Merge tag 'gcc-plugins-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull gcc plugin updates from Kees Cook:
 "Primarily improvements to STACKLEAK from Alexander Popov, along with
  some additional cleanups.

    - Update URLs for HTTPS scheme where available (Alexander A. Klimov)

   - Improve STACKLEAK code generation on x86 (Alexander Popov)"

* tag 'gcc-plugins-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Replace HTTP links with HTTPS ones
  gcc-plugins/stackleak: Add 'verbose' plugin parameter
  gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving
  ARM: vdso: Don't use gcc plugins for building vgettimeofday.c
  gcc-plugins/stackleak: Don't instrument itself

Author: torvalds

arch/arm/vdso/Makefile

@@ -29,7 +29,7 @@ CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 CFLAGS_REMOVE_vdso.o = -pg
 
 # Force -O2 to avoid libgcc dependencies
-CFLAGS_REMOVE_vgettimeofday.o = -pg -Os
+CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(GCC_PLUGINS_CFLAGS)
 ifeq ($(c-gettimeofday-y),)
 CFLAGS_vgettimeofday.o = -O2
 else

include/linux/compiler_attributes.h

@@ -37,6 +37,7 @@
 # define __GCC4_has_attribute___copy__                0
 # define __GCC4_has_attribute___designated_init__     0
 # define __GCC4_has_attribute___externally_visible__  1
+# define __GCC4_has_attribute___no_caller_saved_registers__ 0
 # define __GCC4_has_attribute___noclone__             1
 # define __GCC4_has_attribute___nonstring__           0
 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
@@ -176,6 +177,18 @@
  */
 #define __mode(x)                       __attribute__((__mode__(x)))
 
+/*
+ * Optional: only supported since gcc >= 7
+ *
+ *   gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86
+ * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers
+ */
+#if __has_attribute(__no_caller_saved_registers__)
+# define __no_caller_saved_registers	__attribute__((__no_caller_saved_registers__))
+#else
+# define __no_caller_saved_registers
+#endif
+
 /*
  * Optional: not supported by clang
  *

kernel/Makefile

@@ -125,6 +125,7 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o
 
 obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
 
+CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN)
 obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
 KASAN_SANITIZE_stackleak.o := n
 KCSAN_SANITIZE_stackleak.o := n

kernel/stackleak.c

@@ -104,19 +104,9 @@ asmlinkage void notrace stackleak_erase(void)
 }
 NOKPROBE_SYMBOL(stackleak_erase);
 
-void __used notrace stackleak_track_stack(void)
+void __used __no_caller_saved_registers notrace stackleak_track_stack(void)
 {
-	/*
-	 * N.B. stackleak_erase() fills the kernel stack with the poison value,
-	 * which has the register width. That code assumes that the value
-	 * of 'lowest_stack' is aligned on the register width boundary.
-	 *
-	 * That is true for x86 and x86_64 because of the kernel stack
-	 * alignment on these platforms (for details, see 'cc_stack_align' in
-	 * arch/x86/Makefile). Take care of that when you port STACKLEAK to
-	 * new platforms.
-	 */
-	unsigned long sp = (unsigned long)&sp;
+	unsigned long sp = current_stack_pointer;
 
 	/*
 	 * Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than
@@ -125,6 +115,8 @@ void __used notrace stackleak_track_stack(void)
 	 */
 	BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH);
 
+	/* 'lowest_stack' should be aligned on the register width boundary */
+	sp = ALIGN(sp, sizeof(unsigned long));
 	if (sp < current->lowest_stack &&
 	    sp >= (unsigned long)task_stack_page(current) +
 						sizeof(unsigned long)) {

scripts/Makefile.gcc-plugins

@@ -33,6 +33,8 @@ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
 		+= -DSTACKLEAK_PLUGIN
 gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
 		+= -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE)
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
+		+= -fplugin-arg-stackleak_plugin-arch=$(SRCARCH)
 ifdef CONFIG_GCC_PLUGIN_STACKLEAK
     DISABLE_STACKLEAK_PLUGIN += -fplugin-arg-stackleak_plugin-disable
 endif

scripts/gcc-plugins/cyc_complexity_plugin.c

@@ -5,7 +5,7 @@
  * Homepage:
  * https://github.com/ephox-gcc-plugins/cyclomatic_complexity
  *
- * http://en.wikipedia.org/wiki/Cyclomatic_complexity
+ * https://en.wikipedia.org/wiki/Cyclomatic_complexity
  * The complexity M is then defined as:
  * M = E - N + 2P
  * where

scripts/gcc-plugins/sancov_plugin.c

@@ -11,7 +11,7 @@
  *
  * You can read about it more here:
  *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
- *  http://lwn.net/Articles/674854/
+ *  https://lwn.net/Articles/674854/
  *  https://github.com/google/syzkaller
  *  https://lwn.net/Articles/677764/
  *