kernel: support gcc-optimized inlining on all architectures

Optimized inlining was disabled by default when gcc 4 was still
relatively new. By now, all gcc versions handle this well and there
seems to be no real reason to keep it x86-only.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 70 insertions, 0 deletions

diff --git a/target/linux/generic/pending-4.9/220-optimize_inlining.patch b/target/linux/generic/pending-4.9/220-optimize_inlining.patch
new file mode 100644
index 0000000000..75c04ea15c
--- /dev/null
+++ b/target/linux/generic/pending-4.9/220-optimize_inlining.patch
@@ -0,0 +1,70 @@
+--- a/arch/x86/Kconfig.debug
++++ b/arch/x86/Kconfig.debug
+@@ -287,20 +287,6 @@ config CPA_DEBUG
+ 	---help---
+ 	  Do change_page_attr() self-tests every 30 seconds.
+ 
+-config OPTIMIZE_INLINING
+-	bool "Allow gcc to uninline functions marked 'inline'"
+-	---help---
+-	  This option determines if the kernel forces gcc to inline the functions
+-	  developers have marked 'inline'. Doing so takes away freedom from gcc to
+-	  do what it thinks is best, which is desirable for the gcc 3.x series of
+-	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
+-	  enabling this option will generate a smaller kernel there. Hopefully
+-	  this algorithm is so good that allowing gcc 4.x and above to make the
+-	  decision will become the default in the future. Until then this option
+-	  is there to test gcc for this.
+-
+-	  If unsure, say N.
+-
+ config DEBUG_ENTRY
+ 	bool "Debug low-level entry code"
+ 	depends on DEBUG_KERNEL
+--- a/lib/Kconfig.debug
++++ b/lib/Kconfig.debug
+@@ -117,6 +117,20 @@ endmenu # "printk and dmesg options"
+ 
+ menu "Compile-time checks and compiler options"
+ 
++config OPTIMIZE_INLINING
++	bool "Allow gcc to uninline functions marked 'inline'"
++	---help---
++	  This option determines if the kernel forces gcc to inline the functions
++	  developers have marked 'inline'. Doing so takes away freedom from gcc to
++	  do what it thinks is best, which is desirable for the gcc 3.x series of
++	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
++	  enabling this option will generate a smaller kernel there. Hopefully
++	  this algorithm is so good that allowing gcc 4.x and above to make the
++	  decision will become the default in the future. Until then this option
++	  is there to test gcc for this.
++
++	  If unsure, say N.
++
+ config DEBUG_INFO
+ 	bool "Compile the kernel with debug info"
+ 	depends on DEBUG_KERNEL && !COMPILE_TEST
+--- a/arch/x86/Kconfig
++++ b/arch/x86/Kconfig
+@@ -273,9 +273,6 @@ config ZONE_DMA32
+ config AUDIT_ARCH
+ 	def_bool y if X86_64
+ 
+-config ARCH_SUPPORTS_OPTIMIZED_INLINING
+-	def_bool y
+-
+ config ARCH_SUPPORTS_DEBUG_PAGEALLOC
+ 	def_bool y
+ 
+--- a/include/linux/compiler-gcc.h
++++ b/include/linux/compiler-gcc.h
+@@ -89,8 +89,7 @@
+  * of extern inline functions at link time.
+  * A lot of inline functions can cause havoc with function tracing.
+  */
+-#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) ||		\
+-    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
++#if !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
+ #define inline \
+ 	inline __attribute__((always_inline, unused)) notrace __gnu_inline
+ #else