* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-01 21:26 ` Matthias Kaehlcke
0 siblings, 0 replies; 14+ messages in thread
From: Matthias Kaehlcke @ 2017-05-01 21:26 UTC (permalink / raw)
To: linux-arm-kernel
clang raises 'asm-operand-widths' warnings in inline assembly code when
the size of an operand is < 64 bits and the operand width is unspecified.
Most warnings are raised in macros, i.e. the datatype of the operand may
vary. Forcing the use of an x register through the 'x' operand modifier
would silence the warning however it involves the risk that for operands
< 64 bits 'unused' bits may be assigned to 64-bit values (more details at
http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
Instead we cast the operand to 64 bits, which also forces the use of a
x register, but without the unexpected behavior.
In gic_write_bpr1() use write_sysreg_s() to write the register. This
aligns the functions with others in this header and fixes an
'asm-operand-widths' warning.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
arch/arm64/include/asm/arch_gicv3.h | 2 +-
arch/arm64/include/asm/barrier.h | 2 +-
arch/arm64/include/asm/uaccess.h | 2 +-
arch/arm64/kernel/armv8_deprecated.c | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
index f37e3a21f6e7..9092d612d8c2 100644
--- a/arch/arm64/include/asm/arch_gicv3.h
+++ b/arch/arm64/include/asm/arch_gicv3.h
@@ -166,7 +166,7 @@ static inline void gic_write_sre(u32 val)
static inline void gic_write_bpr1(u32 val)
{
- asm volatile("msr_s " __stringify(ICC_BPR1_EL1) ", %0" : : "r" (val));
+ write_sysreg_s(val, ICC_BPR1_EL1);
}
#define gic_read_typer(c) readq_relaxed(c)
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 4e0497f581a0..1248401b07ab 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -60,7 +60,7 @@ do { \
break; \
case 8: \
asm volatile ("stlr %1, %0" \
- : "=Q" (*p) : "r" (v) : "memory"); \
+ : "=Q" (*p) : "r" ((__u64)v) : "memory"); \
break; \
} \
} while (0)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 5308d696311b..7db143689694 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -302,7 +302,7 @@ do { \
" .previous\n" \
_ASM_EXTABLE(1b, 3b) \
: "+r" (err) \
- : "r" (x), "r" (addr), "i" (-EFAULT))
+ : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
#define __put_user_err(x, ptr, err) \
do { \
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index 657977e77ec8..79b9fef48b14 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -306,7 +306,7 @@ do { \
_ASM_EXTABLE(0b, 4b) \
_ASM_EXTABLE(1b, 4b) \
: "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \
- : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \
+ : "r" ((__u64)addr), "i" (-EAGAIN), "i" (-EFAULT), \
"i" (__SWP_LL_SC_LOOPS) \
: "memory"); \
uaccess_disable(); \
--
2.13.0.rc0.306.g87b477812d-goog
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-01 21:26 ` Matthias Kaehlcke
@ 2017-05-02 8:25 ` Marc Zyngier
-1 siblings, 0 replies; 14+ messages in thread
From: Marc Zyngier @ 2017-05-02 8:25 UTC (permalink / raw)
To: Matthias Kaehlcke, Catalin Marinas, Will Deacon, Mark Rutland,
Ard Biesheuvel, Christoffer Dall, Vladimir Murzin
Cc: linux-arm-kernel, linux-kernel, Grant Grundler, Greg Hackmann,
Michael Davidson
On 01/05/17 22:26, Matthias Kaehlcke wrote:
> clang raises 'asm-operand-widths' warnings in inline assembly code when
> the size of an operand is < 64 bits and the operand width is unspecified.
> Most warnings are raised in macros, i.e. the datatype of the operand may
> vary. Forcing the use of an x register through the 'x' operand modifier
> would silence the warning however it involves the risk that for operands
> < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> Instead we cast the operand to 64 bits, which also forces the use of a
> x register, but without the unexpected behavior.
>
> In gic_write_bpr1() use write_sysreg_s() to write the register. This
> aligns the functions with others in this header and fixes an
> 'asm-operand-widths' warning.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> arch/arm64/include/asm/arch_gicv3.h | 2 +-
> arch/arm64/include/asm/barrier.h | 2 +-
> arch/arm64/include/asm/uaccess.h | 2 +-
> arch/arm64/kernel/armv8_deprecated.c | 2 +-
> 4 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
> index f37e3a21f6e7..9092d612d8c2 100644
> --- a/arch/arm64/include/asm/arch_gicv3.h
> +++ b/arch/arm64/include/asm/arch_gicv3.h
> @@ -166,7 +166,7 @@ static inline void gic_write_sre(u32 val)
>
> static inline void gic_write_bpr1(u32 val)
> {
> - asm volatile("msr_s " __stringify(ICC_BPR1_EL1) ", %0" : : "r" (val));
> + write_sysreg_s(val, ICC_BPR1_EL1);
> }
For the GICv3 part:
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-02 8:25 ` Marc Zyngier
0 siblings, 0 replies; 14+ messages in thread
From: Marc Zyngier @ 2017-05-02 8:25 UTC (permalink / raw)
To: linux-arm-kernel
On 01/05/17 22:26, Matthias Kaehlcke wrote:
> clang raises 'asm-operand-widths' warnings in inline assembly code when
> the size of an operand is < 64 bits and the operand width is unspecified.
> Most warnings are raised in macros, i.e. the datatype of the operand may
> vary. Forcing the use of an x register through the 'x' operand modifier
> would silence the warning however it involves the risk that for operands
> < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> Instead we cast the operand to 64 bits, which also forces the use of a
> x register, but without the unexpected behavior.
>
> In gic_write_bpr1() use write_sysreg_s() to write the register. This
> aligns the functions with others in this header and fixes an
> 'asm-operand-widths' warning.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> arch/arm64/include/asm/arch_gicv3.h | 2 +-
> arch/arm64/include/asm/barrier.h | 2 +-
> arch/arm64/include/asm/uaccess.h | 2 +-
> arch/arm64/kernel/armv8_deprecated.c | 2 +-
> 4 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
> index f37e3a21f6e7..9092d612d8c2 100644
> --- a/arch/arm64/include/asm/arch_gicv3.h
> +++ b/arch/arm64/include/asm/arch_gicv3.h
> @@ -166,7 +166,7 @@ static inline void gic_write_sre(u32 val)
>
> static inline void gic_write_bpr1(u32 val)
> {
> - asm volatile("msr_s " __stringify(ICC_BPR1_EL1) ", %0" : : "r" (val));
> + write_sysreg_s(val, ICC_BPR1_EL1);
> }
For the GICv3 part:
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-01 21:26 ` Matthias Kaehlcke
@ 2017-05-02 10:27 ` Mark Rutland
-1 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-02 10:27 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Christoffer Dall,
Marc Zyngier, Vladimir Murzin, linux-arm-kernel, linux-kernel,
Grant Grundler, Greg Hackmann, Michael Davidson
Hi Matthias,
On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> clang raises 'asm-operand-widths' warnings in inline assembly code when
> the size of an operand is < 64 bits and the operand width is unspecified.
> Most warnings are raised in macros, i.e. the datatype of the operand may
> vary. Forcing the use of an x register through the 'x' operand modifier
> would silence the warning however it involves the risk that for operands
> < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> Instead we cast the operand to 64 bits, which also forces the use of a
> x register, but without the unexpected behavior.
>
> In gic_write_bpr1() use write_sysreg_s() to write the register. This
> aligns the functions with others in this header and fixes an
> 'asm-operand-widths' warning.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> arch/arm64/include/asm/arch_gicv3.h | 2 +-
> arch/arm64/include/asm/barrier.h | 2 +-
> arch/arm64/include/asm/uaccess.h | 2 +-
> arch/arm64/kernel/armv8_deprecated.c | 2 +-
> 4 files changed, 4 insertions(+), 4 deletions(-)
Thanks for putting this together.
Just to check, are these the only instances that you see clang warning
about?
There are a number of other cases where we can see similar problems
(e.g. passing a u8 value to an smp_store_release() on a u32 variable),
so we need to fix more than the clang warnings.
I'm currently attempting a systematic audit of our inline asm to correct
all instances, looking at:
git grep -e asm \
--and --not -e 'include' \
--and --not -e 'asmlinkage' \
-- arch/arm64
I hope to have patches shortly, and will keep you informed.
Thanks,
Mark.
>
> diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
> index f37e3a21f6e7..9092d612d8c2 100644
> --- a/arch/arm64/include/asm/arch_gicv3.h
> +++ b/arch/arm64/include/asm/arch_gicv3.h
> @@ -166,7 +166,7 @@ static inline void gic_write_sre(u32 val)
>
> static inline void gic_write_bpr1(u32 val)
> {
> - asm volatile("msr_s " __stringify(ICC_BPR1_EL1) ", %0" : : "r" (val));
> + write_sysreg_s(val, ICC_BPR1_EL1);
> }
>
> #define gic_read_typer(c) readq_relaxed(c)
> diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
> index 4e0497f581a0..1248401b07ab 100644
> --- a/arch/arm64/include/asm/barrier.h
> +++ b/arch/arm64/include/asm/barrier.h
> @@ -60,7 +60,7 @@ do { \
> break; \
> case 8: \
> asm volatile ("stlr %1, %0" \
> - : "=Q" (*p) : "r" (v) : "memory"); \
> + : "=Q" (*p) : "r" ((__u64)v) : "memory"); \
> break; \
> } \
> } while (0)
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 5308d696311b..7db143689694 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -302,7 +302,7 @@ do { \
> " .previous\n" \
> _ASM_EXTABLE(1b, 3b) \
> : "+r" (err) \
> - : "r" (x), "r" (addr), "i" (-EFAULT))
> + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
>
> #define __put_user_err(x, ptr, err) \
> do { \
> diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
> index 657977e77ec8..79b9fef48b14 100644
> --- a/arch/arm64/kernel/armv8_deprecated.c
> +++ b/arch/arm64/kernel/armv8_deprecated.c
> @@ -306,7 +306,7 @@ do { \
> _ASM_EXTABLE(0b, 4b) \
> _ASM_EXTABLE(1b, 4b) \
> : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \
> - : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \
> + : "r" ((__u64)addr), "i" (-EAGAIN), "i" (-EFAULT), \
> "i" (__SWP_LL_SC_LOOPS) \
> : "memory"); \
> uaccess_disable(); \
> --
> 2.13.0.rc0.306.g87b477812d-goog
>
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-02 10:27 ` Mark Rutland
0 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-02 10:27 UTC (permalink / raw)
To: linux-arm-kernel
Hi Matthias,
On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> clang raises 'asm-operand-widths' warnings in inline assembly code when
> the size of an operand is < 64 bits and the operand width is unspecified.
> Most warnings are raised in macros, i.e. the datatype of the operand may
> vary. Forcing the use of an x register through the 'x' operand modifier
> would silence the warning however it involves the risk that for operands
> < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> Instead we cast the operand to 64 bits, which also forces the use of a
> x register, but without the unexpected behavior.
>
> In gic_write_bpr1() use write_sysreg_s() to write the register. This
> aligns the functions with others in this header and fixes an
> 'asm-operand-widths' warning.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> arch/arm64/include/asm/arch_gicv3.h | 2 +-
> arch/arm64/include/asm/barrier.h | 2 +-
> arch/arm64/include/asm/uaccess.h | 2 +-
> arch/arm64/kernel/armv8_deprecated.c | 2 +-
> 4 files changed, 4 insertions(+), 4 deletions(-)
Thanks for putting this together.
Just to check, are these the only instances that you see clang warning
about?
There are a number of other cases where we can see similar problems
(e.g. passing a u8 value to an smp_store_release() on a u32 variable),
so we need to fix more than the clang warnings.
I'm currently attempting a systematic audit of our inline asm to correct
all instances, looking at:
git grep -e asm \
--and --not -e 'include' \
--and --not -e 'asmlinkage' \
-- arch/arm64
I hope to have patches shortly, and will keep you informed.
Thanks,
Mark.
>
> diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
> index f37e3a21f6e7..9092d612d8c2 100644
> --- a/arch/arm64/include/asm/arch_gicv3.h
> +++ b/arch/arm64/include/asm/arch_gicv3.h
> @@ -166,7 +166,7 @@ static inline void gic_write_sre(u32 val)
>
> static inline void gic_write_bpr1(u32 val)
> {
> - asm volatile("msr_s " __stringify(ICC_BPR1_EL1) ", %0" : : "r" (val));
> + write_sysreg_s(val, ICC_BPR1_EL1);
> }
>
> #define gic_read_typer(c) readq_relaxed(c)
> diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
> index 4e0497f581a0..1248401b07ab 100644
> --- a/arch/arm64/include/asm/barrier.h
> +++ b/arch/arm64/include/asm/barrier.h
> @@ -60,7 +60,7 @@ do { \
> break; \
> case 8: \
> asm volatile ("stlr %1, %0" \
> - : "=Q" (*p) : "r" (v) : "memory"); \
> + : "=Q" (*p) : "r" ((__u64)v) : "memory"); \
> break; \
> } \
> } while (0)
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 5308d696311b..7db143689694 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -302,7 +302,7 @@ do { \
> " .previous\n" \
> _ASM_EXTABLE(1b, 3b) \
> : "+r" (err) \
> - : "r" (x), "r" (addr), "i" (-EFAULT))
> + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
>
> #define __put_user_err(x, ptr, err) \
> do { \
> diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
> index 657977e77ec8..79b9fef48b14 100644
> --- a/arch/arm64/kernel/armv8_deprecated.c
> +++ b/arch/arm64/kernel/armv8_deprecated.c
> @@ -306,7 +306,7 @@ do { \
> _ASM_EXTABLE(0b, 4b) \
> _ASM_EXTABLE(1b, 4b) \
> : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \
> - : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \
> + : "r" ((__u64)addr), "i" (-EAGAIN), "i" (-EFAULT), \
> "i" (__SWP_LL_SC_LOOPS) \
> : "memory"); \
> uaccess_disable(); \
> --
> 2.13.0.rc0.306.g87b477812d-goog
>
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-02 10:27 ` Mark Rutland
@ 2017-05-02 17:26 ` Matthias Kaehlcke
-1 siblings, 0 replies; 14+ messages in thread
From: Matthias Kaehlcke @ 2017-05-02 17:26 UTC (permalink / raw)
To: Mark Rutland
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Christoffer Dall,
Marc Zyngier, Vladimir Murzin, linux-arm-kernel, linux-kernel,
Grant Grundler, Greg Hackmann, Michael Davidson
Hi Mark,
El Tue, May 02, 2017 at 11:27:18AM +0100 Mark Rutland ha dit:
> On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > clang raises 'asm-operand-widths' warnings in inline assembly code when
> > the size of an operand is < 64 bits and the operand width is unspecified.
> > Most warnings are raised in macros, i.e. the datatype of the operand may
> > vary. Forcing the use of an x register through the 'x' operand modifier
> > would silence the warning however it involves the risk that for operands
> > < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> > Instead we cast the operand to 64 bits, which also forces the use of a
> > x register, but without the unexpected behavior.
> >
> > In gic_write_bpr1() use write_sysreg_s() to write the register. This
> > aligns the functions with others in this header and fixes an
> > 'asm-operand-widths' warning.
> >
> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > ---
> > arch/arm64/include/asm/arch_gicv3.h | 2 +-
> > arch/arm64/include/asm/barrier.h | 2 +-
> > arch/arm64/include/asm/uaccess.h | 2 +-
> > arch/arm64/kernel/armv8_deprecated.c | 2 +-
> > 4 files changed, 4 insertions(+), 4 deletions(-)
>
> Thanks for putting this together.
>
> Just to check, are these the only instances that you see clang warning
> about?
Yes, these are the only warnings clang raises in my builds (custom and
defconfig).
> There are a number of other cases where we can see similar problems
> (e.g. passing a u8 value to an smp_store_release() on a u32 variable),
> so we need to fix more than the clang warnings.
>
> I'm currently attempting a systematic audit of our inline asm to correct
> all instances, looking at:
>
> git grep -e asm \
> --and --not -e 'include' \
> --and --not -e 'asmlinkage' \
> -- arch/arm64
>
> I hope to have patches shortly, and will keep you informed.
Sounds good!
Thanks
Matthias
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-02 17:26 ` Matthias Kaehlcke
0 siblings, 0 replies; 14+ messages in thread
From: Matthias Kaehlcke @ 2017-05-02 17:26 UTC (permalink / raw)
To: linux-arm-kernel
Hi Mark,
El Tue, May 02, 2017 at 11:27:18AM +0100 Mark Rutland ha dit:
> On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > clang raises 'asm-operand-widths' warnings in inline assembly code when
> > the size of an operand is < 64 bits and the operand width is unspecified.
> > Most warnings are raised in macros, i.e. the datatype of the operand may
> > vary. Forcing the use of an x register through the 'x' operand modifier
> > would silence the warning however it involves the risk that for operands
> > < 64 bits 'unused' bits may be assigned to 64-bit values (more details at
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503816.html).
> > Instead we cast the operand to 64 bits, which also forces the use of a
> > x register, but without the unexpected behavior.
> >
> > In gic_write_bpr1() use write_sysreg_s() to write the register. This
> > aligns the functions with others in this header and fixes an
> > 'asm-operand-widths' warning.
> >
> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > ---
> > arch/arm64/include/asm/arch_gicv3.h | 2 +-
> > arch/arm64/include/asm/barrier.h | 2 +-
> > arch/arm64/include/asm/uaccess.h | 2 +-
> > arch/arm64/kernel/armv8_deprecated.c | 2 +-
> > 4 files changed, 4 insertions(+), 4 deletions(-)
>
> Thanks for putting this together.
>
> Just to check, are these the only instances that you see clang warning
> about?
Yes, these are the only warnings clang raises in my builds (custom and
defconfig).
> There are a number of other cases where we can see similar problems
> (e.g. passing a u8 value to an smp_store_release() on a u32 variable),
> so we need to fix more than the clang warnings.
>
> I'm currently attempting a systematic audit of our inline asm to correct
> all instances, looking at:
>
> git grep -e asm \
> --and --not -e 'include' \
> --and --not -e 'asmlinkage' \
> -- arch/arm64
>
> I hope to have patches shortly, and will keep you informed.
Sounds good!
Thanks
Matthias
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-01 21:26 ` Matthias Kaehlcke
@ 2017-05-02 17:29 ` Mark Rutland
-1 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-02 17:29 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Christoffer Dall,
Marc Zyngier, Vladimir Murzin, linux-arm-kernel, linux-kernel,
Grant Grundler, Greg Hackmann, Michael Davidson
Hi,
On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 5308d696311b..7db143689694 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -302,7 +302,7 @@ do { \
> " .previous\n" \
> _ASM_EXTABLE(1b, 3b) \
> : "+r" (err) \
> - : "r" (x), "r" (addr), "i" (-EFAULT))
> + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
>
For reference, do you have the warning for this case to hand?
In __put_user_err() we make __pu_val the same type as *ptr, then we
switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
For cases 1, 2, and 4, we use "%w" as the register template.
So I can't see why we'd need this cast in __put_user_err().
I must be missing something.
Thanks,
Mark.
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-02 17:29 ` Mark Rutland
0 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-02 17:29 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 5308d696311b..7db143689694 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -302,7 +302,7 @@ do { \
> " .previous\n" \
> _ASM_EXTABLE(1b, 3b) \
> : "+r" (err) \
> - : "r" (x), "r" (addr), "i" (-EFAULT))
> + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
>
For reference, do you have the warning for this case to hand?
In __put_user_err() we make __pu_val the same type as *ptr, then we
switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
For cases 1, 2, and 4, we use "%w" as the register template.
So I can't see why we'd need this cast in __put_user_err().
I must be missing something.
Thanks,
Mark.
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-02 17:29 ` Mark Rutland
@ 2017-05-02 18:52 ` Matthias Kaehlcke
-1 siblings, 0 replies; 14+ messages in thread
From: Matthias Kaehlcke @ 2017-05-02 18:52 UTC (permalink / raw)
To: Mark Rutland
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Christoffer Dall,
Marc Zyngier, Vladimir Murzin, linux-arm-kernel, linux-kernel,
Grant Grundler, Greg Hackmann, Michael Davidson
Hi,
El Tue, May 02, 2017 at 06:29:48PM +0100 Mark Rutland ha dit:
> On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > index 5308d696311b..7db143689694 100644
> > --- a/arch/arm64/include/asm/uaccess.h
> > +++ b/arch/arm64/include/asm/uaccess.h
> > @@ -302,7 +302,7 @@ do { \
> > " .previous\n" \
> > _ASM_EXTABLE(1b, 3b) \
> > : "+r" (err) \
> > - : "r" (x), "r" (addr), "i" (-EFAULT))
> > + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
> >
>
> For reference, do you have the warning for this case to hand?
>
> In __put_user_err() we make __pu_val the same type as *ptr, then we
> switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
> For cases 1, 2, and 4, we use "%w" as the register template.
>
> So I can't see why we'd need this cast in __put_user_err().
>
> I must be missing something.
This is one of many instances:
./include/linux/pagemap.h:554:10: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
return __put_user(0, end);
^
./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
__put_user_err((x), (ptr), __pu_err); \
^
./arch/arm64/include/asm/uaccess.h:326:38: note: expanded from macro '__put_user_err'
__put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
^
./include/linux/pagemap.h:554:10: note: use constraint modifier "w"
./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
__put_user_err((x), (ptr), __pu_err); \
^
./arch/arm64/include/asm/uaccess.h:326:34: note: expanded from macro '__put_user_err'
__put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
^
'end' is a char pointer, it is not clear to me why we would end up in
the width == 8 branch.
Matthias
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-02 18:52 ` Matthias Kaehlcke
0 siblings, 0 replies; 14+ messages in thread
From: Matthias Kaehlcke @ 2017-05-02 18:52 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
El Tue, May 02, 2017 at 06:29:48PM +0100 Mark Rutland ha dit:
> On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > index 5308d696311b..7db143689694 100644
> > --- a/arch/arm64/include/asm/uaccess.h
> > +++ b/arch/arm64/include/asm/uaccess.h
> > @@ -302,7 +302,7 @@ do { \
> > " .previous\n" \
> > _ASM_EXTABLE(1b, 3b) \
> > : "+r" (err) \
> > - : "r" (x), "r" (addr), "i" (-EFAULT))
> > + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
> >
>
> For reference, do you have the warning for this case to hand?
>
> In __put_user_err() we make __pu_val the same type as *ptr, then we
> switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
> For cases 1, 2, and 4, we use "%w" as the register template.
>
> So I can't see why we'd need this cast in __put_user_err().
>
> I must be missing something.
This is one of many instances:
./include/linux/pagemap.h:554:10: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
return __put_user(0, end);
^
./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
__put_user_err((x), (ptr), __pu_err); \
^
./arch/arm64/include/asm/uaccess.h:326:38: note: expanded from macro '__put_user_err'
__put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
^
./include/linux/pagemap.h:554:10: note: use constraint modifier "w"
./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
__put_user_err((x), (ptr), __pu_err); \
^
./arch/arm64/include/asm/uaccess.h:326:34: note: expanded from macro '__put_user_err'
__put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
^
'end' is a char pointer, it is not clear to me why we would end up in
the width == 8 branch.
Matthias
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
2017-05-02 18:52 ` Matthias Kaehlcke
@ 2017-05-03 10:51 ` Mark Rutland
-1 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-03 10:51 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Christoffer Dall,
Marc Zyngier, Vladimir Murzin, linux-arm-kernel, linux-kernel,
Grant Grundler, Greg Hackmann, Michael Davidson
On Tue, May 02, 2017 at 11:52:12AM -0700, Matthias Kaehlcke wrote:
> El Tue, May 02, 2017 at 06:29:48PM +0100 Mark Rutland ha dit:
> > On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > index 5308d696311b..7db143689694 100644
> > > --- a/arch/arm64/include/asm/uaccess.h
> > > +++ b/arch/arm64/include/asm/uaccess.h
> > > @@ -302,7 +302,7 @@ do { \
> > > " .previous\n" \
> > > _ASM_EXTABLE(1b, 3b) \
> > > : "+r" (err) \
> > > - : "r" (x), "r" (addr), "i" (-EFAULT))
> > > + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
> > >
> >
> > For reference, do you have the warning for this case to hand?
> >
> > In __put_user_err() we make __pu_val the same type as *ptr, then we
> > switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
> > For cases 1, 2, and 4, we use "%w" as the register template.
> >
> > So I can't see why we'd need this cast in __put_user_err().
> >
> > I must be missing something.
>
> This is one of many instances:
>
> ./include/linux/pagemap.h:554:10: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
> return __put_user(0, end);
> ^
> ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
> __put_user_err((x), (ptr), __pu_err); \
> ^
> ./arch/arm64/include/asm/uaccess.h:326:38: note: expanded from macro '__put_user_err'
> __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
> ^
> ./include/linux/pagemap.h:554:10: note: use constraint modifier "w"
> ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
> __put_user_err((x), (ptr), __pu_err); \
> ^
> ./arch/arm64/include/asm/uaccess.h:326:34: note: expanded from macro '__put_user_err'
> __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
> ^
Thanks for the log above!
> 'end' is a char pointer, it is not clear to me why we would end up in
> the width == 8 branch.
Indeed.
I took a look, and I think the issue is that clang instantiates the
assembly in all cases, producing the warning, *then* optimizes away the
unreachable cases.
If you ask clang to build the following:
----
#define __put_user(val, ptr) \
do { \
__typeof__(*(ptr)) __pu_val = (val); \
switch (sizeof(*(ptr))) { \
case 1: \
asm volatile ("strb %w1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 2: \
asm volatile ("strh %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 4: \
asm volatile ("str %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 8: \
asm volatile ("str %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
} \
} while (0)
void put_char(char in, char *ptr)
{
__put_user(in, ptr);
}
----
It complains for all of the unmatched cases:
----
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:11:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:10:23: note: expanded from macro '__put_user'
asm volatile ("strh %1, %0" \
^
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:15:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:14:22: note: expanded from macro '__put_user'
asm volatile ("str %1, %0" \
^
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:19:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:18:22: note: expanded from macro '__put_user'
asm volatile ("str %1, %0" \
^
3 warnings generated.
----
AFAICT, in all other cases where we switch(sizeof(...)), we (will) use
an explicit cast on the parameter, which placates clang.
I think the best option is to get rid of __pu_val, and have an explicit
cast of x in each case of the switch statement. I'll add that to my asm
fixups series, with your Reported-by.
Thanks,
Mark.
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings
@ 2017-05-03 10:51 ` Mark Rutland
0 siblings, 0 replies; 14+ messages in thread
From: Mark Rutland @ 2017-05-03 10:51 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, May 02, 2017 at 11:52:12AM -0700, Matthias Kaehlcke wrote:
> El Tue, May 02, 2017 at 06:29:48PM +0100 Mark Rutland ha dit:
> > On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote:
> > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > index 5308d696311b..7db143689694 100644
> > > --- a/arch/arm64/include/asm/uaccess.h
> > > +++ b/arch/arm64/include/asm/uaccess.h
> > > @@ -302,7 +302,7 @@ do { \
> > > " .previous\n" \
> > > _ASM_EXTABLE(1b, 3b) \
> > > : "+r" (err) \
> > > - : "r" (x), "r" (addr), "i" (-EFAULT))
> > > + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT))
> > >
> >
> > For reference, do you have the warning for this case to hand?
> >
> > In __put_user_err() we make __pu_val the same type as *ptr, then we
> > switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x.
> > For cases 1, 2, and 4, we use "%w" as the register template.
> >
> > So I can't see why we'd need this cast in __put_user_err().
> >
> > I must be missing something.
>
> This is one of many instances:
>
> ./include/linux/pagemap.h:554:10: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
> return __put_user(0, end);
> ^
> ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
> __put_user_err((x), (ptr), __pu_err); \
> ^
> ./arch/arm64/include/asm/uaccess.h:326:38: note: expanded from macro '__put_user_err'
> __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
> ^
> ./include/linux/pagemap.h:554:10: note: use constraint modifier "w"
> ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user'
> __put_user_err((x), (ptr), __pu_err); \
> ^
> ./arch/arm64/include/asm/uaccess.h:326:34: note: expanded from macro '__put_user_err'
> __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
> ^
Thanks for the log above!
> 'end' is a char pointer, it is not clear to me why we would end up in
> the width == 8 branch.
Indeed.
I took a look, and I think the issue is that clang instantiates the
assembly in all cases, producing the warning, *then* optimizes away the
unreachable cases.
If you ask clang to build the following:
----
#define __put_user(val, ptr) \
do { \
__typeof__(*(ptr)) __pu_val = (val); \
switch (sizeof(*(ptr))) { \
case 1: \
asm volatile ("strb %w1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 2: \
asm volatile ("strh %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 4: \
asm volatile ("str %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
case 8: \
asm volatile ("str %1, %0" \
: "+Q" (*(ptr)) : "r" (__pu_val)); \
break; \
} \
} while (0)
void put_char(char in, char *ptr)
{
__put_user(in, ptr);
}
----
It complains for all of the unmatched cases:
----
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:11:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:10:23: note: expanded from macro '__put_user'
asm volatile ("strh %1, %0" \
^
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:15:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:14:22: note: expanded from macro '__put_user'
asm volatile ("str %1, %0" \
^
size-switch.c:26:2: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
__put_user(in, ptr);
^
size-switch.c:19:28: note: expanded from macro '__put_user'
: "+Q" (*(ptr)) : "r" (__pu_val)); \
^
size-switch.c:26:2: note: use constraint modifier "w"
size-switch.c:18:22: note: expanded from macro '__put_user'
asm volatile ("str %1, %0" \
^
3 warnings generated.
----
AFAICT, in all other cases where we switch(sizeof(...)), we (will) use
an explicit cast on the parameter, which placates clang.
I think the best option is to get rid of __pu_val, and have an explicit
cast of x in each case of the switch statement. I'll add that to my asm
fixups series, with your Reported-by.
Thanks,
Mark.
^ permalink raw reply [flat|nested] 14+ messages in thread