| /* Target-dependent code for GDB, the GNU debugger. |
| |
| Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, |
| 1997, 2000, 2001, 2002, 2003 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 "osabi.h" |
| |
| #include "solib-svr4.h" |
| #include "ppc-tdep.h" |
| |
| /* The following instructions are used in the signal trampoline code |
| on GNU/Linux PPC. The kernel used to use magic syscalls 0x6666 and |
| 0x7777 but now uses the sigreturn syscalls. We check for both. */ |
| #define INSTR_LI_R0_0x6666 0x38006666 |
| #define INSTR_LI_R0_0x7777 0x38007777 |
| #define INSTR_LI_R0_NR_sigreturn 0x38000077 |
| #define INSTR_LI_R0_NR_rt_sigreturn 0x380000AC |
| |
| #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 frame's type (if a SIGTRAMP_FRAME). Because of our strange |
| definition of in_sigtramp below, we can't rely on the frame's type |
| getting set correctly from within blockframe.c. This is why we |
| take pains to set it in init_extra_frame_info(). |
| |
| NOTE: cagney/2002-11-10: I suspect the real problem here is that |
| the get_prev_frame() only initializes the frame's type after the |
| call to INIT_FRAME_INFO. get_prev_frame() should be fixed, this |
| code shouldn't be working its way around a bug :-(. */ |
| |
| 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); |
| } |
| |
| static int |
| insn_is_sigreturn (unsigned long pcinsn) |
| { |
| switch(pcinsn) |
| { |
| case INSTR_LI_R0_0x6666: |
| case INSTR_LI_R0_0x7777: |
| case INSTR_LI_R0_NR_sigreturn: |
| case INSTR_LI_R0_NR_rt_sigreturn: |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * 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 ( |
| (insn_is_sigreturn (pcinsn) |
| && extract_unsigned_integer (buf + 8, 4) == INSTR_SC) |
| || |
| (pcinsn == INSTR_SC |
| && insn_is_sigreturn (extract_unsigned_integer (buf, 4)))); |
| } |
| |
| static 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_unsigned_integer (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 ((get_frame_type (fi) == SIGTRAMP_FRAME)) |
| { |
| CORE_ADDR regs_addr = |
| read_memory_integer (get_frame_base (fi) |
| + 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 (get_next_frame (fi) |
| && (get_frame_type (get_next_frame (fi)) == SIGTRAMP_FRAME)) |
| { |
| CORE_ADDR regs_addr = |
| read_memory_integer (get_frame_base (get_next_frame (fi)) |
| + 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 (get_next_frame (fi) != 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 (get_frame_pc (fi))) |
| deprecated_set_frame_type (fi, SIGTRAMP_FRAME); |
| else |
| /* FIXME: cagney/2002-11-10: Is this double bogus? What |
| happens if the frame has previously been marked as a dummy? */ |
| deprecated_set_frame_type (fi, NORMAL_FRAME); |
| } |
| } |
| |
| 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 (get_frame_pc (fi))) |
| return 0; |
| else |
| return rs6000_frameless_function_invocation (fi); |
| } |
| |
| void |
| ppc_linux_frame_init_saved_regs (struct frame_info *fi) |
| { |
| if ((get_frame_type (fi) == SIGTRAMP_FRAME)) |
| { |
| CORE_ADDR regs_addr; |
| int i; |
| if (get_frame_saved_regs (fi)) |
| return; |
| |
| frame_saved_regs_zalloc (fi); |
| |
| regs_addr = |
| read_memory_integer (get_frame_base (fi) |
| + PPC_LINUX_REGS_PTR_OFFSET, 4); |
| get_frame_saved_regs (fi)[PC_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_NIP; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_ps_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_MSR; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_cr_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_CCR; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_lr_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_LNK; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_ctr_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_CTR; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_xer_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_XER; |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_mq_regnum] = |
| regs_addr + 4 * PPC_LINUX_PT_MQ; |
| for (i = 0; i < 32; i++) |
| get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum + i] = |
| regs_addr + 4 * PPC_LINUX_PT_R0 + 4 * i; |
| for (i = 0; i < 32; i++) |
| get_frame_saved_regs (fi)[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 ((get_frame_type (thisframe) == SIGTRAMP_FRAME)) |
| return read_memory_integer (get_frame_base (thisframe), 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; |
| } |
| |
| /* For historic reasons, PPC 32 GNU/Linux follows PowerOpen rather |
| than the 32 bit SYSV R4 ABI structure return convention - all |
| structures, no matter their size, are put in memory. Vectors, |
| which were added later, do get returned in a register though. */ |
| |
| static int |
| ppc_linux_use_struct_convention (int gcc_p, struct type *value_type) |
| { |
| if ((TYPE_LENGTH (value_type) == 16 || TYPE_LENGTH (value_type) == 8) |
| && TYPE_VECTOR (value_type)) |
| return 0; |
| return 1; |
| } |
| |
| /* 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; |
| } |
| |
| |
| /* Macros for matching instructions. Note that, since all the |
| operands are masked off before they're or-ed into the instruction, |
| you can use -1 to make masks. */ |
| |
| #define insn_d(opcd, rts, ra, d) \ |
| ((((opcd) & 0x3f) << 26) \ |
| | (((rts) & 0x1f) << 21) \ |
| | (((ra) & 0x1f) << 16) \ |
| | ((d) & 0xffff)) |
| |
| #define insn_ds(opcd, rts, ra, d, xo) \ |
| ((((opcd) & 0x3f) << 26) \ |
| | (((rts) & 0x1f) << 21) \ |
| | (((ra) & 0x1f) << 16) \ |
| | ((d) & 0xfffc) \ |
| | ((xo) & 0x3)) |
| |
| #define insn_xfx(opcd, rts, spr, xo) \ |
| ((((opcd) & 0x3f) << 26) \ |
| | (((rts) & 0x1f) << 21) \ |
| | (((spr) & 0x1f) << 16) \ |
| | (((spr) & 0x3e0) << 6) \ |
| | (((xo) & 0x3ff) << 1)) |
| |
| /* Read a PPC instruction from memory. PPC instructions are always |
| big-endian, no matter what endianness the program is running in, so |
| we can't use read_memory_integer or one of its friends here. */ |
| static unsigned int |
| read_insn (CORE_ADDR pc) |
| { |
| unsigned char buf[4]; |
| |
| read_memory (pc, buf, 4); |
| return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]; |
| } |
| |
| |
| /* An instruction to match. */ |
| struct insn_pattern |
| { |
| unsigned int mask; /* mask the insn with this... */ |
| unsigned int data; /* ...and see if it matches this. */ |
| int optional; /* If non-zero, this insn may be absent. */ |
| }; |
| |
| /* Return non-zero if the instructions at PC match the series |
| described in PATTERN, or zero otherwise. PATTERN is an array of |
| 'struct insn_pattern' objects, terminated by an entry whose mask is |
| zero. |
| |
| When the match is successful, fill INSN[i] with what PATTERN[i] |
| matched. If PATTERN[i] is optional, and the instruction wasn't |
| present, set INSN[i] to 0 (which is not a valid PPC instruction). |
| INSN should have as many elements as PATTERN. Note that, if |
| PATTERN contains optional instructions which aren't present in |
| memory, then INSN will have holes, so INSN[i] isn't necessarily the |
| i'th instruction in memory. */ |
| static int |
| insns_match_pattern (CORE_ADDR pc, |
| struct insn_pattern *pattern, |
| unsigned int *insn) |
| { |
| int i; |
| |
| for (i = 0; pattern[i].mask; i++) |
| { |
| insn[i] = read_insn (pc); |
| if ((insn[i] & pattern[i].mask) == pattern[i].data) |
| pc += 4; |
| else if (pattern[i].optional) |
| insn[i] = 0; |
| else |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| |
| /* Return the 'd' field of the d-form instruction INSN, properly |
| sign-extended. */ |
| static CORE_ADDR |
| insn_d_field (unsigned int insn) |
| { |
| return ((((CORE_ADDR) insn & 0xffff) ^ 0x8000) - 0x8000); |
| } |
| |
| |
| /* Return the 'ds' field of the ds-form instruction INSN, with the two |
| zero bits concatenated at the right, and properly |
| sign-extended. */ |
| static CORE_ADDR |
| insn_ds_field (unsigned int insn) |
| { |
| return ((((CORE_ADDR) insn & 0xfffc) ^ 0x8000) - 0x8000); |
| } |
| |
| |
| /* If DESC is the address of a 64-bit PowerPC GNU/Linux function |
| descriptor, return the descriptor's entry point. */ |
| static CORE_ADDR |
| ppc64_desc_entry_point (CORE_ADDR desc) |
| { |
| /* The first word of the descriptor is the entry point. */ |
| return (CORE_ADDR) read_memory_unsigned_integer (desc, 8); |
| } |
| |
| |
| /* Pattern for the standard linkage function. These are built by |
| build_plt_stub in elf64-ppc.c, whose GLINK argument is always |
| zero. */ |
| static struct insn_pattern ppc64_standard_linkage[] = |
| { |
| /* addis r12, r2, <any> */ |
| { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 }, |
| |
| /* std r2, 40(r1) */ |
| { -1, insn_ds (62, 2, 1, 40, 0), 0 }, |
| |
| /* ld r11, <any>(r12) */ |
| { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 }, |
| |
| /* addis r12, r12, 1 <optional> */ |
| { insn_d (-1, -1, -1, -1), insn_d (15, 12, 2, 1), 1 }, |
| |
| /* ld r2, <any>(r12) */ |
| { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 }, |
| |
| /* addis r12, r12, 1 <optional> */ |
| { insn_d (-1, -1, -1, -1), insn_d (15, 12, 2, 1), 1 }, |
| |
| /* mtctr r11 */ |
| { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467), |
| 0 }, |
| |
| /* ld r11, <any>(r12) */ |
| { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 }, |
| |
| /* bctr */ |
| { -1, 0x4e800420, 0 }, |
| |
| { 0, 0, 0 } |
| }; |
| #define PPC64_STANDARD_LINKAGE_LEN \ |
| (sizeof (ppc64_standard_linkage) / sizeof (ppc64_standard_linkage[0])) |
| |
| |
| /* Recognize a 64-bit PowerPC GNU/Linux linkage function --- what GDB |
| calls a "solib trampoline". */ |
| static int |
| ppc64_in_solib_call_trampoline (CORE_ADDR pc, char *name) |
| { |
| /* Detecting solib call trampolines on PPC64 GNU/Linux is a pain. |
| |
| It's not specifically solib call trampolines that are the issue. |
| Any call from one function to another function that uses a |
| different TOC requires a trampoline, to save the caller's TOC |
| pointer and then load the callee's TOC. An executable or shared |
| library may have more than one TOC, so even intra-object calls |
| may require a trampoline. Since executable and shared libraries |
| will all have their own distinct TOCs, every inter-object call is |
| also an inter-TOC call, and requires a trampoline --- so "solib |
| call trampolines" are just a special case. |
| |
| The 64-bit PowerPC GNU/Linux ABI calls these call trampolines |
| "linkage functions". Since they need to be near the functions |
| that call them, they all appear in .text, not in any special |
| section. The .plt section just contains an array of function |
| descriptors, from which the linkage functions load the callee's |
| entry point, TOC value, and environment pointer. So |
| in_plt_section is useless. The linkage functions don't have any |
| special linker symbols to name them, either. |
| |
| The only way I can see to recognize them is to actually look at |
| their code. They're generated by ppc_build_one_stub and some |
| other functions in bfd/elf64-ppc.c, so that should show us all |
| the instruction sequences we need to recognize. */ |
| unsigned int insn[PPC64_STANDARD_LINKAGE_LEN]; |
| |
| return insns_match_pattern (pc, ppc64_standard_linkage, insn); |
| } |
| |
| |
| /* When the dynamic linker is doing lazy symbol resolution, the first |
| call to a function in another object will go like this: |
| |
| - The user's function calls the linkage function: |
| |
| 100007c4: 4b ff fc d5 bl 10000498 |
| 100007c8: e8 41 00 28 ld r2,40(r1) |
| |
| - The linkage function loads the entry point (and other stuff) from |
| the function descriptor in the PLT, and jumps to it: |
| |
| 10000498: 3d 82 00 00 addis r12,r2,0 |
| 1000049c: f8 41 00 28 std r2,40(r1) |
| 100004a0: e9 6c 80 98 ld r11,-32616(r12) |
| 100004a4: e8 4c 80 a0 ld r2,-32608(r12) |
| 100004a8: 7d 69 03 a6 mtctr r11 |
| 100004ac: e9 6c 80 a8 ld r11,-32600(r12) |
| 100004b0: 4e 80 04 20 bctr |
| |
| - But since this is the first time that PLT entry has been used, it |
| sends control to its glink entry. That loads the number of the |
| PLT entry and jumps to the common glink0 code: |
| |
| 10000c98: 38 00 00 00 li r0,0 |
| 10000c9c: 4b ff ff dc b 10000c78 |
| |
| - The common glink0 code then transfers control to the dynamic |
| linker's fixup code: |
| |
| 10000c78: e8 41 00 28 ld r2,40(r1) |
| 10000c7c: 3d 82 00 00 addis r12,r2,0 |
| 10000c80: e9 6c 80 80 ld r11,-32640(r12) |
| 10000c84: e8 4c 80 88 ld r2,-32632(r12) |
| 10000c88: 7d 69 03 a6 mtctr r11 |
| 10000c8c: e9 6c 80 90 ld r11,-32624(r12) |
| 10000c90: 4e 80 04 20 bctr |
| |
| Eventually, this code will figure out how to skip all of this, |
| including the dynamic linker. At the moment, we just get through |
| the linkage function. */ |
| |
| /* If the current thread is about to execute a series of instructions |
| at PC matching the ppc64_standard_linkage pattern, and INSN is the result |
| from that pattern match, return the code address to which the |
| standard linkage function will send them. (This doesn't deal with |
| dynamic linker lazy symbol resolution stubs.) */ |
| static CORE_ADDR |
| ppc64_standard_linkage_target (CORE_ADDR pc, unsigned int *insn) |
| { |
| struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch); |
| |
| /* The address of the function descriptor this linkage function |
| references. */ |
| CORE_ADDR desc |
| = ((CORE_ADDR) read_register (tdep->ppc_gp0_regnum + 2) |
| + (insn_d_field (insn[0]) << 16) |
| + insn_ds_field (insn[2])); |
| |
| /* The first word of the descriptor is the entry point. Return that. */ |
| return ppc64_desc_entry_point (desc); |
| } |
| |
| |
| /* Given that we've begun executing a call trampoline at PC, return |
| the entry point of the function the trampoline will go to. */ |
| static CORE_ADDR |
| ppc64_skip_trampoline_code (CORE_ADDR pc) |
| { |
| unsigned int ppc64_standard_linkage_insn[PPC64_STANDARD_LINKAGE_LEN]; |
| |
| if (insns_match_pattern (pc, ppc64_standard_linkage, |
| ppc64_standard_linkage_insn)) |
| return ppc64_standard_linkage_target (pc, ppc64_standard_linkage_insn); |
| else |
| return 0; |
| } |
| |
| |
| /* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR) on PPC64 GNU/Linux. |
| |
| Usually a function pointer's representation is simply the address |
| of the function. On GNU/Linux on the 64-bit PowerPC however, a |
| function pointer is represented by a pointer to a TOC entry. This |
| TOC entry contains three words, the first word is the address of |
| the function, the second word is the TOC pointer (r2), and the |
| third word is the static chain value. Throughout GDB it is |
| currently assumed that a function pointer contains the address of |
| the function, which is not easy to fix. In addition, the |
| conversion of a function address to a function pointer would |
| require allocation of a TOC entry in the inferior's memory space, |
| with all its drawbacks. To be able to call C++ virtual methods in |
| the inferior (which are called via function pointers), |
| find_function_addr uses this function to get the function address |
| from a function pointer. */ |
| |
| /* Return real function address if ADDR (a function pointer) is in the data |
| space and is therefore a special function pointer. */ |
| |
| static CORE_ADDR |
| ppc64_linux_convert_from_func_ptr_addr (CORE_ADDR addr) |
| { |
| struct obj_section *s; |
| |
| s = find_pc_section (addr); |
| if (s && s->the_bfd_section->flags & SEC_CODE) |
| return addr; |
| |
| /* ADDR is in the data space, so it's a pointer to a descriptor, not |
| the entry point. */ |
| return ppc64_desc_entry_point (addr); |
| } |
| |
| |
| enum { |
| ELF_NGREG = 48, |
| ELF_NFPREG = 33, |
| ELF_NVRREG = 33 |
| }; |
| |
| enum { |
| ELF_GREGSET_SIZE = (ELF_NGREG * 4), |
| ELF_FPREGSET_SIZE = (ELF_NFPREG * 8) |
| }; |
| |
| void |
| ppc_linux_supply_gregset (char *buf) |
| { |
| int regi; |
| struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch); |
| |
| for (regi = 0; regi < 32; regi++) |
| supply_register (regi, buf + 4 * regi); |
| |
| supply_register (PC_REGNUM, buf + 4 * PPC_LINUX_PT_NIP); |
| supply_register (tdep->ppc_lr_regnum, buf + 4 * PPC_LINUX_PT_LNK); |
| supply_register (tdep->ppc_cr_regnum, buf + 4 * PPC_LINUX_PT_CCR); |
| supply_register (tdep->ppc_xer_regnum, buf + 4 * PPC_LINUX_PT_XER); |
| supply_register (tdep->ppc_ctr_regnum, buf + 4 * PPC_LINUX_PT_CTR); |
| if (tdep->ppc_mq_regnum != -1) |
| supply_register (tdep->ppc_mq_regnum, buf + 4 * PPC_LINUX_PT_MQ); |
| supply_register (tdep->ppc_ps_regnum, buf + 4 * PPC_LINUX_PT_MSR); |
| } |
| |
| void |
| ppc_linux_supply_fpregset (char *buf) |
| { |
| int regi; |
| struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch); |
| |
| for (regi = 0; regi < 32; regi++) |
| supply_register (FP0_REGNUM + regi, buf + 8 * regi); |
| |
| /* The FPSCR is stored in the low order word of the last doubleword in the |
| fpregset. */ |
| supply_register (tdep->ppc_fpscr_regnum, buf + 8 * 32 + 4); |
| } |
| |
| /* |
| Use a local version of this function to get the correct types for regsets. |
| */ |
| |
| static void |
| fetch_core_registers (char *core_reg_sect, |
| unsigned core_reg_size, |
| int which, |
| CORE_ADDR reg_addr) |
| { |
| if (which == 0) |
| { |
| if (core_reg_size == ELF_GREGSET_SIZE) |
| ppc_linux_supply_gregset (core_reg_sect); |
| else |
| warning ("wrong size gregset struct in core file"); |
| } |
| else if (which == 2) |
| { |
| if (core_reg_size == ELF_FPREGSET_SIZE) |
| ppc_linux_supply_fpregset (core_reg_sect); |
| else |
| warning ("wrong size fpregset struct in core file"); |
| } |
| } |
| |
| /* Register that we are able to handle ELF file formats using standard |
| procfs "regset" structures. */ |
| |
| static struct core_fns ppc_linux_regset_core_fns = |
| { |
| bfd_target_elf_flavour, /* core_flavour */ |
| default_check_format, /* check_format */ |
| default_core_sniffer, /* core_sniffer */ |
| fetch_core_registers, /* core_read_registers */ |
| NULL /* next */ |
| }; |
| |
| static void |
| ppc_linux_init_abi (struct gdbarch_info info, |
| struct gdbarch *gdbarch) |
| { |
| struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| |
| if (tdep->wordsize == 4) |
| { |
| /* Until November 2001, gcc did not comply with the 32 bit SysV |
| R4 ABI requirement that structures less than or equal to 8 |
| bytes should be returned in registers. Instead GCC was using |
| the the AIX/PowerOpen ABI - everything returned in memory |
| (well ignoring vectors that is). When this was corrected, it |
| wasn't fixed for GNU/Linux native platform. Use the |
| PowerOpen struct convention. */ |
| set_gdbarch_use_struct_convention (gdbarch, ppc_linux_use_struct_convention); |
| |
| /* 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_deprecated_frame_chain (gdbarch, ppc_linux_frame_chain); |
| set_gdbarch_deprecated_frame_saved_pc (gdbarch, ppc_linux_frame_saved_pc); |
| |
| set_gdbarch_deprecated_frame_init_saved_regs (gdbarch, |
| ppc_linux_frame_init_saved_regs); |
| set_gdbarch_deprecated_init_extra_frame_info (gdbarch, |
| ppc_linux_init_extra_frame_info); |
| |
| set_gdbarch_memory_remove_breakpoint (gdbarch, |
| ppc_linux_memory_remove_breakpoint); |
| /* Shared library handling. */ |
| set_gdbarch_in_solib_call_trampoline (gdbarch, in_plt_section); |
| set_gdbarch_skip_trampoline_code (gdbarch, |
| ppc_linux_skip_trampoline_code); |
| set_solib_svr4_fetch_link_map_offsets |
| (gdbarch, ppc_linux_svr4_fetch_link_map_offsets); |
| } |
| |
| if (tdep->wordsize == 8) |
| { |
| /* Handle PPC64 GNU/Linux function pointers (which are really |
| function descriptors). */ |
| set_gdbarch_convert_from_func_ptr_addr |
| (gdbarch, ppc64_linux_convert_from_func_ptr_addr); |
| |
| set_gdbarch_in_solib_call_trampoline |
| (gdbarch, ppc64_in_solib_call_trampoline); |
| set_gdbarch_skip_trampoline_code (gdbarch, ppc64_skip_trampoline_code); |
| } |
| } |
| |
| void |
| _initialize_ppc_linux_tdep (void) |
| { |
| gdbarch_register_osabi (bfd_arch_powerpc, 0, GDB_OSABI_LINUX, |
| ppc_linux_init_abi); |
| add_core_fns (&ppc_linux_regset_core_fns); |
| } |