binutils-gdb/gdb/gdbcore.h
Jan Kratochvil bb805577d2 PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression
Regression: gdb --pid $(pidof qemu-system-x86_64) stopped working with gdb 7.11.1
https://sourceware.org/bugzilla/show_bug.cgi?id=20609

It was reported for qemu-system-x86_64 but it happens for any multithreaded
inferior with a JIT debugging hook.

136613ef0c is the first bad commit
Author: Pedro Alves <palves@redhat.com>
    Fix PR gdb/19828: gdb -p <process from a container>: internal error
Message-ID: <cbdf2e04-4fa8-872a-2a23-08c9c1b26e00@redhat.com>
https://sourceware.org/ml/gdb-patches/2016-05/msg00450.html

jit_breakpoint_re_set() is specific by trying to insert a breakpoint into the
main executable, not into a shared library.  During attachment GDB thinks it
needs to use 'breakpoint always-inserted' from
breakpoints_should_be_inserted_now() as a newly attached thread is
'thread_info->executing' due to 'lwp_info->must_set_ptrace_flags' enabled and
the task not yet stopped.  This did not happen before the 'bad commit' above
which adds tracking of such thread.

GDB then fails to insert the breakpoints to invalid address as PIE executable
gets properly relocated during later phase of attachment.  One can see in the
backtraces below:
 -> jit_breakpoint_re_set_internal()
later:
 -> svr4_exec_displacement()

One can suppress the initial breakpoint_re_set() call as there will be another
breakpoint_re_set() done from the final post_create_inferior() call in
setup_inferior().

BTW additionally 'threads_executing' cache bool is somehow stale (somewhere is
missing update_threads_executing()).  I was trying to deal with that in my
first/second attempt below but in my final third attempt (attached) I have
left it as it is.

First attempt trying not to falsely require 'breakpoint always-inserted':
  https://people.redhat.com/jkratoch/rhbz1375553-fix1.patch
Reduced first attempt:
  https://people.redhat.com/jkratoch/rhbz1375553-fix2.patch

The third attempt suppresses breakpoint insertion until PIE executable gets
relocated by svr4_exec_displacement().  Applied.

gdb/ChangeLog
2016-09-29  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression
	* exec.c (exec_file_locate_attach): Add parameter defer_bp_reset.
	Use it.
	* gdbcore.h (exec_file_locate_attach): Add parameter defer_bp_reset.
	* infcmd.c (setup_inferior): Update caller.
	* remote.c (remote_add_inferior): Likewise.

gdb/testsuite/ChangeLog
2016-09-29  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression
	* gdb.base/jit-attach-pie.c: New file.
	* gdb.base/jit-attach-pie.exp: New file.
2016-09-29 17:39:39 +02:00

242 lines
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/* Machine independent variables that describe the core file under GDB.
Copyright (C) 1986-2016 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 3 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, see <http://www.gnu.org/licenses/>. */
/* Interface routines for core, executable, etc. */
#if !defined (GDBCORE_H)
#define GDBCORE_H 1
struct type;
struct regcache;
#include "bfd.h"
#include "exec.h"
#include "target.h"
/* Return the name of the executable file as a string.
ERR nonzero means get error if there is none specified;
otherwise return 0 in that case. */
extern char *get_exec_file (int err);
/* Nonzero if there is a core file. */
extern int have_core_file_p (void);
/* Report a memory error with error(). */
extern void memory_error (enum target_xfer_status status, CORE_ADDR memaddr);
/* The string 'memory_error' would use as exception message. Space
for the result is malloc'd, caller must free. */
extern char *memory_error_message (enum target_xfer_status err,
struct gdbarch *gdbarch, CORE_ADDR memaddr);
/* Like target_read_memory, but report an error if can't read. */
extern void read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len);
/* Like target_read_stack, but report an error if can't read. */
extern void read_stack (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len);
/* Like target_read_code, but report an error if can't read. */
extern void read_code (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len);
/* Read an integer from debugged memory, given address and number of
bytes. */
extern LONGEST read_memory_integer (CORE_ADDR memaddr,
int len, enum bfd_endian byte_order);
extern int safe_read_memory_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order,
LONGEST *return_value);
/* Read an unsigned integer from debugged memory, given address and
number of bytes. */
extern ULONGEST read_memory_unsigned_integer (CORE_ADDR memaddr,
int len,
enum bfd_endian byte_order);
extern int safe_read_memory_unsigned_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order,
ULONGEST *return_value);
/* Read an integer from debugged code memory, given address,
number of bytes, and byte order for code. */
extern LONGEST read_code_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order);
/* Read an unsigned integer from debugged code memory, given address,
number of bytes, and byte order for code. */
extern ULONGEST read_code_unsigned_integer (CORE_ADDR memaddr,
int len,
enum bfd_endian byte_order);
/* Read a null-terminated string from the debuggee's memory, given
address, a buffer into which to place the string, and the maximum
available space. */
extern void read_memory_string (CORE_ADDR, char *, int);
/* Read the pointer of type TYPE at ADDR, and return the address it
represents. */
CORE_ADDR read_memory_typed_address (CORE_ADDR addr, struct type *type);
/* Same as target_write_memory, but report an error if can't
write. */
extern void write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr,
ssize_t len);
/* Same as write_memory, but notify 'memory_changed' observers. */
extern void write_memory_with_notification (CORE_ADDR memaddr,
const bfd_byte *myaddr,
ssize_t len);
/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned integer. */
extern void write_memory_unsigned_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
ULONGEST value);
/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned integer. */
extern void write_memory_signed_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
LONGEST value);
/* Hook for `exec_file_command' command to call. */
extern void (*deprecated_exec_file_display_hook) (const char *filename);
/* Hook for "file_command", which is more useful than above
(because it is invoked AFTER symbols are read, not before). */
extern void (*deprecated_file_changed_hook) (char *filename);
extern void specify_exec_file_hook (void (*hook) (const char *filename));
/* Binary File Diddler for the core file. */
extern bfd *core_bfd;
extern struct target_ops *core_target;
/* Whether to open exec and core files read-only or read-write. */
extern int write_files;
extern void core_file_command (char *filename, int from_tty);
extern void exec_file_attach (const char *filename, int from_tty);
/* If the filename of the main executable is unknown, attempt to
determine it. If a filename is determined, proceed as though
it was just specified with the "file" command. Do nothing if
the filename of the main executable is already known.
DEFER_BP_RESET uses SYMFILE_DEFER_BP_RESET for the main symbol file. */
extern void exec_file_locate_attach (int pid, int defer_bp_reset, int from_tty);
extern void exec_file_clear (int from_tty);
extern void validate_files (void);
/* The current default bfd target. */
extern char *gnutarget;
extern void set_gnutarget (char *);
/* Structure to keep track of core register reading functions for
various core file types. */
struct core_fns
{
/* BFD flavour that a core file handler is prepared to read. This
can be used by the handler's core tasting function as a first
level filter to reject BFD's that don't have the right
flavour. */
enum bfd_flavour core_flavour;
/* Core file handler function to call to recognize corefile
formats that BFD rejects. Some core file format just don't fit
into the BFD model, or may require other resources to identify
them, that simply aren't available to BFD (such as symbols from
another file). Returns nonzero if the handler recognizes the
format, zero otherwise. */
int (*check_format) (bfd *);
/* Core file handler function to call to ask if it can handle a
given core file format or not. Returns zero if it can't,
nonzero otherwise. */
int (*core_sniffer) (struct core_fns *, bfd *);
/* Extract the register values out of the core file and supply them
into REGCACHE.
CORE_REG_SECT points to the register values themselves, read into
memory.
CORE_REG_SIZE is the size of that area.
WHICH says which set of registers we are handling:
0 --- integer registers
2 --- floating-point registers, on machines where they are
discontiguous
3 --- extended floating-point registers, on machines where
these are present in yet a third area. (GNU/Linux uses
this to get at the SSE registers.)
REG_ADDR is the offset from u.u_ar0 to the register values relative to
core_reg_sect. This is used with old-fashioned core files to locate the
registers in a large upage-plus-stack ".reg" section. Original upage
address X is at location core_reg_sect+x+reg_addr. */
void (*core_read_registers) (struct regcache *regcache,
char *core_reg_sect,
unsigned core_reg_size,
int which, CORE_ADDR reg_addr);
/* Finds the next struct core_fns. They are allocated and
initialized in whatever module implements the functions pointed
to; an initializer calls deprecated_add_core_fns to add them to
the global chain. */
struct core_fns *next;
};
/* NOTE: cagney/2004-04-05: Replaced by "regset.h" and
regset_from_core_section(). */
extern void deprecated_add_core_fns (struct core_fns *cf);
extern int default_core_sniffer (struct core_fns *cf, bfd * abfd);
extern int default_check_format (bfd * abfd);
#endif /* !defined (GDBCORE_H) */