Enable libunwind in ganesha

Currently, Ganesha uses backtrace during crashes,
which may not provide sufficient useful information:
07/02/2024 19:09:18: epoch 65c3d55b: xueqian-hu: nfs-ganesha-39008[main] gsh_backtrace: NFS STARTUP: MAJ: stack
backtrace follows:
/lib64/libganesha_nfsd.so.5.6(+0x83ba1)[0x7f64d9172ba1]
/lib64/libganesha_nfsd.so.5.6(+0x5d618)[0x7f64d914c618]
/lib64/libpthread.so.0(+0xf630)[0x7f64d7d1a630]
/lib64/libpthread.so.0(pthread_join+0xa7)[0x7f64d7d14017]
/lib64/libganesha_nfsd.so.5.6(nfs_start+0x323)[0x7f64d914eff3]
ganesha.nfsd(main+0xbef)[0x4025cf]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f64d753d555]
ganesha.nfsd[0x402663]

This patch introduces an option to use libunwind, which can display function information:
08/02/2024 20:06:04: epoch 65c53429: xueqian-hu: nfs-ganesha-99814[main] gsh_libunwind: NFS STARTUP: MAJ: BACKTRACE:
08/02/2024 20:06:04 : epoch 65c53429 : xueqian-hu : nfs-ganesha-99814[main] gsh_libunwind :NFS STARTUP :MAJ :BACKTRACE:
 #0 gsh_libunwind + 0x29 [ip=0x7f90b1a10859] [sp=0x7ffd49d53c00]
 #1 crash_handler + 0x8 [ip=0x7f90b19e9fd8] [sp=0x7ffd49d54670]
 #2 _L_unlock_13 + 0x34 [ip=0x7f90b039d630] [sp=0x7ffd49d54680]
 #3 pthread_join + 0xa7 [ip=0x7f90b0397017] [sp=0x7ffd49d55380]
 #4 nfs_start + 0x323 [ip=0x7f90b19ec9b3] [sp=0x7ffd49d553e0]
 #5 main + 0xbef [ip=0x4025df] [sp=0x7ffd49d55480]

Change-Id: I194853e25ec0c89c7f552dc4872c37a420ea8d4a
Signed-off-by: Xueqian Hu <xh140312@outlook.com>

src/CMakeLists.txt

@@ -1193,6 +1193,21 @@ add_custom_command(TARGET srpm
 
 # Roll up required libraries
 
+# enable libunwind if available
+goption(USE_UNWIND "Enable libunwind" ON)
+gopt_test(USE_UNWIND)
+if (USE_UNWIND)
+  find_package(Unwind)
+  if (UNWIND_FOUND)
+    set(SYSTEM_LIBRARIES ${UNWIND_LIBRARIES} ${SYSTEM_LIBRARIES})
+    include_directories(${UNWIND_INCLUDE_DIR})
+    message(STATUS "libunwind found: ${UNWIND_LIBRARIES}")
+  else (UNWIND_FOUND)
+    message(WARNING "libunwind not found. Disabling USE_UNWIND")
+    set(USE_UNWIND OFF)
+  endif (UNWIND_FOUND)
+endif(USE_UNWIND)
+
 if(USE_9P_RDMA)
   find_package(PkgConfig)
   pkg_check_modules(MOOSHIKA REQUIRED libmooshika>=0.6)
@@ -1381,6 +1396,7 @@ message(STATUS "USE_MAN_PAGE = ${USE_MAN_PAGE}")
 message(STATUS "USE_RADOS_RECOV = ${USE_RADOS_RECOV}")
 message(STATUS "RADOS_URLS = ${RADOS_URLS}")
 message(STATUS "USE_CUNIT = ${USE_CUNIT}")
+message(STATUS "USE_UNWIND = ${USE_UNWIND}")
 message(STATUS "SANITIZE_ADDRESS = ${SANITIZE_ADDRESS}")
 
 set(USE_CB_SIMULATOR ${USE_CB_SIMULATOR}
@@ -1608,6 +1624,12 @@ else(RPCBIND)
     set(BCOND_RPCBIND "%bcond_with")
 endif(RPCBIND)
 
+if(USE_UNWIND)
+    set(BCOND_UNWIND "%bcond_without")
+else(USE_UNWIND)
+    set(BCOND_UNWIND "%bcond_with")
+endif(USE_UNWIND)
+
 if(_MSPAC_SUPPORT)
     set(BCOND_MSPAC_SUPPORT "%bcond_without")
 else(_MSPAC_SUPPORT)

src/MainNFSD/nfs_init.c

@@ -253,7 +253,11 @@ static void *sigmgr_thread(void *UnusedArg)
 
 static void crash_handler(int signo, siginfo_t *info, void *ctx)
 {
+#ifdef USE_UNWIND
+	gsh_libunwind();
+#else
 	gsh_backtrace();
+#endif
 	/* re-raise the signal for the default signal handler to dump core */
 	raise(signo);
 }

src/cmake/modules/FindUnwind.cmake

@@ -0,0 +1,27 @@
+# FindUnwind.cmake
+
+if(UNWIND_PATH_HINT)
+  message(STATUS "Using UNWIND_PATH_HINT: ${UNWIND_PATH_HINT}")
+else()
+  set(UNWIND_PATH_HINT)
+endif()
+
+find_path(UNWIND_INCLUDE_DIR
+  NAMES libunwind.h
+  PATHS ${UNWIND_PATH_HINT}
+  PATH_SUFFIXES include
+  DOC "The libunwind include directory")
+
+find_library(UNWIND_LIBRARY
+  NAMES unwind
+  PATHS ${UNWIND_PATH_HINT}
+  PATH_SUFFIXES lib lib64
+  DOC "The libunwind library")
+
+set(UNWIND_LIBRARIES ${UNWIND_LIBRARY})
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(Unwind REQUIRED_VARS UNWIND_LIBRARY UNWIND_INCLUDE_DIR)
+
+mark_as_advanced(UNWIND_INCLUDE_DIR UNWIND_LIBRARY)
+

src/include/config-h.in.cmake

@@ -54,6 +54,7 @@
 #cmakedefine _MSPAC_SUPPORT 1
 #cmakedefine USE_NFSIDMAP 1
 #cmakedefine USE_DBUS 1
+#cmakedefine USE_UNWIND 1
 #cmakedefine _USE_CB_SIMULATOR 1
 #cmakedefine USE_CAPS 1
 #cmakedefine USE_BLKID 1

src/include/log.h

@@ -106,6 +106,10 @@ void LogMallocFailure(const char *file, int line, const char *function,
 int read_log_config(config_file_t in_config,
 		    struct config_error_type *err_type);
 
+#ifdef USE_UNWIND
+void gsh_libunwind(void);
+#endif
+
 void gsh_backtrace(void);
 
 /* These functions display a timeval or timespec into the display buffer

src/log/log_functions.c

@@ -45,6 +45,11 @@
 #include <execinfo.h>
 #include <assert.h>
 
+#ifdef USE_UNWIND
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#endif
+
 #include "log.h"
 #include "gsh_list.h"
 #include "gsh_rpc.h"
@@ -2632,6 +2637,94 @@ int read_log_config(config_file_t in_config,
 		return -1;
 }				/* read_log_config */
 
+#ifdef USE_UNWIND
+void gsh_libunwind(void)
+{
+	unw_cursor_t cursor;
+	unw_context_t uc;
+	unsigned int i = 0;
+	char procname[256];
+	unw_word_t ip, sp, off;
+
+	struct log_facility *facility;
+	struct glist_head *glist;
+	int fd = -1;
+	char buffer[256];
+	int n;
+
+	procname[sizeof(procname) - 1] = '\0';
+
+	if (unw_getcontext(&uc) != 0)
+		goto libunwind_failed;
+
+	if (unw_init_local(&cursor, &uc) != 0)
+		goto libunwind_failed;
+
+	/* Find an active log facility */
+	PTHREAD_RWLOCK_rdlock(&log_rwlock);
+	glist_for_each(glist, &active_facility_list) {
+		facility = glist_entry(glist, struct log_facility, lf_active);
+		if (facility->lf_func == log_to_file) {
+			fd = open((char *)facility->lf_private,
+				O_WRONLY | O_APPEND | O_CREAT, log_mask);
+			break;
+		}
+	}
+
+	LogMajor(COMPONENT_INIT, "BACKTRACE:");
+
+	do {
+		ip = sp = 0;
+		unw_get_reg(&cursor, UNW_REG_IP, &ip);
+		unw_get_reg(&cursor, UNW_REG_SP, &sp);
+		switch (unw_get_proc_name(&cursor,
+			procname, sizeof(procname) - 1, &off)) {
+			case 0:
+				/* Name found. */
+			case -UNW_ENOMEM:
+				/* Name truncated. */
+				if (fd != -1) {
+					n = snprintf(buffer, sizeof(buffer),
+						" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
+						i, procname, (long long)off,
+						(long long)ip, (long long) sp);
+						write(fd, buffer, n);
+				} else {
+					LogMajor(COMPONENT_INIT,
+					" #%u %s + %#llx [ip=%#llx] [sp=%#llx]",
+					i, procname, (long long)off,
+					(long long)ip, (long long) sp);
+				}
+				break;
+			default:
+			/* case -UNW_ENOINFO: */
+			/* case -UNW_EUNSPEC: */
+				if (fd != -1) {
+					snprintf(buffer, sizeof(buffer),
+						" #%u %s [ip=%#llx] [sp=%#llx]\n",
+						i, "<unknown symbol>",
+						(long long)ip, (long long) sp);
+						write(fd, buffer, n);
+				} else {
+					LogMajor(COMPONENT_INIT,
+						" #%u %s [ip=%#llx] [sp=%#llx]",
+						i, "<unknown symbol>",
+						(long long)ip, (long long) sp);
+				}
+		}
+		++i;
+	} while (unw_step(&cursor) > 0);
+
+PTHREAD_RWLOCK_unlock(&log_rwlock);
+return;
+
+libunwind_failed:
+	LogCrit(COMPONENT_INIT,
+		"unable to produce a stack trace with libunwind");
+}
+
+#endif
+
 void gsh_backtrace(void)
 {
 #define MAX_STACK_DEPTH		32	/* enough ? */

src/nfs-ganesha.spec-in.cmake

@@ -86,6 +86,9 @@ Requires: openSUSE-release
 @BCOND_RPCBIND@ rpcbind
 %global use_rpcbind %{on_off_switch rpcbind}
 
+@BCOND_UNWIND@ unwind
+%global use_unwind %{on_off_switch unwind}
+
 @BCOND_MSPAC_SUPPORT@ mspac_support
 %global use_mspac_support %{on_off_switch mspac_support}
 
@@ -270,6 +273,17 @@ BuildRequires:  python3-installer
 %endif
 %endif
 
+%if %{with unwind}
+%if ( 0%{?rhel} && 0%{?rhel} < 8 )
+Requires: libc6-dev
+%else
+Requires: libc-devel
+%endif
+%if ( 0%{?suse_version} )
+Requires: glibc-devel
+%endif
+%endif
+
 %if %{with gui_utils}
 %if ( 0%{?suse_version} )
 BuildRequires:	python-qt5-devel
@@ -529,6 +543,7 @@ cmake .	-DCMAKE_BUILD_TYPE=Debug			\
 	-DUSE_SYSTEM_NTIRPC=%{use_system_ntirpc}	\
 	-DUSE_9P_RDMA=%{use_rdma}			\
 	-DUSE_LTTNG=%{use_lttng}			\
+	-DUSE_UNWIND=%{use_unwind}			\
 	-DUSE_ADMIN_TOOLS=%{use_utils}			\
 	-DUSE_GUI_ADMIN_TOOLS=%{use_gui_utils}		\
 	-DUSE_RADOS_RECOV=%{use_rados_recov}		\