/* Native-dependent code for Linux/x86. Copyright 1999, 2000 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 <sys/ptrace.h> #include <sys/user.h> #include <sys/procfs.h> #ifdef HAVE_SYS_REG_H #include <sys/reg.h> #endif /* Prototypes for supply_gregset etc. */ #include "gregset.h" /* Prototypes for i387_supply_fsave etc. */ #include "i387-nat.h" /* Prototypes for local functions. */ static void dummy_sse_values (void); /* On Linux, threads are implemented as pseudo-processes, in which case we may be tracing more than one process at a time. In that case, inferior_pid will contain the main process ID and the individual thread (process) ID mashed together. These macros are used to separate them out. These definitions should be overridden if thread support is included. */ #if !defined (PIDGET) /* Default definition for PIDGET/TIDGET. */ #define PIDGET(PID) PID #define TIDGET(PID) 0 #endif /* The register sets used in 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 }; /* Which ptrace request retrieves which registers? These apply to the corresponding SET requests as well. */ #define GETREGS_SUPPLIES(regno) \ (0 <= (regno) && (regno) <= 15) #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 ; /* Fetching registers directly from the U area, one at a time. */ /* FIXME: kettenis/2000-03-05: This duplicates code from `inptrace.c'. The problem is that we define FETCH_INFERIOR_REGISTERS since we want to use our own versions of {fetch,store}_inferior_registers that use the GETREGS request. This means that the code in `infptrace.c' is #ifdef'd out. But we need to fall back on that code when GDB is running on top of a kernel that doesn't support the GETREGS request. I want to avoid changing `infptrace.c' right now. */ #ifndef PT_READ_U #define PT_READ_U PTRACE_PEEKUSR #endif #ifndef PT_WRITE_U #define PT_WRITE_U PTRACE_POKEUSR #endif /* Default the type of the ptrace transfer to int. */ #ifndef PTRACE_XFER_TYPE #define PTRACE_XFER_TYPE int #endif /* Registers we shouldn't try to fetch. */ #define OLD_CANNOT_FETCH_REGISTER(regno) ((regno) >= NUM_GREGS) /* Fetch one register. */ static void fetch_register (int regno) { /* This isn't really an address. But ptrace thinks of it as one. */ CORE_ADDR regaddr; char mess[128]; /* For messages */ register int i; unsigned int offset; /* Offset of registers within the u area. */ char buf[MAX_REGISTER_RAW_SIZE]; int tid; if (OLD_CANNOT_FETCH_REGISTER (regno)) { memset (buf, '\0', REGISTER_RAW_SIZE (regno)); /* Supply zeroes */ supply_register (regno, buf); return; } /* Overload thread id onto process id */ if ((tid = TIDGET (inferior_pid)) == 0) tid = inferior_pid; /* no thread id, just use process id */ offset = U_REGS_OFFSET; regaddr = register_addr (regno, offset); for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE)) { errno = 0; *(PTRACE_XFER_TYPE *) & buf[i] = ptrace (PT_READ_U, tid, (PTRACE_ARG3_TYPE) regaddr, 0); regaddr += sizeof (PTRACE_XFER_TYPE); if (errno != 0) { sprintf (mess, "reading register %s (#%d)", REGISTER_NAME (regno), regno); perror_with_name (mess); } } supply_register (regno, buf); } /* Fetch register values from the inferior. If REGNO is negative, do this for all registers. Otherwise, REGNO specifies which register (so we can save time). */ void old_fetch_inferior_registers (int regno) { if (regno >= 0) { fetch_register (regno); } else { for (regno = 0; regno < ARCH_NUM_REGS; regno++) { fetch_register (regno); } } } /* Registers we shouldn't try to store. */ #define OLD_CANNOT_STORE_REGISTER(regno) ((regno) >= NUM_GREGS) /* Store one register. */ static void store_register (int regno) { /* This isn't really an address. But ptrace thinks of it as one. */ CORE_ADDR regaddr; char mess[128]; /* For messages */ register int i; unsigned int offset; /* Offset of registers within the u area. */ int tid; if (OLD_CANNOT_STORE_REGISTER (regno)) { return; } /* Overload thread id onto process id */ if ((tid = TIDGET (inferior_pid)) == 0) tid = inferior_pid; /* no thread id, just use process id */ offset = U_REGS_OFFSET; regaddr = register_addr (regno, offset); for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE)) { errno = 0; ptrace (PT_WRITE_U, tid, (PTRACE_ARG3_TYPE) regaddr, *(PTRACE_XFER_TYPE *) & registers[REGISTER_BYTE (regno) + i]); regaddr += sizeof (PTRACE_XFER_TYPE); if (errno != 0) { sprintf (mess, "writing register %s (#%d)", REGISTER_NAME (regno), regno); perror_with_name (mess); } } } /* Store our register values back into the inferior. If REGNO is negative, do this for all registers. Otherwise, REGNO specifies which register (so we can save time). */ void old_store_inferior_registers (int regno) { if (regno >= 0) { store_register (regno); } else { for (regno = 0; regno < ARCH_NUM_REGS; regno++) { store_register (regno); } } } /* Transfering the general-purpose registers between GDB, inferiors and core files. */ /* Fill GDB's register array with the genereal-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 < NUM_GREGS; i++) supply_register (i, (char *) (regp + regmap[i])); } /* 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 < NUM_GREGS; i++) if ((regno == -1 || regno == i)) *(regp + regmap[i]) = *(elf_greg_t *) ®isters[REGISTER_BYTE (i)]; } #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 ((char *) fpregsetp); dummy_sse_values (); } /* 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. */ static void supply_fpxregset (elf_fpxregset_t *fpxregsetp) { i387_supply_fxsave ((char *) 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. */ static 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) 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; } /* Fill the XMM registers in the register array with dummy values. For cases where we don't have access to the XMM registers. I think this is cleaner than printing a warning. For a cleaner solution, we should gdbarchify the i386 family. */ static void dummy_sse_values (void) { /* C doesn't have a syntax for NaN's, so write it out as an array of longs. */ static long dummy[4] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff }; static long mxcsr = 0x1f80; int reg; for (reg = 0; reg < 8; reg++) supply_register (XMM0_REGNUM + reg, (char *) dummy); supply_register (MXCSR_REGNUM, (char *) &mxcsr); } #else static int fetch_fpxregs (int tid) { return 0; } static int store_fpxregs (int tid, int regno) { return 0; } static void dummy_sse_values (void) {} #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) { if (! have_ptrace_getregs) return OLD_CANNOT_FETCH_REGISTER (regno); return 0; } int cannot_store_register (int regno) { if (! have_ptrace_getregs) return OLD_CANNOT_STORE_REGISTER (regno); return 0; } /* 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) { old_fetch_inferior_registers (regno); return; } /* Linux LWP ID's are process ID's. */ if ((tid = TIDGET (inferior_pid)) == 0) tid = inferior_pid; /* 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) { old_fetch_inferior_registers (-1); 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 ("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) { old_store_inferior_registers (regno); return; } /* Linux LWP ID's are process ID's. */ if ((tid = TIDGET (inferior_pid)) == 0) tid = inferior_pid; /* 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 ("Got request to store bad register number %d.", regno); } /* Interpreting register set info found in core files. */ /* Provide registers to GDB from a core file. (We can't use the generic version of this function in core-regset.c, because Linux has *three* different kinds of register set notes. core-regset.c would have to call supply_fpxregset, which most platforms don't have.) CORE_REG_SECT points to an array of bytes, which are the contents of a `note' from a core file which BFD thinks might contain register contents. CORE_REG_SIZE is its size. WHICH says which register set corelow suspects this is: 0 --- the general-purpose register set, in elf_gregset_t format 2 --- the floating-point register set, in elf_fpregset_t format 3 --- the extended floating-point register set, in elf_fpxregset_t format REG_ADDR isn't used on Linux. */ static void fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which, CORE_ADDR reg_addr) { elf_gregset_t gregset; elf_fpregset_t fpregset; switch (which) { case 0: if (core_reg_size != sizeof (gregset)) warning ("Wrong size gregset in core file."); else { memcpy (&gregset, core_reg_sect, sizeof (gregset)); supply_gregset (&gregset); } break; case 2: if (core_reg_size != sizeof (fpregset)) warning ("Wrong size fpregset in core file."); else { memcpy (&fpregset, core_reg_sect, sizeof (fpregset)); supply_fpregset (&fpregset); } break; #ifdef HAVE_PTRACE_GETFPXREGS { elf_fpxregset_t fpxregset; case 3: if (core_reg_size != sizeof (fpxregset)) warning ("Wrong size fpxregset in core file."); else { memcpy (&fpxregset, core_reg_sect, sizeof (fpxregset)); supply_fpxregset (&fpxregset); } break; } #endif default: /* We've covered all the kinds of registers we know about here, so this must be something we wouldn't know what to do with anyway. Just ignore it. */ break; } } /* The instruction for a 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 0 /* %eax */ /* 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 (int pid, int step, enum target_signal signal) { 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_pid" are the same. */ pid = inferior_pid; if (step) { CORE_ADDR pc = read_pc_pid (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 (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); /* Then check the system call number. */ if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn) { CORE_ADDR sp = read_register (SP_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"); } /* Register that we are able to handle Linux ELF core file formats. */ static struct core_fns linux_elf_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 */ }; void _initialize_i386_linux_nat (void) { add_core_fns (&linux_elf_core_fns); }