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Andreas Arnez 87c336f60e inf-ptrace: Do not stop memory transfers after a single word
When inf_ptrace_xfer_partial performs a memory transfer via ptrace with
PT_READ_I, PT_WRITE_I (aka PTRACE_PEEKTEXT, PTRACE_POKETEXT), etc., then
it currently transfers at most one word.  This behavior yields degraded
performance, particularly if the caller has significant preparation work
for each invocation.  And indeed it has for writing, in
memory_xfer_partial in target.c, where all of the remaining data to be
transferred is copied to a temporary buffer each time, for breakpoint
shadow handling.  Thus large writes have quadratic runtime and can take
hours.

Note: On GNU/Linux targets GDB usually does not use
inf_ptrace_xfer_partial for large memory transfers, but attempts a single
read/write from/to /proc/<pid>/mem instead.  However, the kernel may
reject writes to /proc/<pid>/mem (such as kernels prior to 2.6.39), or
/proc may not be mounted.  In both cases GDB falls back to the ptrace
mechanism.

This patch fixes the performance issue by attempting to fulfill the whole
transfer request in inf_ptrace_xfer_partial, using a loop around the
ptrace call.

gdb/ChangeLog:

	PR gdb/21220
	* inf-ptrace.c (inf_ptrace_xfer_partial): In "case
	TARGET_OBJECT_MEMORY", extract the logic for ptrace peek/poke...
	(inf_ptrace_peek_poke): ...here.  New function.  Now also loop
	over ptrace peek/poke until end of buffer or error.
2017-03-14 19:20:46 +01:00
bfd Automatic date update in version.in 2017-03-14 00:00:40 +00:00
binutils Try harder to find the correct symbol to associate with OPEN GNU BUILD notes. 2017-03-14 12:57:09 +00:00
config picflag.m4 high bit set in comment 2017-01-05 00:02:57 +10:30
cpu Add fall through comment to source in cpu/ 2016-10-06 22:48:37 +10:30
elfcpp Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
etc update-copyright.py for binutils 2017-01-05 00:03:07 +10:30
gas RISC-V: Define DWARF2_USE_FIXED_ADVANCE_PC. 2017-03-14 09:51:29 -07:00
gdb inf-ptrace: Do not stop memory transfers after a single word 2017-03-14 19:20:46 +01:00
gold PowerPC ld segfault on script discarding dynamic sections 2017-02-22 08:44:41 +10:30
gprof Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
include Sync libiberty sources with GCC. 2017-03-13 17:49:32 +00:00
intl
ld Use addr_mask to check VMA and LMA 2017-03-14 09:09:54 -07:00
libdecnumber
libiberty Merge libiberty: Initialize d_printing in all cplus_demangle_fill_* functions. 2017-03-13 20:51:42 +01:00
opcodes RISC-V: Fix [dis]assembly of srai/srli 2017-03-14 09:23:18 -07:00
readline Improve MinGW support in Readline 2016-09-17 11:50:37 +03:00
sim Fix umulh and smulh bugs. Fix bugs in last week's sumov.s testsuite. 2017-03-03 13:10:45 -08:00
texinfo
zlib Sync ZLIB with FSF GCC sources, bringing in version 1.2.11. 2017-02-20 12:52:22 +00:00
.cvsignore
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.gitignore Add archives and make stamps to the .gitignore file. 2016-09-27 15:10:42 +01:00
ChangeLog Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
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config.guess Sync config.sub,config.guess with upstream. 2016-11-07 13:08:55 -08:00
config.rpath
config.sub Import config.sub 2016-12-31 11:47:16 +10:30
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libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
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MAINTAINERS
Makefile.def Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
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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.