Files
binutils-gdb/gdb/amd64-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/amd64.
Copyright (C) 2003-2025 Free Software Foundation, 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 "arch-utils.h"
#include "frame.h"
#include "gdbcore.h"
#include "osabi.h"
#include "symtab.h"
#include "amd64-tdep.h"
#include "gdbsupport/x86-xstate.h"
#include "netbsd-tdep.h"
#include "solib-svr4.h"
/* Support for signal handlers. */
/* Return whether THIS_FRAME corresponds to a NetBSD sigtramp
routine. */
static int
amd64nbsd_sigtramp_p (const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
const char *name;
find_pc_partial_function (pc, &name, NULL, NULL);
return nbsd_pc_in_sigtramp (pc, name);
}
/* Assuming THIS_FRAME corresponds to a NetBSD sigtramp routine,
return the address of the associated mcontext structure. */
static CORE_ADDR
amd64nbsd_mcontext_addr (const frame_info_ptr &this_frame)
{
CORE_ADDR addr;
/* The register %r15 points at `struct ucontext' upon entry of a
signal trampoline. */
addr = get_frame_register_unsigned (this_frame, AMD64_R15_REGNUM);
/* The mcontext structure lives as offset 56 in `struct ucontext'. */
return addr + 56;
}
/* NetBSD 2.0 or later. */
/* Mapping between the general-purpose registers in `struct reg'
format and GDB's register cache layout. */
/* From <machine/reg.h>. */
int amd64nbsd_r_reg_offset[] =
{
14 * 8, /* %rax */
13 * 8, /* %rbx */
3 * 8, /* %rcx */
2 * 8, /* %rdx */
1 * 8, /* %rsi */
0 * 8, /* %rdi */
12 * 8, /* %rbp */
24 * 8, /* %rsp */
4 * 8, /* %r8 .. */
5 * 8,
6 * 8,
7 * 8,
8 * 8,
9 * 8,
10 * 8,
11 * 8, /* ... %r15 */
21 * 8, /* %rip */
23 * 8, /* %eflags */
22 * 8, /* %cs */
25 * 8, /* %ss */
18 * 8, /* %ds */
17 * 8, /* %es */
16 * 8, /* %fs */
15 * 8 /* %gs */
};
static void
amd64nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
/* Initialize general-purpose register set details first. */
tdep->gregset_reg_offset = amd64nbsd_r_reg_offset;
tdep->gregset_num_regs = ARRAY_SIZE (amd64nbsd_r_reg_offset);
tdep->sizeof_gregset = 26 * 8;
amd64_init_abi (info, gdbarch,
amd64_target_description (X86_XSTATE_SSE_MASK, true));
nbsd_init_abi (info, gdbarch);
tdep->jb_pc_offset = 7 * 8;
/* NetBSD has its own convention for signal trampolines. */
tdep->sigtramp_p = amd64nbsd_sigtramp_p;
tdep->sigcontext_addr = amd64nbsd_mcontext_addr;
tdep->sc_reg_offset = amd64nbsd_r_reg_offset;
tdep->sc_num_regs = ARRAY_SIZE (amd64nbsd_r_reg_offset);
/* NetBSD uses SVR4-style shared libraries. */
set_solib_svr4_ops (gdbarch, make_svr4_lp64_solib_ops);
}
INIT_GDB_FILE (amd64nbsd_tdep)
{
/* The NetBSD/amd64 native dependent code makes this assumption. */
gdb_assert (ARRAY_SIZE (amd64nbsd_r_reg_offset) == AMD64_NUM_GREGS);
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
GDB_OSABI_NETBSD, amd64nbsd_init_abi);
}