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Pedro Alves 90ad5e1d4f Linux/ptrace: don't convert ptids when asking inf-ptrace layer to resume LWP
Ref: https://sourceware.org/ml/gdb-patches/2015-03/msg00060.html

The record-btrace target can hit an assertion here:

 Breakpoint 1, record_btrace_fetch_registers (ops=0x974bfc0 <record_btrace_ops>,
     regcache=0x9a0a798, regno=8) at gdb/record-btrace.c:1202
 1202	  gdb_assert (tp != NULL);

 (gdb) p regcache->ptid
 $3 = {pid = 23856, lwp = 0, tid = 0}

The problem is that the linux-nat layer converts the ptid to a
single-process ptid before passing the request down to the inf-ptrace
layer, which loses information, and then record-btrace can't find the
corresponding thread in GDB's thread list:

 (gdb) bt
 #0  record_btrace_fetch_registers (ops=0x974bfc0 <record_btrace_ops>, regcache=0x9a0a798, regno=8)
     at gdb/record-btrace.c:1202
 #1  0x083f4ee2 in delegate_fetch_registers (self=0x974bfc0 <record_btrace_ops>, arg1=0x9a0a798,
     arg2=8) at gdb/target-delegates.c:149
 #2  0x08406562 in target_fetch_registers (regcache=0x9a0a798, regno=8)
     at gdb/target.c:3279
 #3  0x08355255 in regcache_raw_read (regcache=0x9a0a798, regnum=8,
     buf=0xbfffe6c0 "¨\003\222\tÀ8kIøæÿ¿HO5\b\035]")
     at gdb/regcache.c:643
 #4  0x083558a7 in regcache_cooked_read (regcache=0x9a0a798, regnum=8,
     buf=0xbfffe6c0 "¨\003\222\tÀ8kIøæÿ¿HO5\b\035]")
     at gdb/regcache.c:734
 #5  0x08355de3 in regcache_cooked_read_unsigned (regcache=0x9a0a798, regnum=8, val=0xbfffe738)
     at gdb/regcache.c:838
 #6  0x0827a106 in i386_linux_resume (ops=0x9737ca0 <linux_ops_saved>, ptid=..., step=1,
     signal=GDB_SIGNAL_0) at gdb/i386-linux-nat.c:670
 #7  0x08280c12 in linux_resume_one_lwp (lp=0x9a0a5b8, step=1, signo=GDB_SIGNAL_0)
     at gdb/linux-nat.c:1529
 #8  0x08281281 in linux_nat_resume (ops=0x98da608, ptid=..., step=1, signo=GDB_SIGNAL_0)
     at gdb/linux-nat.c:1708
 #9  0x0850738e in record_btrace_resume (ops=0x98da608, ptid=..., step=1, signal=GDB_SIGNAL_0)
     at gdb/record-btrace.c:1760
 ...

The fix is just to not lose information, and let the intact ptid reach
record-btrace.c.

Tested on x86-64 Fedora 20, -m32.

gdb/ChangeLog:
2015-03-03  Pedro Alves  <palves@redhat.com>

	* i386-linux-nat.c (i386_linux_resume): Get the ptrace PID out of
	the lwp field of ptid.  Pass the full ptid to get_thread_regcache.
	* inf-ptrace.c (get_ptrace_pid): New function.
	(inf_ptrace_resume): Use it.
	* linux-nat.c (linux_resume_one_lwp): Pass the LWP's ptid ummodified
	to the lower layer.
2015-03-03 13:33:44 +00:00
bfd Automatic date update in version.in 2015-03-03 00:00:07 +00:00
binutils objcopy: Add --update-section option. 2015-02-28 21:25:51 +00:00
config Fix --diable-shared --enable-plugins build breakage 2014-08-19 21:59:56 +09:30
cpu or1k: add missing l.msync, l.psync and l.psync instructions. 2014-07-20 20:26:09 +03:00
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etc PR external/{16327,16328}: Remove etc/configure.texi and etc/standards.texi. 2014-06-27 11:33:25 +02:00
gas Pad only text sections at end by default 2015-02-28 22:26:56 +10:30
gdb Linux/ptrace: don't convert ptids when asking inf-ptrace layer to resume LWP 2015-03-03 13:33:44 +00:00
gold Fix crash when processing merge section with entsize of 0. 2015-03-02 10:20:21 -08:00
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include Add ADR :tlsgd: directive and TLSGD_ADR_PREL21 support. 2015-02-26 22:23:09 +00:00
intl
ld Correct -z nocopyreloc doc 2015-03-02 16:57:08 +10:30
libdecnumber Another part of fixing "make TAGS". 2015-01-22 21:07:31 +02:00
libiberty strerror.c: Do not declare sys_nerr or sys_errlist if already macros 2015-01-19 16:29:07 +01:00
opcodes [SH] Fix clrs, sets, pref insn arch memberships. 2015-02-25 21:26:59 +01:00
readline Fix executable indicator in file name completion on Windows. 2014-12-30 21:14:25 +02:00
sim Fixes problems building the V850 simulator introduced with the previous delta. 2015-02-27 09:53:03 +00:00
texinfo
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore
ChangeLog FT32 initial support 2015-01-28 16:25:18 +10:30
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in
config.guess config.sub, config.guess: Update from upstream, to 2015-01-01 version. 2015-01-02 10:40:57 +01:00
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config.sub config.sub, config.guess: Update from upstream, to 2015-01-01 version. 2015-01-02 10:40:57 +01:00
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COPYING
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COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Update libtool.m4 from GCC trunk 2014-11-24 09:14:09 -08:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
Makefile.in [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
Makefile.tpl [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
makefile.vms
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move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode
setup.com
src-release.sh src-release.sh: configure using --target. 2014-10-15 09:50:53 +02:00
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ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

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