devicepkg-dev: ship compiler-gcc.h for GCC8

We used to put a "compiler-gcc6.h" file inside every vendor kernel's
aport. This is redundant and only works with GCC6. With this patch,
a common "compiler-gcc.h" file will be used, that works independently
of the GCC version.

The file is from Decatf's android_kernel_samsung_p4 repository, where
it was taken from upstream Linux, but adjusted to work with older
vendor kernels (different #ifndef check at the top etc).

bd0772df21/include/linux/compiler-gcc.h

main/devicepkg-dev/APKBUILD

@@ -1,11 +1,12 @@
 pkgname="devicepkg-dev"
-pkgver=0.3
+pkgver=0.4
 pkgrel=0
 pkgdesc="Provides default device package functions"
 url="https://postmarketos.org"
 arch="all"
 license="MIT"
 source="
+	compiler-gcc.h
 	devicepkg_build.sh
 	devicepkg_package.sh
 	downstreamkernel_prepare.sh
@@ -18,7 +19,10 @@ package() {
 		"$pkgdir/usr/bin/devicepkg_package"
 	install -Dm755 "$srcdir/downstreamkernel_prepare.sh" \
 		"$pkgdir/usr/bin/downstreamkernel_prepare"
+	install -Dm644 "$srcdir/compiler-gcc.h" \
+		"$pkgdir/usr/share/devicepkg-dev/compiler-gcc.h"
 }
-sha512sums="638d50e6388eabf0da6bf0cff2fe9719ad8a808946f0077228db57fa13a26d9eeb39c1f2689c9a6f93ff9b3bcfdcfb7c358b180bba90e5bba8b9a9e78d25ed18  devicepkg_build.sh
+sha512sums="d69930dd790b00fb39760a37d95a10899f0d167e10e2804feb05d9ce04f94185dc32d36edc90214aba2ea2aa09bf18f7dab93f1d2eff23f67beb2cc83be30e7c  compiler-gcc.h
+638d50e6388eabf0da6bf0cff2fe9719ad8a808946f0077228db57fa13a26d9eeb39c1f2689c9a6f93ff9b3bcfdcfb7c358b180bba90e5bba8b9a9e78d25ed18  devicepkg_build.sh
 c732792596f56860f6ab9ddd53b9a7a80224400dd20097b20cebe17a6e7330e9178783f09db16132a28a555f83e29ef3643bfe069638b62998912a9a7ffefdc0  devicepkg_package.sh
-9f240217084215e6a085616ae7dbe4ed7446f9cd4a1ca32631c083a1c74ea380bb8585a32a506491e54db091683bbe7300e94dba3a0d994a580017686386abc8  downstreamkernel_prepare.sh"
+18de8ed6aa8aefea7c40b817023c276c3e63024086cde243c4c4fbe36e42fe51440c21dcded6b4f342054f59046c198d9c9775059b32f8a7cf822793d855ef4d  downstreamkernel_prepare.sh"

main/devicepkg-dev/compiler-gcc.h

@@ -0,0 +1,250 @@
+#ifndef __LINUX_COMPILER_H
+#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
+#endif
+
+/*
+ * Common definitions for all gcc versions go here.
+ */
+#define GCC_VERSION (__GNUC__ * 10000		\
+		     + __GNUC_MINOR__ * 100	\
+		     + __GNUC_PATCHLEVEL__)
+
+/* Optimization barrier */
+
+/* The "volatile" is due to gcc bugs */
+#define barrier() __asm__ __volatile__("": : :"memory")
+/*
+ * This version is i.e. to prevent dead stores elimination on @ptr
+ * where gcc and llvm may behave differently when otherwise using
+ * normal barrier(): while gcc behavior gets along with a normal
+ * barrier(), llvm needs an explicit input variable to be assumed
+ * clobbered. The issue is as follows: while the inline asm might
+ * access any memory it wants, the compiler could have fit all of
+ * @ptr into memory registers instead, and since @ptr never escaped
+ * from that, it proofed that the inline asm wasn't touching any of
+ * it. This version works well with both compilers, i.e. we're telling
+ * the compiler that the inline asm absolutely may see the contents
+ * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
+ */
+#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
+
+/*
+ * This macro obfuscates arithmetic on a variable address so that gcc
+ * shouldn't recognize the original var, and make assumptions about it.
+ *
+ * This is needed because the C standard makes it undefined to do
+ * pointer arithmetic on "objects" outside their boundaries and the
+ * gcc optimizers assume this is the case. In particular they
+ * assume such arithmetic does not wrap.
+ *
+ * A miscompilation has been observed because of this on PPC.
+ * To work around it we hide the relationship of the pointer and the object
+ * using this macro.
+ *
+ * Versions of the ppc64 compiler before 4.1 had a bug where use of
+ * RELOC_HIDE could trash r30. The bug can be worked around by changing
+ * the inline assembly constraint from =g to =r, in this particular
+ * case either is valid.
+ */
+#define RELOC_HIDE(ptr, off)						\
+({									\
+	unsigned long __ptr;						\
+	__asm__ ("" : "=r"(__ptr) : "0"(ptr));				\
+	(typeof(ptr)) (__ptr + (off));					\
+})
+
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define OPTIMIZER_HIDE_VAR(var)						\
+	__asm__ ("" : "=r" (var) : "0" (var))
+
+#ifdef __CHECKER__
+#define __must_be_array(a)	0
+#else
+/* &a[0] degrades to a pointer: a different type from an array */
+#define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
+#endif
+
+/*
+ * Force always-inline if the user requests it so via the .config,
+ * or if gcc is too old:
+ */
+#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) ||		\
+    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
+#define inline		inline		__attribute__((always_inline)) notrace
+#define __inline__	__inline__	__attribute__((always_inline)) notrace
+#define __inline	__inline	__attribute__((always_inline)) notrace
+#else
+/* A lot of inline functions can cause havoc with function tracing */
+#define inline		inline		notrace
+#define __inline__	__inline__	notrace
+#define __inline	__inline	notrace
+#endif
+
+#define __always_inline	inline __attribute__((always_inline))
+#define  noinline	__attribute__((noinline))
+
+#define __deprecated	__attribute__((deprecated))
+#define __packed	__attribute__((packed))
+#define __weak		__attribute__((weak))
+#define __alias(symbol)	__attribute__((alias(#symbol)))
+
+/*
+ * it doesn't make sense on ARM (currently the only user of __naked)
+ * to trace naked functions because then mcount is called without
+ * stack and frame pointer being set up and there is no chance to
+ * restore the lr register to the value before mcount was called.
+ *
+ * The asm() bodies of naked functions often depend on standard calling
+ * conventions, therefore they must be noinline and noclone.
+ *
+ * GCC 4.[56] currently fail to enforce this, so we must do so ourselves.
+ * See GCC PR44290.
+ */
+#define __naked		__attribute__((naked)) noinline __noclone notrace
+
+#define __noreturn	__attribute__((noreturn))
+
+/*
+ * From the GCC manual:
+ *
+ * Many functions have no effects except the return value and their
+ * return value depends only on the parameters and/or global
+ * variables.  Such a function can be subject to common subexpression
+ * elimination and loop optimization just as an arithmetic operator
+ * would be.
+ * [...]
+ */
+#define __pure			__attribute__((pure))
+#define __aligned(x)		__attribute__((aligned(x)))
+#define __printf(a, b)		__attribute__((format(printf, a, b)))
+#define __scanf(a, b)		__attribute__((format(scanf, a, b)))
+#define __attribute_const__	__attribute__((__const__))
+#define __maybe_unused		__attribute__((unused))
+#define __always_unused		__attribute__((unused))
+
+/* gcc version specific checks */
+
+#if GCC_VERSION < 30200
+# error Sorry, your compiler is too old - please upgrade it.
+#endif
+
+#if GCC_VERSION < 30300
+# define __used			__attribute__((__unused__))
+#else
+# define __used			__attribute__((__used__))
+#endif
+
+#ifdef CONFIG_GCOV_KERNEL
+# if GCC_VERSION < 30400
+#   error "GCOV profiling support for gcc versions below 3.4 not included"
+# endif /* __GNUC_MINOR__ */
+#endif /* CONFIG_GCOV_KERNEL */
+
+#if GCC_VERSION >= 30400
+#define __must_check		__attribute__((warn_unused_result))
+#endif
+
+#if GCC_VERSION >= 40000
+
+/* GCC 4.1.[01] miscompiles __weak */
+#ifdef __KERNEL__
+# if GCC_VERSION >= 40100 &&  GCC_VERSION <= 40101
+#  error Your version of gcc miscompiles the __weak directive
+# endif
+#endif
+
+#define __used			__attribute__((__used__))
+#define __compiler_offsetof(a, b)					\
+	__builtin_offsetof(a, b)
+
+#if GCC_VERSION >= 40100 && GCC_VERSION < 40600
+# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
+#endif
+
+#if GCC_VERSION >= 40300
+/* Mark functions as cold. gcc will assume any path leading to a call
+ * to them will be unlikely.  This means a lot of manual unlikely()s
+ * are unnecessary now for any paths leading to the usual suspects
+ * like BUG(), printk(), panic() etc. [but let's keep them for now for
+ * older compilers]
+ *
+ * Early snapshots of gcc 4.3 don't support this and we can't detect this
+ * in the preprocessor, but we can live with this because they're unreleased.
+ * Maketime probing would be overkill here.
+ *
+ * gcc also has a __attribute__((__hot__)) to move hot functions into
+ * a special section, but I don't see any sense in this right now in
+ * the kernel context
+ */
+#define __cold			__attribute__((__cold__))
+
+#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+#ifndef __CHECKER__
+# define __compiletime_warning(message) __attribute__((warning(message)))
+# define __compiletime_error(message) __attribute__((error(message)))
+#endif /* __CHECKER__ */
+#endif /* GCC_VERSION >= 40300 */
+
+#if GCC_VERSION >= 40500
+/*
+ * Mark a position in code as unreachable.  This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+ * control elsewhere.
+ *
+ * Early snapshots of gcc 4.5 don't support this and we can't detect
+ * this in the preprocessor, but we can live with this because they're
+ * unreleased.  Really, we need to have autoconf for the kernel.
+ */
+#define unreachable() __builtin_unreachable()
+
+/* Mark a function definition as prohibited from being cloned. */
+#define __noclone	__attribute__((__noclone__))
+
+#endif /* GCC_VERSION >= 40500 */
+
+#if GCC_VERSION >= 40600
+/*
+ * Tell the optimizer that something else uses this function or variable.
+ */
+#define __visible	__attribute__((externally_visible))
+#endif
+
+/*
+ * GCC 'asm goto' miscompiles certain code sequences:
+ *
+ *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
+ *
+ * (asm goto is automatically volatile - the naming reflects this.)
+ */
+#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
+
+#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
+#if GCC_VERSION >= 40400
+#define __HAVE_BUILTIN_BSWAP32__
+#define __HAVE_BUILTIN_BSWAP64__
+#endif
+#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
+#define __HAVE_BUILTIN_BSWAP16__
+#endif
+#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
+
+#if GCC_VERSION >= 50000
+#define KASAN_ABI_VERSION 4
+#elif GCC_VERSION >= 40902
+#define KASAN_ABI_VERSION 3
+#endif
+
+#endif	/* gcc version >= 40000 specific checks */
+
+#if !defined(__noclone)
+#define __noclone	/* not needed */
+#endif
+
+/*
+ * A trick to suppress uninitialized variable warning without generating any
+ * code
+ */
+#define uninitialized_var(x) x = x

main/devicepkg-dev/downstreamkernel_prepare.sh

@@ -13,8 +13,8 @@ if [ -z "$srcdir" ] || [ -z "$builddir" ] || [ -z "$_config" ] ||
 	exit 1
 fi
 
-# gcc6 support
+# support newer GCC versions
-cp -v "$srcdir/compiler-gcc6.h" "$builddir/include/linux/"
+cp -v "/usr/share/devicepkg-dev/compiler-gcc.h" "$builddir/include/linux/"
 
 # Remove -Werror from all makefiles
 makefiles="$(find . -type f -name Makefile)