mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-21 04:42:53 +08:00
08106042d9
I built GDB for all targets on a x86-64/GNU-Linux system, and
then (accidentally) passed GDB a RISC-V binary, and asked GDB to "run"
the binary on the native target. I got this error:
(gdb) show architecture
The target architecture is set to "auto" (currently "i386").
(gdb) file /tmp/hello.rv32.exe
Reading symbols from /tmp/hello.rv32.exe...
(gdb) show architecture
The target architecture is set to "auto" (currently "riscv:rv32").
(gdb) run
Starting program: /tmp/hello.rv32.exe
../../src/gdb/i387-tdep.c:596: internal-error: i387_supply_fxsave: Assertion `tdep->st0_regnum >= I386_ST0_REGNUM' failed.
What's going on here is this; initially the architecture is i386, this
is based on the default architecture, which is set based on the native
target. After loading the RISC-V executable the architecture of the
current inferior is updated based on the architecture of the
executable.
When we "run", GDB does a fork & exec, with the inferior being
controlled through ptrace. GDB sees an initial stop from the inferior
as soon as the inferior comes to life. In response to this stop GDB
ends up calling save_stop_reason (linux-nat.c), which ends up trying
to read register from the inferior, to do this we end up calling
target_ops::fetch_registers, which, for the x86-64 native target,
calls amd64_linux_nat_target::fetch_registers.
After this I eventually end up in i387_supply_fxsave, different x86
based targets will end in different functions to fetch registers, but
it doesn't really matter which function we end up in, the problem is
this line, which is repeated in many places:
i386_gdbarch_tdep *tdep = (i386_gdbarch_tdep *) gdbarch_tdep (arch);
The problem here is that the ARCH in this line comes from the current
inferior, which, as we discussed above, will be a RISC-V gdbarch, the
tdep field will actually be of type riscv_gdbarch_tdep, not
i386_gdbarch_tdep. After this cast we are relying on undefined
behaviour, in my case I happen to trigger an assert, but this might
not always be the case.
The thing I tried that exposed this problem was of course, trying to
start an executable of the wrong architecture on a native target. I
don't think that the correct solution for this problem is to detect,
at the point of cast, that the gdbarch_tdep object is of the wrong
type, but, I did wonder, is there a way that we could protect
ourselves from incorrectly casting the gdbarch_tdep object?
I think that there is something we can do here, and this commit is the
first step in that direction, though no actual check is added by this
commit.
This commit can be split into two parts:
(1) In gdbarch.h and arch-utils.c. In these files I have modified
gdbarch_tdep (the function) so that it now takes a template argument,
like this:
template<typename TDepType>
static inline TDepType *
gdbarch_tdep (struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep_1 (gdbarch);
return static_cast<TDepType *> (tdep);
}
After this change we are no better protected, but the cast is now
done within the gdbarch_tdep function rather than at the call sites,
this leads to the second, much larger change in this commit,
(2) Everywhere gdbarch_tdep is called, we make changes like this:
- i386_gdbarch_tdep *tdep = (i386_gdbarch_tdep *) gdbarch_tdep (arch);
+ i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (arch);
There should be no functional change after this commit.
In the next commit I will build on this change to add an assertion in
gdbarch_tdep that checks we are casting to the correct type.
476 lines
13 KiB
C
476 lines
13 KiB
C
/* Target-dependent code for GNU/Linux SPARC.
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Copyright (C) 2003-2022 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "dwarf2/frame.h"
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#include "frame.h"
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#include "frame-unwind.h"
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#include "gdbtypes.h"
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#include "regset.h"
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#include "gdbarch.h"
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#include "gdbcore.h"
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#include "osabi.h"
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#include "regcache.h"
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#include "solib-svr4.h"
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#include "symtab.h"
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#include "trad-frame.h"
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#include "tramp-frame.h"
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#include "xml-syscall.h"
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#include "linux-tdep.h"
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/* The syscall's XML filename for sparc 32-bit. */
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#define XML_SYSCALL_FILENAME_SPARC32 "syscalls/sparc-linux.xml"
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#include "sparc-tdep.h"
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/* Signal trampoline support. */
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static void sparc32_linux_sigframe_init (const struct tramp_frame *self,
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struct frame_info *this_frame,
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struct trad_frame_cache *this_cache,
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CORE_ADDR func);
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/* GNU/Linux has two flavors of signals. Normal signal handlers, and
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"realtime" (RT) signals. The RT signals can provide additional
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information to the signal handler if the SA_SIGINFO flag is set
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when establishing a signal handler using `sigaction'. It is not
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unlikely that future versions of GNU/Linux will support SA_SIGINFO
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for normal signals too. */
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/* When the sparc Linux kernel calls a signal handler and the
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SA_RESTORER flag isn't set, the return address points to a bit of
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code on the stack. This code checks whether the PC appears to be
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within this bit of code.
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The instruction sequence for normal signals is encoded below.
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Checking for the code sequence should be somewhat reliable, because
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the effect is to call the system call sigreturn. This is unlikely
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to occur anywhere other than a signal trampoline. */
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static const struct tramp_frame sparc32_linux_sigframe =
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{
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SIGTRAMP_FRAME,
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4,
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{
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{ 0x821020d8, ULONGEST_MAX }, /* mov __NR_sigreturn, %g1 */
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{ 0x91d02010, ULONGEST_MAX }, /* ta 0x10 */
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{ TRAMP_SENTINEL_INSN, ULONGEST_MAX }
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},
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sparc32_linux_sigframe_init
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};
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/* The instruction sequence for RT signals is slightly different. The
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effect is to call the system call rt_sigreturn. */
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static const struct tramp_frame sparc32_linux_rt_sigframe =
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{
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SIGTRAMP_FRAME,
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4,
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{
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{ 0x82102065, ULONGEST_MAX }, /* mov __NR_rt_sigreturn, %g1 */
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{ 0x91d02010, ULONGEST_MAX }, /* ta 0x10 */
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{ TRAMP_SENTINEL_INSN, ULONGEST_MAX }
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},
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sparc32_linux_sigframe_init
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};
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/* This enum represents the signals' numbers on the SPARC
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architecture. It just contains the signal definitions which are
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different from the generic implementation.
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It is derived from the file <arch/sparc/include/uapi/asm/signal.h>,
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from the Linux kernel tree. */
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enum
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{
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SPARC_LINUX_SIGEMT = 7,
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SPARC_LINUX_SIGBUS = 10,
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SPARC_LINUX_SIGSYS = 12,
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SPARC_LINUX_SIGURG = 16,
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SPARC_LINUX_SIGSTOP = 17,
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SPARC_LINUX_SIGTSTP = 18,
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SPARC_LINUX_SIGCONT = 19,
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SPARC_LINUX_SIGCHLD = 20,
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SPARC_LINUX_SIGIO = 23,
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SPARC_LINUX_SIGPOLL = SPARC_LINUX_SIGIO,
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SPARC_LINUX_SIGLOST = 29,
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SPARC_LINUX_SIGPWR = SPARC_LINUX_SIGLOST,
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SPARC_LINUX_SIGUSR1 = 30,
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SPARC_LINUX_SIGUSR2 = 31,
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};
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static void
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sparc32_linux_sigframe_init (const struct tramp_frame *self,
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struct frame_info *this_frame,
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struct trad_frame_cache *this_cache,
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CORE_ADDR func)
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{
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CORE_ADDR base, addr, sp_addr;
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int regnum;
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base = get_frame_register_unsigned (this_frame, SPARC_O1_REGNUM);
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if (self == &sparc32_linux_rt_sigframe)
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base += 128;
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/* Offsets from <bits/sigcontext.h>. */
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trad_frame_set_reg_addr (this_cache, SPARC32_PSR_REGNUM, base + 0);
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trad_frame_set_reg_addr (this_cache, SPARC32_PC_REGNUM, base + 4);
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trad_frame_set_reg_addr (this_cache, SPARC32_NPC_REGNUM, base + 8);
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trad_frame_set_reg_addr (this_cache, SPARC32_Y_REGNUM, base + 12);
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/* Since %g0 is always zero, keep the identity encoding. */
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addr = base + 20;
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sp_addr = base + 16 + ((SPARC_SP_REGNUM - SPARC_G0_REGNUM) * 4);
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for (regnum = SPARC_G1_REGNUM; regnum <= SPARC_O7_REGNUM; regnum++)
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{
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trad_frame_set_reg_addr (this_cache, regnum, addr);
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addr += 4;
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}
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base = get_frame_register_unsigned (this_frame, SPARC_SP_REGNUM);
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addr = get_frame_memory_unsigned (this_frame, sp_addr, 4);
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for (regnum = SPARC_L0_REGNUM; regnum <= SPARC_I7_REGNUM; regnum++)
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{
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trad_frame_set_reg_addr (this_cache, regnum, addr);
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addr += 4;
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}
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trad_frame_set_id (this_cache, frame_id_build (base, func));
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}
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/* Return the address of a system call's alternative return
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address. */
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static CORE_ADDR
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sparc32_linux_step_trap (struct frame_info *frame, unsigned long insn)
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{
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if (insn == 0x91d02010)
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{
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ULONGEST sc_num = get_frame_register_unsigned (frame, SPARC_G1_REGNUM);
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/* __NR_rt_sigreturn is 101 and __NR_sigreturn is 216. */
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if (sc_num == 101 || sc_num == 216)
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{
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struct gdbarch *gdbarch = get_frame_arch (frame);
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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ULONGEST sp, pc_offset;
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sp = get_frame_register_unsigned (frame, SPARC_SP_REGNUM);
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/* The kernel puts the sigreturn registers on the stack,
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and this is where the signal unwinding state is take from
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when returning from a signal.
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For __NR_sigreturn, this register area sits 96 bytes from
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the base of the stack. The saved PC sits 4 bytes into the
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sigreturn register save area.
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For __NR_rt_sigreturn a siginfo_t, which is 128 bytes, sits
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right before the sigreturn register save area. */
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pc_offset = 96 + 4;
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if (sc_num == 101)
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pc_offset += 128;
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return read_memory_unsigned_integer (sp + pc_offset, 4, byte_order);
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}
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}
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return 0;
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}
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const struct sparc_gregmap sparc32_linux_core_gregmap =
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{
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32 * 4, /* %psr */
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33 * 4, /* %pc */
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34 * 4, /* %npc */
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35 * 4, /* %y */
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-1, /* %wim */
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-1, /* %tbr */
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1 * 4, /* %g1 */
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16 * 4, /* %l0 */
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4, /* y size */
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};
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static void
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sparc32_linux_supply_core_gregset (const struct regset *regset,
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struct regcache *regcache,
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int regnum, const void *gregs, size_t len)
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{
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sparc32_supply_gregset (&sparc32_linux_core_gregmap,
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regcache, regnum, gregs);
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}
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static void
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sparc32_linux_collect_core_gregset (const struct regset *regset,
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const struct regcache *regcache,
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int regnum, void *gregs, size_t len)
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{
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sparc32_collect_gregset (&sparc32_linux_core_gregmap,
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regcache, regnum, gregs);
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}
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static void
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sparc32_linux_supply_core_fpregset (const struct regset *regset,
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struct regcache *regcache,
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int regnum, const void *fpregs, size_t len)
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{
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sparc32_supply_fpregset (&sparc32_bsd_fpregmap, regcache, regnum, fpregs);
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}
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static void
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sparc32_linux_collect_core_fpregset (const struct regset *regset,
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const struct regcache *regcache,
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int regnum, void *fpregs, size_t len)
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{
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sparc32_collect_fpregset (&sparc32_bsd_fpregmap, regcache, regnum, fpregs);
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}
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/* Set the program counter for process PTID to PC. */
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#define PSR_SYSCALL 0x00004000
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static void
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sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
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{
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gdbarch *arch = regcache->arch ();
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sparc_gdbarch_tdep *tdep = gdbarch_tdep<sparc_gdbarch_tdep> (arch);
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ULONGEST psr;
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regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
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regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
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/* Clear the "in syscall" bit to prevent the kernel from
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messing with the PCs we just installed, if we happen to be
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within an interrupted system call that the kernel wants to
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restart.
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Note that after we return from the dummy call, the PSR et al.
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registers will be automatically restored, and the kernel
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continues to restart the system call at this point. */
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regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
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psr &= ~PSR_SYSCALL;
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regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
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}
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static LONGEST
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sparc32_linux_get_syscall_number (struct gdbarch *gdbarch,
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thread_info *thread)
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{
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struct regcache *regcache = get_thread_regcache (thread);
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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/* The content of a register. */
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gdb_byte buf[4];
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/* The result. */
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LONGEST ret;
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/* Getting the system call number from the register.
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When dealing with the sparc architecture, this information
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is stored at the %g1 register. */
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regcache->cooked_read (SPARC_G1_REGNUM, buf);
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ret = extract_signed_integer (buf, 4, byte_order);
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return ret;
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}
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/* Implementation of `gdbarch_gdb_signal_from_target', as defined in
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gdbarch.h. */
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static enum gdb_signal
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sparc32_linux_gdb_signal_from_target (struct gdbarch *gdbarch,
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int signal)
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{
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switch (signal)
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{
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case SPARC_LINUX_SIGEMT:
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return GDB_SIGNAL_EMT;
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case SPARC_LINUX_SIGBUS:
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return GDB_SIGNAL_BUS;
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case SPARC_LINUX_SIGSYS:
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return GDB_SIGNAL_SYS;
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case SPARC_LINUX_SIGURG:
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return GDB_SIGNAL_URG;
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case SPARC_LINUX_SIGSTOP:
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return GDB_SIGNAL_STOP;
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case SPARC_LINUX_SIGTSTP:
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return GDB_SIGNAL_TSTP;
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case SPARC_LINUX_SIGCONT:
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return GDB_SIGNAL_CONT;
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case SPARC_LINUX_SIGCHLD:
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return GDB_SIGNAL_CHLD;
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/* No way to differentiate between SIGIO and SIGPOLL.
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Therefore, we just handle the first one. */
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case SPARC_LINUX_SIGIO:
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return GDB_SIGNAL_IO;
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/* No way to differentiate between SIGLOST and SIGPWR.
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Therefore, we just handle the first one. */
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case SPARC_LINUX_SIGLOST:
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return GDB_SIGNAL_LOST;
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case SPARC_LINUX_SIGUSR1:
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return GDB_SIGNAL_USR1;
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case SPARC_LINUX_SIGUSR2:
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return GDB_SIGNAL_USR2;
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}
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return linux_gdb_signal_from_target (gdbarch, signal);
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}
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/* Implementation of `gdbarch_gdb_signal_to_target', as defined in
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gdbarch.h. */
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static int
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sparc32_linux_gdb_signal_to_target (struct gdbarch *gdbarch,
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enum gdb_signal signal)
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{
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switch (signal)
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{
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case GDB_SIGNAL_EMT:
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return SPARC_LINUX_SIGEMT;
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case GDB_SIGNAL_BUS:
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return SPARC_LINUX_SIGBUS;
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case GDB_SIGNAL_SYS:
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return SPARC_LINUX_SIGSYS;
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case GDB_SIGNAL_URG:
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return SPARC_LINUX_SIGURG;
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case GDB_SIGNAL_STOP:
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return SPARC_LINUX_SIGSTOP;
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case GDB_SIGNAL_TSTP:
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return SPARC_LINUX_SIGTSTP;
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case GDB_SIGNAL_CONT:
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return SPARC_LINUX_SIGCONT;
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case GDB_SIGNAL_CHLD:
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return SPARC_LINUX_SIGCHLD;
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case GDB_SIGNAL_IO:
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return SPARC_LINUX_SIGIO;
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case GDB_SIGNAL_POLL:
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return SPARC_LINUX_SIGPOLL;
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case GDB_SIGNAL_LOST:
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return SPARC_LINUX_SIGLOST;
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case GDB_SIGNAL_PWR:
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return SPARC_LINUX_SIGPWR;
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case GDB_SIGNAL_USR1:
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return SPARC_LINUX_SIGUSR1;
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case GDB_SIGNAL_USR2:
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return SPARC_LINUX_SIGUSR2;
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}
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return linux_gdb_signal_to_target (gdbarch, signal);
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}
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static const struct regset sparc32_linux_gregset =
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{
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NULL,
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sparc32_linux_supply_core_gregset,
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sparc32_linux_collect_core_gregset
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};
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static const struct regset sparc32_linux_fpregset =
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{
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NULL,
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sparc32_linux_supply_core_fpregset,
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sparc32_linux_collect_core_fpregset
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};
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static void
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sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
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{
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sparc_gdbarch_tdep *tdep = gdbarch_tdep<sparc_gdbarch_tdep> (gdbarch);
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linux_init_abi (info, gdbarch, 0);
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tdep->gregset = &sparc32_linux_gregset;
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tdep->sizeof_gregset = 152;
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tdep->fpregset = &sparc32_linux_fpregset;
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tdep->sizeof_fpregset = 396;
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tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
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||
tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
|
||
|
||
/* GNU/Linux has SVR4-style shared libraries... */
|
||
set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
|
||
set_solib_svr4_fetch_link_map_offsets
|
||
(gdbarch, linux_ilp32_fetch_link_map_offsets);
|
||
|
||
/* ...which means that we need some special handling when doing
|
||
prologue analysis. */
|
||
tdep->plt_entry_size = 12;
|
||
|
||
/* Enable TLS support. */
|
||
set_gdbarch_fetch_tls_load_module_address (gdbarch,
|
||
svr4_fetch_objfile_link_map);
|
||
|
||
/* Make sure we can single-step over signal return system calls. */
|
||
tdep->step_trap = sparc32_linux_step_trap;
|
||
|
||
/* Hook in the DWARF CFI frame unwinder. */
|
||
dwarf2_append_unwinders (gdbarch);
|
||
|
||
set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
|
||
|
||
/* Functions for 'catch syscall'. */
|
||
set_xml_syscall_file_name (gdbarch, XML_SYSCALL_FILENAME_SPARC32);
|
||
set_gdbarch_get_syscall_number (gdbarch,
|
||
sparc32_linux_get_syscall_number);
|
||
|
||
set_gdbarch_gdb_signal_from_target (gdbarch,
|
||
sparc32_linux_gdb_signal_from_target);
|
||
set_gdbarch_gdb_signal_to_target (gdbarch,
|
||
sparc32_linux_gdb_signal_to_target);
|
||
}
|
||
|
||
void _initialize_sparc_linux_tdep ();
|
||
void
|
||
_initialize_sparc_linux_tdep ()
|
||
{
|
||
gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
|
||
sparc32_linux_init_abi);
|
||
}
|