/* Native support code for PPC AIX, for GDB the GNU debugger. Copyright (C) 2006, 2007, 2008, 2009 Free Software Foundation, Inc. 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 3 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, see . */ #include "defs.h" #include "gdb_string.h" #include "gdb_assert.h" #include "osabi.h" #include "regcache.h" #include "regset.h" #include "gdbtypes.h" #include "gdbcore.h" #include "target.h" #include "value.h" #include "infcall.h" #include "objfiles.h" #include "breakpoint.h" #include "rs6000-tdep.h" #include "ppc-tdep.h" /* Hook for determining the TOC address when calling functions in the inferior under AIX. The initialization code in rs6000-nat.c sets this hook to point to find_toc_address. */ CORE_ADDR (*rs6000_find_toc_address_hook) (CORE_ADDR) = NULL; /* If the kernel has to deliver a signal, it pushes a sigcontext structure on the stack and then calls the signal handler, passing the address of the sigcontext in an argument register. Usually the signal handler doesn't save this register, so we have to access the sigcontext structure via an offset from the signal handler frame. The following constants were determined by experimentation on AIX 3.2. */ #define SIG_FRAME_PC_OFFSET 96 #define SIG_FRAME_LR_OFFSET 108 #define SIG_FRAME_FP_OFFSET 284 /* Core file support. */ static struct ppc_reg_offsets rs6000_aix32_reg_offsets = { /* General-purpose registers. */ 208, /* r0_offset */ 4, /* gpr_size */ 4, /* xr_size */ 24, /* pc_offset */ 28, /* ps_offset */ 32, /* cr_offset */ 36, /* lr_offset */ 40, /* ctr_offset */ 44, /* xer_offset */ 48, /* mq_offset */ /* Floating-point registers. */ 336, /* f0_offset */ 56, /* fpscr_offset */ 4, /* fpscr_size */ /* AltiVec registers. */ -1, /* vr0_offset */ -1, /* vscr_offset */ -1 /* vrsave_offset */ }; static struct ppc_reg_offsets rs6000_aix64_reg_offsets = { /* General-purpose registers. */ 0, /* r0_offset */ 8, /* gpr_size */ 4, /* xr_size */ 264, /* pc_offset */ 256, /* ps_offset */ 288, /* cr_offset */ 272, /* lr_offset */ 280, /* ctr_offset */ 292, /* xer_offset */ -1, /* mq_offset */ /* Floating-point registers. */ 312, /* f0_offset */ 296, /* fpscr_offset */ 4, /* fpscr_size */ /* AltiVec registers. */ -1, /* vr0_offset */ -1, /* vscr_offset */ -1 /* vrsave_offset */ }; /* Supply register REGNUM in the general-purpose register set REGSET from the buffer specified by GREGS and LEN to register cache REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */ static void rs6000_aix_supply_regset (const struct regset *regset, struct regcache *regcache, int regnum, const void *gregs, size_t len) { ppc_supply_gregset (regset, regcache, regnum, gregs, len); ppc_supply_fpregset (regset, regcache, regnum, gregs, len); } /* Collect register REGNUM in the general-purpose register set REGSET. from register cache REGCACHE into the buffer specified by GREGS and LEN. If REGNUM is -1, do this for all registers in REGSET. */ static void rs6000_aix_collect_regset (const struct regset *regset, const struct regcache *regcache, int regnum, void *gregs, size_t len) { ppc_collect_gregset (regset, regcache, regnum, gregs, len); ppc_collect_fpregset (regset, regcache, regnum, gregs, len); } /* AIX register set. */ static struct regset rs6000_aix32_regset = { &rs6000_aix32_reg_offsets, rs6000_aix_supply_regset, rs6000_aix_collect_regset, }; static struct regset rs6000_aix64_regset = { &rs6000_aix64_reg_offsets, rs6000_aix_supply_regset, rs6000_aix_collect_regset, }; /* Return the appropriate register set for the core section identified by SECT_NAME and SECT_SIZE. */ static const struct regset * rs6000_aix_regset_from_core_section (struct gdbarch *gdbarch, const char *sect_name, size_t sect_size) { if (gdbarch_tdep (gdbarch)->wordsize == 4) { if (strcmp (sect_name, ".reg") == 0 && sect_size >= 592) return &rs6000_aix32_regset; } else { if (strcmp (sect_name, ".reg") == 0 && sect_size >= 576) return &rs6000_aix64_regset; } return NULL; } /* Pass the arguments in either registers, or in the stack. In RS/6000, the first eight words of the argument list (that might be less than eight parameters if some parameters occupy more than one word) are passed in r3..r10 registers. float and double parameters are passed in fpr's, in addition to that. Rest of the parameters if any are passed in user stack. There might be cases in which half of the parameter is copied into registers, the other half is pushed into stack. Stack must be aligned on 64-bit boundaries when synthesizing function calls. If the function is returning a structure, then the return address is passed in r3, then the first 7 words of the parameters can be passed in registers, starting from r4. */ static CORE_ADDR rs6000_push_dummy_call (struct gdbarch *gdbarch, struct value *function, struct regcache *regcache, CORE_ADDR bp_addr, int nargs, struct value **args, CORE_ADDR sp, int struct_return, CORE_ADDR struct_addr) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); int ii; int len = 0; int argno; /* current argument number */ int argbytes; /* current argument byte */ gdb_byte tmp_buffer[50]; int f_argno = 0; /* current floating point argno */ int wordsize = gdbarch_tdep (gdbarch)->wordsize; CORE_ADDR func_addr = find_function_addr (function, NULL); struct value *arg = 0; struct type *type; ULONGEST saved_sp; /* The calling convention this function implements assumes the processor has floating-point registers. We shouldn't be using it on PPC variants that lack them. */ gdb_assert (ppc_floating_point_unit_p (gdbarch)); /* The first eight words of ther arguments are passed in registers. Copy them appropriately. */ ii = 0; /* If the function is returning a `struct', then the first word (which will be passed in r3) is used for struct return address. In that case we should advance one word and start from r4 register to copy parameters. */ if (struct_return) { regcache_raw_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3, struct_addr); ii++; } /* effectively indirect call... gcc does... return_val example( float, int); eabi: float in fp0, int in r3 offset of stack on overflow 8/16 for varargs, must go by type. power open: float in r3&r4, int in r5 offset of stack on overflow different both: return in r3 or f0. If no float, must study how gcc emulates floats; pay attention to arg promotion. User may have to cast\args to handle promotion correctly since gdb won't know if prototype supplied or not. */ for (argno = 0, argbytes = 0; argno < nargs && ii < 8; ++ii) { int reg_size = register_size (gdbarch, ii + 3); arg = args[argno]; type = check_typedef (value_type (arg)); len = TYPE_LENGTH (type); if (TYPE_CODE (type) == TYPE_CODE_FLT) { /* Floating point arguments are passed in fpr's, as well as gpr's. There are 13 fpr's reserved for passing parameters. At this point there is no way we would run out of them. */ gdb_assert (len <= 8); regcache_cooked_write (regcache, tdep->ppc_fp0_regnum + 1 + f_argno, value_contents (arg)); ++f_argno; } if (len > reg_size) { /* Argument takes more than one register. */ while (argbytes < len) { gdb_byte word[MAX_REGISTER_SIZE]; memset (word, 0, reg_size); memcpy (word, ((char *) value_contents (arg)) + argbytes, (len - argbytes) > reg_size ? reg_size : len - argbytes); regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3 + ii, word); ++ii, argbytes += reg_size; if (ii >= 8) goto ran_out_of_registers_for_arguments; } argbytes = 0; --ii; } else { /* Argument can fit in one register. No problem. */ int adj = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? reg_size - len : 0; gdb_byte word[MAX_REGISTER_SIZE]; memset (word, 0, reg_size); memcpy (word, value_contents (arg), len); regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3 +ii, word); } ++argno; } ran_out_of_registers_for_arguments: regcache_cooked_read_unsigned (regcache, gdbarch_sp_regnum (gdbarch), &saved_sp); /* Location for 8 parameters are always reserved. */ sp -= wordsize * 8; /* Another six words for back chain, TOC register, link register, etc. */ sp -= wordsize * 6; /* Stack pointer must be quadword aligned. */ sp &= -16; /* If there are more arguments, allocate space for them in the stack, then push them starting from the ninth one. */ if ((argno < nargs) || argbytes) { int space = 0, jj; if (argbytes) { space += ((len - argbytes + 3) & -4); jj = argno + 1; } else jj = argno; for (; jj < nargs; ++jj) { struct value *val = args[jj]; space += ((TYPE_LENGTH (value_type (val))) + 3) & -4; } /* Add location required for the rest of the parameters. */ space = (space + 15) & -16; sp -= space; /* This is another instance we need to be concerned about securing our stack space. If we write anything underneath %sp (r1), we might conflict with the kernel who thinks he is free to use this area. So, update %sp first before doing anything else. */ regcache_raw_write_signed (regcache, gdbarch_sp_regnum (gdbarch), sp); /* If the last argument copied into the registers didn't fit there completely, push the rest of it into stack. */ if (argbytes) { write_memory (sp + 24 + (ii * 4), value_contents (arg) + argbytes, len - argbytes); ++argno; ii += ((len - argbytes + 3) & -4) / 4; } /* Push the rest of the arguments into stack. */ for (; argno < nargs; ++argno) { arg = args[argno]; type = check_typedef (value_type (arg)); len = TYPE_LENGTH (type); /* Float types should be passed in fpr's, as well as in the stack. */ if (TYPE_CODE (type) == TYPE_CODE_FLT && f_argno < 13) { gdb_assert (len <= 8); regcache_cooked_write (regcache, tdep->ppc_fp0_regnum + 1 + f_argno, value_contents (arg)); ++f_argno; } write_memory (sp + 24 + (ii * 4), value_contents (arg), len); ii += ((len + 3) & -4) / 4; } } /* Set the stack pointer. According to the ABI, the SP is meant to be set _before_ the corresponding stack space is used. On AIX, this even applies when the target has been completely stopped! Not doing this can lead to conflicts with the kernel which thinks that it still has control over this not-yet-allocated stack region. */ regcache_raw_write_signed (regcache, gdbarch_sp_regnum (gdbarch), sp); /* Set back chain properly. */ store_unsigned_integer (tmp_buffer, wordsize, saved_sp); write_memory (sp, tmp_buffer, wordsize); /* Point the inferior function call's return address at the dummy's breakpoint. */ regcache_raw_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr); /* Set the TOC register, get the value from the objfile reader which, in turn, gets it from the VMAP table. */ if (rs6000_find_toc_address_hook != NULL) { CORE_ADDR tocvalue = (*rs6000_find_toc_address_hook) (func_addr); regcache_raw_write_signed (regcache, tdep->ppc_toc_regnum, tocvalue); } target_store_registers (regcache, -1); return sp; } static enum return_value_convention rs6000_return_value (struct gdbarch *gdbarch, struct type *func_type, struct type *valtype, struct regcache *regcache, gdb_byte *readbuf, const gdb_byte *writebuf) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); gdb_byte buf[8]; /* The calling convention this function implements assumes the processor has floating-point registers. We shouldn't be using it on PowerPC variants that lack them. */ gdb_assert (ppc_floating_point_unit_p (gdbarch)); /* AltiVec extension: Functions that declare a vector data type as a return value place that return value in VR2. */ if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY && TYPE_VECTOR (valtype) && TYPE_LENGTH (valtype) == 16) { if (readbuf) regcache_cooked_read (regcache, tdep->ppc_vr0_regnum + 2, readbuf); if (writebuf) regcache_cooked_write (regcache, tdep->ppc_vr0_regnum + 2, writebuf); return RETURN_VALUE_REGISTER_CONVENTION; } /* If the called subprogram returns an aggregate, there exists an implicit first argument, whose value is the address of a caller- allocated buffer into which the callee is assumed to store its return value. All explicit parameters are appropriately relabeled. */ if (TYPE_CODE (valtype) == TYPE_CODE_STRUCT || TYPE_CODE (valtype) == TYPE_CODE_UNION || TYPE_CODE (valtype) == TYPE_CODE_ARRAY) return RETURN_VALUE_STRUCT_CONVENTION; /* Scalar floating-point values are returned in FPR1 for float or double, and in FPR1:FPR2 for quadword precision. Fortran complex*8 and complex*16 are returned in FPR1:FPR2, and complex*32 is returned in FPR1:FPR4. */ if (TYPE_CODE (valtype) == TYPE_CODE_FLT && (TYPE_LENGTH (valtype) == 4 || TYPE_LENGTH (valtype) == 8)) { struct type *regtype = register_type (gdbarch, tdep->ppc_fp0_regnum); gdb_byte regval[8]; /* FIXME: kettenis/2007-01-01: Add support for quadword precision and complex. */ if (readbuf) { regcache_cooked_read (regcache, tdep->ppc_fp0_regnum + 1, regval); convert_typed_floating (regval, regtype, readbuf, valtype); } if (writebuf) { convert_typed_floating (writebuf, valtype, regval, regtype); regcache_cooked_write (regcache, tdep->ppc_fp0_regnum + 1, regval); } return RETURN_VALUE_REGISTER_CONVENTION; } /* Values of the types int, long, short, pointer, and char (length is less than or equal to four bytes), as well as bit values of lengths less than or equal to 32 bits, must be returned right justified in GPR3 with signed values sign extended and unsigned values zero extended, as necessary. */ if (TYPE_LENGTH (valtype) <= tdep->wordsize) { if (readbuf) { ULONGEST regval; /* For reading we don't have to worry about sign extension. */ regcache_cooked_read_unsigned (regcache, tdep->ppc_gp0_regnum + 3, ®val); store_unsigned_integer (readbuf, TYPE_LENGTH (valtype), regval); } if (writebuf) { /* For writing, use unpack_long since that should handle any required sign extension. */ regcache_cooked_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3, unpack_long (valtype, writebuf)); } return RETURN_VALUE_REGISTER_CONVENTION; } /* Eight-byte non-floating-point scalar values must be returned in GPR3:GPR4. */ if (TYPE_LENGTH (valtype) == 8) { gdb_assert (TYPE_CODE (valtype) != TYPE_CODE_FLT); gdb_assert (tdep->wordsize == 4); if (readbuf) { gdb_byte regval[8]; regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 3, regval); regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 4, regval + 4); memcpy (readbuf, regval, 8); } if (writebuf) { regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3, writebuf); regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 4, writebuf + 4); } return RETURN_VALUE_REGISTER_CONVENTION; } return RETURN_VALUE_STRUCT_CONVENTION; } /* Support for CONVERT_FROM_FUNC_PTR_ADDR (ARCH, ADDR, TARG). Usually a function pointer's representation is simply the address of the function. On the RS/6000 however, a function pointer is represented by a pointer to an OPD entry. This OPD 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 an OPD 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 rs6000_convert_from_func_ptr_addr (struct gdbarch *gdbarch, CORE_ADDR addr, struct target_ops *targ) { struct obj_section *s; s = find_pc_section (addr); /* Normally, functions live inside a section that is executable. So, if ADDR points to a non-executable section, then treat it as a function descriptor and return the target address iff the target address itself points to a section that is executable. */ if (s && (s->the_bfd_section->flags & SEC_CODE) == 0) { CORE_ADDR pc = read_memory_unsigned_integer (addr, gdbarch_tdep (gdbarch)->wordsize); struct obj_section *pc_section = find_pc_section (pc); if (pc_section && (pc_section->the_bfd_section->flags & SEC_CODE)) return pc; } return addr; } /* Calculate the destination of a branch/jump. Return -1 if not a branch. */ static CORE_ADDR branch_dest (struct frame_info *frame, int opcode, int instr, CORE_ADDR pc, CORE_ADDR safety) { struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (frame)); CORE_ADDR dest; int immediate; int absolute; int ext_op; absolute = (int) ((instr >> 1) & 1); switch (opcode) { case 18: immediate = ((instr & ~3) << 6) >> 6; /* br unconditional */ if (absolute) dest = immediate; else dest = pc + immediate; break; case 16: immediate = ((instr & ~3) << 16) >> 16; /* br conditional */ if (absolute) dest = immediate; else dest = pc + immediate; break; case 19: ext_op = (instr >> 1) & 0x3ff; if (ext_op == 16) /* br conditional register */ { dest = get_frame_register_unsigned (frame, tdep->ppc_lr_regnum) & ~3; /* If we are about to return from a signal handler, dest is something like 0x3c90. The current frame is a signal handler caller frame, upon completion of the sigreturn system call execution will return to the saved PC in the frame. */ if (dest < AIX_TEXT_SEGMENT_BASE) dest = read_memory_unsigned_integer (get_frame_base (frame) + SIG_FRAME_PC_OFFSET, tdep->wordsize); } else if (ext_op == 528) /* br cond to count reg */ { dest = get_frame_register_unsigned (frame, tdep->ppc_ctr_regnum) & ~3; /* If we are about to execute a system call, dest is something like 0x22fc or 0x3b00. Upon completion the system call will return to the address in the link register. */ if (dest < AIX_TEXT_SEGMENT_BASE) dest = get_frame_register_unsigned (frame, tdep->ppc_lr_regnum) & ~3; } else return -1; break; default: return -1; } return (dest < AIX_TEXT_SEGMENT_BASE) ? safety : dest; } /* AIX does not support PT_STEP. Simulate it. */ static int rs6000_software_single_step (struct frame_info *frame) { int ii, insn; CORE_ADDR loc; CORE_ADDR breaks[2]; int opcode; loc = get_frame_pc (frame); insn = read_memory_integer (loc, 4); if (ppc_deal_with_atomic_sequence (frame)) return 1; breaks[0] = loc + PPC_INSN_SIZE; opcode = insn >> 26; breaks[1] = branch_dest (frame, opcode, insn, loc, breaks[0]); /* Don't put two breakpoints on the same address. */ if (breaks[1] == breaks[0]) breaks[1] = -1; for (ii = 0; ii < 2; ++ii) { /* ignore invalid breakpoint. */ if (breaks[ii] == -1) continue; insert_single_step_breakpoint (breaks[ii]); } errno = 0; /* FIXME, don't ignore errors! */ /* What errors? {read,write}_memory call error(). */ return 1; } static enum gdb_osabi rs6000_aix_osabi_sniffer (bfd *abfd) { if (bfd_get_flavour (abfd) == bfd_target_xcoff_flavour); return GDB_OSABI_AIX; return GDB_OSABI_UNKNOWN; } static void rs6000_aix_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); /* RS6000/AIX does not support PT_STEP. Has to be simulated. */ set_gdbarch_software_single_step (gdbarch, rs6000_software_single_step); /* Displaced stepping is currently not supported in combination with software single-stepping. */ set_gdbarch_displaced_step_copy_insn (gdbarch, NULL); set_gdbarch_displaced_step_fixup (gdbarch, NULL); set_gdbarch_displaced_step_free_closure (gdbarch, NULL); set_gdbarch_displaced_step_location (gdbarch, NULL); set_gdbarch_push_dummy_call (gdbarch, rs6000_push_dummy_call); set_gdbarch_return_value (gdbarch, rs6000_return_value); set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT); /* Handle RS/6000 function pointers (which are really function descriptors). */ set_gdbarch_convert_from_func_ptr_addr (gdbarch, rs6000_convert_from_func_ptr_addr); /* Core file support. */ set_gdbarch_regset_from_core_section (gdbarch, rs6000_aix_regset_from_core_section); if (tdep->wordsize == 8) tdep->lr_frame_offset = 16; else tdep->lr_frame_offset = 8; if (tdep->wordsize == 4) /* PowerOpen / AIX 32 bit. The saved area or red zone consists of 19 4 byte GPRS + 18 8 byte FPRs giving a total of 220 bytes. Problem is, 220 isn't frame (16 byte) aligned. Round it up to 224. */ set_gdbarch_frame_red_zone_size (gdbarch, 224); else set_gdbarch_frame_red_zone_size (gdbarch, 0); } void _initialize_rs6000_aix_tdep (void) { gdbarch_register_osabi_sniffer (bfd_arch_rs6000, bfd_target_xcoff_flavour, rs6000_aix_osabi_sniffer); gdbarch_register_osabi_sniffer (bfd_arch_powerpc, bfd_target_xcoff_flavour, rs6000_aix_osabi_sniffer); gdbarch_register_osabi (bfd_arch_rs6000, 0, GDB_OSABI_AIX, rs6000_aix_init_osabi); gdbarch_register_osabi (bfd_arch_powerpc, 0, GDB_OSABI_AIX, rs6000_aix_init_osabi); }