| Message ID | 20170620122443.35880-1-luc.vanoostenryck@gmail.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Tue, Jun 20, 2017 at 02:24:43PM +0200, Luc Van Oostenryck wrote: > When using sparse on the arm64 tree we get many thousands of > warnings like 'constant ... is so big it is unsigned long long' > or 'shift too big (32) for type unsigned long'. This happens > because by default sparse considers the machine as 32bit and > defines the size of the types accordingly. > > Fix this by passing the '-m64' flag to sparse so that > sparse can correctly define longs as being 64bit. > > CC: Catalin Marinas <catalin.marinas@arm.com> > CC: Will Deacon <will.deacon@arm.com> > CC: linux-arm-kernel@lists.infradead.org > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> > --- > arch/arm64/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index f839ecd91..15d6c1476 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -62,7 +62,7 @@ LD += -EL > UTS_MACHINE := aarch64 > endif > > -CHECKFLAGS += -D__aarch64__ > +CHECKFLAGS += -D__aarch64__ -m64 Looks fine to me, but just wondering whether or not we should also be passing something to indicate the endianness of the target. Does sparse care about that? Will
On Tue, Jun 20, 2017 at 04:49:39PM +0100, Will Deacon wrote: > On Tue, Jun 20, 2017 at 02:24:43PM +0200, Luc Van Oostenryck wrote: > > When using sparse on the arm64 tree we get many thousands of > > warnings like 'constant ... is so big it is unsigned long long' > > or 'shift too big (32) for type unsigned long'. This happens > > because by default sparse considers the machine as 32bit and > > defines the size of the types accordingly. > > > > Fix this by passing the '-m64' flag to sparse so that > > sparse can correctly define longs as being 64bit. > > > > CC: Catalin Marinas <catalin.marinas@arm.com> > > CC: Will Deacon <will.deacon@arm.com> > > CC: linux-arm-kernel@lists.infradead.org > > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> > > --- > > arch/arm64/Makefile | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > > index f839ecd91..15d6c1476 100644 > > --- a/arch/arm64/Makefile > > +++ b/arch/arm64/Makefile > > @@ -62,7 +62,7 @@ LD += -EL > > UTS_MACHINE := aarch64 > > endif > > > > -CHECKFLAGS += -D__aarch64__ > > +CHECKFLAGS += -D__aarch64__ -m64 > > Looks fine to me, but just wondering whether or not we should also be > passing something to indicate the endianness of the target. Does sparse care > about that? Yes, we should. sparse doesn't care per-se but some macros, structures or whole portion of code may depends on '__{LITTLE,BIG}_ENDIAN__' being defined or not, for example (but I don't think it will make a big difference, at least nothing like the 629904 'constant is so big' warnings we have now due to the missing -m64). For this, you have two possibilities: 1) just doing something like PPC: +ifdef CONFIG_CPU_BIG_ENDIAN +CHECKFLAGS += -D__BIG_ENDIAN__ +else +CHECKFLAGS += -D__LITTLE_ENDIAN__ +endif This will work now. I can't send you a proper patch if you wish. 2) a cleaner solution, IMO, would be to teach sparse about -mlittle-endian/-mbig-endian. In fact I already wrote the patch earlier today. But of course, you will need to wait for the patch to reach sparse's master and then compile sparse yourself or wait for a new release (which shouldn't take much long, though). Regards, -- Luc Van Oostenryck
On Tue, Jun 20, 2017 at 06:24:32PM +0200, Luc Van Oostenryck wrote: > On Tue, Jun 20, 2017 at 04:49:39PM +0100, Will Deacon wrote: > > On Tue, Jun 20, 2017 at 02:24:43PM +0200, Luc Van Oostenryck wrote: > > > When using sparse on the arm64 tree we get many thousands of > > > warnings like 'constant ... is so big it is unsigned long long' > > > or 'shift too big (32) for type unsigned long'. This happens > > > because by default sparse considers the machine as 32bit and > > > defines the size of the types accordingly. > > > > > > Fix this by passing the '-m64' flag to sparse so that > > > sparse can correctly define longs as being 64bit. > > > > > > CC: Catalin Marinas <catalin.marinas@arm.com> > > > CC: Will Deacon <will.deacon@arm.com> > > > CC: linux-arm-kernel@lists.infradead.org > > > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> > > > --- > > > arch/arm64/Makefile | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > > > index f839ecd91..15d6c1476 100644 > > > --- a/arch/arm64/Makefile > > > +++ b/arch/arm64/Makefile > > > @@ -62,7 +62,7 @@ LD += -EL > > > UTS_MACHINE := aarch64 > > > endif > > > > > > -CHECKFLAGS += -D__aarch64__ > > > +CHECKFLAGS += -D__aarch64__ -m64 > > > > Looks fine to me, but just wondering whether or not we should also be > > passing something to indicate the endianness of the target. Does sparse care > > about that? > > Yes, we should. sparse doesn't care per-se but some macros, structures > or whole portion of code may depends on '__{LITTLE,BIG}_ENDIAN__' > being defined or not, for example (but I don't think it will make > a big difference, at least nothing like the 629904 'constant is so big' > warnings we have now due to the missing -m64). > > For this, you have two possibilities: > 1) just doing something like PPC: > +ifdef CONFIG_CPU_BIG_ENDIAN > +CHECKFLAGS += -D__BIG_ENDIAN__ > +else > +CHECKFLAGS += -D__LITTLE_ENDIAN__ > +endif > This will work now. I can't send you a proper patch if you wish. > > 2) a cleaner solution, IMO, would be to teach sparse about > -mlittle-endian/-mbig-endian. In fact I already wrote the patch > earlier today. But of course, you will need to wait for the patch > to reach sparse's master and then compile sparse yourself or wait > for a new release (which shouldn't take much long, though). If you do that, you could also teach it that AArch64 is 64-bit ;) Will
On Tue, Jun 20, 2017 at 06:04:01PM +0100, Will Deacon wrote: > On Tue, Jun 20, 2017 at 06:24:32PM +0200, Luc Van Oostenryck wrote: > > On Tue, Jun 20, 2017 at 04:49:39PM +0100, Will Deacon wrote: > > > Looks fine to me, but just wondering whether or not we should also be > > > passing something to indicate the endianness of the target. Does sparse care > > > about that? > > > > Yes, we should. sparse doesn't care per-se but some macros, structures > > or whole portion of code may depends on '__{LITTLE,BIG}_ENDIAN__' > > being defined or not, for example (but I don't think it will make > > a big difference, at least nothing like the 629904 'constant is so big' > > warnings we have now due to the missing -m64). > > > > For this, you have two possibilities: > > 1) just doing something like PPC: > > +ifdef CONFIG_CPU_BIG_ENDIAN > > +CHECKFLAGS += -D__BIG_ENDIAN__ > > +else > > +CHECKFLAGS += -D__LITTLE_ENDIAN__ > > +endif > > This will work now. I can't send you a proper patch if you wish. > > > > 2) a cleaner solution, IMO, would be to teach sparse about > > -mlittle-endian/-mbig-endian. In fact I already wrote the patch > > earlier today. But of course, you will need to wait for the patch > > to reach sparse's master and then compile sparse yourself or wait > > for a new release (which shouldn't take much long, though). > > If you do that, you could also teach it that AArch64 is 64-bit ;) Well, currently sparse is arch agnostic and I think it's a good thing. For the few arch specifities you have to use some of the '-m' flags (like -m32/-m64, -msize-long). So, for the moment the '-m64' flag is needed, thus the patch. -- Luc
On Tue, Jun 20, 2017 at 09:07:40PM +0200, Luc Van Oostenryck wrote: > On Tue, Jun 20, 2017 at 06:04:01PM +0100, Will Deacon wrote: > > On Tue, Jun 20, 2017 at 06:24:32PM +0200, Luc Van Oostenryck wrote: > > > On Tue, Jun 20, 2017 at 04:49:39PM +0100, Will Deacon wrote: > > > > Looks fine to me, but just wondering whether or not we should also be > > > > passing something to indicate the endianness of the target. Does sparse care > > > > about that? > > > > > > Yes, we should. sparse doesn't care per-se but some macros, structures > > > or whole portion of code may depends on '__{LITTLE,BIG}_ENDIAN__' > > > being defined or not, for example (but I don't think it will make > > > a big difference, at least nothing like the 629904 'constant is so big' > > > warnings we have now due to the missing -m64). > > > > > > For this, you have two possibilities: > > > 1) just doing something like PPC: > > > +ifdef CONFIG_CPU_BIG_ENDIAN > > > +CHECKFLAGS += -D__BIG_ENDIAN__ > > > +else > > > +CHECKFLAGS += -D__LITTLE_ENDIAN__ > > > +endif > > > This will work now. I can't send you a proper patch if you wish. > > > > > > 2) a cleaner solution, IMO, would be to teach sparse about > > > -mlittle-endian/-mbig-endian. In fact I already wrote the patch > > > earlier today. But of course, you will need to wait for the patch > > > to reach sparse's master and then compile sparse yourself or wait > > > for a new release (which shouldn't take much long, though). > > > > If you do that, you could also teach it that AArch64 is 64-bit ;) > > Well, currently sparse is arch agnostic and I think it's a good thing. > For the few arch specifities you have to use some of the '-m' flags > (like -m32/-m64, -msize-long). So, for the moment the '-m64' flag > is needed, thus the patch. Ok, I'll pick your patch up then. The endianness case is more interesting, because I don't think __BIG_ENDIAN__ and __LITTLE_ENDIAN__ are the defines to use; the kernel seems to omit the trailing underscores afaict. Will
On Wed, Jun 21, 2017 at 05:12:54PM +0100, Will Deacon wrote: > On Tue, Jun 20, 2017 at 09:07:40PM +0200, Luc Van Oostenryck wrote: > > Well, currently sparse is arch agnostic and I think it's a good thing. > > For the few arch specifities you have to use some of the '-m' flags > > (like -m32/-m64, -msize-long). So, for the moment the '-m64' flag > > is needed, thus the patch. > > Ok, I'll pick your patch up then. The endianness case is more interesting, > because I don't think __BIG_ENDIAN__ and __LITTLE_ENDIAN__ are the defines > to use; the kernel seems to omit the trailing underscores afaict. I just checked, it's a bit messy. The kernel seems to rely, at least partly, maybe mostly, on CONFIG_CPU_{BIG,LITTLE}_ENDIAN and then __{BIG,LITTLE}_ENDIAN is defined via include/uapi/linux/byteorder/{big,little}_endian.h Otherwise, from the compiler side it seems that __BYTE_ORDER__ & __ORDER_{BIG,LITTLE}_ENDIAN__ is defined consistently. But, for example for arm64, 'gcc -mlittle-endian' gives #define __LITTLE_ENDIAN__ 1 while 'gcc -mbig-endian' doesn't define __BIG_ENDIAN__ but #define __ARM_BIG_ENDIAN 1 *shrugh* I've added support for the -m{big,little}-endian flag to sparse but it seems it will be more complicated for the defines. -- Luc
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index f839ecd91..15d6c1476 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -62,7 +62,7 @@ LD += -EL UTS_MACHINE := aarch64 endif -CHECKFLAGS += -D__aarch64__ +CHECKFLAGS += -D__aarch64__ -m64 ifeq ($(CONFIG_ARM64_MODULE_CMODEL_LARGE), y) KBUILD_CFLAGS_MODULE += -mcmodel=large
When using sparse on the arm64 tree we get many thousands of warnings like 'constant ... is so big it is unsigned long long' or 'shift too big (32) for type unsigned long'. This happens because by default sparse considers the machine as 32bit and defines the size of the types accordingly. Fix this by passing the '-m64' flag to sparse so that sparse can correctly define longs as being 64bit. CC: Catalin Marinas <catalin.marinas@arm.com> CC: Will Deacon <will.deacon@arm.com> CC: linux-arm-kernel@lists.infradead.org Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> --- arch/arm64/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)