/* Native-dependent code for GNU/Linux i386. Copyright 1999, 2000, 2001, 2002, 2003, 2004 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 "gdbcore.h" #include "regcache.h" #include "linux-nat.h" #include "gdb_assert.h" #include "gdb_string.h" #include <sys/ptrace.h> #include <sys/user.h> #include <sys/procfs.h> #ifdef HAVE_SYS_REG_H #include <sys/reg.h> #endif #ifndef ORIG_EAX #define ORIG_EAX -1 #endif #ifdef HAVE_SYS_DEBUGREG_H #include <sys/debugreg.h> #endif #ifndef DR_FIRSTADDR #define DR_FIRSTADDR 0 #endif #ifndef DR_LASTADDR #define DR_LASTADDR 3 #endif #ifndef DR_STATUS #define DR_STATUS 6 #endif #ifndef DR_CONTROL #define DR_CONTROL 7 #endif /* Prototypes for supply_gregset etc. */ #include "gregset.h" /* Prototypes for i387_supply_fsave etc. */ #include "i387-tdep.h" /* Defines for XMM0_REGNUM etc. */ #include "i386-tdep.h" /* Defines I386_LINUX_ORIG_EAX_REGNUM. */ #include "i386-linux-tdep.h" /* Defines ps_err_e, struct ps_prochandle. */ #include "gdb_proc_service.h" /* The register sets used in GNU/Linux ELF core-dumps are identical to the register sets in `struct user' that is used for a.out core-dumps, and is also used by `ptrace'. The corresponding types are `elf_gregset_t' for the general-purpose registers (with `elf_greg_t' the type of a single GP register) and `elf_fpregset_t' for the floating-point registers. Those types used to be available under the names `gregset_t' and `fpregset_t' too, and this file used those names in the past. But those names are now used for the register sets used in the `mcontext_t' type, and have a different size and layout. */ /* Mapping between the general-purpose registers in `struct user' format and GDB's register array layout. */ static int regmap[] = { EAX, ECX, EDX, EBX, UESP, EBP, ESI, EDI, EIP, EFL, CS, SS, DS, ES, FS, GS, -1, -1, -1, -1, /* st0, st1, st2, st3 */ -1, -1, -1, -1, /* st4, st5, st6, st7 */ -1, -1, -1, -1, /* fctrl, fstat, ftag, fiseg */ -1, -1, -1, -1, /* fioff, foseg, fooff, fop */ -1, -1, -1, -1, /* xmm0, xmm1, xmm2, xmm3 */ -1, -1, -1, -1, /* xmm4, xmm5, xmm6, xmm6 */ -1, /* mxcsr */ ORIG_EAX }; /* Which ptrace request retrieves which registers? These apply to the corresponding SET requests as well. */ #define GETREGS_SUPPLIES(regno) \ ((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM) #define GETFPREGS_SUPPLIES(regno) \ (FP0_REGNUM <= (regno) && (regno) <= LAST_FPU_CTRL_REGNUM) #define GETFPXREGS_SUPPLIES(regno) \ (FP0_REGNUM <= (regno) && (regno) <= MXCSR_REGNUM) /* Does the current host support the GETREGS request? */ int have_ptrace_getregs = #ifdef HAVE_PTRACE_GETREGS 1 #else 0 #endif ; /* Does the current host support the GETFPXREGS request? The header file may or may not define it, and even if it is defined, the kernel will return EIO if it's running on a pre-SSE processor. My instinct is to attach this to some architecture- or target-specific data structure, but really, a particular GDB process can only run on top of one kernel at a time. So it's okay for this to be a simple variable. */ int have_ptrace_getfpxregs = #ifdef HAVE_PTRACE_GETFPXREGS 1 #else 0 #endif ; /* Support for the user struct. */ /* Return the address of register REGNUM. BLOCKEND is the value of u.u_ar0, which should point to the registers. */ CORE_ADDR register_u_addr (CORE_ADDR blockend, int regnum) { return (blockend + 4 * regmap[regnum]); } /* Return the size of the user struct. */ int kernel_u_size (void) { return (sizeof (struct user)); } /* Accessing registers through the U area, one at a time. */ /* Fetch one register. */ static void fetch_register (int regno) { int tid; int val; gdb_assert (!have_ptrace_getregs); if (cannot_fetch_register (regno)) { regcache_raw_supply (current_regcache, regno, NULL); return; } /* GNU/Linux LWP ID's are process ID's. */ tid = TIDGET (inferior_ptid); if (tid == 0) tid = PIDGET (inferior_ptid); /* Not a threaded program. */ errno = 0; val = ptrace (PTRACE_PEEKUSER, tid, register_addr (regno, 0), 0); if (errno != 0) error ("Couldn't read register %s (#%d): %s.", REGISTER_NAME (regno), regno, safe_strerror (errno)); regcache_raw_supply (current_regcache, regno, &val); } /* Store one register. */ static void store_register (int regno) { int tid; int val; gdb_assert (!have_ptrace_getregs); if (cannot_store_register (regno)) return; /* GNU/Linux LWP ID's are process ID's. */ tid = TIDGET (inferior_ptid); if (tid == 0) tid = PIDGET (inferior_ptid); /* Not a threaded program. */ errno = 0; regcache_raw_collect (current_regcache, regno, &val); ptrace (PTRACE_POKEUSER, tid, register_addr (regno, 0), val); if (errno != 0) error ("Couldn't write register %s (#%d): %s.", REGISTER_NAME (regno), regno, safe_strerror (errno)); } /* Transfering the general-purpose registers between GDB, inferiors and core files. */ /* Fill GDB's register array with the general-purpose register values in *GREGSETP. */ void supply_gregset (elf_gregset_t *gregsetp) { elf_greg_t *regp = (elf_greg_t *) gregsetp; int i; for (i = 0; i < I386_NUM_GREGS; i++) regcache_raw_supply (current_regcache, i, regp + regmap[i]); if (I386_LINUX_ORIG_EAX_REGNUM < NUM_REGS) regcache_raw_supply (current_regcache, I386_LINUX_ORIG_EAX_REGNUM, regp + ORIG_EAX); } /* Fill register REGNO (if it is a general-purpose register) in *GREGSETPS with the value in GDB's register array. If REGNO is -1, do this for all registers. */ void fill_gregset (elf_gregset_t *gregsetp, int regno) { elf_greg_t *regp = (elf_greg_t *) gregsetp; int i; for (i = 0; i < I386_NUM_GREGS; i++) if (regno == -1 || regno == i) regcache_raw_collect (current_regcache, i, regp + regmap[i]); if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM) && I386_LINUX_ORIG_EAX_REGNUM < NUM_REGS) regcache_raw_collect (current_regcache, I386_LINUX_ORIG_EAX_REGNUM, regp + ORIG_EAX); } #ifdef HAVE_PTRACE_GETREGS /* Fetch all general-purpose registers from process/thread TID and store their values in GDB's register array. */ static void fetch_regs (int tid) { elf_gregset_t regs; if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0) { if (errno == EIO) { /* The kernel we're running on doesn't support the GETREGS request. Reset `have_ptrace_getregs'. */ have_ptrace_getregs = 0; return; } perror_with_name ("Couldn't get registers"); } supply_gregset (®s); } /* Store all valid general-purpose registers in GDB's register array into the process/thread specified by TID. */ static void store_regs (int tid, int regno) { elf_gregset_t regs; if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0) perror_with_name ("Couldn't get registers"); fill_gregset (®s, regno); if (ptrace (PTRACE_SETREGS, tid, 0, (int) ®s) < 0) perror_with_name ("Couldn't write registers"); } #else static void fetch_regs (int tid) {} static void store_regs (int tid, int regno) {} #endif /* Transfering floating-point registers between GDB, inferiors and cores. */ /* Fill GDB's register array with the floating-point register values in *FPREGSETP. */ void supply_fpregset (elf_fpregset_t *fpregsetp) { i387_supply_fsave (current_regcache, -1, fpregsetp); } /* Fill register REGNO (if it is a floating-point register) in *FPREGSETP with the value in GDB's register array. If REGNO is -1, do this for all registers. */ void fill_fpregset (elf_fpregset_t *fpregsetp, int regno) { i387_fill_fsave ((char *) fpregsetp, regno); } #ifdef HAVE_PTRACE_GETREGS /* Fetch all floating-point registers from process/thread TID and store thier values in GDB's register array. */ static void fetch_fpregs (int tid) { elf_fpregset_t fpregs; if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0) perror_with_name ("Couldn't get floating point status"); supply_fpregset (&fpregs); } /* Store all valid floating-point registers in GDB's register array into the process/thread specified by TID. */ static void store_fpregs (int tid, int regno) { elf_fpregset_t fpregs; if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0) perror_with_name ("Couldn't get floating point status"); fill_fpregset (&fpregs, regno); if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0) perror_with_name ("Couldn't write floating point status"); } #else static void fetch_fpregs (int tid) {} static void store_fpregs (int tid, int regno) {} #endif /* Transfering floating-point and SSE registers to and from GDB. */ #ifdef HAVE_PTRACE_GETFPXREGS /* Fill GDB's register array with the floating-point and SSE register values in *FPXREGSETP. */ void supply_fpxregset (elf_fpxregset_t *fpxregsetp) { i387_supply_fxsave (current_regcache, -1, fpxregsetp); } /* Fill register REGNO (if it is a floating-point or SSE register) in *FPXREGSETP with the value in GDB's register array. If REGNO is -1, do this for all registers. */ void fill_fpxregset (elf_fpxregset_t *fpxregsetp, int regno) { i387_fill_fxsave ((char *) fpxregsetp, regno); } /* Fetch all registers covered by the PTRACE_GETFPXREGS request from process/thread TID and store their values in GDB's register array. Return non-zero if successful, zero otherwise. */ static int fetch_fpxregs (int tid) { elf_fpxregset_t fpxregs; if (! have_ptrace_getfpxregs) return 0; if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0) { if (errno == EIO) { have_ptrace_getfpxregs = 0; return 0; } perror_with_name ("Couldn't read floating-point and SSE registers"); } supply_fpxregset (&fpxregs); return 1; } /* Store all valid registers in GDB's register array covered by the PTRACE_SETFPXREGS request into the process/thread specified by TID. Return non-zero if successful, zero otherwise. */ static int store_fpxregs (int tid, int regno) { elf_fpxregset_t fpxregs; if (! have_ptrace_getfpxregs) return 0; if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1) { if (errno == EIO) { have_ptrace_getfpxregs = 0; return 0; } perror_with_name ("Couldn't read floating-point and SSE registers"); } fill_fpxregset (&fpxregs, regno); if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1) perror_with_name ("Couldn't write floating-point and SSE registers"); return 1; } #else static int fetch_fpxregs (int tid) { return 0; } static int store_fpxregs (int tid, int regno) { return 0; } #endif /* HAVE_PTRACE_GETFPXREGS */ /* Transferring arbitrary registers between GDB and inferior. */ /* Check if register REGNO in the child process is accessible. If we are accessing registers directly via the U area, only the general-purpose registers are available. All registers should be accessible if we have GETREGS support. */ int cannot_fetch_register (int regno) { gdb_assert (regno >= 0 && regno < NUM_REGS); return (!have_ptrace_getregs && regmap[regno] == -1); } int cannot_store_register (int regno) { gdb_assert (regno >= 0 && regno < NUM_REGS); return (!have_ptrace_getregs && regmap[regno] == -1); } /* Fetch register REGNO from the child process. If REGNO is -1, do this for all registers (including the floating point and SSE registers). */ void fetch_inferior_registers (int regno) { int tid; /* Use the old method of peeking around in `struct user' if the GETREGS request isn't available. */ if (!have_ptrace_getregs) { int i; for (i = 0; i < NUM_REGS; i++) if (regno == -1 || regno == i) fetch_register (i); return; } /* GNU/Linux LWP ID's are process ID's. */ tid = TIDGET (inferior_ptid); if (tid == 0) tid = PIDGET (inferior_ptid); /* Not a threaded program. */ /* Use the PTRACE_GETFPXREGS request whenever possible, since it transfers more registers in one system call, and we'll cache the results. But remember that fetch_fpxregs can fail, and return zero. */ if (regno == -1) { fetch_regs (tid); /* The call above might reset `have_ptrace_getregs'. */ if (!have_ptrace_getregs) { fetch_inferior_registers (regno); return; } if (fetch_fpxregs (tid)) return; fetch_fpregs (tid); return; } if (GETREGS_SUPPLIES (regno)) { fetch_regs (tid); return; } if (GETFPXREGS_SUPPLIES (regno)) { if (fetch_fpxregs (tid)) return; /* Either our processor or our kernel doesn't support the SSE registers, so read the FP registers in the traditional way, and fill the SSE registers with dummy values. It would be more graceful to handle differences in the register set using gdbarch. Until then, this will at least make things work plausibly. */ fetch_fpregs (tid); return; } internal_error (__FILE__, __LINE__, "Got request for bad register number %d.", regno); } /* Store register REGNO back into the child process. If REGNO is -1, do this for all registers (including the floating point and SSE registers). */ void store_inferior_registers (int regno) { int tid; /* Use the old method of poking around in `struct user' if the SETREGS request isn't available. */ if (!have_ptrace_getregs) { int i; for (i = 0; i < NUM_REGS; i++) if (regno == -1 || regno == i) store_register (i); return; } /* GNU/Linux LWP ID's are process ID's. */ tid = TIDGET (inferior_ptid); if (tid == 0) tid = PIDGET (inferior_ptid); /* Not a threaded program. */ /* Use the PTRACE_SETFPXREGS requests whenever possible, since it transfers more registers in one system call. But remember that store_fpxregs can fail, and return zero. */ if (regno == -1) { store_regs (tid, regno); if (store_fpxregs (tid, regno)) return; store_fpregs (tid, regno); return; } if (GETREGS_SUPPLIES (regno)) { store_regs (tid, regno); return; } if (GETFPXREGS_SUPPLIES (regno)) { if (store_fpxregs (tid, regno)) return; /* Either our processor or our kernel doesn't support the SSE registers, so just write the FP registers in the traditional way. */ store_fpregs (tid, regno); return; } internal_error (__FILE__, __LINE__, "Got request to store bad register number %d.", regno); } /* Support for debug registers. */ static unsigned long i386_linux_dr_get (int regnum) { int tid; unsigned long value; /* FIXME: kettenis/2001-01-29: It's not clear what we should do with multi-threaded processes here. For now, pretend there is just one thread. */ tid = PIDGET (inferior_ptid); /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the ptrace call fails breaks debugging remote targets. The correct way to fix this is to add the hardware breakpoint and watchpoint stuff to the target vector. For now, just return zero if the ptrace call fails. */ errno = 0; value = ptrace (PTRACE_PEEKUSER, tid, offsetof (struct user, u_debugreg[regnum]), 0); if (errno != 0) #if 0 perror_with_name ("Couldn't read debug register"); #else return 0; #endif return value; } static void i386_linux_dr_set (int regnum, unsigned long value) { int tid; /* FIXME: kettenis/2001-01-29: It's not clear what we should do with multi-threaded processes here. For now, pretend there is just one thread. */ tid = PIDGET (inferior_ptid); errno = 0; ptrace (PTRACE_POKEUSER, tid, offsetof (struct user, u_debugreg[regnum]), value); if (errno != 0) perror_with_name ("Couldn't write debug register"); } void i386_linux_dr_set_control (unsigned long control) { i386_linux_dr_set (DR_CONTROL, control); } void i386_linux_dr_set_addr (int regnum, CORE_ADDR addr) { gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR); i386_linux_dr_set (DR_FIRSTADDR + regnum, addr); } void i386_linux_dr_reset_addr (int regnum) { gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR); i386_linux_dr_set (DR_FIRSTADDR + regnum, 0L); } unsigned long i386_linux_dr_get_status (void) { return i386_linux_dr_get (DR_STATUS); } /* Called by libthread_db. Returns a pointer to the thread local storage (or its descriptor). */ ps_err_e ps_get_thread_area (const struct ps_prochandle *ph, lwpid_t lwpid, int idx, void **base) { /* NOTE: cagney/2003-08-26: The definition of this buffer is found in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x 4 byte integers in size: `entry_number', `base_addr', `limit', and a bunch of status bits. The values returned by this ptrace call should be part of the regcache buffer, and ps_get_thread_area should channel its request through the regcache. That way remote targets could provide the value using the remote protocol and not this direct call. Is this function needed? I'm guessing that the `base' is the address of a a descriptor that libthread_db uses to find the thread local address base that GDB needs. Perhaps that descriptor is defined by the ABI. Anyway, given that libthread_db calls this function without prompting (gdb requesting tls base) I guess it needs info in there anyway. */ unsigned int desc[4]; gdb_assert (sizeof (int) == 4); #ifndef PTRACE_GET_THREAD_AREA #define PTRACE_GET_THREAD_AREA 25 #endif if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, (void *) idx, (unsigned long) &desc) < 0) return PS_ERR; *(int *)base = desc[1]; return PS_OK; } /* The instruction for a GNU/Linux system call is: int $0x80 or 0xcd 0x80. */ static const unsigned char linux_syscall[] = { 0xcd, 0x80 }; #define LINUX_SYSCALL_LEN (sizeof linux_syscall) /* The system call number is stored in the %eax register. */ #define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM /* We are specifically interested in the sigreturn and rt_sigreturn system calls. */ #ifndef SYS_sigreturn #define SYS_sigreturn 0x77 #endif #ifndef SYS_rt_sigreturn #define SYS_rt_sigreturn 0xad #endif /* Offset to saved processor flags, from <asm/sigcontext.h>. */ #define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64) /* Resume execution of the inferior process. If STEP is nonzero, single-step it. If SIGNAL is nonzero, give it that signal. */ void child_resume (ptid_t ptid, int step, enum target_signal signal) { int pid = PIDGET (ptid); int request = PTRACE_CONT; if (pid == -1) /* Resume all threads. */ /* I think this only gets used in the non-threaded case, where "resume all threads" and "resume inferior_ptid" are the same. */ pid = PIDGET (inferior_ptid); if (step) { CORE_ADDR pc = read_pc_pid (pid_to_ptid (pid)); unsigned char buf[LINUX_SYSCALL_LEN]; request = PTRACE_SINGLESTEP; /* Returning from a signal trampoline is done by calling a special system call (sigreturn or rt_sigreturn, see i386-linux-tdep.c for more information). This system call restores the registers that were saved when the signal was raised, including %eflags. That means that single-stepping won't work. Instead, we'll have to modify the signal context that's about to be restored, and set the trace flag there. */ /* First check if PC is at a system call. */ if (deprecated_read_memory_nobpt (pc, (char *) buf, LINUX_SYSCALL_LEN) == 0 && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0) { int syscall = read_register_pid (LINUX_SYSCALL_REGNUM, pid_to_ptid (pid)); /* Then check the system call number. */ if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn) { CORE_ADDR sp = read_register (I386_ESP_REGNUM); CORE_ADDR addr = sp; unsigned long int eflags; if (syscall == SYS_rt_sigreturn) addr = read_memory_integer (sp + 8, 4) + 20; /* Set the trace flag in the context that's about to be restored. */ addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET; read_memory (addr, (char *) &eflags, 4); eflags |= 0x0100; write_memory (addr, (char *) &eflags, 4); } } } if (ptrace (request, pid, 0, target_signal_to_host (signal)) == -1) perror_with_name ("ptrace"); } void child_post_startup_inferior (ptid_t ptid) { i386_cleanup_dregs (); linux_child_post_startup_inferior (ptid); }