linux-kernel - [tip: x86/urgent] x86/boot/compressed: Enable -Wundef

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Date:   Wed, 12 May 2021 20:01:58 -0000
From:   "tip-bot2 for Nick Desaulniers" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Joe Perches <joe@...ches.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Ingo Molnar <mingo@...nel.org>,
        Kees Cook <keescook@...omium.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/boot/compressed: Enable -Wundef

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     a554e740b66a83c7560b30e6b50bece37555ced3
Gitweb:        https://git.kernel.org/tip/a554e740b66a83c7560b30e6b50bece37555ced3
Author:        Nick Desaulniers <ndesaulniers@...gle.com>
AuthorDate:    Thu, 22 Apr 2021 12:04:42 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 12 May 2021 21:39:56 +02:00

x86/boot/compressed: Enable -Wundef

A discussion around -Wundef showed that there were still a few boolean
Kconfigs where #if was used rather than #ifdef to guard different code.
Kconfig doesn't define boolean configs, which can result in -Wundef
warnings.

arch/x86/boot/compressed/Makefile resets the CFLAGS used for this
directory, and doesn't re-enable -Wundef as the top level Makefile does.
If re-added, with RANDOMIZE_BASE and X86_NEED_RELOCS disabled, the
following warnings are visible.

  arch/x86/boot/compressed/misc.h:82:5: warning: 'CONFIG_RANDOMIZE_BASE'
  is not defined, evaluates to 0 [-Wundef]
      ^
  arch/x86/boot/compressed/misc.c:175:5: warning: 'CONFIG_X86_NEED_RELOCS'
  is not defined, evaluates to 0 [-Wundef]
      ^

Simply fix these and re-enable this warning for this directory.

Suggested-by: Nathan Chancellor <nathan@...nel.org>
Suggested-by: Joe Perches <joe@...ches.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Nathan Chancellor <nathan@...nel.org>
Link: https://lore.kernel.org/r/20210422190450.3903999-1-ndesaulniers@google.com
---
 arch/x86/boot/compressed/Makefile | 1 +
 arch/x86/boot/compressed/misc.c   | 2 +-
 arch/x86/boot/compressed/misc.h   | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 2a29752..431bf7f 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -30,6 +30,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
 
 KBUILD_CFLAGS := -m$(BITS) -O2
 KBUILD_CFLAGS += -fno-strict-aliasing -fPIE
+KBUILD_CFLAGS += -Wundef
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
 cflags-$(CONFIG_X86_32) := -march=i386
 cflags-$(CONFIG_X86_64) := -mcmodel=small -mno-red-zone
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index dde042f..743f13e 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -172,7 +172,7 @@ void __puthex(unsigned long value)
 	}
 }
 
-#if CONFIG_X86_NEED_RELOCS
+#ifdef CONFIG_X86_NEED_RELOCS
 static void handle_relocations(void *output, unsigned long output_len,
 			       unsigned long virt_addr)
 {
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index e5612f0..3113925 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -79,7 +79,7 @@ struct mem_vector {
 	u64 size;
 };
 
-#if CONFIG_RANDOMIZE_BASE
+#ifdef CONFIG_RANDOMIZE_BASE
 /* kaslr.c */
 void choose_random_location(unsigned long input,
 			    unsigned long input_size,