build: add systemtap's sys/sdt.h as depends

The sys/sdt.h header is required to build Bitcoin Core with Userspace
Statically Defined Tracing support. Systemtap version 4.5 (May 2021)
is used as the most recent version 4.6 (Nov 2021) fails to build.
See e.g. https://sourceware.org/git/?p=systemtap.git;a=commit;h=1d3653936fc1fd13135a723a27e6c7e959793ad0

As Systemtap itself is not needed, the build steps (configure and
make) are skipped. We require fewer build dependecies and don't
waste time building depends we don't end up using. However, the
configure step would normally processes sys/sdt-config.h.in. The
resulting sdt-config.h defines _SDT_ASM_SECTION_AUTOGROUP_SUPPORT
(either 0 or 1 to indicate whether the assembler supports "?" in
.pushsection directives). For now, we assume all currently used
assemblers supports this feature and remove the check from the
sys/sdt.h header file in a patch.

Co-authored-by: Michael Ford <[email protected]>

Author: 0xB10C

depends/Makefile

@@ -39,6 +39,7 @@ NO_SQLITE ?=
 NO_WALLET ?=
 NO_ZMQ ?=
 NO_UPNP ?=
+NO_USDT ?=
 NO_NATPMP ?=
 MULTIPROCESS ?=
 FALLBACK_DOWNLOAD_PATH ?= https://bitcoincore.org/depends-sources
@@ -149,8 +150,9 @@ natpmp_packages_$(NO_NATPMP) = $(natpmp_packages)
 
 zmq_packages_$(NO_ZMQ) = $(zmq_packages)
 multiprocess_packages_$(MULTIPROCESS) = $(multiprocess_packages)
+usdt_packages_$(NO_USDT) = $(usdt_$(host_os)_packages)
 
-packages += $($(host_arch)_$(host_os)_packages) $($(host_os)_packages) $(qt_packages_) $(wallet_packages_) $(upnp_packages_) $(natpmp_packages_)
+packages += $($(host_arch)_$(host_os)_packages) $($(host_os)_packages) $(qt_packages_) $(wallet_packages_) $(upnp_packages_) $(natpmp_packages_) $(usdt_packages_)
 native_packages += $($(host_arch)_$(host_os)_native_packages) $($(host_os)_native_packages)
 
 ifneq ($(zmq_packages_),)
@@ -228,6 +230,7 @@ $(host_prefix)/share/config.site : config.site.in $(host_prefix)/.stamp_$(final_
             -e 's|@no_bdb@|$(NO_BDB)|' \
             -e 's|@no_sqlite@|$(NO_SQLITE)|' \
             -e 's|@no_upnp@|$(NO_UPNP)|' \
+            -e 's|@no_usdt@|$(NO_USDT)|' \
             -e 's|@no_natpmp@|$(NO_NATPMP)|' \
             -e 's|@multiprocess@|$(MULTIPROCESS)|' \
             -e 's|@debug@|$(DEBUG)|' \

depends/config.site.in

@@ -70,6 +70,10 @@ if test -z "$enable_zmq" && test -n "@no_zmq@"; then
   enable_zmq=no
 fi
 
+if test -z "$enable_usdt" && test -n "@no_usdt@"; then
+  enable_usdt=no
+fi
+
 if test "@host_os@" = darwin; then
   BREW=no
 fi

depends/packages/packages.mk

@@ -19,6 +19,8 @@ natpmp_packages=libnatpmp
 multiprocess_packages = libmultiprocess capnp
 multiprocess_native_packages = native_libmultiprocess native_capnp
 
+usdt_linux_packages=systemtap
+
 darwin_native_packages = native_ds_store native_mac_alias
 
 $(host_arch)_$(host_os)_native_packages += native_b2

depends/packages/systemtap.mk

@@ -0,0 +1,12 @@
+package=systemtap
+$(package)_version=4.5
+$(package)_download_path=https://sourceware.org/systemtap/ftp/releases/
+$(package)_file_name=$(package)-$($(package)_version).tar.gz
+$(package)_sha256_hash=75078ed37e0dd2a769c9d1f9394170b2d9f4d7daa425f43ca80c13bad6cfc925
+$(package)_patches=remove_SDT_ASM_SECTION_AUTOGROUP_SUPPORT_check.patch
+
+define $(package)_preprocess_cmds
+  patch -p1 < $($(package)_patch_dir)/remove_SDT_ASM_SECTION_AUTOGROUP_SUPPORT_check.patch && \
+  mkdir -p $($(package)_staging_prefix_dir)/include/sys && \
+  cp includes/sys/sdt.h $($(package)_staging_prefix_dir)/include/sys/sdt.h
+endef

depends/patches/systemtap/remove_SDT_ASM_SECTION_AUTOGROUP_SUPPORT_check.patch

@@ -0,0 +1,31 @@
+commit b92d4c121486f3c6e8a2cea537c53eb09894479a
+Author: 0xb10c <[email protected]>
+Date:   Tue Dec 7 11:02:07 2021 +0100
+
+    Remove _SDT_ASM_SECTION_AUTOGROUP_SUPPORT check
+    
+    We assume that the assembler supports "?" in .pushsection directives.
+    This enables us to skip configure and make.
+    
+    See https://github.com/bitcoin/bitcoin/issues/23297.
+
+diff --git a/includes/sys/sdt.h b/includes/sys/sdt.h
+index 97766e710..352b4ee25 100644
+--- a/includes/sys/sdt.h
++++ b/includes/sys/sdt.h
+@@ -230,12 +230,10 @@ __extension__ extern unsigned long long __sdt_unsp;
+    nice with code in COMDAT sections, which comes up in C++ code.
+    Without that assembler support, some combinations of probe placements
+    in certain kinds of C++ code may produce link-time errors.  */
+-#include "sdt-config.h"
+-#if _SDT_ASM_SECTION_AUTOGROUP_SUPPORT
++/* PATCH: We assume that the assembler supports the feature. This
++   enables us to skip configure and make. In turn, this means we
++   require fewer dependencies and have shorter depend build times. */
+ # define _SDT_ASM_AUTOGROUP "?"
+-#else
+-# define _SDT_ASM_AUTOGROUP ""
+-#endif
+ 
+ #define _SDT_ASM_BODY(provider, name, pack_args, args)			      \
+   _SDT_ASM_1(990:	_SDT_NOP)					      \

doc/dependencies.md

@@ -24,7 +24,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
 | Qt | [5.12.11](https://download.qt.io/official_releases/qt/) | [5.9.5](https://github.com/bitcoin/bitcoin/issues/20104) | No |  |  |
 | SQLite | [3.32.1](https://sqlite.org/download.html) | [3.7.17](https://github.com/bitcoin/bitcoin/pull/19077) |  |  |  |
 | XCB |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) (Linux only) |
-| systemtap ([tracing](tracing.md))|  |  |  |  | |
+| systemtap ([tracing](tracing.md))| [4.5](https://sourceware.org/systemtap/ftp/releases/) |  |  |  | |
 | xkbcommon |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) (Linux only) |
 | ZeroMQ | [4.3.1](https://github.com/zeromq/libzmq/releases) | 4.0.0 | No |  |  |
 | zlib |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) |