binutils-gdb/gdb/nat
Markus Metzger db58b3735f btrace: read entire aux buffer
The data_head of a perf event data buffer grows indefinitely.  Users are
expected to compute data_head % data_size to find the location inside the perf
event data buffer.

The aux_head of a perf event aux buffer wraps around and always stays within the
perf event aux buffer.

Well, at least that's the behaviour for BTS and PT - where BTS uses the data
buffer and PT the aux buffer.

GDB does not read beyond data_head or aux_head.  This is OK for BTS but wrong
for PT.  It causes only a portion of the trace to be considered by GDB.  In the
extreme case, the buffer may appear (almost) empty.

Thanks to Tim Wiederhake  <tim.wiederhake@intel.com> for reporting the anomaly.

Change it to read the entire aux buffer for PT.  The buffer is initially zero so
any extra zeroes we read before aux_head wraps around the first time will be
ignored when searching for the first PSB packet in order to synchronize onto the
trace stream.

gdb/
	* nat/linux-btrace.c (perf_event_read): Allow data_head < size.
	* nat/linux-btrace.c (perf_event_read_all): Do not adjust size.

Change-Id: If4f8049a2080a5f16f336309450b32a3eb1e3ec9
2016-11-14 10:15:42 +01:00
..
aarch64-linux-hw-point.c Fix ARMv8.1/v8.2 for hw watchpoint and breakpoint 2016-07-23 10:10:32 -07:00
aarch64-linux-hw-point.h Fix ARMv8.1/v8.2 for hw watchpoint and breakpoint 2016-07-23 10:10:32 -07:00
aarch64-linux.c Sync proc_service definition with GLIBC 2016-08-25 08:42:03 +01:00
aarch64-linux.h Sync proc_service definition with GLIBC 2016-08-25 08:42:03 +01:00
amd64-linux-siginfo.c Fix PR gdb/20287 - x32 and "gdb_static_assert (sizeof (nat_siginfo_t) == sizeof (siginfo_t))" 2016-07-26 19:35:40 +01:00
amd64-linux-siginfo.h
gdb_ptrace.h
gdb_thread_db.h
glibc_thread_db.h
linux-btrace.c btrace: read entire aux buffer 2016-11-14 10:15:42 +01:00
linux-btrace.h
linux-namespaces.c
linux-namespaces.h
linux-nat.h linux-nat: Add function lwp_is_stepping 2016-09-16 19:25:55 +02:00
linux-osdata.c Replace sprintf with xsnprintf in nat/linux-osdata.c 2016-09-23 17:27:26 +01:00
linux-osdata.h
linux-personality.c
linux-personality.h
linux-procfs.c linux-procfs: Handle lowercase "t (tracing stop)" state 2016-07-25 12:58:38 +01:00
linux-procfs.h
linux-ptrace.c Fix fallout from gdb/20413's fix (x32: linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER) 2016-08-11 12:01:22 +01:00
linux-ptrace.h
linux-waitpid.c
linux-waitpid.h
mips-linux-watch.c
mips-linux-watch.h
ppc-linux.c
ppc-linux.h
x86-cpuid.h
x86-dregs.c
x86-dregs.h
x86-gcc-cpuid.h
x86-linux-dregs.c
x86-linux-dregs.h
x86-linux.c
x86-linux.h