-/* Target-dependent code for Linux running on i386's, for GDB.
- Copyright (C) 2000 Free Software Foundation, Inc.
+/* Target-dependent code for GNU/Linux running on i386's, for GDB.
+
+ Copyright 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of GDB.
#include "gdbcore.h"
#include "frame.h"
#include "value.h"
+#include "regcache.h"
+#include "inferior.h"
+#include "osabi.h"
+#include "reggroups.h"
+#include "solib-svr4.h"
+
+#include "gdb_string.h"
+
+#include "i386-tdep.h"
+#include "i386-linux-tdep.h"
+#include "glibc-tdep.h"
+
+/* Return the name of register REG. */
+
+static const char *
+i386_linux_register_name (int reg)
+{
+ /* Deal with the extra "orig_eax" pseudo register. */
+ if (reg == I386_LINUX_ORIG_EAX_REGNUM)
+ return "orig_eax";
+
+ return i386_register_name (reg);
+}
+
+/* Return non-zero, when the register is in the corresponding register
+ group. Put the LINUX_ORIG_EAX register in the system group. */
+static int
+i386_linux_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
+ struct reggroup *group)
+{
+ if (regnum == I386_LINUX_ORIG_EAX_REGNUM)
+ return (group == system_reggroup
+ || group == save_reggroup
+ || group == restore_reggroup);
+ return i386_register_reggroup_p (gdbarch, regnum, group);
+}
\f
/* Recognizing signal handler frames. */
-/* Linux has two flavors of signals. Normal signal handlers, and
+/* GNU/Linux has two flavors of signals. Normal signal handlers, and
"realtime" (RT) signals. The RT signals can provide additional
information to the signal handler if the SA_SIGINFO flag is set
when establishing a signal handler using `sigaction'. It is not
- unlikely that future versions of Linux will support SA_SIGINFO for
- normal signals too. */
+ unlikely that future versions of GNU/Linux will support SA_SIGINFO
+ for normal signals too. */
/* When the i386 Linux kernel calls a signal handler and the
SA_RESTORER flag isn't set, the return address points to a bit of
The instruction sequence for normal signals is
pop %eax
- mov $0x77,%eax
+ mov $0x77, %eax
int $0x80
or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80.
It kind of sucks that we have to read memory from the process in
order to identify a signal trampoline, but there doesn't seem to be
- any other way. The IN_SIGTRAMP macro in tm-linux.h arranges to
+ any other way. The PC_IN_SIGTRAMP macro in tm-linux.h arranges to
only call us if no function name could be identified, which should
be the case since the code is on the stack.
to the ones used by the kernel. Therefore, these trampolines are
supported too. */
-#define LINUX_SIGTRAMP_INSN0 (0x58) /* pop %eax */
-#define LINUX_SIGTRAMP_OFFSET0 (0)
-#define LINUX_SIGTRAMP_INSN1 (0xb8) /* mov $NNNN,%eax */
-#define LINUX_SIGTRAMP_OFFSET1 (1)
-#define LINUX_SIGTRAMP_INSN2 (0xcd) /* int */
-#define LINUX_SIGTRAMP_OFFSET2 (6)
+#define LINUX_SIGTRAMP_INSN0 0x58 /* pop %eax */
+#define LINUX_SIGTRAMP_OFFSET0 0
+#define LINUX_SIGTRAMP_INSN1 0xb8 /* mov $NNNN, %eax */
+#define LINUX_SIGTRAMP_OFFSET1 1
+#define LINUX_SIGTRAMP_INSN2 0xcd /* int */
+#define LINUX_SIGTRAMP_OFFSET2 6
static const unsigned char linux_sigtramp_code[] =
{
LINUX_SIGTRAMP_INSN0, /* pop %eax */
- LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00, /* mov $0x77,%eax */
+ LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00, /* mov $0x77, %eax */
LINUX_SIGTRAMP_INSN2, 0x80 /* int $0x80 */
};
/* This function does the same for RT signals. Here the instruction
sequence is
- mov $0xad,%eax
+ mov $0xad, %eax
int $0x80
or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80.
The effect is to call the system call rt_sigreturn. */
-#define LINUX_RT_SIGTRAMP_INSN0 (0xb8) /* mov $NNNN,%eax */
-#define LINUX_RT_SIGTRAMP_OFFSET0 (0)
-#define LINUX_RT_SIGTRAMP_INSN1 (0xcd) /* int */
-#define LINUX_RT_SIGTRAMP_OFFSET1 (5)
+#define LINUX_RT_SIGTRAMP_INSN0 0xb8 /* mov $NNNN, %eax */
+#define LINUX_RT_SIGTRAMP_OFFSET0 0
+#define LINUX_RT_SIGTRAMP_INSN1 0xcd /* int */
+#define LINUX_RT_SIGTRAMP_OFFSET1 5
static const unsigned char linux_rt_sigtramp_code[] =
{
- LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad,%eax */
+ LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad, %eax */
LINUX_RT_SIGTRAMP_INSN1, 0x80 /* int $0x80 */
};
return pc;
}
-/* Return whether PC is in a Linux sigtramp routine. */
+/* Return whether PC is in a GNU/Linux sigtramp routine. */
-int
-i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
+static int
+i386_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
{
- if (name)
- return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
-
- return (i386_linux_sigtramp_start (pc) != 0
- || i386_linux_rt_sigtramp_start (pc) != 0);
+ /* If we have NAME, we can optimize the search. The trampolines are
+ named __restore and __restore_rt. However, they aren't dynamically
+ exported from the shared C library, so the trampoline may appear to
+ be part of the preceding function. This should always be sigaction,
+ __sigaction, or __libc_sigaction (all aliases to the same function). */
+ if (name == NULL || strstr (name, "sigaction") != NULL)
+ return (i386_linux_sigtramp_start (pc) != 0
+ || i386_linux_rt_sigtramp_start (pc) != 0);
+
+ return (strcmp ("__restore", name) == 0
+ || strcmp ("__restore_rt", name) == 0);
}
-/* Assuming FRAME is for a Linux sigtramp routine, return the address
- of the associated sigcontext structure. */
+/* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */
+#define I386_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 20
+
+/* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp
+ routine, return the address of the associated sigcontext structure. */
-CORE_ADDR
-i386_linux_sigcontext_addr (struct frame_info *frame)
+static CORE_ADDR
+i386_linux_sigcontext_addr (struct frame_info *next_frame)
{
CORE_ADDR pc;
+ CORE_ADDR sp;
+ char buf[4];
+
+ frame_unwind_register (next_frame, I386_ESP_REGNUM, buf);
+ sp = extract_unsigned_integer (buf, 4);
- pc = i386_linux_sigtramp_start (frame->pc);
+ pc = i386_linux_sigtramp_start (frame_pc_unwind (next_frame));
if (pc)
{
- CORE_ADDR sp;
-
- if (frame->next)
- /* If this isn't the top frame, the next frame must be for the
- signal handler itself. The sigcontext structure lives on
- the stack, right after the signum argument. */
- return frame->next->frame + 12;
-
- /* This is the top frame. We'll have to find the address of the
- sigcontext structure by looking at the stack pointer. Keep
- in mind that the first instruction of the sigtramp code is
- "pop %eax". If the PC is at this instruction, adjust the
- returned value accordingly. */
- sp = read_register (SP_REGNUM);
- if (pc == frame->pc)
+ /* The sigcontext structure lives on the stack, right after
+ the signum argument. We determine the address of the
+ sigcontext structure by looking at the frame's stack
+ pointer. Keep in mind that the first instruction of the
+ sigtramp code is "pop %eax". If the PC is after this
+ instruction, adjust the returned value accordingly. */
+ if (pc == frame_pc_unwind (next_frame))
return sp + 4;
return sp;
}
- pc = i386_linux_rt_sigtramp_start (frame->pc);
+ pc = i386_linux_rt_sigtramp_start (frame_pc_unwind (next_frame));
if (pc)
{
- if (frame->next)
- /* If this isn't the top frame, the next frame must be for the
- signal handler itself. The sigcontext structure is part of
- the user context. A pointer to the user context is passed
- as the third argument to the signal handler. */
- return read_memory_integer (frame->next->frame + 16, 4) + 20;
-
- /* This is the top frame. Again, use the stack pointer to find
- the address of the sigcontext structure. */
- return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20;
+ CORE_ADDR ucontext_addr;
+
+ /* The sigcontext structure is part of the user context. A
+ pointer to the user context is passed as the third argument
+ to the signal handler. */
+ read_memory (sp + 8, buf, 4);
+ ucontext_addr = extract_unsigned_integer (buf, 4) + 20;
+ return ucontext_addr + I386_LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
}
error ("Couldn't recognize signal trampoline.");
return 0;
}
-/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
-#define LINUX_SIGCONTEXT_PC_OFFSET (56)
+/* Set the program counter for process PTID to PC. */
+
+static void
+i386_linux_write_pc (CORE_ADDR pc, ptid_t ptid)
+{
+ write_register_pid (I386_EIP_REGNUM, pc, ptid);
+
+ /* We must be careful with modifying the program counter. If we
+ just interrupted a system call, the kernel might try to restart
+ it when we resume the inferior. On restarting the system call,
+ the kernel will try backing up the program counter even though it
+ no longer points at the system call. This typically results in a
+ SIGSEGV or SIGILL. We can prevent this by writing `-1' in the
+ "orig_eax" pseudo-register.
+
+ Note that "orig_eax" is saved when setting up a dummy call frame.
+ This means that it is properly restored when that frame is
+ popped, and that the interrupted system call will be restarted
+ when we resume the inferior on return from a function call from
+ within GDB. In all other cases the system call will not be
+ restarted. */
+ write_register_pid (I386_LINUX_ORIG_EAX_REGNUM, -1, ptid);
+}
+\f
+/* Fetch (and possibly build) an appropriate link_map_offsets
+ structure for native GNU/Linux x86 targets using the struct offsets
+ defined in link.h (but without actual reference to that file).
-/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- program counter. */
+ This makes it possible to access GNU/Linux x86 shared libraries
+ from a GDB that was not built on an GNU/Linux x86 host (for cross
+ debugging). */
-CORE_ADDR
-i386_linux_sigtramp_saved_pc (struct frame_info *frame)
+static struct link_map_offsets *
+i386_linux_svr4_fetch_link_map_offsets (void)
{
- CORE_ADDR addr;
- addr = i386_linux_sigcontext_addr (frame);
- return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
+ 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 552 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;
}
+\f
+
+/* The register sets used in GNU/Linux ELF core-dumps are identical to
+ the register sets in `struct user' that are used for a.out
+ core-dumps. These are also used by ptrace(2). 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.
-/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
-#define LINUX_SIGCONTEXT_SP_OFFSET (28)
+ Those types used to be available under the names `gregset_t' and
+ `fpregset_t' too, and GDB used those names in the past. But those
+ names are now used for the register sets used in the `mcontext_t'
+ type, which have a different size and layout. */
-/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- stack pointer. */
+/* Mapping between the general-purpose registers in `struct user'
+ format and GDB's register cache layout. */
-CORE_ADDR
-i386_linux_sigtramp_saved_sp (struct frame_info *frame)
+/* From <sys/reg.h>. */
+static int i386_linux_gregset_reg_offset[] =
{
- CORE_ADDR addr;
- addr = i386_linux_sigcontext_addr (frame);
- return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
-}
+ 6 * 4, /* %eax */
+ 1 * 4, /* %ecx */
+ 2 * 4, /* %edx */
+ 0 * 4, /* %ebx */
+ 15 * 4, /* %esp */
+ 5 * 4, /* %ebp */
+ 3 * 4, /* %esi */
+ 4 * 4, /* %edi */
+ 12 * 4, /* %eip */
+ 14 * 4, /* %eflags */
+ 13 * 4, /* %cs */
+ 16 * 4, /* %ss */
+ 7 * 4, /* %ds */
+ 8 * 4, /* %es */
+ 9 * 4, /* %fs */
+ 10 * 4, /* %gs */
+ -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1,
+ -1,
+ 11 * 4 /* "orig_eax" */
+};
+
+/* Mapping between the general-purpose registers in `struct
+ sigcontext' format and GDB's register cache layout. */
-/* Immediately after a function call, return the saved pc. */
+/* From <asm/sigcontext.h>. */
+static int i386_linux_sc_reg_offset[] =
+{
+ 11 * 4, /* %eax */
+ 10 * 4, /* %ecx */
+ 9 * 4, /* %edx */
+ 8 * 4, /* %ebx */
+ 7 * 4, /* %esp */
+ 6 * 4, /* %ebp */
+ 5 * 4, /* %esi */
+ 4 * 4, /* %edi */
+ 14 * 4, /* %eip */
+ 16 * 4, /* %eflags */
+ 15 * 4, /* %cs */
+ 18 * 4, /* %ss */
+ 3 * 4, /* %ds */
+ 2 * 4, /* %es */
+ 1 * 4, /* %fs */
+ 0 * 4 /* %gs */
+};
-CORE_ADDR
-i386_linux_saved_pc_after_call (struct frame_info *frame)
+static void
+i386_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
- if (frame->signal_handler_caller)
- return i386_linux_sigtramp_saved_pc (frame);
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- return read_memory_integer (read_register (SP_REGNUM), 4);
+ /* GNU/Linux uses ELF. */
+ i386_elf_init_abi (info, gdbarch);
+
+ /* Since we have the extra "orig_eax" register on GNU/Linux, we have
+ to adjust a few things. */
+
+ set_gdbarch_write_pc (gdbarch, i386_linux_write_pc);
+ set_gdbarch_num_regs (gdbarch, I386_LINUX_NUM_REGS);
+ set_gdbarch_register_name (gdbarch, i386_linux_register_name);
+ set_gdbarch_register_reggroup_p (gdbarch, i386_linux_register_reggroup_p);
+
+ tdep->gregset_reg_offset = i386_linux_gregset_reg_offset;
+ tdep->gregset_num_regs = ARRAY_SIZE (i386_linux_gregset_reg_offset);
+ tdep->sizeof_gregset = 17 * 4;
+
+ tdep->jb_pc_offset = 20; /* From <bits/setjmp.h>. */
+
+ tdep->sigcontext_addr = i386_linux_sigcontext_addr;
+ tdep->sc_reg_offset = i386_linux_sc_reg_offset;
+ tdep->sc_num_regs = ARRAY_SIZE (i386_linux_sc_reg_offset);
+
+ /* When the i386 Linux kernel calls a signal handler, the return
+ address points to a bit of code on the stack. This function is
+ used to identify this bit of code as a signal trampoline in order
+ to support backtracing through calls to signal handlers. */
+ set_gdbarch_pc_in_sigtramp (gdbarch, i386_linux_pc_in_sigtramp);
+
+ set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
+ set_solib_svr4_fetch_link_map_offsets (gdbarch,
+ i386_linux_svr4_fetch_link_map_offsets);
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes. */
+extern void _initialize_i386_linux_tdep (void);
+
+void
+_initialize_i386_linux_tdep (void)
+{
+ gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_LINUX,
+ i386_linux_init_abi);
}
projects / deliverable / binutils-gdb.git / blobdiff