um: Enable CONFIG_CONSTRUCTORS

We do need to call the constructors for *modules*, and at least for KASAN in the future, we must call even the kernel constructors only later when the kernel has been initialized. Instead of relying on libc to call them, emit an empty section for libc and let the kernel's CONSTRUCTORS code do the rest of the job. Tested that it indeed doesn't work in modules, and does work after the fixes in both, with a few functions with __attribute__((constructor)) in both dynamic and static builds. Signed-off-by: Johannes Berg <[email protected]> Signed-off-by: Richard Weinberger <[email protected]>
mitsuchi · Sep 15, 2019 · 786b238 · 786b238
1 parent 324f80c
commit 786b238
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Showing 4 changed files with 2 additions and 4 deletions.
diff --git a/arch/um/include/asm/common.lds.S b/arch/um/include/asm/common.lds.S
@@ -83,8 +83,8 @@
 	__preinit_array_end = .;
   }
   .init_array : {
+        /* dummy - we call this ourselves */
 	__init_array_start = .;
-	*(.init_array)
 	__init_array_end = .;
   }
   .fini_array : {

diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
@@ -103,7 +103,6 @@ SECTIONS
      be empty, which isn't pretty.  */
   . = ALIGN(32 / 8);
   .preinit_array     : { *(.preinit_array) }
-  .init_array     : { *(.init_array) }
   .fini_array     : { *(.fini_array) }
   .data           : {
     INIT_TASK_DATA(KERNEL_STACK_SIZE)

diff --git a/init/Kconfig b/init/Kconfig
@@ -48,7 +48,6 @@ config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
 
 config CONSTRUCTORS
 	bool
-	depends on !UML
 
 config IRQ_WORK
 	bool

diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
@@ -4,7 +4,7 @@ menu "GCOV-based kernel profiling"
 config GCOV_KERNEL
 	bool "Enable gcov-based kernel profiling"
 	depends on DEBUG_FS
-	select CONSTRUCTORS if !UML
+	select CONSTRUCTORS
 	default n
 	---help---
 	This option enables gcov-based code profiling (e.g. for code coverage
-Original file line number
+Diff line change
@@ Expand Up / @@ -48,7 +48,6 @@ config CC_DISABLE_WARN_MAYBE_UNINITIALIZED @@
     config CONSTRUCTORS
     	bool
-    	depends on !UML
     config IRQ_WORK
     	bool
@@ Expand Down @@