binutils-gdb/gdb/i386-fbsd-tdep.c
John Baldwin ce25aa57a3 Support TLS variables on FreeBSD/i386.
Derive the pointer to the DTV array from the gs_base register.  As
with FreeBSD/amd64, gs_base is currently only available via the native
target.

gdb/ChangeLog:

	* i386-fbsd-tdep.c (i386fbsd_get_thread_local_address): New.
	(i386fbsd_init_abi): Install gdbarch
	"fetch_tls_load_module_address" and "get_thread_local_address"
	methods.
2019-03-12 13:45:48 -07:00

458 lines
13 KiB
C

/* Target-dependent code for FreeBSD/i386.
Copyright (C) 2003-2019 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 "arch-utils.h"
#include "gdbcore.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "i386-fbsd-tdep.h"
#include "common/x86-xstate.h"
#include "i386-tdep.h"
#include "i387-tdep.h"
#include "fbsd-tdep.h"
#include "solib-svr4.h"
/* Support for signal handlers. */
/* Return whether THIS_FRAME corresponds to a FreeBSD sigtramp
routine. */
/* FreeBSD/i386 supports three different signal trampolines, one for
versions before 4.0, a second for 4.x, and a third for 5.0 and
later. To complicate matters, FreeBSD/i386 binaries running under
an amd64 kernel use a different set of trampolines. These
trampolines differ from the i386 kernel trampolines in that they
omit a middle section that conditionally restores %gs. */
static const gdb_byte i386fbsd_sigtramp_start[] =
{
0x8d, 0x44, 0x24, 0x20, /* lea SIGF_UC(%esp),%eax */
0x50 /* pushl %eax */
};
static const gdb_byte i386fbsd_sigtramp_middle[] =
{
0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
/* testl $PSL_VM,UC_EFLAGS(%eax) */
0x75, 0x03, /* jne +3 */
0x8e, 0x68, 0x14 /* mov UC_GS(%eax),%gs */
};
static const gdb_byte i386fbsd_sigtramp_end[] =
{
0xb8, 0xa1, 0x01, 0x00, 0x00, /* movl $SYS_sigreturn,%eax */
0x50, /* pushl %eax */
0xcd, 0x80 /* int $0x80 */
};
static const gdb_byte i386fbsd_freebsd4_sigtramp_start[] =
{
0x8d, 0x44, 0x24, 0x14, /* lea SIGF_UC4(%esp),%eax */
0x50 /* pushl %eax */
};
static const gdb_byte i386fbsd_freebsd4_sigtramp_middle[] =
{
0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
/* testl $PSL_VM,UC4_EFLAGS(%eax) */
0x75, 0x03, /* jne +3 */
0x8e, 0x68, 0x14 /* mov UC4_GS(%eax),%gs */
};
static const gdb_byte i386fbsd_freebsd4_sigtramp_end[] =
{
0xb8, 0x58, 0x01, 0x00, 0x00, /* movl $344,%eax */
0x50, /* pushl %eax */
0xcd, 0x80 /* int $0x80 */
};
static const gdb_byte i386fbsd_osigtramp_start[] =
{
0x8d, 0x44, 0x24, 0x14, /* lea SIGF_SC(%esp),%eax */
0x50 /* pushl %eax */
};
static const gdb_byte i386fbsd_osigtramp_middle[] =
{
0xf7, 0x40, 0x18, 0x00, 0x00, 0x02, 0x00,
/* testl $PSL_VM,SC_PS(%eax) */
0x75, 0x03, /* jne +3 */
0x8e, 0x68, 0x44 /* mov SC_GS(%eax),%gs */
};
static const gdb_byte i386fbsd_osigtramp_end[] =
{
0xb8, 0x67, 0x00, 0x00, 0x00, /* movl $103,%eax */
0x50, /* pushl %eax */
0xcd, 0x80 /* int $0x80 */
};
/* The three different trampolines are all the same size. */
gdb_static_assert (sizeof i386fbsd_sigtramp_start
== sizeof i386fbsd_freebsd4_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_start
== sizeof i386fbsd_osigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
== sizeof i386fbsd_freebsd4_sigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
== sizeof i386fbsd_osigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
== sizeof i386fbsd_freebsd4_sigtramp_end);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
== sizeof i386fbsd_osigtramp_end);
/* We assume that the middle is the largest chunk below. */
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
> sizeof i386fbsd_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
> sizeof i386fbsd_sigtramp_end);
static int
i386fbsd_sigtramp_p (struct frame_info *this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
gdb_byte buf[sizeof i386fbsd_sigtramp_middle];
const gdb_byte *middle, *end;
/* Look for a matching start. */
if (!safe_frame_unwind_memory (this_frame, pc, buf,
sizeof i386fbsd_sigtramp_start))
return 0;
if (memcmp (buf, i386fbsd_sigtramp_start, sizeof i386fbsd_sigtramp_start)
== 0)
{
middle = i386fbsd_sigtramp_middle;
end = i386fbsd_sigtramp_end;
}
else if (memcmp (buf, i386fbsd_freebsd4_sigtramp_start,
sizeof i386fbsd_freebsd4_sigtramp_start) == 0)
{
middle = i386fbsd_freebsd4_sigtramp_middle;
end = i386fbsd_freebsd4_sigtramp_end;
}
else if (memcmp (buf, i386fbsd_osigtramp_start,
sizeof i386fbsd_osigtramp_start) == 0)
{
middle = i386fbsd_osigtramp_middle;
end = i386fbsd_osigtramp_end;
}
else
return 0;
/* Since the end is shorter than the middle, check for a matching end
next. */
pc += sizeof i386fbsd_sigtramp_start;
if (!safe_frame_unwind_memory (this_frame, pc, buf,
sizeof i386fbsd_sigtramp_end))
return 0;
if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) == 0)
return 1;
/* If the end didn't match, check for a matching middle. */
if (!safe_frame_unwind_memory (this_frame, pc, buf,
sizeof i386fbsd_sigtramp_middle))
return 0;
if (memcmp (buf, middle, sizeof i386fbsd_sigtramp_middle) != 0)
return 0;
/* The middle matched, check for a matching end. */
pc += sizeof i386fbsd_sigtramp_middle;
if (!safe_frame_unwind_memory (this_frame, pc, buf,
sizeof i386fbsd_sigtramp_end))
return 0;
if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) != 0)
return 0;
return 1;
}
/* FreeBSD 3.0-RELEASE or later. */
/* From <machine/reg.h>. */
static int i386fbsd_r_reg_offset[] =
{
9 * 4, 8 * 4, 7 * 4, 6 * 4, /* %eax, %ecx, %edx, %ebx */
15 * 4, 4 * 4, /* %esp, %ebp */
3 * 4, 2 * 4, /* %esi, %edi */
12 * 4, 14 * 4, /* %eip, %eflags */
13 * 4, 16 * 4, /* %cs, %ss */
1 * 4, 0 * 4, -1, -1 /* %ds, %es, %fs, %gs */
};
/* Sigtramp routine location. */
CORE_ADDR i386fbsd_sigtramp_start_addr;
CORE_ADDR i386fbsd_sigtramp_end_addr;
/* From <machine/signal.h>. */
int i386fbsd_sc_reg_offset[] =
{
8 + 14 * 4, /* %eax */
8 + 13 * 4, /* %ecx */
8 + 12 * 4, /* %edx */
8 + 11 * 4, /* %ebx */
8 + 0 * 4, /* %esp */
8 + 1 * 4, /* %ebp */
8 + 10 * 4, /* %esi */
8 + 9 * 4, /* %edi */
8 + 3 * 4, /* %eip */
8 + 4 * 4, /* %eflags */
8 + 7 * 4, /* %cs */
8 + 8 * 4, /* %ss */
8 + 6 * 4, /* %ds */
8 + 5 * 4, /* %es */
8 + 15 * 4, /* %fs */
8 + 16 * 4 /* %gs */
};
/* Get XSAVE extended state xcr0 from core dump. */
uint64_t
i386fbsd_core_read_xcr0 (bfd *abfd)
{
asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
uint64_t xcr0;
if (xstate)
{
size_t size = bfd_section_size (abfd, xstate);
/* Check extended state size. */
if (size < X86_XSTATE_AVX_SIZE)
xcr0 = X86_XSTATE_SSE_MASK;
else
{
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 X86_XSTATE_SSE_MASK;
}
xcr0 = bfd_get_64 (abfd, contents);
}
}
else
xcr0 = X86_XSTATE_SSE_MASK;
return xcr0;
}
/* 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)
{
return i386_target_description (i386fbsd_core_read_xcr0 (abfd), 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)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
cb (".reg", tdep->sizeof_gregset, tdep->sizeof_gregset, &i386_gregset, NULL,
cb_data);
cb (".reg2", tdep->sizeof_fpregset, tdep->sizeof_fpregset, &i386_fpregset,
NULL, cb_data);
if (tdep->xcr0 & X86_XSTATE_AVX)
cb (".reg-xstate", X86_XSTATE_SIZE (tdep->xcr0),
X86_XSTATE_SIZE (tdep->xcr0), &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)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
struct regcache *regcache;
if (tdep->fsbase_regnum == -1)
error (_("Unable to fetch %%gsbase"));
regcache = get_thread_arch_regcache (ptid, gdbarch);
target_fetch_registers (regcache, tdep->fsbase_regnum + 1);
ULONGEST gsbase;
if (regcache->cooked_read (tdep->fsbase_regnum + 1, &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)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
/* Obviously FreeBSD is BSD-based. */
i386bsd_init_abi (info, gdbarch);
/* FreeBSD has a different `struct reg', and reserves some space for
its FPU emulator in `struct fpreg'. */
tdep->gregset_reg_offset = i386fbsd_r_reg_offset;
tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd_r_reg_offset);
tdep->sizeof_gregset = 18 * 4;
tdep->sizeof_fpregset = 176;
/* FreeBSD uses -freg-struct-return by default. */
tdep->struct_return = reg_struct_return;
tdep->sigtramp_p = i386fbsd_sigtramp_p;
/* FreeBSD uses a different memory layout. */
tdep->sigtramp_start = i386fbsd_sigtramp_start_addr;
tdep->sigtramp_end = i386fbsd_sigtramp_end_addr;
/* FreeBSD has a more complete `struct sigcontext'. */
tdep->sc_reg_offset = i386fbsd_sc_reg_offset;
tdep->sc_num_regs = ARRAY_SIZE (i386fbsd_sc_reg_offset);
i386_elf_init_abi (info, gdbarch);
/* FreeBSD uses SVR4-style shared libraries. */
set_solib_svr4_fetch_link_map_offsets
(gdbarch, svr4_ilp32_fetch_link_map_offsets);
}
/* FreeBSD 4.0-RELEASE or later. */
/* From <machine/reg.h>. */
static int i386fbsd4_r_reg_offset[] =
{
10 * 4, 9 * 4, 8 * 4, 7 * 4, /* %eax, %ecx, %edx, %ebx */
16 * 4, 5 * 4, /* %esp, %ebp */
4 * 4, 3 * 4, /* %esi, %edi */
13 * 4, 15 * 4, /* %eip, %eflags */
14 * 4, 17 * 4, /* %cs, %ss */
2 * 4, 1 * 4, 0 * 4, 18 * 4 /* %ds, %es, %fs, %gs */
};
/* From <machine/signal.h>. */
int i386fbsd4_sc_reg_offset[] =
{
20 + 11 * 4, /* %eax */
20 + 10 * 4, /* %ecx */
20 + 9 * 4, /* %edx */
20 + 8 * 4, /* %ebx */
20 + 17 * 4, /* %esp */
20 + 6 * 4, /* %ebp */
20 + 5 * 4, /* %esi */
20 + 4 * 4, /* %edi */
20 + 14 * 4, /* %eip */
20 + 16 * 4, /* %eflags */
20 + 15 * 4, /* %cs */
20 + 18 * 4, /* %ss */
20 + 3 * 4, /* %ds */
20 + 2 * 4, /* %es */
20 + 1 * 4, /* %fs */
20 + 0 * 4 /* %gs */
};
static void
i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
/* Generic FreeBSD support. */
fbsd_init_abi (info, gdbarch);
/* Inherit stuff from older releases. We assume that FreeBSD
4.0-RELEASE always uses ELF. */
i386fbsd_init_abi (info, gdbarch);
/* FreeBSD 4.0 introduced a new `struct reg'. */
tdep->gregset_reg_offset = i386fbsd4_r_reg_offset;
tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd4_r_reg_offset);
tdep->sizeof_gregset = 19 * 4;
/* FreeBSD 4.0 introduced a new `struct sigcontext'. */
tdep->sc_reg_offset = i386fbsd4_sc_reg_offset;
tdep->sc_num_regs = ARRAY_SIZE (i386fbsd4_sc_reg_offset);
tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
/* 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);
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)
{
gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
i386fbsd4_init_abi);
}