Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-09-06 Thread Catalin Marinas
On Fri, 1 Jul 2022 15:53:22 +0200, Ard Biesheuvel wrote: > The 32-bit ARM kernel implements fixups on behalf of user space when > using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit > aligned. This is not something that is supported by the architecture, > but was done anyway

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-09-05 Thread Catalin Marinas
On Mon, Sep 05, 2022 at 12:04:47PM +0200, Ard Biesheuvel wrote: > On Wed, 31 Aug 2022 at 19:07, Catalin Marinas wrote: > > On Fri, Jul 01, 2022 at 03:53:22PM +0200, Ard Biesheuvel wrote: > > > +config COMPAT_ALIGNMENT_FIXUPS > > > + bool "Fix up misaligned multi-word loads and stores in user

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-09-05 Thread Ard Biesheuvel
On Wed, 31 Aug 2022 at 19:07, Catalin Marinas wrote: > > On Fri, Jul 01, 2022 at 03:53:22PM +0200, Ard Biesheuvel wrote: > > The 32-bit ARM kernel implements fixups on behalf of user space when > > using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit > > aligned. This is not

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-31 Thread Catalin Marinas
On Fri, Jul 01, 2022 at 03:53:22PM +0200, Ard Biesheuvel wrote: > The 32-bit ARM kernel implements fixups on behalf of user space when > using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit > aligned. This is not something that is supported by the architecture, > but was done

Clarification [WAS Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads]

2022-08-19 Thread Andrew M.A. Cater
On Fri, Aug 19, 2022 at 03:19:23PM +0200, LinAdmin wrote: > Good night Andy > > Is it possible you never have heard of the Streisand effect? > > Regards > LinAdmin > Hi LinAdmin, As one of the people who wrote the FAQ for the debian-user mailing list, not only have I heard of it, I

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-19 Thread LinAdmin
Good night Andy Is it possible you never have heard of the Streisand effect? Regards LinAdmin On 18.08.22 18:58, Andrew M.A. Cater wrote: > On Thu, Aug 18, 2022 at 05:21:19PM +0200, LinAdmin wrote: >> I do know that you do not like my comment that 32bit on Pi4 >> is much more efficient than 64

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-18 Thread Andrew M.A. Cater
On Thu, Aug 18, 2022 at 05:21:19PM +0200, LinAdmin wrote: > I do know that you do not like my comment that 32bit on Pi4 > is much more efficient than 64 Bit ... > Linadmin > > Good afternoon, LinAdmin It does appear to me that this comment is not directly relevant to this message and might not

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-18 Thread LinAdmin
I do know that you do not like my comment that 32bit on Pi4 is much more efficient than 64 Bit ... Linadmin On 17.08.22 11:47, Arnd Bergmann wrote: > On Tue, Aug 16, 2022 at 10:29 PM Ard Biesheuvel wrote: >> Thanks for chiming in. >> >> At this point, it is really up to the maintainers to decide

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-17 Thread Arnd Bergmann
On Tue, Aug 16, 2022 at 10:29 PM Ard Biesheuvel wrote: > > Thanks for chiming in. > > At this point, it is really up to the maintainers to decide whether > the maintenance burden is worth it. The code itself seems pretty > uncontroversial afaict. > > Might other distros be in a similar situation?

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-16 Thread Ard Biesheuvel
On Tue, 16 Aug 2022 at 21:29, Aurelien Jarno wrote: > > Hi, > > On 2022-07-14 02:52, Wookey wrote: > > On 2022-07-01 15:53 +0200, Ard Biesheuvel wrote: > > > The 32-bit ARM kernel implements fixups on behalf of user space when > > > using LDM/STM or LDRD/STRD instructions on addresses that are

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-08-16 Thread Aurelien Jarno
Hi, On 2022-07-14 02:52, Wookey wrote: > On 2022-07-01 15:53 +0200, Ard Biesheuvel wrote: > > The 32-bit ARM kernel implements fixups on behalf of user space when > > using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit > > aligned. > > > This feature is one of the remaining

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-07-15 Thread LinAdmin
Pi 4 has much more throughput in 32-bit modes but the so called experts of Debian decided to abandon it :-( On 14.07.22 03:52, Wookey wrote: > On 2022-07-01 15:53 +0200, Ard Biesheuvel wrote: >> The 32-bit ARM kernel implements fixups on behalf of user space when >> using LDM/STM or LDRD/STRD

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-07-13 Thread Wookey
On 2022-07-01 15:53 +0200, Ard Biesheuvel wrote: > The 32-bit ARM kernel implements fixups on behalf of user space when > using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit > aligned. > This feature is one of the remaining impediments to being able to switch > to 64-bit

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-07-01 Thread gene heskett
On 7/1/22 10:14, Ard Biesheuvel wrote: The 32-bit ARM kernel implements fixups on behalf of user space when using LDM/STM or LDRD/STRD instructions on addresses that are not 32-bit aligned. This is not something that is supported by the architecture, but was done anyway to increase compatibility

Re: [PATCH v2] arm64: compat: Implement misalignment fixups for multiword loads

2022-07-01 Thread Arnd Bergmann
On Fri, Jul 1, 2022 at 3:53 PM Ard Biesheuvel wrote: > > v2: - drop some obsolete comments > - emit a perf alignment-fault event for every handled instruction > - use arm64_skip_faulting_instruction() to get the correct behavior > wrt IT state and single step > - use types with