311 lines
9.7 KiB
C
311 lines
9.7 KiB
C
/* Target-dependent code for GNU/Linux SPARC.
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Copyright 2003 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 2 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, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "floatformat.h"
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#include "frame.h"
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#include "frame-unwind.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 "gdb_assert.h"
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#include "gdb_string.h"
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#include "sparc-tdep.h"
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/* Recognizing signal handler frames. */
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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 function returns whether the PC appears to
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be within this bit of code.
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The instruction sequence for normal signals is
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mov __NR_sigreturn, %g1 ! hex: 0x821020d8
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ta 0x10 ! hex: 0x91d02010
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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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It kind of sucks that we have to read memory from the process in
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order to identify a signal trampoline, but there doesn't seem to be
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any other way. However, sparc32_linux_pc_in_sigtramp arranges to
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only call us if no function name could be identified, which should
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be the case since the code is on the stack. */
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#define LINUX32_SIGTRAMP_INSN0 0x821020d8 /* mov __NR_sigreturn, %g1 */
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#define LINUX32_SIGTRAMP_INSN1 0x91d02010 /* ta 0x10 */
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/* The instruction sequence for RT signals is
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mov __NR_rt_sigreturn, %g1 ! hex: 0x82102065
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ta {0x10,0x6d} ! hex: 0x91d02010 or 0x91d0206d
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The effect is to call the system call rt_sigreturn. The trap number
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is variable based upon whether this is a 32-bit or 64-bit sparc binary.
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Note that 64-bit binaries only use this RT signal return method. */
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#define LINUX32_RT_SIGTRAMP_INSN0 0x82102065
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#define LINUX32_RT_SIGTRAMP_INSN1 0x91d02010
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/* If PC is in a sigtramp routine consisting of the instructions INSN0
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and INSN1, return the address of the start of the routine.
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Otherwise, return 0. */
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CORE_ADDR
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sparc_linux_sigtramp_start (CORE_ADDR pc, ULONGEST insn0, ULONGEST insn1)
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{
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ULONGEST word0, word1;
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char buf[8]; /* Two instructions. */
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/* We only recognize a signal trampoline if PC is at the start of
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one of the instructions. We optimize for finding the PC at the
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start of the instruction sequence, as will be the case when the
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trampoline is not the first frame on the stack. We assume that
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in the case where the PC is not at the start of the instruction
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sequence, there will be a few trailing readable bytes on the
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stack. */
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if (read_memory_nobpt (pc, buf, sizeof buf) != 0)
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return 0;
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word0 = extract_unsigned_integer (buf, 4);
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if (word0 != insn0)
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{
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if (word0 != insn1)
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return 0;
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pc -= 4;
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if (read_memory_nobpt (pc, buf, sizeof buf) != 0)
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return 0;
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word0 = extract_unsigned_integer (buf, 4);
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}
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word1 = extract_unsigned_integer (buf + 4, 4);
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if (word0 != insn0 || word1 != insn1)
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return 0;
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return pc;
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}
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static CORE_ADDR
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sparc32_linux_sigtramp_start (CORE_ADDR pc)
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{
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return sparc_linux_sigtramp_start (pc, LINUX32_SIGTRAMP_INSN0,
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LINUX32_SIGTRAMP_INSN1);
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}
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static CORE_ADDR
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sparc32_linux_rt_sigtramp_start (CORE_ADDR pc)
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{
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return sparc_linux_sigtramp_start (pc, LINUX32_RT_SIGTRAMP_INSN0,
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LINUX32_RT_SIGTRAMP_INSN1);
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}
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static int
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sparc32_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
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{
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/* If we have NAME, we can optimize the search. The trampolines are
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named __restore and __restore_rt. However, they aren't dynamically
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exported from the shared C library, so the trampoline may appear to
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be part of the preceding function. This should always be sigaction,
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__sigaction, or __libc_sigaction (all aliases to the same function). */
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if (name == NULL || strstr (name, "sigaction") != NULL)
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return (sparc32_linux_sigtramp_start (pc) != 0
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|| sparc32_linux_rt_sigtramp_start (pc) != 0);
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return (strcmp ("__restore", name) == 0
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|| strcmp ("__restore_rt", name) == 0);
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}
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static struct sparc_frame_cache *
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sparc32_linux_sigtramp_frame_cache (struct frame_info *next_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 sigcontext_addr, addr;
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int regnum;
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if (*this_cache)
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return *this_cache;
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cache = sparc32_frame_cache (next_frame, this_cache);
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gdb_assert (cache == *this_cache);
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/* ??? What about signal trampolines that aren't frameless? */
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regnum = SPARC_SP_REGNUM;
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cache->base = frame_unwind_register_unsigned (next_frame, regnum);
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regnum = SPARC_O1_REGNUM;
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sigcontext_addr = frame_unwind_register_unsigned (next_frame, regnum);
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cache->pc = frame_pc_unwind (next_frame);
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addr = sparc32_linux_sigtramp_start (cache->pc);
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if (addr == 0)
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{
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/* If this is a RT signal trampoline, adjust SIGCONTEXT_ADDR
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accordingly. */
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addr = sparc32_linux_rt_sigtramp_start (cache->pc);
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if (addr)
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sigcontext_addr += 128;
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else
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addr = frame_func_unwind (next_frame);
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}
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cache->pc = addr;
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cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
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cache->saved_regs[SPARC32_PSR_REGNUM].addr = sigcontext_addr + 0;
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cache->saved_regs[SPARC32_PC_REGNUM].addr = sigcontext_addr + 4;
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cache->saved_regs[SPARC32_NPC_REGNUM].addr = sigcontext_addr + 8;
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cache->saved_regs[SPARC32_Y_REGNUM].addr = sigcontext_addr + 12;
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/* Since %g0 is always zero, keep the identity encoding. */
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for (regnum = SPARC_G1_REGNUM, addr = sigcontext_addr + 20;
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regnum <= SPARC_O7_REGNUM; regnum++, addr += 4)
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cache->saved_regs[regnum].addr = addr;
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for (regnum = SPARC_L0_REGNUM, addr = cache->base;
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regnum <= SPARC_I7_REGNUM; regnum++, addr += 4)
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cache->saved_regs[regnum].addr = addr;
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return cache;
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}
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static void
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sparc32_linux_sigtramp_frame_this_id (struct frame_info *next_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_linux_sigtramp_frame_cache (next_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 void
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sparc32_linux_sigtramp_frame_prev_register (struct frame_info *next_frame,
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void **this_cache,
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int regnum, int *optimizedp,
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enum lval_type *lvalp,
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CORE_ADDR *addrp,
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int *realnump, void *valuep)
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{
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struct sparc_frame_cache *cache =
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sparc32_linux_sigtramp_frame_cache (next_frame, this_cache);
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trad_frame_prev_register (next_frame, cache->saved_regs, regnum,
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optimizedp, lvalp, addrp, realnump, valuep);
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}
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static const struct frame_unwind sparc32_linux_sigtramp_frame_unwind =
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{
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SIGTRAMP_FRAME,
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sparc32_linux_sigtramp_frame_this_id,
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sparc32_linux_sigtramp_frame_prev_register
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};
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static const struct frame_unwind *
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sparc32_linux_sigtramp_frame_sniffer (struct frame_info *next_frame)
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{
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CORE_ADDR pc = frame_pc_unwind (next_frame);
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char *name;
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find_pc_partial_function (pc, &name, NULL, NULL);
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if (sparc32_linux_pc_in_sigtramp (pc, name))
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return &sparc32_linux_sigtramp_frame_unwind;
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return NULL;
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}
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static struct link_map_offsets *
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sparc32_linux_svr4_fetch_link_map_offsets (void)
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{
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static struct link_map_offsets lmo;
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static struct link_map_offsets *lmp = NULL;
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if (lmp == NULL)
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{
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lmp = &lmo;
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/* Everything we need is in the first 8 bytes. */
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lmo.r_debug_size = 8;
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lmo.r_map_offset = 4;
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lmo.r_map_size = 4;
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/* Everything we need is in the first 20 bytes. */
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lmo.link_map_size = 20;
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lmo.l_addr_offset = 0;
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lmo.l_addr_size = 4;
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lmo.l_name_offset = 4;
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lmo.l_name_size = 4;
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lmo.l_next_offset = 12;
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lmo.l_next_size = 4;
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lmo.l_prev_offset = 16;
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lmo.l_prev_size = 4;
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}
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return lmp;
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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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/* GNU/Linux is very similar to Solaris ... */
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sparc32_sol2_init_abi (info, gdbarch);
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/* ... but doesn't have kernel-assisted single-stepping support. */
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set_gdbarch_software_single_step (gdbarch, sparc_software_single_step);
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/* GNU/Linux doesn't support the 128-bit `long double' from the psABI. */
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set_gdbarch_long_double_bit (gdbarch, 64);
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set_gdbarch_long_double_format (gdbarch, &floatformat_ieee_double_big);
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frame_unwind_append_sniffer (gdbarch, sparc32_linux_sigtramp_frame_sniffer);
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set_solib_svr4_fetch_link_map_offsets
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(gdbarch, sparc32_linux_svr4_fetch_link_map_offsets);
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}
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/* Provide a prototype to silence -Wmissing-prototypes. */
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extern void _initialize_sparc_linux_tdep (void);
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void
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_initialize_sparc_linux_tdep (void)
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{
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gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
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sparc32_linux_init_abi);
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}
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