Merge pull request #192 from mpe/rust

Use RUST_OPT_LEVEL_0 for ppc64le CI and related changes

Author: ojeda

.github/workflows/kernel-ppc64le-debug.config

@@ -356,7 +356,7 @@ CONFIG_ILLEGAL_POINTER_VALUE=0x5deadbeef0000000
 # CONFIG_PPC_4K_PAGES is not set
 CONFIG_PPC_64K_PAGES=y
 CONFIG_PPC_PAGE_SHIFT=16
-CONFIG_THREAD_SHIFT=14
+CONFIG_THREAD_SHIFT=15
 CONFIG_DATA_SHIFT=16
 CONFIG_FORCE_MAX_ZONEORDER=9
 # CONFIG_PPC_SUBPAGE_PROT is not set
@@ -1581,8 +1581,8 @@ CONFIG_RUNTIME_TESTING_MENU=y
 #
 CONFIG_RUST_DEBUG_ASSERTIONS=y
 CONFIG_RUST_OVERFLOW_CHECKS=y
-CONFIG_RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C=y
-# CONFIG_RUST_OPT_LEVEL_0 is not set
+# CONFIG_RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C is not set
+CONFIG_RUST_OPT_LEVEL_0=y
 # CONFIG_RUST_OPT_LEVEL_1 is not set
 # CONFIG_RUST_OPT_LEVEL_2 is not set
 # CONFIG_RUST_OPT_LEVEL_3 is not set

Documentation/rust/arch-support.rst

@@ -26,7 +26,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
      - None
    * - ``powerpc``
      - Maintained
-     - ``ppc64le`` only, ``RUST_OPT_LEVEL >= 2``
+     - ``ppc64le`` only, ``RUST_OPT_LEVEL < 2`` requires ``CONFIG_THREAD_SHIFT=15``
    * - ``x86``
      - Maintained
      - ``x86_64`` only

lib/Kconfig.debug

@@ -2607,12 +2607,18 @@ config RUST_OPT_LEVEL_0
 	  directly). Use the corresponding configuration options to control
 	  that instead, orthogonally.
 
+	  Note this level may cause excessive stack usage, which can lead to stack
+	  overflow and subsequent crashes.
+
 config RUST_OPT_LEVEL_1
 	bool "Basic optimizations (-Copt-level=1)"
 	help
 	  Useful for debugging without getting too lost, but without
 	  the overhead and boilerplate of no optimizations at all.
 
+	  Note this level may cause excessive stack usage, which can lead to stack
+	  overflow and subsequent crashes.
+
 config RUST_OPT_LEVEL_2
 	bool "Some optimizations (-Copt-level=2)"
 	help