| Message ID | 1415235534.3398.35.camel@decadent.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Dne 6.11.2014 v 01:58 Ben Hutchings napsal(a): > gcc 4.8 and later include <stdc-predef.h> by default. In some > versions of eglibc that includes <bits/predefs.h>, but that may be > missing when building with a biarch compiler. Also <stdc-predef.h> > itself could be missing as we are only trying to build a kernel, not > userland. > > The -nostdinc option disables this, though it isn't explicitly > documented. This option is already used when actually building > the kernel, but not by cc-option and other tests. This can result > in silently miscompiling the kernel. > > References: https://bugs.debian.org/717557 > References: https://bugs.debian.org/726861 > Signed-off-by: Ben Hutchings <ben@decadent.org.uk> > --- > This specific issue appeared and then was fixed in Debian about a year > ago, but it seems like it can also affect cross-builds. > > It may also be worth adding some sort of sanity test, so we stop > immediately if $(cc-option $(empty),broken) yields 'broken'. > > Ben. > > Makefile | 4 +++- > scripts/Kbuild.include | 15 ++++++++------- > 2 files changed, 11 insertions(+), 8 deletions(-) > > diff --git a/Makefile b/Makefile > index ffc1ce2..c0fbf67 100644 > --- a/Makefile > +++ b/Makefile > @@ -619,6 +619,8 @@ endif > # Tell gcc to never replace conditional load with a non-conditional one > KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) > > +NOSTDINC_FLAGS += -nostdinc > + > ifdef CONFIG_READABLE_ASM > # Disable optimizations that make assembler listings hard to read. > # reorder blocks reorders the control in the function > @@ -742,7 +744,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) > endif > > # arch Makefile may override CC so keep this after arch Makefile is included > -NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) > +NOSTDINC_FLAGS += -isystem $(shell $(CC) -print-file-name=include) Why not simply move the whole assignment up? Also, there are two cc-option tests and one cc-disable-warning test before the first part assignment. Looks like a result of a mismerge. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2014-11-25 22:53, Michal Marek wrote: > Dne 6.11.2014 v 01:58 Ben Hutchings napsal(a): >> gcc 4.8 and later include <stdc-predef.h> by default. In some >> versions of eglibc that includes <bits/predefs.h>, but that may be >> missing when building with a biarch compiler. Also <stdc-predef.h> >> itself could be missing as we are only trying to build a kernel, not >> userland. >> >> The -nostdinc option disables this, though it isn't explicitly >> documented. This option is already used when actually building >> the kernel, but not by cc-option and other tests. This can result >> in silently miscompiling the kernel. >> >> References: https://bugs.debian.org/717557 >> References: https://bugs.debian.org/726861 >> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> >> --- >> This specific issue appeared and then was fixed in Debian about a year >> ago, but it seems like it can also affect cross-builds. >> >> It may also be worth adding some sort of sanity test, so we stop >> immediately if $(cc-option $(empty),broken) yields 'broken'. >> >> Ben. >> >> Makefile | 4 +++- >> scripts/Kbuild.include | 15 ++++++++------- >> 2 files changed, 11 insertions(+), 8 deletions(-) >> >> diff --git a/Makefile b/Makefile >> index ffc1ce2..c0fbf67 100644 >> --- a/Makefile >> +++ b/Makefile >> @@ -619,6 +619,8 @@ endif >> # Tell gcc to never replace conditional load with a non-conditional one >> KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) >> >> +NOSTDINC_FLAGS += -nostdinc >> + >> ifdef CONFIG_READABLE_ASM >> # Disable optimizations that make assembler listings hard to read. >> # reorder blocks reorders the control in the function >> @@ -742,7 +744,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) >> endif >> >> # arch Makefile may override CC so keep this after arch Makefile is included >> -NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) >> +NOSTDINC_FLAGS += -isystem $(shell $(CC) -print-file-name=include) > > Why not simply move the whole assignment up? Ah, I see the reason now -- we need $(CC) for the second part of the assignment. > Also, there are two > cc-option tests and one cc-disable-warning test before the first part > assignment. Looks like a result of a mismerge. But this still looks like a bug to me. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index ffc1ce2..c0fbf67 100644 --- a/Makefile +++ b/Makefile @@ -619,6 +619,8 @@ endif # Tell gcc to never replace conditional load with a non-conditional one KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) +NOSTDINC_FLAGS += -nostdinc + ifdef CONFIG_READABLE_ASM # Disable optimizations that make assembler listings hard to read. # reorder blocks reorders the control in the function @@ -742,7 +744,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) endif # arch Makefile may override CC so keep this after arch Makefile is included -NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) +NOSTDINC_FLAGS += -isystem $(shell $(CC) -print-file-name=include) CHECKFLAGS += $(NOSTDINC_FLAGS) # warn about C99 declaration after statement diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 65e7b08..e87fc08 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -111,12 +111,12 @@ as-instr = $(call try-run,\ # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586) cc-option = $(call try-run,\ - $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2)) + $(CC) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2)) # cc-option-yn # Usage: flag := $(call cc-option-yn,-march=winchip-c6) cc-option-yn = $(call try-run,\ - $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n) + $(CC) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n) # cc-option-align # Prefix align with either -falign or -malign @@ -126,16 +126,17 @@ cc-option-align = $(subst -functions=0,,\ # cc-disable-warning # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable) cc-disable-warning = $(call try-run,\ - $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1))) + $(CC) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1))) # cc-version # Usage gcc-ver := $(call cc-version) -cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) +cc-version = $(shell $(CONFIG_SHELL) \ + $(srctree)/scripts/gcc-version.sh $(CC) $(NOSTDINC_FLAGS)) # cc-fullversion # Usage gcc-ver := $(call cc-fullversion) cc-fullversion = $(shell $(CONFIG_SHELL) \ - $(srctree)/scripts/gcc-version.sh -p $(CC)) + $(srctree)/scripts/gcc-version.sh -p $(CC) $(NOSTDINC_FLAGS)) # cc-ifversion # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) @@ -144,12 +145,12 @@ cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3)) # cc-ldoption # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) cc-ldoption = $(call try-run,\ - $(CC) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) + $(CC) $(NOSTDINC_FLAGS) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) # ld-option # Usage: LDFLAGS += $(call ld-option, -X) ld-option = $(call try-run,\ - $(CC) -x c /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) + $(CC) $(NOSTDINC_FLAGS) -x c /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) # ar-option # Usage: KBUILD_ARFLAGS := $(call ar-option,D)
gcc 4.8 and later include <stdc-predef.h> by default. In some versions of eglibc that includes <bits/predefs.h>, but that may be missing when building with a biarch compiler. Also <stdc-predef.h> itself could be missing as we are only trying to build a kernel, not userland. The -nostdinc option disables this, though it isn't explicitly documented. This option is already used when actually building the kernel, but not by cc-option and other tests. This can result in silently miscompiling the kernel. References: https://bugs.debian.org/717557 References: https://bugs.debian.org/726861 Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- This specific issue appeared and then was fixed in Debian about a year ago, but it seems like it can also affect cross-builds. It may also be worth adding some sort of sanity test, so we stop immediately if $(cc-option $(empty),broken) yields 'broken'. Ben. Makefile | 4 +++- scripts/Kbuild.include | 15 ++++++++------- 2 files changed, 11 insertions(+), 8 deletions(-)