/* Cache and manage the values of registers for GDB, the GNU debugger. Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001 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 "inferior.h" #include "target.h" #include "gdbarch.h" #include "gdbcmd.h" #include "regcache.h" #include "gdb_assert.h" /* * DATA STRUCTURE * * Here is the actual register cache. */ /* NOTE: this is a write-through cache. There is no "dirty" bit for recording if the register values have been changed (eg. by the user). Therefore all registers must be written back to the target when appropriate. */ /* REGISTERS contains the cached register values (in target byte order). */ char *registers; /* REGISTER_VALID is 0 if the register needs to be fetched, 1 if it has been fetched, and -1 if the register value was not available. "Not available" means don't try to fetch it again. */ signed char *register_valid; /* The thread/process associated with the current set of registers. */ static ptid_t registers_ptid; /* * FUNCTIONS: */ /* REGISTER_CACHED() Returns 0 if the value is not in the cache (needs fetch). >0 if the value is in the cache. <0 if the value is permanently unavailable (don't ask again). */ int register_cached (int regnum) { return register_valid[regnum]; } /* Record that REGNUM's value is cached if STATE is >0, uncached but fetchable if STATE is 0, and uncached and unfetchable if STATE is <0. */ void set_register_cached (int regnum, int state) { register_valid[regnum] = state; } /* REGISTER_CHANGED invalidate a single register REGNUM in the cache */ void register_changed (int regnum) { set_register_cached (regnum, 0); } /* If REGNUM >= 0, return a pointer to register REGNUM's cache buffer area, else return a pointer to the start of the cache buffer. */ static char * register_buffer (int regnum) { gdb_assert (regnum >= 0 && regnum < (NUM_REGS + NUM_PSEUDO_REGS)); return ®isters[REGISTER_BYTE (regnum)]; } /* Return whether register REGNUM is a real register. */ static int real_register (int regnum) { return regnum >= 0 && regnum < NUM_REGS; } /* Return whether register REGNUM is a pseudo register. */ static int pseudo_register (int regnum) { return regnum >= NUM_REGS && regnum < NUM_REGS + NUM_PSEUDO_REGS; } /* Fetch register REGNUM into the cache. */ static void fetch_register (int regnum) { /* NOTE: cagney/2001-12-04: Legacy targets were using fetch/store pseudo-register as a way of handling registers that needed to be constructed from one or more raw registers. New targets instead use gdbarch register read/write. */ if (FETCH_PSEUDO_REGISTER_P () && pseudo_register (regnum)) FETCH_PSEUDO_REGISTER (regnum); else target_fetch_registers (regnum); } /* Write register REGNUM cached value to the target. */ static void store_register (int regnum) { /* NOTE: cagney/2001-12-04: Legacy targets were using fetch/store pseudo-register as a way of handling registers that needed to be constructed from one or more raw registers. New targets instead use gdbarch register read/write. */ if (STORE_PSEUDO_REGISTER_P () && pseudo_register (regnum)) STORE_PSEUDO_REGISTER (regnum); else target_store_registers (regnum); } /* Low level examining and depositing of registers. The caller is responsible for making sure that the inferior is stopped before calling the fetching routines, or it will get garbage. (a change from GDB version 3, in which the caller got the value from the last stop). */ /* REGISTERS_CHANGED () Indicate that registers may have changed, so invalidate the cache. */ void registers_changed (void) { int i; registers_ptid = pid_to_ptid (-1); /* Force cleanup of any alloca areas if using C alloca instead of a builtin alloca. This particular call is used to clean up areas allocated by low level target code which may build up during lengthy interactions between gdb and the target before gdb gives control to the user (ie watchpoints). */ alloca (0); for (i = 0; i < NUM_REGS + NUM_PSEUDO_REGS; i++) set_register_cached (i, 0); if (registers_changed_hook) registers_changed_hook (); } /* REGISTERS_FETCHED () Indicate that all registers have been fetched, so mark them all valid. */ /* NOTE: cagney/2001-12-04: This function does not set valid on the pseudo-register range since pseudo registers are always supplied using supply_register(). */ /* FIXME: cagney/2001-12-04: This function is DEPRECATED. The target code was blatting the registers[] array and then calling this. Since targets should only be using supply_register() the need for this function/hack is eliminated. */ void registers_fetched (void) { int i; for (i = 0; i < NUM_REGS; i++) set_register_cached (i, 1); /* Do not assume that the pseudo-regs have also been fetched. Fetching all real regs NEVER accounts for pseudo-regs. */ } /* read_register_bytes and write_register_bytes are generally a *BAD* idea. They are inefficient because they need to check for partial updates, which can only be done by scanning through all of the registers and seeing if the bytes that are being read/written fall inside of an invalid register. [The main reason this is necessary is that register sizes can vary, so a simple index won't suffice.] It is far better to call read_register_gen and write_register_gen if you want to get at the raw register contents, as it only takes a regnum as an argument, and therefore can't do a partial register update. Prior to the recent fixes to check for partial updates, both read and write_register_bytes always checked to see if any registers were stale, and then called target_fetch_registers (-1) to update the whole set. This caused really slowed things down for remote targets. */ /* Copy INLEN bytes of consecutive data from registers starting with the INREGBYTE'th byte of register data into memory at MYADDR. */ void read_register_bytes (int in_start, char *in_buf, int in_len) { int in_end = in_start + in_len; int regnum; char *reg_buf = alloca (MAX_REGISTER_RAW_SIZE); /* See if we are trying to read bytes from out-of-date registers. If so, update just those registers. */ for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++) { int reg_start; int reg_end; int reg_len; int start; int end; int byte; reg_start = REGISTER_BYTE (regnum); reg_len = REGISTER_RAW_SIZE (regnum); reg_end = reg_start + reg_len; if (reg_end <= in_start || in_end <= reg_start) /* The range the user wants to read doesn't overlap with regnum. */ continue; if (REGISTER_NAME (regnum) != NULL && *REGISTER_NAME (regnum) != '\0') /* Force the cache to fetch the entire register. */ read_register_gen (regnum, reg_buf); else /* Legacy note: even though this register is ``invalid'' we still need to return something. It would appear that some code relies on apparent gaps in the register array also being returned. */ /* FIXME: cagney/2001-08-18: This is just silly. It defeats the entire register read/write flow of control. Must resist temptation to return 0xdeadbeef. */ memcpy (reg_buf, registers + reg_start, reg_len); /* Legacy note: This function, for some reason, allows a NULL input buffer. If the buffer is NULL, the registers are still fetched, just the final transfer is skipped. */ if (in_buf == NULL) continue; /* start = max (reg_start, in_start) */ if (reg_start > in_start) start = reg_start; else start = in_start; /* end = min (reg_end, in_end) */ if (reg_end < in_end) end = reg_end; else end = in_end; /* Transfer just the bytes common to both IN_BUF and REG_BUF */ for (byte = start; byte < end; byte++) { in_buf[byte - in_start] = reg_buf[byte - reg_start]; } } } /* Read register REGNUM into memory at MYADDR, which must be large enough for REGISTER_RAW_BYTES (REGNUM). Target byte-order. If the register is known to be the size of a CORE_ADDR or smaller, read_register can be used instead. */ static void legacy_read_register_gen (int regnum, char *myaddr) { gdb_assert (regnum >= 0 && regnum < (NUM_REGS + NUM_PSEUDO_REGS)); if (! ptid_equal (registers_ptid, inferior_ptid)) { registers_changed (); registers_ptid = inferior_ptid; } if (!register_cached (regnum)) fetch_register (regnum); memcpy (myaddr, register_buffer (regnum), REGISTER_RAW_SIZE (regnum)); } void regcache_read (int rawnum, char *buf) { gdb_assert (rawnum >= 0 && rawnum < (NUM_REGS + NUM_PSEUDO_REGS)); /* For moment, just use underlying legacy code. Ulgh!!! */ legacy_read_register_gen (rawnum, buf); } void read_register_gen (int regnum, char *buf) { if (! gdbarch_register_read_p (current_gdbarch)) { legacy_read_register_gen (regnum, buf); return; } gdbarch_register_read (current_gdbarch, regnum, buf); } /* Write register REGNUM at MYADDR to the target. MYADDR points at REGISTER_RAW_BYTES(REGNUM), which must be in target byte-order. */ static void legacy_write_register_gen (int regnum, char *myaddr) { int size; gdb_assert (regnum >= 0 && regnum < (NUM_REGS + NUM_PSEUDO_REGS)); /* On the sparc, writing %g0 is a no-op, so we don't even want to change the registers array if something writes to this register. */ if (CANNOT_STORE_REGISTER (regnum)) return; if (! ptid_equal (registers_ptid, inferior_ptid)) { registers_changed (); registers_ptid = inferior_ptid; } size = REGISTER_RAW_SIZE (regnum); if (real_register (regnum)) { /* If we have a valid copy of the register, and new value == old value, then don't bother doing the actual store. */ if (register_cached (regnum) && memcmp (register_buffer (regnum), myaddr, size) == 0) return; else target_prepare_to_store (); } memcpy (register_buffer (regnum), myaddr, size); set_register_cached (regnum, 1); store_register (regnum); } void regcache_write (int rawnum, char *buf) { gdb_assert (rawnum >= 0 && rawnum < (NUM_REGS + NUM_PSEUDO_REGS)); /* For moment, just use underlying legacy code. Ulgh!!! */ legacy_write_register_gen (rawnum, buf); } void write_register_gen (int regnum, char *buf) { if (! gdbarch_register_write_p (current_gdbarch)) { legacy_write_register_gen (regnum, buf); return; } gdbarch_register_write (current_gdbarch, regnum, buf); } /* Copy INLEN bytes of consecutive data from memory at MYADDR into registers starting with the MYREGSTART'th byte of register data. */ void write_register_bytes (int myregstart, char *myaddr, int inlen) { int myregend = myregstart + inlen; int regnum; target_prepare_to_store (); /* Scan through the registers updating any that are covered by the range myregstart<=>myregend using write_register_gen, which does nice things like handling threads, and avoiding updates when the new and old contents are the same. */ for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++) { int regstart, regend; regstart = REGISTER_BYTE (regnum); regend = regstart + REGISTER_RAW_SIZE (regnum); /* Is this register completely outside the range the user is writing? */ if (myregend <= regstart || regend <= myregstart) /* do nothing */ ; /* Is this register completely within the range the user is writing? */ else if (myregstart <= regstart && regend <= myregend) write_register_gen (regnum, myaddr + (regstart - myregstart)); /* The register partially overlaps the range being written. */ else { char *regbuf = (char*) alloca (MAX_REGISTER_RAW_SIZE); /* What's the overlap between this register's bytes and those the caller wants to write? */ int overlapstart = max (regstart, myregstart); int overlapend = min (regend, myregend); /* We may be doing a partial update of an invalid register. Update it from the target before scribbling on it. */ read_register_gen (regnum, regbuf); memcpy (registers + overlapstart, myaddr + (overlapstart - myregstart), overlapend - overlapstart); store_register (regnum); } } } /* Return the contents of register REGNUM as an unsigned integer. */ ULONGEST read_register (int regnum) { char *buf = alloca (REGISTER_RAW_SIZE (regnum)); read_register_gen (regnum, buf); return (extract_unsigned_integer (buf, REGISTER_RAW_SIZE (regnum))); } ULONGEST read_register_pid (int regnum, ptid_t ptid) { ptid_t save_ptid; int save_pid; CORE_ADDR retval; if (ptid_equal (ptid, inferior_ptid)) return read_register (regnum); save_ptid = inferior_ptid; inferior_ptid = ptid; retval = read_register (regnum); inferior_ptid = save_ptid; return retval; } /* Return the contents of register REGNUM as a signed integer. */ LONGEST read_signed_register (int regnum) { void *buf = alloca (REGISTER_RAW_SIZE (regnum)); read_register_gen (regnum, buf); return (extract_signed_integer (buf, REGISTER_RAW_SIZE (regnum))); } LONGEST read_signed_register_pid (int regnum, ptid_t ptid) { ptid_t save_ptid; LONGEST retval; if (ptid_equal (ptid, inferior_ptid)) return read_signed_register (regnum); save_ptid = inferior_ptid; inferior_ptid = ptid; retval = read_signed_register (regnum); inferior_ptid = save_ptid; return retval; } /* Store VALUE into the raw contents of register number REGNUM. */ void write_register (int regnum, LONGEST val) { void *buf; int size; size = REGISTER_RAW_SIZE (regnum); buf = alloca (size); store_signed_integer (buf, size, (LONGEST) val); write_register_gen (regnum, buf); } void write_register_pid (int regnum, CORE_ADDR val, ptid_t ptid) { ptid_t save_ptid; if (ptid_equal (ptid, inferior_ptid)) { write_register (regnum, val); return; } save_ptid = inferior_ptid; inferior_ptid = ptid; write_register (regnum, val); inferior_ptid = save_ptid; } /* SUPPLY_REGISTER() Record that register REGNUM contains VAL. This is used when the value is obtained from the inferior or core dump, so there is no need to store the value there. If VAL is a NULL pointer, then it's probably an unsupported register. We just set its value to all zeros. We might want to record this fact, and report it to the users of read_register and friends. */ void supply_register (int regnum, char *val) { #if 1 if (! ptid_equal (registers_ptid, inferior_ptid)) { registers_changed (); registers_ptid = inferior_ptid; } #endif set_register_cached (regnum, 1); if (val) memcpy (register_buffer (regnum), val, REGISTER_RAW_SIZE (regnum)); else memset (register_buffer (regnum), '\000', REGISTER_RAW_SIZE (regnum)); /* On some architectures, e.g. HPPA, there are a few stray bits in some registers, that the rest of the code would like to ignore. */ /* NOTE: cagney/2001-03-16: The macro CLEAN_UP_REGISTER_VALUE is going to be deprecated. Instead architectures will leave the raw register value as is and instead clean things up as they pass through the method gdbarch_register_read() clean up the values. */ #ifdef DEPRECATED_CLEAN_UP_REGISTER_VALUE DEPRECATED_CLEAN_UP_REGISTER_VALUE (regnum, register_buffer (regnum)); #endif } void regcache_collect (int regnum, void *buf) { memcpy (buf, register_buffer (regnum), REGISTER_RAW_SIZE (regnum)); } /* read_pc, write_pc, read_sp, write_sp, read_fp, etc. Special handling for registers PC, SP, and FP. */ /* NOTE: cagney/2001-02-18: The functions generic_target_read_pc(), read_pc_pid(), read_pc(), generic_target_write_pc(), write_pc_pid(), write_pc(), generic_target_read_sp(), read_sp(), generic_target_write_sp(), write_sp(), generic_target_read_fp() and read_fp(), will eventually be moved out of the reg-cache into either frame.[hc] or to the multi-arch framework. The are not part of the raw register cache. */ /* This routine is getting awfully cluttered with #if's. It's probably time to turn this into READ_PC and define it in the tm.h file. Ditto for write_pc. 1999-06-08: The following were re-written so that it assumes the existence of a TARGET_READ_PC et.al. macro. A default generic version of that macro is made available where needed. Since the ``TARGET_READ_PC'' et.al. macro is going to be controlled by the multi-arch framework, it will eventually be possible to eliminate the intermediate read_pc_pid(). The client would call TARGET_READ_PC directly. (cagney). */ CORE_ADDR generic_target_read_pc (ptid_t ptid) { #ifdef PC_REGNUM if (PC_REGNUM >= 0) { CORE_ADDR pc_val = ADDR_BITS_REMOVE ((CORE_ADDR) read_register_pid (PC_REGNUM, ptid)); return pc_val; } #endif internal_error (__FILE__, __LINE__, "generic_target_read_pc"); return 0; } CORE_ADDR read_pc_pid (ptid_t ptid) { ptid_t saved_inferior_ptid; CORE_ADDR pc_val; /* In case ptid != inferior_ptid. */ saved_inferior_ptid = inferior_ptid; inferior_ptid = ptid; pc_val = TARGET_READ_PC (ptid); inferior_ptid = saved_inferior_ptid; return pc_val; } CORE_ADDR read_pc (void) { return read_pc_pid (inferior_ptid); } void generic_target_write_pc (CORE_ADDR pc, ptid_t ptid) { #ifdef PC_REGNUM if (PC_REGNUM >= 0) write_register_pid (PC_REGNUM, pc, ptid); if (NPC_REGNUM >= 0) write_register_pid (NPC_REGNUM, pc + 4, ptid); if (NNPC_REGNUM >= 0) write_register_pid (NNPC_REGNUM, pc + 8, ptid); #else internal_error (__FILE__, __LINE__, "generic_target_write_pc"); #endif } void write_pc_pid (CORE_ADDR pc, ptid_t ptid) { ptid_t saved_inferior_ptid; /* In case ptid != inferior_ptid. */ saved_inferior_ptid = inferior_ptid; inferior_ptid = ptid; TARGET_WRITE_PC (pc, ptid); inferior_ptid = saved_inferior_ptid; } void write_pc (CORE_ADDR pc) { write_pc_pid (pc, inferior_ptid); } /* Cope with strage ways of getting to the stack and frame pointers */ CORE_ADDR generic_target_read_sp (void) { #ifdef SP_REGNUM if (SP_REGNUM >= 0) return read_register (SP_REGNUM); #endif internal_error (__FILE__, __LINE__, "generic_target_read_sp"); } CORE_ADDR read_sp (void) { return TARGET_READ_SP (); } void generic_target_write_sp (CORE_ADDR val) { #ifdef SP_REGNUM if (SP_REGNUM >= 0) { write_register (SP_REGNUM, val); return; } #endif internal_error (__FILE__, __LINE__, "generic_target_write_sp"); } void write_sp (CORE_ADDR val) { TARGET_WRITE_SP (val); } CORE_ADDR generic_target_read_fp (void) { #ifdef FP_REGNUM if (FP_REGNUM >= 0) return read_register (FP_REGNUM); #endif internal_error (__FILE__, __LINE__, "generic_target_read_fp"); } CORE_ADDR read_fp (void) { return TARGET_READ_FP (); } /* ARGSUSED */ static void reg_flush_command (char *command, int from_tty) { /* Force-flush the register cache. */ registers_changed (); if (from_tty) printf_filtered ("Register cache flushed.\n"); } static void build_regcache (void) { int i; int sizeof_register_valid; /* Come up with the real size of the registers buffer. */ int sizeof_registers = REGISTER_BYTES; /* OK use. */ for (i = 0; i < NUM_REGS + NUM_PSEUDO_REGS; i++) { long regend; /* Keep extending the buffer so that there is always enough space for all registers. The comparison is necessary since legacy code is free to put registers in random places in the buffer separated by holes. Once REGISTER_BYTE() is killed this can be greatly simplified. */ /* FIXME: cagney/2001-12-04: This code shouldn't need to use REGISTER_BYTE(). Unfortunatly, legacy code likes to lay the buffer out so that certain registers just happen to overlap. Ulgh! New targets use gdbarch's register read/write and entirely avoid this uglyness. */ regend = REGISTER_BYTE (i) + REGISTER_RAW_SIZE (i); if (sizeof_registers < regend) sizeof_registers = regend; } registers = xmalloc (sizeof_registers); sizeof_register_valid = ((NUM_REGS + NUM_PSEUDO_REGS) * sizeof (*register_valid)); register_valid = xmalloc (sizeof_register_valid); memset (register_valid, 0, sizeof_register_valid); } void _initialize_regcache (void) { register_gdbarch_swap (®isters, sizeof (registers), NULL); register_gdbarch_swap (®ister_valid, sizeof (register_valid), NULL); register_gdbarch_swap (NULL, 0, build_regcache); add_com ("flushregs", class_maintenance, reg_flush_command, "Force gdb to flush its register cache (maintainer command)"); /* Initialize the thread/process associated with the current set of registers. For now, -1 is special, and means `no current process'. */ registers_ptid = pid_to_ptid (-1); }