linux-next: Tree for Feb 9

Message ID 20160209120032.GB19840@leverpostej
State New
Headers show

Commit Message

Mark Rutland Feb. 9, 2016, noon
Hi,

On Tue, Feb 09, 2016 at 01:04:28PM +0530, Sudip Mukherjee wrote:
> On Tue, Feb 09, 2016 at 04:41:04PM +1100, Stephen Rothwell wrote:

> > Hi all,

> > 

> > Changes since 20160208:

> 

> tilepro, tilegx, mips defconfig build fails with the error:

> ../include/asm-generic/fixmap.h: In function '__set_fixmap_offset':

> ../include/asm-generic/fixmap.h:77:2: error: implicit declaration of

> function '__set_fixmap' [-Werror=implicit-function-declaration]

> 

> caused by:

> commit ac4c0ac73485 ("asm-generic: make __set_fixmap_offset a static inline")

> 

> Reverting the commit fixes the issue.


Sorry about this.

Is seems any arch without its own __set_fixmap may be adversely
affected.

I can't easily stub __set_fixmap as it's not implemented as a macro.

I think we can stick with a macro and remove 'addr', by returning the
result of the expression directly. As fix_to_virt gave us an unsigned
long I think the types should line up (i.e. the result will be at least
unsigned long wide).

Arnd, would you be happy with the below patch instead? 

It builds fine for arm, arm64, mips, and tilegx in local testing.

Thanks,
Mark.
---->8----
From d30ae6ebbae2c969ee36ef548711493b64c2be41 Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@arm.com>

Date: Tue, 9 Feb 2016 11:43:55 +0000
Subject: [PATCH] asm-generic: Avoid variable in __set_fixmap_offset

Currently __set_fixmap_offset is a macro function which has a local
variable called 'addr'. If a caller passes a 'phys' parameter which is
derived from a variable also called 'addr', the local variable will
shadow this, and the compiler will complain about the use of an
uninitialized variable.

It is likely that fixmap users may use the name 'addr' for variables
that may be directly passed to __set_fixmap_offset, or that may be
indirectly generated via other macros. Rather than placing the burden on
callers to avoid the name 'addr', this patch removes the temporary
'addr' variable in __set_fixmap_offset, directly returning the result of
the address calculation.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 include/asm-generic/fixmap.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

-- 
1.9.1

Comments

Geert Uytterhoeven Feb. 9, 2016, 1:48 p.m. | #1
On Tue, Feb 9, 2016 at 1:00 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> On Tue, Feb 09, 2016 at 01:04:28PM +0530, Sudip Mukherjee wrote:

>> On Tue, Feb 09, 2016 at 04:41:04PM +1100, Stephen Rothwell wrote:

>> > Changes since 20160208:

>>

>> tilepro, tilegx, mips defconfig build fails with the error:

>> ../include/asm-generic/fixmap.h: In function '__set_fixmap_offset':

>> ../include/asm-generic/fixmap.h:77:2: error: implicit declaration of

>> function '__set_fixmap' [-Werror=implicit-function-declaration]

>>

>> caused by:

>> commit ac4c0ac73485 ("asm-generic: make __set_fixmap_offset a static inline")

>>

>> Reverting the commit fixes the issue.

>

> Sorry about this.

>

> Is seems any arch without its own __set_fixmap may be adversely

> affected.

>

> I can't easily stub __set_fixmap as it's not implemented as a macro.


But you can add a forward declaration?

BTW, it seems the following drivers rely on <asm/fixmap.h>, which is
not available on all architectures:
    drivers/firewire/init_ohci1394_dma.c:#include <asm/fixmap.h>
    drivers/tty/serial/earlycon.c:#include <asm/fixmap.h>
    drivers/usb/early/ehci-dbgp.c:#include <asm/fixmap.h>

> I think we can stick with a macro and remove 'addr', by returning the

> result of the expression directly. As fix_to_virt gave us an unsigned

> long I think the types should line up (i.e. the result will be at least

> unsigned long wide).

>

> Arnd, would you be happy with the below patch instead?


> --- a/include/asm-generic/fixmap.h

> +++ b/include/asm-generic/fixmap.h

> @@ -72,10 +72,8 @@ static inline unsigned long virt_to_fix(const unsigned long vaddr)

>  /* Return a pointer with offset calculated */

>  #define __set_fixmap_offset(idx, phys, flags)                \

>  ({                                                           \

> -       unsigned long addr;                                   \

>         __set_fixmap(idx, phys, flags);                       \


Missing parentheses:

    __set_fixmap((idx), (phys), (flags));

> -       addr = fix_to_virt(idx) + ((phys) & (PAGE_SIZE - 1)); \

> -       addr;                                                 \

> +       fix_to_virt(idx) + ((phys) & (PAGE_SIZE - 1));        \

>  })


"idx" and "phys" are evaluated multiple times, which can lead to subtle bugs.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Mark Rutland Feb. 9, 2016, 2:35 p.m. | #2
On Tue, Feb 09, 2016 at 02:48:26PM +0100, Geert Uytterhoeven wrote:
> On Tue, Feb 9, 2016 at 1:00 PM, Mark Rutland <mark.rutland@arm.com> wrote:

> > On Tue, Feb 09, 2016 at 01:04:28PM +0530, Sudip Mukherjee wrote:

> >> On Tue, Feb 09, 2016 at 04:41:04PM +1100, Stephen Rothwell wrote:

> >> > Changes since 20160208:

> >>

> >> tilepro, tilegx, mips defconfig build fails with the error:

> >> ../include/asm-generic/fixmap.h: In function '__set_fixmap_offset':

> >> ../include/asm-generic/fixmap.h:77:2: error: implicit declaration of

> >> function '__set_fixmap' [-Werror=implicit-function-declaration]

> >>

> >> caused by:

> >> commit ac4c0ac73485 ("asm-generic: make __set_fixmap_offset a static inline")

> >>

> >> Reverting the commit fixes the issue.

> >

> > Sorry about this.

> >

> > Is seems any arch without its own __set_fixmap may be adversely

> > affected.

> >

> > I can't easily stub __set_fixmap as it's not implemented as a macro.

> 

> But you can add a forward declaration?


Good point. That seems to work (tested on arm64, mips, tilegx).

Arnd, Catalin, happy with the bloew fixup to the original patch?

Mark.

---->8----
From e53a0fa34689cca13846475fb5a7cb4c7da87384 Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@arm.com>

Date: Tue, 9 Feb 2016 14:27:36 +0000
Subject: [PATCH] asm-generic: Fix build when __set_fixmap is absent

Commit ac4c0ac73485 ("asm-generic: make __set_fixmap_offset a static
inline") relied on the architecture code to define a __set_fixmap
function, even if unused. This broke the build for architectures which
do not implement __set_fixmap:

../include/asm-generic/fixmap.h:Infunction'__set_fixmap_offset':
../include/asm-generic/fixmap.h:77:2:error:implicitdeclarationof
function'__set_fixmap'[-Werror=implicit-function-declaration]

As we only require the prototype to be present, add this to
asm-generic/fixmap.h, preventing build failures on these architectures.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
---
 include/asm-generic/fixmap.h | 2 ++
 1 file changed, 2 insertions(+)

-- 
1.9.1diff --git a/include/asm-generic/fixmap.h b/include/asm-generic/fixmap.h
index f9c27b6..e5255ff 100644
--- a/include/asm-generic/fixmap.h
+++ b/include/asm-generic/fixmap.h
@@ -69,6 +69,8 @@ static inline unsigned long virt_to_fix(const unsigned long vaddr)
 	__set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR)
 #endif
 
+void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
+
 /* Return a pointer with offset calculated */
 static inline unsigned long __set_fixmap_offset(enum fixed_addresses idx,
 						phys_addr_t phys,

Patch

diff --git a/include/asm-generic/fixmap.h b/include/asm-generic/fixmap.h
index 1cbb833..ae2cc43 100644
--- a/include/asm-generic/fixmap.h
+++ b/include/asm-generic/fixmap.h
@@ -72,10 +72,8 @@  static inline unsigned long virt_to_fix(const unsigned long vaddr)
 /* Return a pointer with offset calculated */
 #define __set_fixmap_offset(idx, phys, flags)		      \
 ({							      \
-	unsigned long addr;				      \
 	__set_fixmap(idx, phys, flags);			      \
-	addr = fix_to_virt(idx) + ((phys) & (PAGE_SIZE - 1)); \
-	addr;						      \
+	fix_to_virt(idx) + ((phys) & (PAGE_SIZE - 1));	      \
 })
 
 #define set_fixmap_offset(idx, phys) \