binutils-gdb/gdb/i386-fbsd-nat.c
John Baldwin a49ce729c8 Add an x86_fbsd_nat_target mixin class for FreeBSD x86 native targets.
This class implements debug register support common between the i386
and amd64 native targets.

While here, remove #ifdef's for HAVE_PT_GETDBREGS in FreeBSD-specific
code.  The ptrace request has been present on FreeBSD x86
architectures since 4.0 (released in March 2000).  The last FreeBSD
release without this support is 3.5 released in June 2000.
2022-03-22 12:05:43 -07:00

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/* Native-dependent code for FreeBSD/i386.
Copyright (C) 2001-2022 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 "inferior.h"
#include "regcache.h"
#include "target.h"
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include "i386-tdep.h"
#include "i386-fbsd-tdep.h"
#include "i387-tdep.h"
#include "x86-nat.h"
#include "gdbsupport/x86-xstate.h"
#include "x86-fbsd-nat.h"
class i386_fbsd_nat_target final : public x86_fbsd_nat_target
{
public:
void fetch_registers (struct regcache *, int) override;
void store_registers (struct regcache *, int) override;
const struct target_desc *read_description () override;
void resume (ptid_t, int, enum gdb_signal) override;
};
static i386_fbsd_nat_target the_i386_fbsd_nat_target;
#ifdef PT_GETXSTATE_INFO
static size_t xsave_len;
#endif
static int have_ptrace_xmmregs;
/* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
for all registers. */
void
i386_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
{
struct gdbarch *gdbarch = regcache->arch ();
#if defined(PT_GETFSBASE) || defined(PT_GETGSBASE)
const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
#endif
pid_t pid = get_ptrace_pid (regcache->ptid ());
if (fetch_register_set<struct reg> (regcache, regnum, PT_GETREGS,
&i386_fbsd_gregset))
{
if (regnum != -1)
return;
}
#ifdef PT_GETFSBASE
if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
{
register_t base;
if (ptrace (PT_GETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
perror_with_name (_("Couldn't get segment register fs_base"));
regcache->raw_supply (I386_FSBASE_REGNUM, &base);
if (regnum != -1)
return;
}
#endif
#ifdef PT_GETGSBASE
if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
{
register_t base;
if (ptrace (PT_GETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
perror_with_name (_("Couldn't get segment register gs_base"));
regcache->raw_supply (I386_GSBASE_REGNUM, &base);
if (regnum != -1)
return;
}
#endif
/* There is no i386_fxsave_supplies or i386_xsave_supplies.
Instead, the earlier register sets return early if the request
was for a specific register that was already satisified to avoid
fetching the FPU/XSAVE state unnecessarily. */
#ifdef PT_GETXSTATE_INFO
if (xsave_len != 0)
{
void *xstateregs = alloca (xsave_len);
if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
perror_with_name (_("Couldn't get extended state status"));
i387_supply_xsave (regcache, regnum, xstateregs);
return;
}
#endif
if (have_ptrace_xmmregs != 0)
{
char xmmregs[I387_SIZEOF_FXSAVE];
if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
perror_with_name (_("Couldn't get XMM registers"));
i387_supply_fxsave (regcache, regnum, xmmregs);
return;
}
struct fpreg fpregs;
if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
perror_with_name (_("Couldn't get floating point status"));
i387_supply_fsave (regcache, regnum, &fpregs);
}
/* Store register REGNUM back into the inferior. If REGNUM is -1, do
this for all registers. */
void
i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
{
struct gdbarch *gdbarch = regcache->arch ();
#if defined(PT_GETFSBASE) || defined(PT_GETGSBASE)
const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
#endif
pid_t pid = get_ptrace_pid (regcache->ptid ());
if (store_register_set<struct reg> (regcache, regnum, PT_GETREGS, PT_SETREGS,
&i386_fbsd_gregset))
{
if (regnum != -1)
return;
}
#ifdef PT_SETFSBASE
if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
{
register_t base;
regcache->raw_collect (I386_FSBASE_REGNUM, &base);
if (ptrace (PT_SETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
perror_with_name (_("Couldn't write segment register fs_base"));
if (regnum != -1)
return;
}
#endif
#ifdef PT_SETGSBASE
if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
{
register_t base;
regcache->raw_collect (I386_GSBASE_REGNUM, &base);
if (ptrace (PT_SETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
perror_with_name (_("Couldn't write segment register gs_base"));
if (regnum != -1)
return;
}
#endif
/* There is no i386_fxsave_supplies or i386_xsave_supplies.
Instead, the earlier register sets return early if the request
was for a specific register that was already satisified to avoid
fetching the FPU/XSAVE state unnecessarily. */
#ifdef PT_GETXSTATE_INFO
if (xsave_len != 0)
{
void *xstateregs = alloca (xsave_len);
if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
perror_with_name (_("Couldn't get extended state status"));
i387_collect_xsave (regcache, regnum, xstateregs, 0);
if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, xsave_len)
== -1)
perror_with_name (_("Couldn't write extended state status"));
return;
}
#endif
if (have_ptrace_xmmregs != 0)
{
char xmmregs[I387_SIZEOF_FXSAVE];
if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
perror_with_name (_("Couldn't get XMM registers"));
i387_collect_fxsave (regcache, regnum, xmmregs);
if (ptrace (PT_SETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
perror_with_name (_("Couldn't write XMM registers"));
return;
}
struct fpreg fpregs;
if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
perror_with_name (_("Couldn't get floating point status"));
i387_collect_fsave (regcache, regnum, &fpregs);
if (ptrace (PT_SETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
perror_with_name (_("Couldn't write floating point status"));
}
/* Resume execution of the inferior process. If STEP is nonzero,
single-step it. If SIGNAL is nonzero, give it that signal. */
void
i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
{
pid_t pid = ptid.pid ();
int request = PT_STEP;
if (pid == -1)
/* Resume all threads. This only gets used in the non-threaded
case, where "resume all threads" and "resume inferior_ptid" are
the same. */
pid = inferior_ptid.pid ();
if (!step)
{
struct regcache *regcache = get_current_regcache ();
ULONGEST eflags;
/* Workaround for a bug in FreeBSD. Make sure that the trace
flag is off when doing a continue. There is a code path
through the kernel which leaves the flag set when it should
have been cleared. If a process has a signal pending (such
as SIGALRM) and we do a PT_STEP, the process never really has
a chance to run because the kernel needs to notify the
debugger that a signal is being sent. Therefore, the process
never goes through the kernel's trap() function which would
normally clear it. */
regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
&eflags);
if (eflags & 0x0100)
regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
eflags & ~0x0100);
request = PT_CONTINUE;
}
/* An addres of (caddr_t) 1 tells ptrace to continue from where it
was. (If GDB wanted it to start some other way, we have already
written a new PC value to the child.) */
if (ptrace (request, pid, (caddr_t) 1,
gdb_signal_to_host (signal)) == -1)
perror_with_name (("ptrace"));
}
/* Support for debugging kernel virtual memory images. */
#include <machine/pcb.h>
#include "bsd-kvm.h"
static int
i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
{
/* The following is true for FreeBSD 4.7:
The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
This accounts for all callee-saved registers specified by the
psABI and then some. Here %esp contains the stack pointer at the
point just after the call to cpu_switch(). From this information
we reconstruct the register state as it would look when we just
returned from cpu_switch(). */
/* The stack pointer shouldn't be zero. */
if (pcb->pcb_esp == 0)
return 0;
pcb->pcb_esp += 4;
regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
return 1;
}
/* Implement the read_description method. */
const struct target_desc *
i386_fbsd_nat_target::read_description ()
{
#ifdef PT_GETXSTATE_INFO
static int xsave_probed;
static uint64_t xcr0;
#endif
static int xmm_probed;
#ifdef PT_GETXSTATE_INFO
if (!xsave_probed)
{
struct ptrace_xstate_info info;
if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (),
(PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
{
xsave_len = info.xsave_len;
xcr0 = info.xsave_mask;
}
xsave_probed = 1;
}
if (xsave_len != 0)
return i386_target_description (xcr0, true);
#endif
if (!xmm_probed)
{
char xmmregs[I387_SIZEOF_FXSAVE];
if (ptrace (PT_GETXMMREGS, inferior_ptid.pid (),
(PTRACE_TYPE_ARG3) xmmregs, 0) == 0)
have_ptrace_xmmregs = 1;
xmm_probed = 1;
}
if (have_ptrace_xmmregs)
return i386_target_description (X86_XSTATE_SSE_MASK, true);
return i386_target_description (X86_XSTATE_X87_MASK, true);
}
void _initialize_i386fbsd_nat ();
void
_initialize_i386fbsd_nat ()
{
add_inf_child_target (&the_i386_fbsd_nat_target);
/* Support debugging kernel virtual memory images. */
bsd_kvm_add_target (i386fbsd_supply_pcb);
}