Merge tag 'kbuild-fixes-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - introduce __diag_* macros and suppress -Wattribute-alias warnings
   from GCC 8

 - fix stack protector test script for x86_64

 - fix line number handling in Kconfig

 - document that '#' starts a comment in Kconfig

 - handle P_SYMBOL property in dump debugging of Kconfig

 - correct help message of LD_DEAD_CODE_DATA_ELIMINATION

 - fix occasional segmentation faults in Kconfig

* tag 'kbuild-fixes-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: loop boundary condition fix
  kbuild: reword help of LD_DEAD_CODE_DATA_ELIMINATION
  kconfig: handle P_SYMBOL in print_symbol()
  kconfig: document Kconfig source file comments
  kconfig: fix line numbers for if-entries in menu tree
  stack-protector: Fix test with 32-bit userland and CONFIG_64BIT=y
  powerpc: Remove -Wattribute-alias pragmas
  disable -Wattribute-alias warning for SYSCALL_DEFINEx()
  kbuild: add macro for controlling warnings to linux/compiler.h

17 files changed, 74 insertions, 41 deletions

diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index 3534a84d206c..64e0775a62d4 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -430,6 +430,12 @@ This sets the config program's title bar if the config program chooses
 to use it. It should be placed at the top of the configuration, before any
 other statement.
 
+'#' Kconfig source file comment:
+
+An unquoted '#' character anywhere in a source file line indicates
+the beginning of a source file comment.  The remainder of that line
+is a comment.
+
 
 Kconfig hints
 -------------
diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
index 4f861055a852..d63b488d34d7 100644
--- a/arch/powerpc/kernel/pci_32.c
+++ b/arch/powerpc/kernel/pci_32.c
@@ -285,9 +285,6 @@ pci_bus_to_hose(int bus)
  * Note that the returned IO or memory base is a physical address
  */
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(pciconfig_iobase, long, which,
                 unsigned long, bus, unsigned long, devfn)
 {
@@ -313,4 +310,3 @@ SYSCALL_DEFINE3(pciconfig_iobase, long, which,
 
         return result;
 }
-#pragma GCC diagnostic pop
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 812171c09f42..dff28f903512 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -203,9 +203,6 @@ void pcibios_setup_phb_io_space(struct pci_controller *hose)
 #define IOBASE_ISA_IO           3
 #define IOBASE_ISA_MEM          4
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(pciconfig_iobase, long, which, unsigned long, in_bus,
                           unsigned long, in_devfn)
 {
@@ -259,7 +256,6 @@ SYSCALL_DEFINE3(pciconfig_iobase, long, which, unsigned long, in_bus,
 
         return -EOPNOTSUPP;
 }
-#pragma GCC diagnostic pop
 
 #ifdef CONFIG_NUMA
 int pcibus_to_node(struct pci_bus *bus)
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 7fb9f83dcde8..8afd146bc9c7 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1051,9 +1051,6 @@ struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
 }
 
 /* We assume to be passed big endian arguments */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 {
         struct rtas_args args;
@@ -1140,7 +1137,6 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 
         return 0;
 }
-#pragma GCC diagnostic pop
 
 /*
  * Call early during boot, before mem init, to retrieve the RTAS
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 5eedbb282d42..e6474a45cef5 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -1038,9 +1038,6 @@ static int do_setcontext_tm(struct ucontext __user *ucp,
 }
 #endif
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 #ifdef CONFIG_PPC64
 COMPAT_SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
                        struct ucontext __user *, new_ctx, int, ctx_size)
@@ -1134,7 +1131,6 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
         set_thread_flag(TIF_RESTOREALL);
         return 0;
 }
-#pragma GCC diagnostic pop
 
 #ifdef CONFIG_PPC64
 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
@@ -1231,9 +1227,6 @@ SYSCALL_DEFINE0(rt_sigreturn)
         return 0;
 }
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 #ifdef CONFIG_PPC32
 SYSCALL_DEFINE3(debug_setcontext, struct ucontext __user *, ctx,
                          int, ndbg, struct sig_dbg_op __user *, dbg)
@@ -1337,7 +1330,6 @@ SYSCALL_DEFINE3(debug_setcontext, struct ucontext __user *, ctx,
         return 0;
 }
 #endif
-#pragma GCC diagnostic pop
 
 /*
  * OK, we're invoking a handler
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d42b60020389..83d51bf586c7 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -625,9 +625,6 @@ static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
 /*
  * Handle {get,set,swap}_context operations
  */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
                 struct ucontext __user *, new_ctx, long, ctx_size)
 {
@@ -693,7 +690,6 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
         set_thread_flag(TIF_RESTOREALL);
         return 0;
 }
-#pragma GCC diagnostic pop
 
 
 /*
diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index 083fa06962fd..466216506eb2 100644
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -62,9 +62,6 @@ out:
         return ret;
 }
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, size_t, len,
                 unsigned long, prot, unsigned long, flags,
                 unsigned long, fd, unsigned long, pgoff)
@@ -78,7 +75,6 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, size_t, len,
 {
         return do_mmap2(addr, len, prot, flags, fd, offset, PAGE_SHIFT);
 }
-#pragma GCC diagnostic pop
 
 #ifdef CONFIG_PPC32
 /*
diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index 75cb646a79c3..9d16ee251fc0 100644
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -186,9 +186,6 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
  * in a 2-bit field won't allow writes to a page that is otherwise
  * write-protected.
  */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
                 unsigned long, len, u32 __user *, map)
 {
@@ -272,4 +269,3 @@ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
         up_write(&mm->mmap_sem);
         return err;
 }
-#pragma GCC diagnostic pop
diff --git a/include/linux/compat.h b/include/linux/compat.h
index b1a5562b3215..c68acc47da57 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -72,6 +72,9 @@
  */
 #ifndef COMPAT_SYSCALL_DEFINEx
 #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__));       \
         asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))        \
                 __attribute__((alias(__stringify(__se_compat_sys##name))));     \
@@ -80,8 +83,11 @@
         asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));  \
         asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))   \
         {                                                                       \
-                return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
+                long ret = __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
+                __MAP(x,__SC_TEST,__VA_ARGS__);                                 \
+                return ret;                                                     \
         }                                                                       \
+        __diag_pop();                                                           \
         static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 #endif /* COMPAT_SYSCALL_DEFINEx */
 
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index f1a7492a5cc8..fd282c7d3e5e 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -347,3 +347,28 @@
 #if GCC_VERSION >= 50100
 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
 #endif
+
+/*
+ * Turn individual warnings and errors on and off locally, depending
+ * on version.
+ */
+#define __diag_GCC(version, severity, s) \
+        __diag_GCC_ ## version(__diag_GCC_ ## severity s)
+
+/* Severity used in pragma directives */
+#define __diag_GCC_ignore       ignored
+#define __diag_GCC_warn         warning
+#define __diag_GCC_error        error
+
+/* Compilers before gcc-4.6 do not understand "#pragma GCC diagnostic push" */
+#if GCC_VERSION >= 40600
+#define __diag_str1(s)          #s
+#define __diag_str(s)           __diag_str1(s)
+#define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
+#endif
+
+#if GCC_VERSION >= 80000
+#define __diag_GCC_8(s)         __diag(s)
+#else
+#define __diag_GCC_8(s)
+#endif
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 6b79a9bba9a7..a8ba6b04152c 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -271,4 +271,22 @@ struct ftrace_likely_data {
 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
 #endif
 
+#ifndef __diag
+#define __diag(string)
+#endif
+
+#ifndef __diag_GCC
+#define __diag_GCC(version, severity, string)
+#endif
+
+#define __diag_push()   __diag(push)
+#define __diag_pop()    __diag(pop)
+
+#define __diag_ignore(compiler, version, option, comment) \
+        __diag_ ## compiler(version, ignore, option)
+#define __diag_warn(compiler, version, option, comment) \
+        __diag_ ## compiler(version, warn, option)
+#define __diag_error(compiler, version, option, comment) \
+        __diag_ ## compiler(version, error, option)
+
 #endif /* __LINUX_COMPILER_TYPES_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 73810808cdf2..a368a68cb667 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -231,6 +231,9 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
  */
 #ifndef __SYSCALL_DEFINEx
 #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(__se_sys##name))));    \
         ALLOW_ERROR_INJECTION(sys##name, ERRNO);                        \
@@ -243,6 +246,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
                 __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__));       \
                 return ret;                                             \
         }                                                               \
+        __diag_pop();                                                   \
         static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 #endif /* __SYSCALL_DEFINEx */
 
diff --git a/init/Kconfig b/init/Kconfig
index fde3d09e8b27..041f3a022122 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1051,10 +1051,9 @@ config LD_DEAD_CODE_DATA_ELIMINATION
         depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
         depends on EXPERT
         help
-          Select this if the architecture wants to do dead code and
-          data elimination with the linker by compiling with
-          -ffunction-sections -fdata-sections, and linking with
-          --gc-sections.
+          Enable this if you want to do dead code and data elimination with
+          the linker by compiling with -ffunction-sections -fdata-sections,
+          and linking with --gc-sections.
 
           This can reduce on disk and in-memory size of the kernel
           code and static data, particularly for small configs and
diff --git a/scripts/gcc-x86_64-has-stack-protector.sh b/scripts/gcc-x86_64-has-stack-protector.sh
index 3755af0cd9f7..75e4e22b986a 100755
--- a/scripts/gcc-x86_64-has-stack-protector.sh
+++ b/scripts/gcc-x86_64-has-stack-protector.sh
@@ -1,4 +1,4 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
-echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -O0 -mcmodel=kernel -fno-PIE -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
+echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -m64 -O0 -mcmodel=kernel -fno-PIE -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 94a383b21df6..f63b41b0dd49 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -171,6 +171,9 @@ struct symbol {
  * config BAZ
  *         int "BAZ Value"
  *         range 1..255
+ *
+ * Please, also check zconf.y:print_symbol() when modifying the
+ * list of property types!
  */
 enum prop_type {
         P_UNKNOWN,
diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index 65da87fce907..5ca2df790d3c 100644
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -156,7 +156,7 @@ static char *do_shell(int argc, char *argv[])
                 nread--;
 
         /* remove trailing new lines */
-        while (buf[nread - 1] == '\n')
+        while (nread > 0 && buf[nread - 1] == '\n')
                 nread--;
 
         buf[nread] = 0;
diff --git a/scripts/kconfig/zconf.y b/scripts/kconfig/zconf.y
index 6f9b0aa32a82..4b68272ebdb9 100644
--- a/scripts/kconfig/zconf.y
+++ b/scripts/kconfig/zconf.y
@@ -31,7 +31,7 @@ struct symbol *symbol_hash[SYMBOL_HASHSIZE];
 static struct menu *current_menu, *current_entry;
 
 %}
-%expect 32
+%expect 31
 
 %union
 {
@@ -337,7 +337,7 @@ choice_block:
 
 /* if entry */
 
-if_entry: T_IF expr nl
+if_entry: T_IF expr T_EOL
 {
         printd(DEBUG_PARSE, "%s:%d:if\n", zconf_curname(), zconf_lineno());
         menu_add_entry(NULL);
@@ -717,6 +717,10 @@ static void print_symbol(FILE *out, struct menu *menu)
                         print_quoted_string(out, prop->text);
                         fputc('\n', out);
                         break;
+                case P_SYMBOL:
+                        fputs( "  symbol ", out);
+                        fprintf(out, "%s\n", prop->sym->name);
+                        break;
                 default:
                         fprintf(out, "  unknown prop %d!\n", prop->type);
                         break;