Depending on ABI "long long" type of a particular 32-bit CPU might be aligned by either word (32-bits) or double word (64-bits). Make sure "data" is really 64-bit aligned for any 32-bit CPU.
At least for 32-bit ARC cores ABI requires "long long" types to be aligned by normal 32-bit word. This makes "data" field aligned to 12 bytes. Which is still OK as long as we use 32-bit data only.
But once we want to use native atomic64_t type (i.e. when we use special instructions LLOCKD/SCONDD for accessing 64-bit data) we easily hit misaligned access exception.
That's because even on CPUs capable of non-aligned data access LL/SC instructions require strict alignment.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org ---
Changes v1 -> v2:
* Reworded commit message * Inserted comment right in source [Thomas]
drivers/base/devres.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/base/devres.c b/drivers/base/devres.c index f98a097e73f2..466fa59c866a 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -24,8 +24,12 @@ struct devres_node {
struct devres { struct devres_node node; - /* -- 3 pointers */ - unsigned long long data[]; /* guarantee ull alignment */ + /* + * Depending on ABI "long long" type of a particular 32-bit CPU + * might be aligned by either word (32-bits) or double word (64-bits). + * Make sure "data" is really 64-bit aligned for any 32-bit CPU. + */ + unsigned long long data[] __aligned(sizeof(unsigned long long)); };
struct devres_group {
On Sun, Jul 08, 2018 at 08:56:21PM +0300, Alexey Brodkin wrote:
Depending on ABI "long long" type of a particular 32-bit CPU might be aligned by either word (32-bits) or double word (64-bits). Make sure "data" is really 64-bit aligned for any 32-bit CPU.
At least for 32-bit ARC cores ABI requires "long long" types to be aligned by normal 32-bit word. This makes "data" field aligned to 12 bytes. Which is still OK as long as we use 32-bit data only.
But once we want to use native atomic64_t type (i.e. when we use special instructions LLOCKD/SCONDD for accessing 64-bit data) we easily hit misaligned access exception.
That's because even on CPUs capable of non-aligned data access LL/SC instructions require strict alignment.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org
Changes v1 -> v2:
- Reworded commit message
- Inserted comment right in source [Thomas]
drivers/base/devres.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Always use scripts/get_maintainer.pl to properly cc: the needed developer/maintainer. As it is, this patch is going to get dropped on the floor, sorry...
greg k-h
Hi Greg,
вс, 8 июл. 2018 г. в 21:40, Greg KH greg@kroah.com:
On Sun, Jul 08, 2018 at 08:56:21PM +0300, Alexey Brodkin wrote:
Depending on ABI "long long" type of a particular 32-bit CPU might be aligned by either word (32-bits) or double word (64-bits). Make sure "data" is really 64-bit aligned for any 32-bit CPU.
At least for 32-bit ARC cores ABI requires "long long" types to be aligned by normal 32-bit word. This makes "data" field aligned to 12 bytes. Which is still OK as long as we use 32-bit data only.
But once we want to use native atomic64_t type (i.e. when we use special instructions LLOCKD/SCONDD for accessing 64-bit data) we easily hit misaligned access exception.
That's because even on CPUs capable of non-aligned data access LL/SC instructions require strict alignment.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org
Changes v1 -> v2:
- Reworded commit message
- Inserted comment right in source [Thomas]
drivers/base/devres.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Always use scripts/get_maintainer.pl to properly cc: the needed developer/maintainer. As it is, this patch is going to get dropped on the floor, sorry...
Right I was way too relaxed dealing with very generic stuff which might get not that much of attention as more narrow topics or subsystems. But anyways get_maintainer.pl says you're the guy so do I need to do anything extra still or it's OK for this time?
-Alexey
On Sun, Jul 08, 2018 at 09:45:31PM +0300, Алексей Бродкин wrote:
Hi Greg,
вс, 8 июл. 2018 г. в 21:40, Greg KH greg@kroah.com:
On Sun, Jul 08, 2018 at 08:56:21PM +0300, Alexey Brodkin wrote:
Depending on ABI "long long" type of a particular 32-bit CPU might be aligned by either word (32-bits) or double word (64-bits). Make sure "data" is really 64-bit aligned for any 32-bit CPU.
At least for 32-bit ARC cores ABI requires "long long" types to be aligned by normal 32-bit word. This makes "data" field aligned to 12 bytes. Which is still OK as long as we use 32-bit data only.
But once we want to use native atomic64_t type (i.e. when we use special instructions LLOCKD/SCONDD for accessing 64-bit data) we easily hit misaligned access exception.
That's because even on CPUs capable of non-aligned data access LL/SC instructions require strict alignment.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org
Changes v1 -> v2:
- Reworded commit message
- Inserted comment right in source [Thomas]
drivers/base/devres.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Always use scripts/get_maintainer.pl to properly cc: the needed developer/maintainer. As it is, this patch is going to get dropped on the floor, sorry...
Right I was way too relaxed dealing with very generic stuff which might get not that much of attention as more narrow topics or subsystems. But anyways get_maintainer.pl says you're the guy so do I need to do anything extra still or it's OK for this time?
Please resend it properly, it is not in my patch queue anywhere...
greg k-h
linux-stable-mirror@lists.linaro.org
-
Alexey Brodkin -
Greg KH -
Алексей Бродкин