+2000-03-04 Mark Kettenis <kettenis@gnu.org>
+
+ Fix support for Linux/i386 signal trampolines. The old approach
+ didn't work for Linux 2.2 and beyond, and didn't work with recent
+ versions of the GNU C library.
+ * i386-tdep.c (LINUX_RT_SIGTRAMP_INSN0, LINUX_RT_SIGTRAMP_OFFSET0,
+ LINUX_RT_SIGTRAMP_INSN1, LINUX_RT_SIGTRAMP_OFFSET1): New defines.
+ (linux_rt_sigtramp_code): New variable.
+ (LINUX_RT_SIGTRAMP_LEN): New define.
+ (i386_linux_rt_sigtramp_start): New function. Detect start of
+ signal trampolines for RT signals.
+ (i386_linux_sigtramp): Removed.
+ (i386_linux_in_sigtramp): New function.
+ (i386_linux_sigcontext_addr): New function. Recognize the names
+ of the signal tranmpolines used by recent versions of the GNU C
+ library, and add support for RT signals.
+ (LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET): New
+ defines. Moved here from config/i386/tm-linux.h.
+ (i386_linux_sigtramp_saved_pc, i386_linux_sigtramp_saved_sp):
+ Reimplement in terms of i386_linux_sigcontext_addr.
+ * config/i386/tm-linux.h (LINUX_SIGCONTEXT_SIZE): Removed.
+ (LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET):
+ Moved to i386-tdep.c.
+ (IN_SIGTRAMP): Redefine to call i386_linux_in_sigtramp.
+
Sat Mar 4 19:38:11 2000 Andrew Cagney <cagney@b1.cygnus.com>
By: Sat Mar 4 04:08:58 2000 Alexandre Oliva <oliva@lsd.ic.unicamp.br>
/* Definitions to target GDB to GNU/Linux on 386.
Copyright 1992, 1993 Free Software Foundation, Inc.
-This file is part of GDB.
+ 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 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.
+ 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. */
+ 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. */
#ifndef TM_LINUX_H
#define TM_LINUX_H
-/* FIXME: If nothing else gets added to this file, it could be removed
- and configure could just use tm-i386.h instead. -fnf */
+#define I386_GNULINUX_TARGET
+#define HAVE_I387_REGS
+#ifdef HAVE_PTRACE_GETXFPREGS
+#define HAVE_SSE_REGS
+#endif
#include "i386/tm-i386.h"
+#include "tm-linux.h"
-/* Offset to saved PC in sigcontext, from <linux/signal.h>. */
-#define SIGCONTEXT_PC_OFFSET 38
+#define LOW_RETURN_REGNUM 0 /* holds low four bytes of result */
+#define HIGH_RETURN_REGNUM 2 /* holds high four bytes of result */
-/* We need this file for the SOLIB_TRAMPOLINE stuff. */
+/* This should probably move to tm-i386.h. */
+#define TARGET_LONG_DOUBLE_BIT 80
-#include "tm-sysv4.h"
+#if defined(HAVE_LONG_DOUBLE) && defined(HOST_I386)
+/* The host and target are i386 machines and the compiler supports
+ long doubles. Long doubles on the host therefore have the same
+ layout as a 387 FPU stack register. */
+#define LD_I387
+
+extern int i387_extract_floating (PTR addr, int len, long double *dretptr);
+extern int i387_store_floating (PTR addr, int len, long double val);
+
+#define TARGET_EXTRACT_FLOATING i387_extract_floating
+#define TARGET_STORE_FLOATING i387_store_floating
+
+#define TARGET_ANALYZE_FLOATING \
+ do \
+ { \
+ unsigned expon; \
+ \
+ low = extract_unsigned_integer (valaddr, 4); \
+ high = extract_unsigned_integer (valaddr + 4, 4); \
+ expon = extract_unsigned_integer (valaddr + 8, 2); \
+ \
+ nonnegative = ((expon & 0x8000) == 0); \
+ is_nan = ((expon & 0x7fff) == 0x7fff) \
+ && ((high & 0x80000000) == 0x80000000) \
+ && (((high & 0x7fffffff) | low) != 0); \
+ } \
+ while (0)
+
+#undef REGISTER_CONVERT_TO_VIRTUAL
+#define REGISTER_CONVERT_TO_VIRTUAL(REGNUM,TYPE,FROM,TO) \
+{ \
+ long double val = *((long double *)FROM); \
+ store_floating ((TO), TYPE_LENGTH (TYPE), val); \
+}
+
+#undef REGISTER_CONVERT_TO_RAW
+#define REGISTER_CONVERT_TO_RAW(TYPE,REGNUM,FROM,TO) \
+{ \
+ long double val = extract_floating ((FROM), TYPE_LENGTH (TYPE)); \
+ *((long double *)TO) = val; \
+}
+
+/* Return the GDB type object for the "standard" data type
+ of data in register N. */
+#undef REGISTER_VIRTUAL_TYPE
+#define REGISTER_VIRTUAL_TYPE(N) \
+ (((N) == PC_REGNUM || (N) == FP_REGNUM || (N) == SP_REGNUM) \
+ ? lookup_pointer_type (builtin_type_void) \
+ : IS_FP_REGNUM(N) ? builtin_type_long_double \
+ : IS_SSE_REGNUM(N) ? builtin_type_v4sf \
+ : builtin_type_int)
+
+#endif
/* The following works around a problem with /usr/include/sys/procfs.h */
#define sys_quotactl 1
-#endif /* #ifndef TM_LINUX_H */
+/* When the i386 Linux kernel calls a signal handler, the return
+ address points to a bit of code on the stack. These definitions
+ are used to identify this bit of code as a signal trampoline in
+ order to support backtracing through calls to signal handlers. */
+
+#define I386_LINUX_SIGTRAMP
+#define IN_SIGTRAMP(pc, name) i386_linux_in_sigtramp (pc, name)
+extern int i386_linux_in_sigtramp (CORE_ADDR, char *);
+
+/* We need our own version of sigtramp_saved_pc to get the saved PC in
+ a sigtramp routine. */
+
+#define sigtramp_saved_pc i386_linux_sigtramp_saved_pc
+extern CORE_ADDR i386_linux_sigtramp_saved_pc (struct frame_info *);
+
+/* Signal trampolines don't have a meaningful frame. As in tm-i386.h,
+ the frame pointer value we use is actually the frame pointer of the
+ calling frame--that is, the frame which was in progress when the
+ signal trampoline was entered. gdb mostly treats this frame
+ pointer value as a magic cookie. We detect the case of a signal
+ trampoline by looking at the SIGNAL_HANDLER_CALLER field, which is
+ set based on IN_SIGTRAMP.
+
+ When a signal trampoline is invoked from a frameless function, we
+ essentially have two frameless functions in a row. In this case,
+ we use the same magic cookie for three frames in a row. We detect
+ this case by seeing whether the next frame has
+ SIGNAL_HANDLER_CALLER set, and, if it does, checking whether the
+ current frame is actually frameless. In this case, we need to get
+ the PC by looking at the SP register value stored in the signal
+ context.
+
+ This should work in most cases except in horrible situations where
+ a signal occurs just as we enter a function but before the frame
+ has been set up. */
+
+#define FRAMELESS_SIGNAL(FRAME) \
+ ((FRAME)->next != NULL \
+ && (FRAME)->next->signal_handler_caller \
+ && frameless_look_for_prologue (FRAME))
+
+#undef FRAME_CHAIN
+#define FRAME_CHAIN(FRAME) \
+ ((FRAME)->signal_handler_caller \
+ ? (FRAME)->frame \
+ : (FRAMELESS_SIGNAL (FRAME) \
+ ? (FRAME)->frame \
+ : (!inside_entry_file ((FRAME)->pc) \
+ ? read_memory_integer ((FRAME)->frame, 4) \
+ : 0)))
+
+#undef FRAME_SAVED_PC
+#define FRAME_SAVED_PC(FRAME) \
+ ((FRAME)->signal_handler_caller \
+ ? sigtramp_saved_pc (FRAME) \
+ : (FRAMELESS_SIGNAL (FRAME) \
+ ? read_memory_integer (i386_linux_sigtramp_saved_sp ((FRAME)->next), 4) \
+ : read_memory_integer ((FRAME)->frame + 4, 4)))
+
+extern CORE_ADDR i386_linux_sigtramp_saved_sp (struct frame_info *);
+
+/* When we call a function in a shared library, and the PLT sends us
+ into the dynamic linker to find the function's real address, we
+ need to skip over the dynamic linker call. This function decides
+ when to skip, and where to skip to. See the comments for
+ SKIP_SOLIB_RESOLVER at the top of infrun.c. */
+#define SKIP_SOLIB_RESOLVER i386_linux_skip_solib_resolver
+extern CORE_ADDR i386_linux_skip_solib_resolver (CORE_ADDR pc);
+
+/* N_FUN symbols in shared libaries have 0 for their values and need
+ to be relocated. */
+#define SOFUN_ADDRESS_MAYBE_MISSING
+
+#endif /* #ifndef TM_LINUX_H */
#ifdef I386_LINUX_SIGTRAMP
-/* When the i386 Linux kernel calls a signal handler, the return
- address points to a bit of code on the stack. This function
- returns whether the PC appears to be within this bit of code.
-
- The instruction sequence is
+/* 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. */
+
+/* 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
+ code on the stack. This function returns whether the PC appears to
+ be within this bit of code.
+
+ The instruction sequence for normal signals is
pop %eax
mov $0x77,%eax
int $0x80
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
only call us if no function name could be identified, which should
- be the case since the code is on the stack. */
+ be the case since the code is on the stack.
+
+ Detection of signal trampolines for handlers that set the
+ SA_RESTORER flag is in general not possible. Unfortunately this is
+ what the GNU C Library has been doing for quite some time now.
+ However, as of version 2.1.2, the GNU C Library uses signal
+ trampolines (named __restore and __restore_rt) that are identical
+ 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)
the routine. Otherwise, return 0. */
static CORE_ADDR
-i386_linux_sigtramp_start (pc)
- CORE_ADDR pc;
+i386_linux_sigtramp_start (CORE_ADDR pc)
{
unsigned char buf[LINUX_SIGTRAMP_LEN];
return pc;
}
+/* This function does the same for RT signals. Here the instruction
+ sequence is
+ 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)
+
+static const unsigned char linux_rt_sigtramp_code[] =
+{
+ LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad,%eax */
+ LINUX_RT_SIGTRAMP_INSN1, 0x80 /* int $0x80 */
+};
+
+#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code)
+
+/* If PC is in a RT sigtramp routine, return the address of the start
+ of the routine. Otherwise, return 0. */
+
+static CORE_ADDR
+i386_linux_rt_sigtramp_start (CORE_ADDR pc)
+{
+ unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
+
+ /* We only recognize a signal trampoline if PC is at the start of
+ one of the two instructions. We optimize for finding the PC at
+ the start, as will be the case when the trampoline is not the
+ first frame on the stack. We assume that in the case where the
+ PC is not at the start of the instruction sequence, there will be
+ a few trailing readable bytes on the stack. */
+
+ if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
+ return 0;
+
+ if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
+ {
+ if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
+ return 0;
+
+ pc -= LINUX_RT_SIGTRAMP_OFFSET1;
+
+ if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
+ return 0;
+ }
+
+ if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
+ return 0;
+
+ return pc;
+}
+
/* Return whether PC is in a Linux sigtramp routine. */
int
-i386_linux_sigtramp (pc)
- CORE_ADDR pc;
+i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
{
- return i386_linux_sigtramp_start (pc) != 0;
+ if (name)
+ return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
+
+ return (i386_linux_sigtramp_start (pc) != 0
+ || i386_linux_rt_sigtramp_start (pc) != 0);
}
-/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- program counter. The Linux kernel will set up a sigcontext
- structure immediately before the sigtramp routine on the stack. */
+/* Assuming FRAME is for a Linux sigtramp routine, return the address
+ of the associated sigcontext structure. */
CORE_ADDR
-i386_linux_sigtramp_saved_pc (frame)
- struct frame_info *frame;
+i386_linux_sigcontext_addr (struct frame_info *frame)
{
CORE_ADDR pc;
pc = i386_linux_sigtramp_start (frame->pc);
- if (pc == 0)
- error ("i386_linux_sigtramp_saved_pc called when no sigtramp");
- return read_memory_integer ((pc
- - LINUX_SIGCONTEXT_SIZE
- + LINUX_SIGCONTEXT_PC_OFFSET),
- 4);
+ 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)
+ return sp + 4;
+ return sp;
+ }
+
+ pc = i386_linux_rt_sigtramp_start (frame->pc);
+ 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;
+ }
+
+ error ("Couldn't recognize signal trampoline.");
+ return 0;
}
+/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
+#define LINUX_SIGCONTEXT_PC_OFFSET (56)
+
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- stack pointer. The Linux kernel will set up a sigcontext structure
- immediately before the sigtramp routine on the stack. */
+ program counter. */
CORE_ADDR
-i386_linux_sigtramp_saved_sp (frame)
- struct frame_info *frame;
+i386_linux_sigtramp_saved_pc (struct frame_info *frame)
{
- CORE_ADDR pc;
+ CORE_ADDR addr;
+ addr = i386_linux_sigcontext_addr (frame);
+ return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
+}
- pc = i386_linux_sigtramp_start (frame->pc);
- if (pc == 0)
- error ("i386_linux_sigtramp_saved_sp called when no sigtramp");
- return read_memory_integer ((pc
- - LINUX_SIGCONTEXT_SIZE
- + LINUX_SIGCONTEXT_SP_OFFSET),
- 4);
+/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
+#define LINUX_SIGCONTEXT_SP_OFFSET (28)
+
+/* Assuming FRAME is for a Linux sigtramp routine, return the saved
+ stack pointer. */
+
+CORE_ADDR
+i386_linux_sigtramp_saved_sp (struct frame_info *frame)
+{
+ CORE_ADDR addr;
+ addr = i386_linux_sigcontext_addr (frame);
+ return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
}
#endif /* I386_LINUX_SIGTRAMP */
OSDN Git Service
