linux-fslc-imx_4.9-1.0.x: Backport patches to fix building with gcc 9

Closes #192.

Signed-off-by: Tom Hochstein <tom.hochstein@nxp.com>

3 files changed, 270 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-fslc-imx/0001-compiler-attributes-add-support-for-copy-gcc-9.patch b/recipes-kernel/linux/linux-fslc-imx/0001-compiler-attributes-add-support-for-copy-gcc-9.patch
new file mode 100644
index 000000000..a234c0c36
--- /dev/null
+++ b/recipes-kernel/linux/linux-fslc-imx/0001-compiler-attributes-add-support-for-copy-gcc-9.patch
@@ -0,0 +1,132 @@
+From mboxrd@z Thu Jan  1 00:00:00 1970
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+From:   Stefan Agner <stefan@agner.ch>
+To:     gregkh@linuxfoundation.org
+Cc:     stable@vger.kernel.org,
+        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
+        Martin Sebor <msebor@gcc.gnu.org>,
+        Nick Desaulniers <ndesaulniers@google.com>,
+        Stefan Agner <stefan@agner.ch>
+Subject: [PATCH BACKPORT 4.19 1/2] Compiler Attributes: add support for __copy (gcc >= 9)
+Date:   Tue,  4 Jun 2019 15:24:40 +0200
+Message-Id: <20190604132441.15383-1-stefan@agner.ch>
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+
+From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
+
+[ Upstream commit c0d9782f5b6d7157635ae2fd782a4b27d55a6013 ]
+
+>From the GCC manual:
+
+  copy
+  copy(function)
+
+    The copy attribute applies the set of attributes with which function
+    has been declared to the declaration of the function to which
+    the attribute is applied. The attribute is designed for libraries
+    that define aliases or function resolvers that are expected
+    to specify the same set of attributes as their targets. The copy
+    attribute can be used with functions, variables, or types. However,
+    the kind of symbol to which the attribute is applied (either
+    function or variable) must match the kind of symbol to which
+    the argument refers. The copy attribute copies only syntactic and
+    semantic attributes but not attributes that affect a symbol’s
+    linkage or visibility such as alias, visibility, or weak.
+    The deprecated attribute is also not copied.
+
+  https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
+
+The upcoming GCC 9 release extends the -Wmissing-attributes warnings
+(enabled by -Wall) to C and aliases: it warns when particular function
+attributes are missing in the aliases but not in their target, e.g.:
+
+    void __cold f(void) {}
+    void __alias("f") g(void);
+
+diagnoses:
+
+    warning: 'g' specifies less restrictive attribute than
+    its target 'f': 'cold' [-Wmissing-attributes]
+
+Using __copy(f) we can copy the __cold attribute from f to g:
+
+    void __cold f(void) {}
+    void __copy(f) __alias("f") g(void);
+
+This attribute is most useful to deal with situations where an alias
+is declared but we don't know the exact attributes the target has.
+
+For instance, in the kernel, the widely used module_init/exit macros
+define the init/cleanup_module aliases, but those cannot be marked
+always as __init/__exit since some modules do not have their
+functions marked as such.
+
+Cc: <stable@vger.kernel.org> # 4.14+
+Suggested-by: Martin Sebor <msebor@gcc.gnu.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
+Signed-off-by: Stefan Agner <stefan@agner.ch>
+---
+ include/linux/compiler-gcc.h   | 4 ++++
+ include/linux/compiler_types.h | 4 ++++
+ 2 files changed, 8 insertions(+)
+
+Index: git/include/linux/compiler-gcc.h
+===================================================================
+--- git.orig/include/linux/compiler-gcc.h
++++ git/include/linux/compiler-gcc.h
+@@ -282,6 +282,10 @@
+ 
+ #endif /* gcc version >= 40000 specific checks */
+ 
++#if GCC_VERSION >= 90100
++#define __copy(symbol)                 __attribute__((__copy__(symbol)))
++#endif
++
+ #if !defined(__noclone)
+ #define __noclone      /* not needed */
+ #endif
diff --git a/recipes-kernel/linux/linux-fslc-imx/0002-include-linux-module.h-copy-init-exit-attrs-to-.patch b/recipes-kernel/linux/linux-fslc-imx/0002-include-linux-module.h-copy-init-exit-attrs-to-.patch
new file mode 100644
index 000000000..758a8a07f
--- /dev/null
+++ b/recipes-kernel/linux/linux-fslc-imx/0002-include-linux-module.h-copy-init-exit-attrs-to-.patch
@@ -0,0 +1,135 @@
+From mboxrd@z Thu Jan  1 00:00:00 1970
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+From:   Stefan Agner <stefan@agner.ch>
+To:     gregkh@linuxfoundation.org
+Cc:     stable@vger.kernel.org,
+        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
+        Martin Sebor <msebor@gcc.gnu.org>,
+        Jessica Yu <jeyu@kernel.org>, Stefan Agner <stefan@agner.ch>
+Subject: [PATCH BACKPORT 4.19 2/2] include/linux/module.h: copy __init/__exit attrs to init/cleanup_module
+Date:   Tue,  4 Jun 2019 15:24:41 +0200
+Message-Id: <20190604132441.15383-2-stefan@agner.ch>
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+
+From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
+
+[ Upstream commit a6e60d84989fa0e91db7f236eda40453b0e44afa ]
+
+The upcoming GCC 9 release extends the -Wmissing-attributes warnings
+(enabled by -Wall) to C and aliases: it warns when particular function
+attributes are missing in the aliases but not in their target.
+
+In particular, it triggers for all the init/cleanup_module
+aliases in the kernel (defined by the module_init/exit macros),
+ending up being very noisy.
+
+These aliases point to the __init/__exit functions of a module,
+which are defined as __cold (among other attributes). However,
+the aliases themselves do not have the __cold attribute.
+
+Since the compiler behaves differently when compiling a __cold
+function as well as when compiling paths leading to calls
+to __cold functions, the warning is trying to point out
+the possibly-forgotten attribute in the alias.
+
+In order to keep the warning enabled, we decided to silence
+this case. Ideally, we would mark the aliases directly
+as __init/__exit. However, there are currently around 132 modules
+in the kernel which are missing __init/__exit in their init/cleanup
+functions (either because they are missing, or for other reasons,
+e.g. the functions being called from somewhere else); and
+a section mismatch is a hard error.
+
+A conservative alternative was to mark the aliases as __cold only.
+However, since we would like to eventually enforce __init/__exit
+to be always marked,  we chose to use the new __copy function
+attribute (introduced by GCC 9 as well to deal with this).
+With it, we copy the attributes used by the target functions
+into the aliases. This way, functions that were not marked
+as __init/__exit won't have their aliases marked either,
+and therefore there won't be a section mismatch.
+
+Note that the warning would go away marking either the extern
+declaration, the definition, or both. However, we only mark
+the definition of the alias, since we do not want callers
+(which only see the declaration) to be compiled as if the function
+was __cold (and therefore the paths leading to those calls
+would be assumed to be unlikely).
+
+Cc: <stable@vger.kernel.org> # 4.14+
+Link: https://lore.kernel.org/lkml/20190123173707.GA16603@gmail.com/
+Link: https://lore.kernel.org/lkml/20190206175627.GA20399@gmail.com/
+Suggested-by: Martin Sebor <msebor@gcc.gnu.org>
+Acked-by: Jessica Yu <jeyu@kernel.org>
+Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
+Signed-off-by: Stefan Agner <stefan@agner.ch>
+---
+ include/linux/module.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+Index: git/include/linux/module.h
+===================================================================
+--- git.orig/include/linux/module.h
++++ git/include/linux/module.h
+@@ -129,13 +129,13 @@ extern void cleanup_module(void);
+ #define module_init(initfn)                                    \
+        static inline initcall_t __inittest(void)               \
+        { return initfn; }                                      \
+-       int init_module(void) __attribute__((alias(#initfn)));
++       int init_module(void) __copy(initfn) __attribute__((alias(#initfn)));
+ 
+ /* This is only required if you want to be unloadable. */
+ #define module_exit(exitfn)                                    \
+        static inline exitcall_t __exittest(void)               \
+        { return exitfn; }                                      \
+-       void cleanup_module(void) __attribute__((alias(#exitfn)));
++       void cleanup_module(void) __copy(exitfn) __attribute__((alias(#exitfn)));
+ 
+ #endif
+ 
diff --git a/recipes-kernel/linux/linux-fslc-imx_4.9-1.0.x.bb b/recipes-kernel/linux/linux-fslc-imx_4.9-1.0.x.bb
index aff27bbf9..3f4371d34 100644
--- a/recipes-kernel/linux/linux-fslc-imx_4.9-1.0.x.bb
+++ b/recipes-kernel/linux/linux-fslc-imx_4.9-1.0.x.bb
@@ -12,5 +12,8 @@ PV .= "+git${SRCPV}"
 
 SRCBRANCH = "4.9-1.0.x-imx"
 SRCREV = "953c6e30c9701fda69ef08e2476c541dc4fb1453"
+SRC_URI += "file://0001-compiler-attributes-add-support-for-copy-gcc-9.patch \
+            file://0002-include-linux-module.h-copy-init-exit-attrs-to-.patch \
+           "
 
 COMPATIBLE_MACHINE = "(mx6|mx7)"