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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.
231 lines
6.6 KiB
C
231 lines
6.6 KiB
C
/* Target-dependent code for Solaris 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 "frame.h"
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#include "frame-unwind.h"
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#include "gdbcore.h"
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#include "symtab.h"
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#include "objfiles.h"
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#include "osabi.h"
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#include "regcache.h"
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#include "regset.h"
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#include "target.h"
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#include "trad-frame.h"
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#include "sol2-tdep.h"
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#include "sparc-tdep.h"
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#include "solib-svr4.h"
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/* From <sys/regset.h>. */
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const struct sparc_gregmap sparc32_sol2_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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36 * 4, /* %wim */
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37 * 4, /* %tbr */
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1 * 4, /* %g1 */
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16 * 4, /* %l0 */
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};
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const struct sparc_fpregmap sparc32_sol2_fpregmap =
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{
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0 * 4, /* %f0 */
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33 * 4, /* %fsr */
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};
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static void
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sparc32_sol2_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_sol2_gregmap, regcache, regnum, gregs);
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}
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static void
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sparc32_sol2_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_sol2_gregmap, regcache, regnum, gregs);
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}
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static void
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sparc32_sol2_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_sol2_fpregmap, regcache, regnum, fpregs);
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}
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static void
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sparc32_sol2_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_sol2_fpregmap, regcache, regnum, fpregs);
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}
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static const struct regset sparc32_sol2_gregset =
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{
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NULL,
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sparc32_sol2_supply_core_gregset,
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sparc32_sol2_collect_core_gregset
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};
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static const struct regset sparc32_sol2_fpregset =
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{
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NULL,
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sparc32_sol2_supply_core_fpregset,
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sparc32_sol2_collect_core_fpregset
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};
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static struct sparc_frame_cache *
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sparc32_sol2_sigtramp_frame_cache (struct frame_info *this_frame,
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void **this_cache)
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{
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struct sparc_frame_cache *cache;
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CORE_ADDR mcontext_addr, addr;
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int regnum;
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if (*this_cache)
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return (struct sparc_frame_cache *) *this_cache;
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cache = sparc_frame_cache (this_frame, this_cache);
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gdb_assert (cache == *this_cache);
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cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
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/* The third argument is a pointer to an instance of `ucontext_t',
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which has a member `uc_mcontext' that contains the saved
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registers. */
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regnum =
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(cache->copied_regs_mask & 0x04) ? SPARC_I2_REGNUM : SPARC_O2_REGNUM;
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mcontext_addr = get_frame_register_unsigned (this_frame, regnum) + 40;
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cache->saved_regs[SPARC32_PSR_REGNUM].set_addr (mcontext_addr + 0 * 4);
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cache->saved_regs[SPARC32_PC_REGNUM].set_addr (mcontext_addr + 1 * 4);
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cache->saved_regs[SPARC32_NPC_REGNUM].set_addr (mcontext_addr + 2 * 4);
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cache->saved_regs[SPARC32_Y_REGNUM].set_addr (mcontext_addr + 3 * 4);
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/* Since %g0 is always zero, keep the identity encoding. */
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for (regnum = SPARC_G1_REGNUM, addr = mcontext_addr + 4 * 4;
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regnum <= SPARC_O7_REGNUM; regnum++, addr += 4)
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cache->saved_regs[regnum].set_addr (addr);
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if (get_frame_memory_unsigned (this_frame, mcontext_addr + 19 * 4, 4))
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{
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/* The register windows haven't been flushed. */
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for (regnum = SPARC_L0_REGNUM; regnum <= SPARC_I7_REGNUM; regnum++)
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cache->saved_regs[regnum].set_unknown ();
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}
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else
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{
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addr = cache->saved_regs[SPARC_SP_REGNUM].addr ();
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addr = get_frame_memory_unsigned (this_frame, addr, 4);
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for (regnum = SPARC_L0_REGNUM;
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regnum <= SPARC_I7_REGNUM; regnum++, addr += 4)
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cache->saved_regs[regnum].set_addr (addr);
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}
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return cache;
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}
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static void
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sparc32_sol2_sigtramp_frame_this_id (struct frame_info *this_frame,
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void **this_cache,
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struct frame_id *this_id)
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{
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struct sparc_frame_cache *cache =
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sparc32_sol2_sigtramp_frame_cache (this_frame, this_cache);
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(*this_id) = frame_id_build (cache->base, cache->pc);
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}
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static struct value *
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sparc32_sol2_sigtramp_frame_prev_register (struct frame_info *this_frame,
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void **this_cache,
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int regnum)
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{
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struct sparc_frame_cache *cache =
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sparc32_sol2_sigtramp_frame_cache (this_frame, this_cache);
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return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
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}
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static int
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sparc32_sol2_sigtramp_frame_sniffer (const struct frame_unwind *self,
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struct frame_info *this_frame,
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void **this_cache)
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{
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return sol2_sigtramp_p (this_frame);
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}
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static const struct frame_unwind sparc32_sol2_sigtramp_frame_unwind =
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{
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"sparc32 solaris sigtramp",
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SIGTRAMP_FRAME,
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default_frame_unwind_stop_reason,
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sparc32_sol2_sigtramp_frame_this_id,
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sparc32_sol2_sigtramp_frame_prev_register,
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NULL,
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sparc32_sol2_sigtramp_frame_sniffer
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};
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static void
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sparc32_sol2_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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tdep->gregset = &sparc32_sol2_gregset;
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tdep->sizeof_gregset = 152;
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tdep->fpregset = &sparc32_sol2_fpregset;
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tdep->sizeof_fpregset = 400;
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sol2_init_abi (info, gdbarch);
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/* Solaris has SVR4-style shared libraries... */
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set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
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set_solib_svr4_fetch_link_map_offsets
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(gdbarch, svr4_ilp32_fetch_link_map_offsets);
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/* ...which means that we need some special handling when doing
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prologue analysis. */
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tdep->plt_entry_size = 12;
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/* Solaris has kernel-assisted single-stepping support. */
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set_gdbarch_software_single_step (gdbarch, NULL);
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frame_unwind_append_unwinder (gdbarch, &sparc32_sol2_sigtramp_frame_unwind);
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}
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void _initialize_sparc_sol2_tdep ();
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void
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_initialize_sparc_sol2_tdep ()
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{
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gdbarch_register_osabi (bfd_arch_sparc, 0,
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GDB_OSABI_SOLARIS, sparc32_sol2_init_abi);
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}
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