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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 05:55:54 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 05:55:54 +0300
commit0e06f5c0deeef0332a5da2ecb8f1fcf3e024d958 (patch)
treee0f0af4aadf10c713c5cf1b65356844b3c9b3215 /Makefile
parentf7816ad0f878dacd5f0120476f9b836ccf8699ea (diff)
parent8f19b0c058d93a678a99dd6fec03af2e769943f2 (diff)
downloadlinux-0e06f5c0deeef0332a5da2ecb8f1fcf3e024d958.tar.xz
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton: - a few misc bits - ocfs2 - most(?) of MM * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (125 commits) thp: fix comments of __pmd_trans_huge_lock() cgroup: remove unnecessary 0 check from css_from_id() cgroup: fix idr leak for the first cgroup root mm: memcontrol: fix documentation for compound parameter mm: memcontrol: remove BUG_ON in uncharge_list mm: fix build warnings in <linux/compaction.h> mm, thp: convert from optimistic swapin collapsing to conservative mm, thp: fix comment inconsistency for swapin readahead functions thp: update Documentation/{vm/transhuge,filesystems/proc}.txt shmem: split huge pages beyond i_size under memory pressure thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE khugepaged: add support of collapse for tmpfs/shmem pages shmem: make shmem_inode_info::lock irq-safe khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page() thp: extract khugepaged from mm/huge_memory.c shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings shmem: add huge pages support shmem: get_unmapped_area align huge page shmem: prepare huge= mount option and sysfs knob mm, rmap: account shmem thp pages ...
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile69
1 files changed, 42 insertions, 27 deletions
diff --git a/Makefile b/Makefile
index 6cd4d62cb1c1..776b6a3c40f1 100644
--- a/Makefile
+++ b/Makefile
@@ -647,41 +647,28 @@ ifneq ($(CONFIG_FRAME_WARN),0)
KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
endif
-# Handle stack protector mode.
-#
-# Since kbuild can potentially perform two passes (first with the old
-# .config values and then with updated .config values), we cannot error out
-# if a desired compiler option is unsupported. If we were to error, kbuild
-# could never get to the second pass and actually notice that we changed
-# the option to something that was supported.
-#
-# Additionally, we don't want to fallback and/or silently change which compiler
-# flags will be used, since that leads to producing kernels with different
-# security feature characteristics depending on the compiler used. ("But I
-# selected CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
-#
-# The middle ground is to warn here so that the failed option is obvious, but
-# to let the build fail with bad compiler flags so that we can't produce a
-# kernel when there is a CONFIG and compiler mismatch.
-#
+# This selects the stack protector compiler flag. Testing it is delayed
+# until after .config has been reprocessed, in the prepare-compiler-check
+# target.
ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
stackp-flag := -fstack-protector
- ifeq ($(call cc-option, $(stackp-flag)),)
- $(warning Cannot use CONFIG_CC_STACKPROTECTOR_REGULAR: \
- -fstack-protector not supported by compiler)
- endif
+ stackp-name := REGULAR
else
ifdef CONFIG_CC_STACKPROTECTOR_STRONG
stackp-flag := -fstack-protector-strong
- ifeq ($(call cc-option, $(stackp-flag)),)
- $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
- -fstack-protector-strong not supported by compiler)
- endif
+ stackp-name := STRONG
else
# Force off for distro compilers that enable stack protector by default.
stackp-flag := $(call cc-option, -fno-stack-protector)
endif
endif
+# Find arch-specific stack protector compiler sanity-checking script.
+ifdef CONFIG_CC_STACKPROTECTOR
+ stackp-path := $(srctree)/scripts/gcc-$(ARCH)_$(BITS)-has-stack-protector.sh
+ ifneq ($(wildcard $(stackp-path)),)
+ stackp-check := $(stackp-path)
+ endif
+endif
KBUILD_CFLAGS += $(stackp-flag)
ifdef CONFIG_KCOV
@@ -1017,8 +1004,10 @@ ifneq ($(KBUILD_SRC),)
fi;
endif
-# prepare2 creates a makefile if using a separate output directory
-prepare2: prepare3 outputmakefile asm-generic
+# prepare2 creates a makefile if using a separate output directory.
+# From this point forward, .config has been reprocessed, so any rules
+# that need to depend on updated CONFIG_* values can be checked here.
+prepare2: prepare3 prepare-compiler-check outputmakefile asm-generic
prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
include/config/auto.conf
@@ -1049,6 +1038,32 @@ endif
PHONY += prepare-objtool
prepare-objtool: $(objtool_target)
+# Check for CONFIG flags that require compiler support. Abort the build
+# after .config has been processed, but before the kernel build starts.
+#
+# For security-sensitive CONFIG options, we don't want to fallback and/or
+# silently change which compiler flags will be used, since that leads to
+# producing kernels with different security feature characteristics
+# depending on the compiler used. (For example, "But I selected
+# CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
+PHONY += prepare-compiler-check
+prepare-compiler-check: FORCE
+# Make sure compiler supports requested stack protector flag.
+ifdef stackp-name
+ ifeq ($(call cc-option, $(stackp-flag)),)
+ @echo Cannot use CONFIG_CC_STACKPROTECTOR_$(stackp-name): \
+ $(stackp-flag) not supported by compiler >&2 && exit 1
+ endif
+endif
+# Make sure compiler does not have buggy stack-protector support.
+ifdef stackp-check
+ ifneq ($(shell $(CONFIG_SHELL) $(stackp-check) $(CC) $(KBUILD_CPPFLAGS) $(biarch)),y)
+ @echo Cannot use CONFIG_CC_STACKPROTECTOR_$(stackp-name): \
+ $(stackp-flag) available but compiler is broken >&2 && exit 1
+ endif
+endif
+ @:
+
# Generate some files
# ---------------------------------------------------------------------------