powerpc: Fix duplicate const clang warning in user access code

BugLink: https://bugs.launchpad.net/bugs/1853915
[ Upstream commit e00d93ac9a189673028ac125a74b9bc8ae73eebc ]

This re-applies commit b91c1e3e7a6f ("powerpc: Fix duplicate const
clang warning in user access code") (Jun 2015) which was undone in
commits:
  f2ca80905929 ("powerpc/sparse: Constify the address pointer in __get_user_nosleep()") (Feb 2017)
  d466f6c5cac1 ("powerpc/sparse: Constify the address pointer in __get_user_nocheck()") (Feb 2017)
  f84ed59a612d ("powerpc/sparse: Constify the address pointer in __get_user_check()") (Feb 2017)

We see a large number of duplicate const errors in the user access
code when building with llvm/clang:

  include/linux/pagemap.h:576:8: warning: duplicate 'const' declaration specifier [-Wduplicate-decl-specifier]
        ret = __get_user(c, uaddr);

The problem is we are doing const __typeof__(*(ptr)), which will hit
the warning if ptr is marked const.

Removing const does not seem to have any effect on GCC code
generation.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 81cfd822f4d2aca9c7b1478da1b81b52f4176adf..fef25eeb1a11e6a5c2a16b57ca7dada2462ff2c2 100644 (file)
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -251,7 +251,7 @@ do {                                                                \
 ({                                                             \
        long __gu_err;                                          \
        __long_type(*(ptr)) __gu_val;                           \
-       const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
+       __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
        __chk_user_ptr(ptr);                                    \
        if (!is_kernel_addr((unsigned long)__gu_addr))          \
                might_fault();                                  \
@@ -265,7 +265,7 @@ do {                                                                \
 ({                                                                     \
        long __gu_err = -EFAULT;                                        \
        __long_type(*(ptr)) __gu_val = 0;                               \
-       const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
+       __typeof__(*(ptr)) __user *__gu_addr = (ptr);           \
        might_fault();                                                  \
        if (access_ok(VERIFY_READ, __gu_addr, (size))) {                \
                barrier_nospec();                                       \
@@ -279,7 +279,7 @@ do {                                                                \
 ({                                                             \
        long __gu_err;                                          \
        __long_type(*(ptr)) __gu_val;                           \
-       const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
+       __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
        __chk_user_ptr(ptr);                                    \
        barrier_nospec();                                       \
        __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \