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Maciej W. Rozycki 3f7f365076 MIPS: Fix microMIPS instruction size determination
Fix a bug in `micromips_insn_at_pc_has_delay_slot' in instruction size
determination via `mips_insn_size'.  In the microMIPS case the latter
function expects a lone 16-bit instruction word containing the major
opcode regardless of whether the opcode requires another 16-bit word to
follow, to form a complete 32-bit instruction.  Code however passes the
16-bit word previously retrieved shifted left by 16 bits.  Consequently
`mips_insn_size', which examines the low 16-bit only, always sees 0.

By pure coincidence a major opcode of 0 denotes a 32-bit instruction in
the microMIPS instruction set, so the size of 4 is always returned here,
and the following 16-bit word is then merged in the low 16 bits of the
instruction previously shifted by 16 bits.  The resulting 32-bit value
is then passed to `micromips_instruction_has_delay_slot' for delay slot
presence determination.  This function in turn first examines the high
16 bits of the instruction word received and ignores the low 16 bits for
16-bit instructions.

Consequently the only effect of this bug is an extraneous memory read
issued to retrieve a subsequent 16-bit word where a 16-bit instruction
is being examined.  Which in turn may fail if the instruction is located
right at the end of a readable memory area, in which case the lack of a
delay slot will be reported to the caller, which may be incorrect.

This code is used in breakpoint maintenance, for delay slot avoidance,
so the bug would only trigger for the unlikely case of someone placing
a breakpoint in a delay slot of an instruction which is at the end of
readable memory.  Which explains why the bug remained unnoticed so long.

	gdb/
	* mips-tdep.c (micromips_insn_at_pc_has_delay_slot): Pass
	unshifted 16-bit microMIPS instruction word to `mips_insn_size'.
2016-01-18 20:24:34 +00:00
bfd Use a 32-bit value to hold the section number in the internal COFF symbol structure. 2016-01-18 15:58:47 +00:00
binutils Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
config Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
cpu Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
elfcpp Remove typename from Mips64_rela_data 2016-01-12 12:08:06 -08:00
etc PR external/{16327,16328}: Remove etc/configure.texi and etc/standards.texi. 2014-06-27 11:33:25 +02:00
gas Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
gdb MIPS: Fix microMIPS instruction size determination 2016-01-18 20:24:34 +00:00
gold [gold][aarch64] PR gold/19472 - DSOs need pc-relative stubs. 2016-01-15 17:10:04 -08:00
gprof Regen configure 2016-01-17 12:28:14 +10:30
include Use a 32-bit value to hold the section number in the internal COFF symbol structure. 2016-01-18 15:58:47 +00:00
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld Re-enable rgn-at11 test for MIPS targets with adjusted section alignment. 2016-01-18 13:00:33 +00:00
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty libiberty: {count,dup,write}argv: constify argv input slightly 2016-01-05 15:25:13 -05:00
opcodes Regen configure 2016-01-17 12:28:14 +10:30
readline Revert "Sync readline/ to version 7.0 alpha" 2015-07-25 15:57:00 -04:00
sim Minor comment fixes in sim/common/sim-fpu.c. 2016-01-17 09:34:29 +04:00
texinfo * texinfo/texinfo.tex: Update to version 2009-03-28.05. 2009-04-21 12:36:46 +00:00
zlib Import zlib 1.2.8 with local change merged in. 2015-11-25 15:14:47 -08:00
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
ChangeLog Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
config.rpath Remove freebsd1 from libtool.m4 macros and config.rpath. 2011-02-13 21:00:14 +00:00
config.sub Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
configure Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
configure.ac Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
COPYING
COPYING.LIB
COPYING.LIBGLOSS 2013-01-07 Jeff Johnston <jjohnstn@redhat.com> 2013-01-07 21:39:26 +00:00
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
COPYING3
COPYING3.LIB
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat * djunpack.bat: Use ".." quoting in Sed command, for the sake of 2009-03-27 13:37:09 +00:00
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
ltgcc.m4 * libtool.m4: Update to libtool 2.2.6. 2008-09-29 15:28:14 +00:00
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
ltsugar.m4 * libtool.m4: Update to libtool 2.2.6. 2008-09-29 15:28:14 +00:00
ltversion.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
lt~obsolete.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def Sync top-level Makefile.def with GCC 2016-01-12 08:34:40 -08:00
Makefile.in Sync top-level Makefile.def with GCC 2016-01-12 08:34:40 -08:00
Makefile.tpl Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode Cleanups after the update to Autoconf 2.64, Automake 1.11. 2009-08-22 17:08:11 +00:00
setup.com 2009-09-01 Tristan Gingold <gingold@adacore.com> 2009-09-01 13:38:26 +00:00
src-release.sh fix gdb version parsing in src-release.sh 2016-01-17 10:01:55 +04:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

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