/branches/18.06.1/target/linux/generic/backport-4.9/013-disable-Wattribute-alias-warning-for-SYSCALL_DEFINEx.patch |
@@ -0,0 +1,88 @@ |
From: Arnd Bergmann <arnd@arndb.de> |
Date: Tue, 19 Jun 2018 13:14:57 -0700 |
Subject: [PATCH] disable -Wattribute-alias warning for SYSCALL_DEFINEx() |
|
gcc-8 warns for every single definition of a system call entry |
point, e.g.: |
|
include/linux/compat.h:56:18: error: 'compat_sys_rt_sigprocmask' alias between functions of incompatible types 'long int(int, compat_sigset_t *, compat_sigset_t *, compat_size_t)' {aka 'long int(int, struct <anonymous> *, struct <anonymous> *, unsigned int)'} and 'long int(long int, long int, long int, long int)' [-Werror=attribute-alias] |
asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\ |
^~~~~~~~~~ |
include/linux/compat.h:45:2: note: in expansion of macro 'COMPAT_SYSCALL_DEFINEx' |
COMPAT_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__) |
^~~~~~~~~~~~~~~~~~~~~~ |
kernel/signal.c:2601:1: note: in expansion of macro 'COMPAT_SYSCALL_DEFINE4' |
COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, |
^~~~~~~~~~~~~~~~~~~~~~ |
include/linux/compat.h:60:18: note: aliased declaration here |
asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__))\ |
^~~~~~~~~~ |
|
The new warning seems reasonable in principle, but it doesn't |
help us here, since we rely on the type mismatch to sanitize the |
system call arguments. After I reported this as GCC PR82435, a new |
-Wno-attribute-alias option was added that could be used to turn the |
warning off globally on the command line, but I'd prefer to do it a |
little more fine-grained. |
|
Interestingly, turning a warning off and on again inside of |
a single macro doesn't always work, in this case I had to add |
an extra statement inbetween and decided to copy the __SC_TEST |
one from the native syscall to the compat syscall macro. See |
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 for more details |
about this. |
|
[paul.burton@mips.com: |
- Rebase atop current master. |
- Split GCC & version arguments to __diag_ignore() in order to match |
changes to the preceding patch. |
- Add the comment argument to match the preceding patch.] |
|
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82435 |
Signed-off-by: Arnd Bergmann <arnd@arndb.de> |
Signed-off-by: Paul Burton <paul.burton@mips.com> |
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr> |
Tested-by: Stafford Horne <shorne@gmail.com> |
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> |
--- |
|
--- a/include/linux/compat.h |
+++ b/include/linux/compat.h |
@@ -47,6 +47,9 @@ |
COMPAT_SYSCALL_DEFINEx(6, _##name, __VA_ARGS__) |
|
#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ |
+ __diag_push(); \ |
+ __diag_ignore(GCC, 8, "-Wattribute-alias", \ |
+ "Type aliasing is used to sanitize syscall arguments");\ |
asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\ |
__attribute__((alias(__stringify(compat_SyS##name)))); \ |
static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ |
@@ -55,6 +58,7 @@ |
{ \ |
return C_SYSC##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \ |
} \ |
+ __diag_pop(); \ |
static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) |
|
#ifndef compat_user_stack_pointer |
--- a/include/linux/syscalls.h |
+++ b/include/linux/syscalls.h |
@@ -192,6 +192,9 @@ extern struct trace_event_functions exit |
|
#define __PROTECT(...) asmlinkage_protect(__VA_ARGS__) |
#define __SYSCALL_DEFINEx(x, name, ...) \ |
+ __diag_push(); \ |
+ __diag_ignore(GCC, 8, "-Wattribute-alias", \ |
+ "Type aliasing is used to sanitize syscall arguments");\ |
asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ |
__attribute__((alias(__stringify(SyS##name)))); \ |
static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ |
@@ -203,6 +206,7 @@ extern struct trace_event_functions exit |
__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ |
return ret; \ |
} \ |
+ __diag_pop(); \ |
static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) |
|
asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special, |