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Markus Metzger 0568462bbf btrace: kernel address filtering
For the BTS recording format, we sometimes get a FROM->TO record where the
FROM address lies in the kernel and the TO address lies in user space at
whatever address the user process was resumed.

GDB has a heuristic to filter out such records based on looking at the most
significant bit in the PC.  This works fine for 64-bit systems but it doesn't
always work for 32-bit systems.  Libraries that are loaded at fairly high
addresses might be mistaken for kernel code and branches inside the library
are filtered out.

Change the heuristic to (again heuristically) try to determine the lowest
address in kernel space.  Any PC that is smaller than that should be in
user space.

On today's systems, there should be a symbol "_text" at that address.
Read /proc/kallsyms and search for that symbol.

It is not guaranteed that /proc/kallsyms is readable on all systems.  On
64-bit systems, we fall back to check the most significant bit.  On 32-bit
systems, we refrain from filtering out addresses.

The filtering should really be done by the kernel.  And it soon will be:
https://lkml.org/lkml/2015/8/31/212.

gdb/
	* nat/linux-btrace.h (struct btrace_target_info) <ptr_bits>: Remove.
	* nat/linux-btrace.c: Include filestuff.h and inttypes.h.
	Remove include of sys/utsname.h.
	(linux_determine_kernel_ptr_bits): Remove.
	(linux_determine_kernel_start): New.
	(perf_event_is_kernel_addr): Remove tinfo argument.  Update users.
	Update check.
	(perf_event_skip_bts_record): Remove tinfo argument.  Update users.
	(linux_enable_bts, linux_enable_pt): Remove tinfo->ptr_bits
	initialization.
	* x86-linux-nat.c (x86_linux_enable_btrace): Remove ptr_bits
	assignment.

gdbserver/
	* linux-low.c (linux_low_enable_btrace): Remove.
	(linux_target_ops): Replace linux_low_enable_btrace with
	linux_enable_btrace.
2015-09-09 10:35:35 +02:00
bfd Automatic date update in version.in 2015-09-09 00:00:08 +00:00
binutils Fix seg-fault in readelf when scanniing a corrupt binary. 2015-09-03 16:15:49 +01:00
config Missing parts of fixes for in-tree libiconv 2015-08-24 10:57:03 +01:00
cpu Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
elfcpp
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gas config/tc-avr.c (md_section_align): Append UL for -1 to avoid the latest gcc's warning 2015-09-08 21:43:35 +08:00
gdb btrace: kernel address filtering 2015-09-09 10:35:35 +02:00
gold Fix internal error caused by IFUNC patch. 2015-09-07 09:44:11 -07:00
gprof Remove trailing spaces in gprof 2015-08-12 04:43:32 -07:00
include Reorder enum output_type for better code generation 2015-08-23 23:21:48 +09:30
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld Extend the descriptiopn of how to access linker defined symbols from C. 2015-09-08 09:36:02 +01:00
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty PR gdb/18669 libiberty demangle.test failure: strtod() on sparc-sun-solaris2.9 2015-08-11 09:14:12 +02:00
opcodes Support for the sparc %pmcdper privileged register. 2015-08-25 17:16:34 +02:00
readline Revert "Sync readline/ to version 7.0 alpha" 2015-07-25 15:57:00 -04:00
sim Fix building GDB for the M32C by providing a stub sim_info function. 2015-08-05 14:58:21 +01:00
texinfo
zlib Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
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ChangeLog Sync config.sub and config.guess with GCC 2015-08-07 07:51:39 -07:00
compile
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Sync config.sub and config.guess with GCC 2015-08-07 07:51:39 -07:00
config.rpath
config.sub Sync config.sub and config.guess with GCC 2015-08-07 07:51:39 -07:00
configure Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
configure.ac Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
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Makefile.def Yaakov Selkowitz: fixes for in-tree libiconv 2015-08-06 23:55:06 -04:00
Makefile.in Yaakov Selkowitz: fixes for in-tree libiconv 2015-08-06 23:55:06 -04:00
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		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.