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os: Prevent backtrace from being stopped in noreturn functions.

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There are two noreturn functions in the X server: FatalError and
AbortServer. Having any of those two functions in the middle of a call
stack will prevent unwinding the program properly and stops the
backtrace at those functions in gdb.

The file containing FatalError and AbortServer, os/log.c, has to be
compiled with the -mapcs-frame option on ARM to get proper
backtraces. Automake imposes its own restrictions on compiling
individual source files with different options. The recommended way to
do this is to put os/log.c into a convenience library and add this
library inside os/libos.la. See the documentation of GNU Automake
manual, version 1.11.1, section 27.8 Per-Object Flags Emulation, for
details.

Signed-off-by: Rami Ylimaki <ext-rami.ylimaki@nokia.com>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Rami Ylimaki 2010-03-17 12:16:57 +02:00 committed by Keith Packard
parent e086b99c1f
commit 579715f830
2 changed files with 25 additions and 5 deletions
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13
configure.ac
View File

@ -315,6 +315,19 @@ AC_CHECK_HEADER([execinfo.h],[
])]
)
dnl ARM needs additional compiler flags for proper backtraces if GCC is
dnl used. Compile a dummy program with the -mapcs-frame option. If it
dnl succeeds, we know that we are building for ARM with GCC.
old_CFLAGS="$CFLAGS"
CFLAGS="-mapcs-frame"
AC_COMPILE_IFELSE(
AC_LANG_PROGRAM([[ ]]),
ARM_BACKTRACE_CFLAGS="$CFLAGS",
ARM_BACKTRACE_CFLAGS=""
)
CFLAGS="$old_CFLAGS"
AC_SUBST(ARM_BACKTRACE_CFLAGS)
dnl ---------------------------------------------------------------------------
dnl Bus options and CPU capabilities. Replaces logic in
dnl hw/xfree86/os-support/bus/Makefile.am, among others.

17
os/Makefile.am
View File

@ -1,11 +1,19 @@
noinst_LTLIBRARIES = libos.la
noinst_LTLIBRARIES = libos.la liblog.la
AM_CFLAGS = $(DIX_CFLAGS) $(SHA1_CFLAGS)
SECURERPC_SRCS = rpcauth.c
XDMCP_SRCS = xdmcp.c
STRLCAT_SRCS = strlcat.c strlcpy.c
XORG_SRCS = log.c
# Build a convenience library liblog.la that will be added into
# libos.la. The split is done so that log.c can be built with
# different compiler options.
liblog_la_SOURCES = log.c
# Add flags needed for proper backtraces of functions marked with GCC
# __attribute__((noreturn)). Currently those flags are needed for
# FatalError and AbortServer in log.c.
liblog_la_CFLAGS = $(AM_CFLAGS) $(ARM_BACKTRACE_CFLAGS)
libos_la_SOURCES = \
WaitFor.c \
@ -24,9 +32,8 @@ libos_la_SOURCES = \
xdmauth.c \
xsha1.c \
xstrans.c \
xprintf.c \
$(XORG_SRCS)
libos_la_LIBADD = @SHA1_LIBS@ $(DLOPEN_LIBS)
xprintf.c
libos_la_LIBADD = @SHA1_LIBS@ $(DLOPEN_LIBS) liblog.la
if SECURE_RPC
libos_la_SOURCES += $(SECURERPC_SRCS)