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binutils-gdb/gdb/i386-fbsd-tdep.c
Simon Marchi 7438771288 gdb: remove regcache's address space 
While looking at the regcache code, I noticed that the address space
(passed to regcache when constructing it, and available through
regcache::aspace) wasn't relevant for the regcache itself.  Callers of
regcache::aspace use that method because it appears to be a convenient
way of getting the address space for a thread, if you already have the
regcache.  But there is always another way to get the address space, as
the callers pretty much always know which thread they are dealing with.
The regcache code itself doesn't use the address space.

This patch removes anything related to address_space from the regcache
code, and updates callers to get it from the thread in context.  This
removes a bit of unnecessary complexity from the regcache code.

The current get_thread_arch_regcache function gets an address_space for
the given thread using the target_thread_address_space function (which
calls the target_ops::thread_address_space method).  This suggest that
there might have been the intention of supporting per-thread address
spaces.  But digging through the history, I did not find any such case.
Maybe this method was just added because we needed a way to get an
address space from a ptid (because constructing a regcache required an
address space), and this seemed like the right way to do it, I don't
know.

The only implementations of thread_address_space and
process_stratum_target::thread_address_space and
linux_nat_target::thread_address_space, which essentially just return
the inferior's address space.  And thread_address_space is only used in
the current get_thread_arch_regcache, which gets removed.  So, I think
that the thread_address_space target method can be removed, and we can
assume that it's fine to use the inferior's address space everywhere.
Callers of regcache::aspace are updated to get the address space from
the relevant inferior, either using some context they already know
about, or in last resort using the current global context.

So, to summarize:

 - remove everything in regcache related to address spaces
 - in particular, remove get_thread_arch_regcache, and rename
   get_thread_arch_aspace_regcache to get_thread_arch_regcache
 - remove target_ops::thread_address_space, and
   target_thread_address_space
 - adjust all users of regcache::aspace to get the address space another
   way

Change-Id: I04fd41b22c83fe486522af7851c75bcfb31c88c7
2023-11-17 20:01:35 +00:00

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/* Target-dependent code for FreeBSD/i386.
Copyright (C) 2003-2023 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,
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 (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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