7b112f9c0c
(ppc-linux-nat.o) (ppc-linux-tdep.o) (rs6000-tdep.o): Use $(ppc_tdep_h). (ppc-sysv-tdep.o) (ppcnbsd-nat.o) (ppcnbsd-tdep.o): New dependency lists. * ppc-tdep.h: Use generic OS ABI framework. * ppc-linux-tdep.c (_initialize_ppc_linux_tdep, ppc_linux_init_abi): New functions. (ppc_sysv_abi_broken_use_struct_convention) (ppc_sysv_abi_use_struct_convention) (ppc_sysv_abi_push_arguments): Move to... * ppc-sysv-tdep.c: ...here. * ppcnbsd-nat.c: Don't include gdbcore.h and regcache.h. * rs6000-tdep.c (process_note_abi_tag_sections) (get_elfosabi): Remove. (rs6000_gdbarch_init): Use generic OS ABI framework. (rs6000_dump_tdep): New function. (_initialize_rs6000_tdep): Use gdbarch_register. * config/powerpc/linux.mt (TDEPFILES): Add ppc-sysv-tdep.o. * config/powerpc/nbsd.mh (NATDEPFILES): Remove solib-legacy.o. * config/powerpc/aix.mt (TDEPFILES): Use ppc-sysv-tdep.o instead of ppc-linux-tdep.o. * config/powerpc/nbsd.mt (TDEPFILES): Likewise. * config/powerpc/ppc-eabi.mt (TDEPFILES): Likewise. * config/powerpc/ppc-sim.mt (TDEPFILES): Likewise. * config/powerpc/ppcle-eabi.mt (TDEPFILES): Likewise. * config/powerpc/ppcle-sim.mt (TDEPFILES): Likewise. * config/powerpc/vxworks.mt (TDEPFILES): Likewise.
643 lines
21 KiB
C
643 lines
21 KiB
C
/* Target-dependent code for GDB, the GNU debugger.
|
|
|
|
Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
|
|
1997, 2000, 2001, 2002 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 2 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, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include "defs.h"
|
|
#include "frame.h"
|
|
#include "inferior.h"
|
|
#include "symtab.h"
|
|
#include "target.h"
|
|
#include "gdbcore.h"
|
|
#include "gdbcmd.h"
|
|
#include "symfile.h"
|
|
#include "objfiles.h"
|
|
#include "regcache.h"
|
|
#include "value.h"
|
|
|
|
#include "solib-svr4.h"
|
|
#include "ppc-tdep.h"
|
|
|
|
/* The following two instructions are used in the signal trampoline
|
|
code on GNU/Linux PPC. */
|
|
#define INSTR_LI_R0_0x7777 0x38007777
|
|
#define INSTR_SC 0x44000002
|
|
|
|
/* Since the *-tdep.c files are platform independent (i.e, they may be
|
|
used to build cross platform debuggers), we can't include system
|
|
headers. Therefore, details concerning the sigcontext structure
|
|
must be painstakingly rerecorded. What's worse, if these details
|
|
ever change in the header files, they'll have to be changed here
|
|
as well. */
|
|
|
|
/* __SIGNAL_FRAMESIZE from <asm/ptrace.h> */
|
|
#define PPC_LINUX_SIGNAL_FRAMESIZE 64
|
|
|
|
/* From <asm/sigcontext.h>, offsetof(struct sigcontext_struct, regs) == 0x1c */
|
|
#define PPC_LINUX_REGS_PTR_OFFSET (PPC_LINUX_SIGNAL_FRAMESIZE + 0x1c)
|
|
|
|
/* From <asm/sigcontext.h>,
|
|
offsetof(struct sigcontext_struct, handler) == 0x14 */
|
|
#define PPC_LINUX_HANDLER_PTR_OFFSET (PPC_LINUX_SIGNAL_FRAMESIZE + 0x14)
|
|
|
|
/* From <asm/ptrace.h>, values for PT_NIP, PT_R1, and PT_LNK */
|
|
#define PPC_LINUX_PT_R0 0
|
|
#define PPC_LINUX_PT_R1 1
|
|
#define PPC_LINUX_PT_R2 2
|
|
#define PPC_LINUX_PT_R3 3
|
|
#define PPC_LINUX_PT_R4 4
|
|
#define PPC_LINUX_PT_R5 5
|
|
#define PPC_LINUX_PT_R6 6
|
|
#define PPC_LINUX_PT_R7 7
|
|
#define PPC_LINUX_PT_R8 8
|
|
#define PPC_LINUX_PT_R9 9
|
|
#define PPC_LINUX_PT_R10 10
|
|
#define PPC_LINUX_PT_R11 11
|
|
#define PPC_LINUX_PT_R12 12
|
|
#define PPC_LINUX_PT_R13 13
|
|
#define PPC_LINUX_PT_R14 14
|
|
#define PPC_LINUX_PT_R15 15
|
|
#define PPC_LINUX_PT_R16 16
|
|
#define PPC_LINUX_PT_R17 17
|
|
#define PPC_LINUX_PT_R18 18
|
|
#define PPC_LINUX_PT_R19 19
|
|
#define PPC_LINUX_PT_R20 20
|
|
#define PPC_LINUX_PT_R21 21
|
|
#define PPC_LINUX_PT_R22 22
|
|
#define PPC_LINUX_PT_R23 23
|
|
#define PPC_LINUX_PT_R24 24
|
|
#define PPC_LINUX_PT_R25 25
|
|
#define PPC_LINUX_PT_R26 26
|
|
#define PPC_LINUX_PT_R27 27
|
|
#define PPC_LINUX_PT_R28 28
|
|
#define PPC_LINUX_PT_R29 29
|
|
#define PPC_LINUX_PT_R30 30
|
|
#define PPC_LINUX_PT_R31 31
|
|
#define PPC_LINUX_PT_NIP 32
|
|
#define PPC_LINUX_PT_MSR 33
|
|
#define PPC_LINUX_PT_CTR 35
|
|
#define PPC_LINUX_PT_LNK 36
|
|
#define PPC_LINUX_PT_XER 37
|
|
#define PPC_LINUX_PT_CCR 38
|
|
#define PPC_LINUX_PT_MQ 39
|
|
#define PPC_LINUX_PT_FPR0 48 /* each FP reg occupies 2 slots in this space */
|
|
#define PPC_LINUX_PT_FPR31 (PPC_LINUX_PT_FPR0 + 2*31)
|
|
#define PPC_LINUX_PT_FPSCR (PPC_LINUX_PT_FPR0 + 2*32 + 1)
|
|
|
|
static int ppc_linux_at_sigtramp_return_path (CORE_ADDR pc);
|
|
|
|
/* Determine if pc is in a signal trampoline...
|
|
|
|
Ha! That's not what this does at all. wait_for_inferior in
|
|
infrun.c calls PC_IN_SIGTRAMP in order to detect entry into a
|
|
signal trampoline just after delivery of a signal. But on
|
|
GNU/Linux, signal trampolines are used for the return path only.
|
|
The kernel sets things up so that the signal handler is called
|
|
directly.
|
|
|
|
If we use in_sigtramp2() in place of in_sigtramp() (see below)
|
|
we'll (often) end up with stop_pc in the trampoline and prev_pc in
|
|
the (now exited) handler. The code there will cause a temporary
|
|
breakpoint to be set on prev_pc which is not very likely to get hit
|
|
again.
|
|
|
|
If this is confusing, think of it this way... the code in
|
|
wait_for_inferior() needs to be able to detect entry into a signal
|
|
trampoline just after a signal is delivered, not after the handler
|
|
has been run.
|
|
|
|
So, we define in_sigtramp() below to return 1 if the following is
|
|
true:
|
|
|
|
1) The previous frame is a real signal trampoline.
|
|
|
|
- and -
|
|
|
|
2) pc is at the first or second instruction of the corresponding
|
|
handler.
|
|
|
|
Why the second instruction? It seems that wait_for_inferior()
|
|
never sees the first instruction when single stepping. When a
|
|
signal is delivered while stepping, the next instruction that
|
|
would've been stepped over isn't, instead a signal is delivered and
|
|
the first instruction of the handler is stepped over instead. That
|
|
puts us on the second instruction. (I added the test for the
|
|
first instruction long after the fact, just in case the observed
|
|
behavior is ever fixed.)
|
|
|
|
PC_IN_SIGTRAMP is called from blockframe.c as well in order to set
|
|
the signal_handler_caller flag. Because of our strange definition
|
|
of in_sigtramp below, we can't rely on signal_handler_caller
|
|
getting set correctly from within blockframe.c. This is why we
|
|
take pains to set it in init_extra_frame_info(). */
|
|
|
|
int
|
|
ppc_linux_in_sigtramp (CORE_ADDR pc, char *func_name)
|
|
{
|
|
CORE_ADDR lr;
|
|
CORE_ADDR sp;
|
|
CORE_ADDR tramp_sp;
|
|
char buf[4];
|
|
CORE_ADDR handler;
|
|
|
|
lr = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);
|
|
if (!ppc_linux_at_sigtramp_return_path (lr))
|
|
return 0;
|
|
|
|
sp = read_register (SP_REGNUM);
|
|
|
|
if (target_read_memory (sp, buf, sizeof (buf)) != 0)
|
|
return 0;
|
|
|
|
tramp_sp = extract_unsigned_integer (buf, 4);
|
|
|
|
if (target_read_memory (tramp_sp + PPC_LINUX_HANDLER_PTR_OFFSET, buf,
|
|
sizeof (buf)) != 0)
|
|
return 0;
|
|
|
|
handler = extract_unsigned_integer (buf, 4);
|
|
|
|
return (pc == handler || pc == handler + 4);
|
|
}
|
|
|
|
/*
|
|
* The signal handler trampoline is on the stack and consists of exactly
|
|
* two instructions. The easiest and most accurate way of determining
|
|
* whether the pc is in one of these trampolines is by inspecting the
|
|
* instructions. It'd be faster though if we could find a way to do this
|
|
* via some simple address comparisons.
|
|
*/
|
|
static int
|
|
ppc_linux_at_sigtramp_return_path (CORE_ADDR pc)
|
|
{
|
|
char buf[12];
|
|
unsigned long pcinsn;
|
|
if (target_read_memory (pc - 4, buf, sizeof (buf)) != 0)
|
|
return 0;
|
|
|
|
/* extract the instruction at the pc */
|
|
pcinsn = extract_unsigned_integer (buf + 4, 4);
|
|
|
|
return (
|
|
(pcinsn == INSTR_LI_R0_0x7777
|
|
&& extract_unsigned_integer (buf + 8, 4) == INSTR_SC)
|
|
||
|
|
(pcinsn == INSTR_SC
|
|
&& extract_unsigned_integer (buf, 4) == INSTR_LI_R0_0x7777));
|
|
}
|
|
|
|
CORE_ADDR
|
|
ppc_linux_skip_trampoline_code (CORE_ADDR pc)
|
|
{
|
|
char buf[4];
|
|
struct obj_section *sect;
|
|
struct objfile *objfile;
|
|
unsigned long insn;
|
|
CORE_ADDR plt_start = 0;
|
|
CORE_ADDR symtab = 0;
|
|
CORE_ADDR strtab = 0;
|
|
int num_slots = -1;
|
|
int reloc_index = -1;
|
|
CORE_ADDR plt_table;
|
|
CORE_ADDR reloc;
|
|
CORE_ADDR sym;
|
|
long symidx;
|
|
char symname[1024];
|
|
struct minimal_symbol *msymbol;
|
|
|
|
/* Find the section pc is in; return if not in .plt */
|
|
sect = find_pc_section (pc);
|
|
if (!sect || strcmp (sect->the_bfd_section->name, ".plt") != 0)
|
|
return 0;
|
|
|
|
objfile = sect->objfile;
|
|
|
|
/* Pick up the instruction at pc. It had better be of the
|
|
form
|
|
li r11, IDX
|
|
|
|
where IDX is an index into the plt_table. */
|
|
|
|
if (target_read_memory (pc, buf, 4) != 0)
|
|
return 0;
|
|
insn = extract_unsigned_integer (buf, 4);
|
|
|
|
if ((insn & 0xffff0000) != 0x39600000 /* li r11, VAL */ )
|
|
return 0;
|
|
|
|
reloc_index = (insn << 16) >> 16;
|
|
|
|
/* Find the objfile that pc is in and obtain the information
|
|
necessary for finding the symbol name. */
|
|
for (sect = objfile->sections; sect < objfile->sections_end; ++sect)
|
|
{
|
|
const char *secname = sect->the_bfd_section->name;
|
|
if (strcmp (secname, ".plt") == 0)
|
|
plt_start = sect->addr;
|
|
else if (strcmp (secname, ".rela.plt") == 0)
|
|
num_slots = ((int) sect->endaddr - (int) sect->addr) / 12;
|
|
else if (strcmp (secname, ".dynsym") == 0)
|
|
symtab = sect->addr;
|
|
else if (strcmp (secname, ".dynstr") == 0)
|
|
strtab = sect->addr;
|
|
}
|
|
|
|
/* Make sure we have all the information we need. */
|
|
if (plt_start == 0 || num_slots == -1 || symtab == 0 || strtab == 0)
|
|
return 0;
|
|
|
|
/* Compute the value of the plt table */
|
|
plt_table = plt_start + 72 + 8 * num_slots;
|
|
|
|
/* Get address of the relocation entry (Elf32_Rela) */
|
|
if (target_read_memory (plt_table + reloc_index, buf, 4) != 0)
|
|
return 0;
|
|
reloc = extract_address (buf, 4);
|
|
|
|
sect = find_pc_section (reloc);
|
|
if (!sect)
|
|
return 0;
|
|
|
|
if (strcmp (sect->the_bfd_section->name, ".text") == 0)
|
|
return reloc;
|
|
|
|
/* Now get the r_info field which is the relocation type and symbol
|
|
index. */
|
|
if (target_read_memory (reloc + 4, buf, 4) != 0)
|
|
return 0;
|
|
symidx = extract_unsigned_integer (buf, 4);
|
|
|
|
/* Shift out the relocation type leaving just the symbol index */
|
|
/* symidx = ELF32_R_SYM(symidx); */
|
|
symidx = symidx >> 8;
|
|
|
|
/* compute the address of the symbol */
|
|
sym = symtab + symidx * 4;
|
|
|
|
/* Fetch the string table index */
|
|
if (target_read_memory (sym, buf, 4) != 0)
|
|
return 0;
|
|
symidx = extract_unsigned_integer (buf, 4);
|
|
|
|
/* Fetch the string; we don't know how long it is. Is it possible
|
|
that the following will fail because we're trying to fetch too
|
|
much? */
|
|
if (target_read_memory (strtab + symidx, symname, sizeof (symname)) != 0)
|
|
return 0;
|
|
|
|
/* This might not work right if we have multiple symbols with the
|
|
same name; the only way to really get it right is to perform
|
|
the same sort of lookup as the dynamic linker. */
|
|
msymbol = lookup_minimal_symbol_text (symname, NULL, NULL);
|
|
if (!msymbol)
|
|
return 0;
|
|
|
|
return SYMBOL_VALUE_ADDRESS (msymbol);
|
|
}
|
|
|
|
/* The rs6000 version of FRAME_SAVED_PC will almost work for us. The
|
|
signal handler details are different, so we'll handle those here
|
|
and call the rs6000 version to do the rest. */
|
|
CORE_ADDR
|
|
ppc_linux_frame_saved_pc (struct frame_info *fi)
|
|
{
|
|
if (fi->signal_handler_caller)
|
|
{
|
|
CORE_ADDR regs_addr =
|
|
read_memory_integer (fi->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
|
|
/* return the NIP in the regs array */
|
|
return read_memory_integer (regs_addr + 4 * PPC_LINUX_PT_NIP, 4);
|
|
}
|
|
else if (fi->next && fi->next->signal_handler_caller)
|
|
{
|
|
CORE_ADDR regs_addr =
|
|
read_memory_integer (fi->next->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
|
|
/* return LNK in the regs array */
|
|
return read_memory_integer (regs_addr + 4 * PPC_LINUX_PT_LNK, 4);
|
|
}
|
|
else
|
|
return rs6000_frame_saved_pc (fi);
|
|
}
|
|
|
|
void
|
|
ppc_linux_init_extra_frame_info (int fromleaf, struct frame_info *fi)
|
|
{
|
|
rs6000_init_extra_frame_info (fromleaf, fi);
|
|
|
|
if (fi->next != 0)
|
|
{
|
|
/* We're called from get_prev_frame_info; check to see if
|
|
this is a signal frame by looking to see if the pc points
|
|
at trampoline code */
|
|
if (ppc_linux_at_sigtramp_return_path (fi->pc))
|
|
fi->signal_handler_caller = 1;
|
|
else
|
|
fi->signal_handler_caller = 0;
|
|
}
|
|
}
|
|
|
|
int
|
|
ppc_linux_frameless_function_invocation (struct frame_info *fi)
|
|
{
|
|
/* We'll find the wrong thing if we let
|
|
rs6000_frameless_function_invocation () search for a signal trampoline */
|
|
if (ppc_linux_at_sigtramp_return_path (fi->pc))
|
|
return 0;
|
|
else
|
|
return rs6000_frameless_function_invocation (fi);
|
|
}
|
|
|
|
void
|
|
ppc_linux_frame_init_saved_regs (struct frame_info *fi)
|
|
{
|
|
if (fi->signal_handler_caller)
|
|
{
|
|
CORE_ADDR regs_addr;
|
|
int i;
|
|
if (fi->saved_regs)
|
|
return;
|
|
|
|
frame_saved_regs_zalloc (fi);
|
|
|
|
regs_addr =
|
|
read_memory_integer (fi->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
|
|
fi->saved_regs[PC_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_NIP;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_ps_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_MSR;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_cr_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_CCR;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_lr_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_LNK;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_ctr_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_CTR;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_xer_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_XER;
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_mq_regnum] =
|
|
regs_addr + 4 * PPC_LINUX_PT_MQ;
|
|
for (i = 0; i < 32; i++)
|
|
fi->saved_regs[gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum + i] =
|
|
regs_addr + 4 * PPC_LINUX_PT_R0 + 4 * i;
|
|
for (i = 0; i < 32; i++)
|
|
fi->saved_regs[FP0_REGNUM + i] = regs_addr + 4 * PPC_LINUX_PT_FPR0 + 8 * i;
|
|
}
|
|
else
|
|
rs6000_frame_init_saved_regs (fi);
|
|
}
|
|
|
|
CORE_ADDR
|
|
ppc_linux_frame_chain (struct frame_info *thisframe)
|
|
{
|
|
/* Kernel properly constructs the frame chain for the handler */
|
|
if (thisframe->signal_handler_caller)
|
|
return read_memory_integer ((thisframe)->frame, 4);
|
|
else
|
|
return rs6000_frame_chain (thisframe);
|
|
}
|
|
|
|
/* ppc_linux_memory_remove_breakpoints attempts to remove a breakpoint
|
|
in much the same fashion as memory_remove_breakpoint in mem-break.c,
|
|
but is careful not to write back the previous contents if the code
|
|
in question has changed in between inserting the breakpoint and
|
|
removing it.
|
|
|
|
Here is the problem that we're trying to solve...
|
|
|
|
Once upon a time, before introducing this function to remove
|
|
breakpoints from the inferior, setting a breakpoint on a shared
|
|
library function prior to running the program would not work
|
|
properly. In order to understand the problem, it is first
|
|
necessary to understand a little bit about dynamic linking on
|
|
this platform.
|
|
|
|
A call to a shared library function is accomplished via a bl
|
|
(branch-and-link) instruction whose branch target is an entry
|
|
in the procedure linkage table (PLT). The PLT in the object
|
|
file is uninitialized. To gdb, prior to running the program, the
|
|
entries in the PLT are all zeros.
|
|
|
|
Once the program starts running, the shared libraries are loaded
|
|
and the procedure linkage table is initialized, but the entries in
|
|
the table are not (necessarily) resolved. Once a function is
|
|
actually called, the code in the PLT is hit and the function is
|
|
resolved. In order to better illustrate this, an example is in
|
|
order; the following example is from the gdb testsuite.
|
|
|
|
We start the program shmain.
|
|
|
|
[kev@arroyo testsuite]$ ../gdb gdb.base/shmain
|
|
[...]
|
|
|
|
We place two breakpoints, one on shr1 and the other on main.
|
|
|
|
(gdb) b shr1
|
|
Breakpoint 1 at 0x100409d4
|
|
(gdb) b main
|
|
Breakpoint 2 at 0x100006a0: file gdb.base/shmain.c, line 44.
|
|
|
|
Examine the instruction (and the immediatly following instruction)
|
|
upon which the breakpoint was placed. Note that the PLT entry
|
|
for shr1 contains zeros.
|
|
|
|
(gdb) x/2i 0x100409d4
|
|
0x100409d4 <shr1>: .long 0x0
|
|
0x100409d8 <shr1+4>: .long 0x0
|
|
|
|
Now run 'til main.
|
|
|
|
(gdb) r
|
|
Starting program: gdb.base/shmain
|
|
Breakpoint 1 at 0xffaf790: file gdb.base/shr1.c, line 19.
|
|
|
|
Breakpoint 2, main ()
|
|
at gdb.base/shmain.c:44
|
|
44 g = 1;
|
|
|
|
Examine the PLT again. Note that the loading of the shared
|
|
library has initialized the PLT to code which loads a constant
|
|
(which I think is an index into the GOT) into r11 and then
|
|
branchs a short distance to the code which actually does the
|
|
resolving.
|
|
|
|
(gdb) x/2i 0x100409d4
|
|
0x100409d4 <shr1>: li r11,4
|
|
0x100409d8 <shr1+4>: b 0x10040984 <sg+4>
|
|
(gdb) c
|
|
Continuing.
|
|
|
|
Breakpoint 1, shr1 (x=1)
|
|
at gdb.base/shr1.c:19
|
|
19 l = 1;
|
|
|
|
Now we've hit the breakpoint at shr1. (The breakpoint was
|
|
reset from the PLT entry to the actual shr1 function after the
|
|
shared library was loaded.) Note that the PLT entry has been
|
|
resolved to contain a branch that takes us directly to shr1.
|
|
(The real one, not the PLT entry.)
|
|
|
|
(gdb) x/2i 0x100409d4
|
|
0x100409d4 <shr1>: b 0xffaf76c <shr1>
|
|
0x100409d8 <shr1+4>: b 0x10040984 <sg+4>
|
|
|
|
The thing to note here is that the PLT entry for shr1 has been
|
|
changed twice.
|
|
|
|
Now the problem should be obvious. GDB places a breakpoint (a
|
|
trap instruction) on the zero value of the PLT entry for shr1.
|
|
Later on, after the shared library had been loaded and the PLT
|
|
initialized, GDB gets a signal indicating this fact and attempts
|
|
(as it always does when it stops) to remove all the breakpoints.
|
|
|
|
The breakpoint removal was causing the former contents (a zero
|
|
word) to be written back to the now initialized PLT entry thus
|
|
destroying a portion of the initialization that had occurred only a
|
|
short time ago. When execution continued, the zero word would be
|
|
executed as an instruction an an illegal instruction trap was
|
|
generated instead. (0 is not a legal instruction.)
|
|
|
|
The fix for this problem was fairly straightforward. The function
|
|
memory_remove_breakpoint from mem-break.c was copied to this file,
|
|
modified slightly, and renamed to ppc_linux_memory_remove_breakpoint.
|
|
In tm-linux.h, MEMORY_REMOVE_BREAKPOINT is defined to call this new
|
|
function.
|
|
|
|
The differences between ppc_linux_memory_remove_breakpoint () and
|
|
memory_remove_breakpoint () are minor. All that the former does
|
|
that the latter does not is check to make sure that the breakpoint
|
|
location actually contains a breakpoint (trap instruction) prior
|
|
to attempting to write back the old contents. If it does contain
|
|
a trap instruction, we allow the old contents to be written back.
|
|
Otherwise, we silently do nothing.
|
|
|
|
The big question is whether memory_remove_breakpoint () should be
|
|
changed to have the same functionality. The downside is that more
|
|
traffic is generated for remote targets since we'll have an extra
|
|
fetch of a memory word each time a breakpoint is removed.
|
|
|
|
For the time being, we'll leave this self-modifying-code-friendly
|
|
version in ppc-linux-tdep.c, but it ought to be migrated somewhere
|
|
else in the event that some other platform has similar needs with
|
|
regard to removing breakpoints in some potentially self modifying
|
|
code. */
|
|
int
|
|
ppc_linux_memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache)
|
|
{
|
|
const unsigned char *bp;
|
|
int val;
|
|
int bplen;
|
|
char old_contents[BREAKPOINT_MAX];
|
|
|
|
/* Determine appropriate breakpoint contents and size for this address. */
|
|
bp = BREAKPOINT_FROM_PC (&addr, &bplen);
|
|
if (bp == NULL)
|
|
error ("Software breakpoints not implemented for this target.");
|
|
|
|
val = target_read_memory (addr, old_contents, bplen);
|
|
|
|
/* If our breakpoint is no longer at the address, this means that the
|
|
program modified the code on us, so it is wrong to put back the
|
|
old value */
|
|
if (val == 0 && memcmp (bp, old_contents, bplen) == 0)
|
|
val = target_write_memory (addr, contents_cache, bplen);
|
|
|
|
return val;
|
|
}
|
|
|
|
/* Fetch (and possibly build) an appropriate link_map_offsets
|
|
structure for GNU/Linux PPC targets using the struct offsets
|
|
defined in link.h (but without actual reference to that file).
|
|
|
|
This makes it possible to access GNU/Linux PPC shared libraries
|
|
from a GDB that was not built on an GNU/Linux PPC host (for cross
|
|
debugging). */
|
|
|
|
struct link_map_offsets *
|
|
ppc_linux_svr4_fetch_link_map_offsets (void)
|
|
{
|
|
static struct link_map_offsets lmo;
|
|
static struct link_map_offsets *lmp = NULL;
|
|
|
|
if (lmp == NULL)
|
|
{
|
|
lmp = &lmo;
|
|
|
|
lmo.r_debug_size = 8; /* The actual size is 20 bytes, but
|
|
this is all we need. */
|
|
lmo.r_map_offset = 4;
|
|
lmo.r_map_size = 4;
|
|
|
|
lmo.link_map_size = 20; /* The actual size is 560 bytes, but
|
|
this is all we need. */
|
|
lmo.l_addr_offset = 0;
|
|
lmo.l_addr_size = 4;
|
|
|
|
lmo.l_name_offset = 4;
|
|
lmo.l_name_size = 4;
|
|
|
|
lmo.l_next_offset = 12;
|
|
lmo.l_next_size = 4;
|
|
|
|
lmo.l_prev_offset = 16;
|
|
lmo.l_prev_size = 4;
|
|
}
|
|
|
|
return lmp;
|
|
}
|
|
|
|
static void
|
|
ppc_linux_init_abi (struct gdbarch_info info,
|
|
struct gdbarch *gdbarch)
|
|
{
|
|
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
|
|
|
|
/* Until November 2001, gcc was not complying to the SYSV ABI for
|
|
returning structures less than or equal to 8 bytes in size. It was
|
|
returning everything in memory. When this was corrected, it wasn't
|
|
fixed for native platforms. */
|
|
set_gdbarch_use_struct_convention (gdbarch,
|
|
ppc_sysv_abi_broken_use_struct_convention);
|
|
|
|
if (tdep->wordsize == 4)
|
|
{
|
|
/* Note: kevinb/2002-04-12: See note in rs6000_gdbarch_init regarding
|
|
*_push_arguments(). The same remarks hold for the methods below. */
|
|
set_gdbarch_frameless_function_invocation (gdbarch,
|
|
ppc_linux_frameless_function_invocation);
|
|
set_gdbarch_frame_chain (gdbarch, ppc_linux_frame_chain);
|
|
set_gdbarch_frame_saved_pc (gdbarch, ppc_linux_frame_saved_pc);
|
|
|
|
set_gdbarch_frame_init_saved_regs (gdbarch,
|
|
ppc_linux_frame_init_saved_regs);
|
|
set_gdbarch_init_extra_frame_info (gdbarch,
|
|
ppc_linux_init_extra_frame_info);
|
|
|
|
set_gdbarch_memory_remove_breakpoint (gdbarch,
|
|
ppc_linux_memory_remove_breakpoint);
|
|
set_solib_svr4_fetch_link_map_offsets
|
|
(gdbarch, ppc_linux_svr4_fetch_link_map_offsets);
|
|
}
|
|
}
|
|
|
|
void
|
|
_initialize_ppc_linux_tdep (void)
|
|
{
|
|
gdbarch_register_osabi (bfd_arch_powerpc, GDB_OSABI_LINUX,
|
|
ppc_linux_init_abi);
|
|
}
|