }, /* sc */
{ TRAMP_SENTINEL_INSN, ULONGEST_MAX }
},
ppcnbsd_sigtramp_cache_init
};
/* NetBSD 2.0 introduced a slightly different signal trampoline. */
const struct tramp_frame ppcnbsd2_sigtramp =
{
SIGTRAMP_FRAME,
4,
{
{ 0x3821fff0, ULONGEST_MAX }, /* add r1,r1,-16 */
{ 0x4e800021, ULONGEST_MAX }, /* blrl */
{ 0x38610010, ULONGEST_MAX }, /* addi r3,r1,16 */
{ 0x38000127, ULONGEST_MAX }, /* li r0,295 */
{ 0x44000002, ULONGEST_MAX }, /* sc */
{ 0x38000001, ULONGEST_MAX }, /* li r0,1 */
{ 0x44000002, ULONGEST_MAX }, /* sc */
{ TRAMP_SENTINEL_INSN, ULONGEST_MAX }
},
ppcnbsd_sigtramp_cache_init
};
static void
ppcnbsd_init_abi (struct gdbarch_info info,
struct gdbarch *gdbarch)
{
nbsd_init_abi (info, gdbarch);
/* For NetBSD, this is an on again, off again thing. Some systems
do use the broken struct convention, and some don't. */
set_gdbarch_return_value (gdbarch, ppcnbsd_return_value);
/* NetBSD uses SVR4-style shared libraries. */
set_solib_svr4_ops (gdbarch, make_svr4_ilp32_solib_ops);
set_gdbarch_iterate_over_regset_sections
(gdbarch, ppcnbsd_iterate_over_regset_sections);
tramp_frame_prepend_unwinder (gdbarch, &ppcnbsd_sigtramp);
tramp_frame_prepend_unwinder (gdbarch, &ppcnbsd2_sigtramp);
}
INIT_GDB_FILE (ppcnbsd_tdep)
{
gdbarch_register_osabi (bfd_arch_powerpc, 0, GDB_OSABI_NETBSD,
ppcnbsd_init_abi);
/* Avoid initializing the register offsets again if they were
already initialized by ppc-netbsd-nat.c. */
if (ppcnbsd_reg_offsets.pc_offset == 0)
{
/* General-purpose registers. */
ppcnbsd_reg_offsets.r0_offset = 0;
ppcnbsd_reg_offsets.gpr_size = 4;
ppcnbsd_reg_offsets.xr_size = 4;
ppcnbsd_reg_offsets.lr_offset = 128;
ppcnbsd_reg_offsets.cr_offset = 132;
ppcnbsd_reg_offsets.xer_offset = 136;
ppcnbsd_reg_offsets.ctr_offset = 140;
ppcnbsd_reg_offsets.pc_offset = 144;
ppcnbsd_reg_offsets.ps_offset = -1;
ppcnbsd_reg_offsets.mq_offset = -1;
/* Floating-point registers. */
ppcnbsd_reg_offsets.f0_offset = 0;
ppcnbsd_reg_offsets.fpscr_offset = 256;
ppcnbsd_reg_offsets.fpscr_size = 4;
}
}
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