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binutils-gdb/gdb/i386-fbsd-tdep.c
Simon Marchi 8480a37e14 gdb: pass frames as const frame_info_ptr & 
We currently pass frames to function by value, as `frame_info_ptr`.
This is somewhat expensive:

 - the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass
   by value
 - the constructors and destructor link/unlink the object in the global
   `frame_info_ptr::frame_list` list.  This is an `intrusive_list`, so
   it's not so bad: it's just assigning a few points, there's no memory
   allocation as if it was `std::list`, but still it's useless to do
   that over and over.

As suggested by Tom Tromey, change many function signatures to accept
`const frame_info_ptr &` instead of `frame_info_ptr`.

Some functions reassign their `frame_info_ptr` parameter, like:

  void
  the_func (frame_info_ptr frame)
  {
    for (; frame != nullptr; frame = get_prev_frame (frame))
      {
        ...
      }
  }

I wondered what to do about them, do I leave them as-is or change them
(and need to introduce a separate local variable that can be
re-assigned).  I opted for the later for consistency.  It might not be
clear why some functions take `const frame_info_ptr &` while others take
`frame_info_ptr`.  Also, if a function took a `frame_info_ptr` because
it did re-assign its parameter, I doubt that we would think to change it
to `const frame_info_ptr &` should the implementation change such that
it doesn't need to take `frame_info_ptr` anymore.  It seems better to
have a simple rule and apply it everywhere.

Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0
Approved-By: Andrew Burgess <aburgess@redhat.com>
2024-02-20 10:42:25 -05:00

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/* Target-dependent code for FreeBSD/i386.
Copyright (C) 2003-2024 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 "defs.h"
#include "gdbcore.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "trad-frame.h"
#include "tramp-frame.h"
#include "i386-fbsd-tdep.h"
#include "i386-tdep.h"
#include "i387-tdep.h"
#include "fbsd-tdep.h"
#include "solib-svr4.h"
#include "inferior.h"
/* The general-purpose regset consists of 19 32-bit slots. */
#define I386_FBSD_SIZEOF_GREGSET (19 * 4)
/* The segment base register set consists of 2 32-bit registers. */
#define I386_FBSD_SIZEOF_SEGBASES_REGSET (2 * 4)
/* Register maps. */
static const struct regcache_map_entry i386_fbsd_gregmap[] =
{
{ 1, I386_FS_REGNUM, 4 },
{ 1, I386_ES_REGNUM, 4 },
{ 1, I386_DS_REGNUM, 4 },
{ 1, I386_EDI_REGNUM, 0 },
{ 1, I386_ESI_REGNUM, 0 },
{ 1, I386_EBP_REGNUM, 0 },
{ 1, REGCACHE_MAP_SKIP, 4 }, /* isp */
{ 1, I386_EBX_REGNUM, 0 },
{ 1, I386_EDX_REGNUM, 0 },
{ 1, I386_ECX_REGNUM, 0 },
{ 1, I386_EAX_REGNUM, 0 },
{ 1, REGCACHE_MAP_SKIP, 4 }, /* trapno */
{ 1, REGCACHE_MAP_SKIP, 4 }, /* err */
{ 1, I386_EIP_REGNUM, 0 },
{ 1, I386_CS_REGNUM, 4 },
{ 1, I386_EFLAGS_REGNUM, 0 },
{ 1, I386_ESP_REGNUM, 0 },
{ 1, I386_SS_REGNUM, 4 },
{ 1, I386_GS_REGNUM, 4 },
{ 0 }
};
static const struct regcache_map_entry i386_fbsd_segbases_regmap[] =
{
{ 1, I386_FSBASE_REGNUM, 0 },
{ 1, I386_GSBASE_REGNUM, 0 },
{ 0 }
};
/* This layout including fsbase and gsbase was adopted in FreeBSD
8.0. */
static const struct regcache_map_entry i386_fbsd_mcregmap[] =
{
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_onstack */
{ 1, I386_GS_REGNUM, 4 },
{ 1, I386_FS_REGNUM, 4 },
{ 1, I386_ES_REGNUM, 4 },
{ 1, I386_DS_REGNUM, 4 },
{ 1, I386_EDI_REGNUM, 0 },
{ 1, I386_ESI_REGNUM, 0 },
{ 1, I386_EBP_REGNUM, 0 },
{ 1, REGCACHE_MAP_SKIP, 4 }, /* isp */
{ 1, I386_EBX_REGNUM, 0 },
{ 1, I386_EDX_REGNUM, 0 },
{ 1, I386_ECX_REGNUM, 0 },
{ 1, I386_EAX_REGNUM, 0 },
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_trapno */
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_err */
{ 1, I386_EIP_REGNUM, 0 },
{ 1, I386_CS_REGNUM, 4 },
{ 1, I386_EFLAGS_REGNUM, 0 },
{ 1, I386_ESP_REGNUM, 0 },
{ 1, I386_SS_REGNUM, 4 },
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_len */
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_fpformat */
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_ownedfp */
{ 1, REGCACHE_MAP_SKIP, 4 }, /* mc_flags */
{ 128, REGCACHE_MAP_SKIP, 4 },/* mc_fpstate */
{ 1, I386_FSBASE_REGNUM, 0 },
{ 1, I386_GSBASE_REGNUM, 0 },
{ 0 }
};
/* Register set definitions. */
const struct regset i386_fbsd_gregset =
{
i386_fbsd_gregmap, regcache_supply_regset, regcache_collect_regset
};
const struct regset i386_fbsd_segbases_regset =
{
i386_fbsd_segbases_regmap, regcache_supply_regset, regcache_collect_regset
};
/* Support for signal handlers. */
/* In a signal frame, esp points to a 'struct sigframe' which is
defined as:
struct sigframe {
register_t sf_signum;
register_t sf_siginfo;
register_t sf_ucontext;
register_t sf_addr;
union {
__siginfohandler_t *sf_action;
__sighandler_t *sf_handler;
} sf_ahu;
ucontext_t sf_uc;
...
}
ucontext_t is defined as:
struct __ucontext {
sigset_t uc_sigmask;
mcontext_t uc_mcontext;
...
};
The mcontext_t contains the general purpose register set as well
as the floating point or XSAVE state. */
/* NB: There is a 12 byte padding hole between sf_ahu and sf_uc. */
#define I386_SIGFRAME_UCONTEXT_OFFSET 32
#define I386_UCONTEXT_MCONTEXT_OFFSET 16
#define I386_SIZEOF_MCONTEXT_T 640
/* Implement the "init" method of struct tramp_frame. */
static void
i386_fbsd_sigframe_init (const struct tramp_frame *self,
const frame_info_ptr &this_frame,
struct trad_frame_cache *this_cache,
CORE_ADDR func)
{
CORE_ADDR sp = get_frame_register_unsigned (this_frame, I386_ESP_REGNUM);
CORE_ADDR mcontext_addr
= (sp
+ I386_SIGFRAME_UCONTEXT_OFFSET
+ I386_UCONTEXT_MCONTEXT_OFFSET);
trad_frame_set_reg_regmap (this_cache, i386_fbsd_mcregmap, mcontext_addr,
I386_SIZEOF_MCONTEXT_T);
/* Don't bother with floating point or XSAVE state for now. The
current helper routines for parsing FXSAVE and XSAVE state only
work with regcaches. This could perhaps create a temporary
regcache, collect the register values from mc_fpstate and
mc_xfpustate, and then set register values in the trad_frame. */
trad_frame_set_id (this_cache, frame_id_build (sp, func));
}
static const struct tramp_frame i386_fbsd_sigframe =
{
SIGTRAMP_FRAME,
1,
{
{0x8d, ULONGEST_MAX}, /* lea SIGF_UC(%esp),%eax */
{0x44, ULONGEST_MAX},
{0x24, ULONGEST_MAX},
{0x20, ULONGEST_MAX},
{0x50, ULONGEST_MAX}, /* pushl %eax */
{0xf7, ULONGEST_MAX}, /* testl $PSL_VM,UC_EFLAGS(%eax) */
{0x40, ULONGEST_MAX},
{0x54, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x02, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x75, ULONGEST_MAX}, /* jne +3 */
{0x03, ULONGEST_MAX},
{0x8e, ULONGEST_MAX}, /* mov UC_GS(%eax),%gs */
{0x68, ULONGEST_MAX},
{0x14, ULONGEST_MAX},
{0xb8, ULONGEST_MAX}, /* movl $SYS_sigreturn,%eax */
{0xa1, ULONGEST_MAX},
{0x01, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x50, ULONGEST_MAX}, /* pushl %eax */
{0xcd, ULONGEST_MAX}, /* int $0x80 */
{0x80, ULONGEST_MAX},
{TRAMP_SENTINEL_INSN, ULONGEST_MAX}
},
i386_fbsd_sigframe_init
};
/* FreeBSD/i386 binaries running under an amd64 kernel use a different
trampoline. This trampoline differs from the i386 kernel trampoline
in that it omits a middle section that conditionally restores
%gs. */
static const struct tramp_frame i386_fbsd64_sigframe =
{
SIGTRAMP_FRAME,
1,
{
{0x8d, ULONGEST_MAX}, /* lea SIGF_UC(%esp),%eax */
{0x44, ULONGEST_MAX},
{0x24, ULONGEST_MAX},
{0x20, ULONGEST_MAX},
{0x50, ULONGEST_MAX}, /* pushl %eax */
{0xb8, ULONGEST_MAX}, /* movl $SYS_sigreturn,%eax */
{0xa1, ULONGEST_MAX},
{0x01, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x00, ULONGEST_MAX},
{0x50, ULONGEST_MAX}, /* pushl %eax */
{0xcd, ULONGEST_MAX}, /* int $0x80 */
{0x80, ULONGEST_MAX},
{TRAMP_SENTINEL_INSN, ULONGEST_MAX}
},
i386_fbsd_sigframe_init
};
/* See i386-fbsd-tdep.h. */
uint64_t
i386_fbsd_core_read_xsave_info (bfd *abfd, x86_xsave_layout &layout)
{
asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
if (xstate == nullptr)
return 0;
/* Check extended state size. */
size_t size = bfd_section_size (xstate);
if (size < X86_XSTATE_AVX_SIZE)
return 0;
char contents[8];
if (! bfd_get_section_contents (abfd, xstate, contents,
I386_FBSD_XSAVE_XCR0_OFFSET, 8))
{
warning (_("Couldn't read `xcr0' bytes from "
"`.reg-xstate' section in core file."));
return 0;
}
uint64_t xcr0 = bfd_get_64 (abfd, contents);
if (!i387_guess_xsave_layout (xcr0, size, layout))
return 0;
return xcr0;
}
/* See i386-fbsd-tdep.h. */
bool
i386_fbsd_core_read_x86_xsave_layout (struct gdbarch *gdbarch,
x86_xsave_layout &layout)
{
return i386_fbsd_core_read_xsave_info (current_program_space->core_bfd (),
layout) != 0;
}
/* Implement the core_read_description gdbarch method. */
static const struct target_desc *
i386fbsd_core_read_description (struct gdbarch *gdbarch,
struct target_ops *target,
bfd *abfd)
{
x86_xsave_layout layout;
uint64_t xcr0 = i386_fbsd_core_read_xsave_info (abfd, layout);
if (xcr0 == 0)
xcr0 = X86_XSTATE_X87_MASK;
return i386_target_description (xcr0, true);
}
/* Similar to i386_supply_fpregset, but use XSAVE extended state. */
static void
i386fbsd_supply_xstateregset (const struct regset *regset,
struct regcache *regcache, int regnum,
const void *xstateregs, size_t len)
{
i387_supply_xsave (regcache, regnum, xstateregs);
}
/* Similar to i386_collect_fpregset, but use XSAVE extended state. */
static void
i386fbsd_collect_xstateregset (const struct regset *regset,
const struct regcache *regcache,
int regnum, void *xstateregs, size_t len)
{
i387_collect_xsave (regcache, regnum, xstateregs, 1);
}
/* Register set definitions. */
static const struct regset i386fbsd_xstateregset =
{
NULL,
i386fbsd_supply_xstateregset,
i386fbsd_collect_xstateregset
};
/* Iterate over core file register note sections. */
static void
i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
cb (".reg", I386_FBSD_SIZEOF_GREGSET, I386_FBSD_SIZEOF_GREGSET,
&i386_fbsd_gregset, NULL, cb_data);
cb (".reg2", tdep->sizeof_fpregset, tdep->sizeof_fpregset, &i386_fpregset,
NULL, cb_data);
cb (".reg-x86-segbases", I386_FBSD_SIZEOF_SEGBASES_REGSET,
I386_FBSD_SIZEOF_SEGBASES_REGSET, &i386_fbsd_segbases_regset,
"segment bases", cb_data);
if (tdep->xsave_layout.sizeof_xsave != 0)
cb (".reg-xstate", tdep->xsave_layout.sizeof_xsave,
tdep->xsave_layout.sizeof_xsave, &i386fbsd_xstateregset,
"XSAVE extended state", cb_data);
}
/* Implement the get_thread_local_address gdbarch method. */
static CORE_ADDR
i386fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
CORE_ADDR lm_addr, CORE_ADDR offset)
{
regcache *regcache
= get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
target_fetch_registers (regcache, I386_GSBASE_REGNUM);
ULONGEST gsbase;
if (regcache->cooked_read (I386_GSBASE_REGNUM, &gsbase) != REG_VALID)
error (_("Unable to fetch %%gsbase"));
CORE_ADDR dtv_addr = gsbase + gdbarch_ptr_bit (gdbarch) / 8;
return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
}
static void
i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
/* Generic FreeBSD support. */
fbsd_init_abi (info, gdbarch);
/* Obviously FreeBSD is BSD-based. */
i386bsd_init_abi (info, gdbarch);
/* FreeBSD reserves some space for its FPU emulator in
`struct fpreg'. */
tdep->sizeof_fpregset = 176;
/* FreeBSD uses -freg-struct-return by default. */
tdep->struct_return = reg_struct_return;
tramp_frame_prepend_unwinder (gdbarch, &i386_fbsd_sigframe);
tramp_frame_prepend_unwinder (gdbarch, &i386_fbsd64_sigframe);
i386_elf_init_abi (info, gdbarch);
tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
set_gdbarch_core_read_x86_xsave_layout
(gdbarch, i386_fbsd_core_read_x86_xsave_layout);
/* Iterate over core file register note sections. */
set_gdbarch_iterate_over_regset_sections
(gdbarch, i386fbsd_iterate_over_regset_sections);
set_gdbarch_core_read_description (gdbarch,
i386fbsd_core_read_description);
/* FreeBSD uses SVR4-style shared libraries. */
set_solib_svr4_fetch_link_map_offsets
(gdbarch, svr4_ilp32_fetch_link_map_offsets);
set_gdbarch_fetch_tls_load_module_address (gdbarch,
svr4_fetch_objfile_link_map);
set_gdbarch_get_thread_local_address (gdbarch,
i386fbsd_get_thread_local_address);
}
void _initialize_i386fbsd_tdep ();
void
_initialize_i386fbsd_tdep ()
{
gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
i386fbsd_init_abi);
}
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