[Pal,LibOS] New logging system

Instead of 'loader.debug_type', introduce 'loader.log_level'
and 'loader.log_file', along with a set of definitions for
logging at a chosen level.

For now, the call sites keep using the legacy macros (SGX_DBG and
debug()), because converting them all will conflict with other
big changes in the code base. The existing LibOS calls are
assumed to be at 'info' level.

Examples/nodejs/Makefile

@@ -15,9 +15,9 @@ GRAPHENEDIR ?= ../..
 SGX_SIGNER_KEY ?= $(GRAPHENEDIR)/Pal/src/host/Linux-SGX/signer/enclave-key.pem
 
 ifeq ($(DEBUG),1)
-GRAPHENEDEBUG = inline
+GRAPHENE_LOG_LEVEL = debug
 else
-GRAPHENEDEBUG = none
+GRAPHENE_LOG_LEVEL = error
 endif
 
 .PHONY: all
@@ -37,7 +37,7 @@ trusted-libs: ../common_tools/get_deps.sh
 
 nodejs.manifest: nodejs.manifest.template trusted-libs
 	(sed -e 's|$$(GRAPHENEDIR)|'"$(GRAPHENEDIR)"'|g' \
-	     -e 's|$$(GRAPHENEDEBUG)|'"$(GRAPHENEDEBUG)"'|g' \
+	     -e 's|$$(GRAPHENE_LOG_LEVEL)|'"$(GRAPHENE_LOG_LEVEL)"'|g' \
 	     -e 's|$$(NODEJS_DIR)|'"$(NODEJS_DIR)"'|g' \
 	     -e 's|$$(ARCH_LIBDIR)|'"$(ARCH_LIBDIR)"'|g' \
 	     $<; \

Examples/nodejs/nodejs.manifest.template

@@ -8,8 +8,8 @@ libos.entrypoint = "file:$(NODEJS_DIR)/nodejs"
 # so it is always set to libsysdb.so.
 loader.preload = "file:$(GRAPHENEDIR)/Runtime/libsysdb.so"
 
-# Show/hide debug log of Graphene ('inline' or 'none' respectively).
-loader.debug_type = "$(GRAPHENEDEBUG)"
+# Graphene log level
+loader.log_level = "$(GRAPHENE_LOG_LEVEL)"
 
 # Read application arguments directly from the command line. Don't use this on production!
 loader.insecure__use_cmdline_argv = 1