From: Dave Martin <Dave.Martin@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: marc.zyngier@arm.com, catalin.marinas@arm.com,
will.deacon@arm.com, linux-kernel@vger.kernel.org,
linux@dominikbrodowski.net, james.morse@arm.com,
viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 06/18] arm64: move sve_user_{enable, disable} to <asm/fpsimd.h>
Date: Tue, 15 May 2018 13:19:26 +0100 [thread overview]
Message-ID: <20180515121921.GN7753@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20180515103936.v5ytofdq3qqtsomn@lakrids.cambridge.arm.com>
On Tue, May 15, 2018 at 11:39:36AM +0100, Mark Rutland wrote:
> On Mon, May 14, 2018 at 12:06:50PM +0100, Dave Martin wrote:
> > On Mon, May 14, 2018 at 10:46:28AM +0100, Mark Rutland wrote:
> > > In subsequent patches, we'll want to make use of sve_user_enable() and
> > > sve_user_disable() outside of kernel/fpsimd.c. Let's move these to
> > > <asm/fpsimd.h> where we can make use of them.
> > >
> > > To avoid ifdeffery in sequences like:
> > >
> > > if (system_supports_sve() && some_condition
> > > sve_user_disable();
> > >
> > > ... empty stubs are provided when support for SVE is not enabled.
> > >
> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Dave Martin <dave.martin@arm.com>
> > > Cc: Will Deacon <will.deacon@arm.com>
> > > ---
> > > arch/arm64/include/asm/fpsimd.h | 17 ++++++++++++++++-
> > > arch/arm64/kernel/fpsimd.c | 11 -----------
> > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
> > > index aa7162ae93e3..7377d7593c06 100644
> > > --- a/arch/arm64/include/asm/fpsimd.h
> > > +++ b/arch/arm64/include/asm/fpsimd.h
> > > @@ -16,11 +16,13 @@
> > > #ifndef __ASM_FP_H
> > > #define __ASM_FP_H
> > >
> > > -#include <asm/ptrace.h>
> > > #include <asm/errno.h>
> > > +#include <asm/ptrace.h>
> > > +#include <asm/sysreg.h>
> > >
> > > #ifndef __ASSEMBLY__
> > >
> > > +#include <linux/build_bug.h>
> > > #include <linux/cache.h>
> > > #include <linux/init.h>
> > > #include <linux/stddef.h>
> > > @@ -81,6 +83,16 @@ extern int sve_set_vector_length(struct task_struct *task,
> > > extern int sve_set_current_vl(unsigned long arg);
> > > extern int sve_get_current_vl(void);
> > >
> > > +static inline void sve_user_disable(void)
> > > +{
> > > + sysreg_clear_set(cpacr_el1, CPACR_EL1_ZEN_EL0EN, 0);
> > > +}
> > > +
> > > +static inline void sve_user_enable(void)
> > > +{
> > > + sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN);
> > > +}
> > > +
> > > /*
> > > * Probing and setup functions.
> > > * Calls to these functions must be serialised with one another.
> > > @@ -107,6 +119,9 @@ static inline int sve_get_current_vl(void)
> > > return -EINVAL;
> > > }
> > >
> > > +static inline void sve_user_disable(void) { }
> > > +static inline void sve_user_enable(void) { }
> > > +
> >
> > Alternatively, just move the full definitions outside the #ifdef
> > CONFIG_ARM64_SVE.
>
> Can do, though I was trying to keep the exsting pattern with empty
> inlines for the !CONFIG_ARM64_SVE case.
There isn't really a pattern. I tried to avoid dummy versions where
there's no real reason to have them. I don't _think_ they're really
needed here, unless I missed something. Did you get build failures
without them?
> > All calls to these should be shadowed by an if
> > (system_supports_sve()) in any case, and setting/clearing ZEN_EL0EN
> > in the CPACR_EL1 ought to be harmless now that the meaning of these
> > bits architecturally committed.
> >
> > Ideally we would have a BUG_ON(!system_supports_sve()) in those
> > functions, but we won't won't to pay the cost in a production kernel.
>
> Earlier I'd put BUILD_BUG() in the body for the !CONFIG_ARM64_SVE case,
> to catch that kind of thing -- I could restore that.
IIUC:
if (0) {
BUILD_BUG_ON(1);
}
can still fire, in which case it's futile checking for CONFIG_ARM64_SVE
in most of the SVE support code.
Anyway, CONFIG_ARM64_SVE doesn't capture the whole condition.
>
> > > static inline void sve_init_vq_map(void) { }
> > > static inline void sve_update_vq_map(void) { }
> > > static inline int sve_verify_vq_map(void) { return 0; }
> > > diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
> > > index 088940387a4d..79a81c7d85c6 100644
> > > --- a/arch/arm64/kernel/fpsimd.c
> > > +++ b/arch/arm64/kernel/fpsimd.c
> > > @@ -159,7 +159,6 @@ static void sve_free(struct task_struct *task)
> > > __sve_free(task);
> > > }
> > >
> > > -
> >
> > Hmmm, Ack. Check for conflicts with the KVM FPSIMD rework [1] (though
> > trivial).
>
> I'll assume that Ack stands regardless. :)
Actually, I was just commenting on the deleted blank line... not that
there is any massive issue with this patch, though.
Cheers
---Dave
next prev parent reply other threads:[~2018-05-15 12:19 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-14 9:46 [PATCH 00/18] arm64: invoke syscalls with pt_regs Mark Rutland
2018-05-14 9:46 ` [PATCH 01/18] arm64: consistently use unsigned long for thread flags Mark Rutland
2018-05-14 9:57 ` Dave Martin
2018-05-14 9:46 ` [PATCH 02/18] arm64: move SCTLR_EL{1,2} assertions to <asm/sysreg.h> Mark Rutland
2018-05-14 10:00 ` Dave Martin
2018-05-14 10:08 ` Mark Rutland
2018-05-14 11:20 ` Dave Martin
2018-05-14 11:56 ` Robin Murphy
2018-05-14 12:06 ` Mark Rutland
2018-05-14 12:41 ` Dave Martin
2018-05-14 13:10 ` Mark Rutland
2018-05-14 9:46 ` [PATCH 03/18] arm64: introduce sysreg_clear_set() Mark Rutland
2018-05-14 10:04 ` Dave Martin
2018-05-14 9:46 ` [PATCH 04/18] arm64: kill config_sctlr_el1() Mark Rutland
2018-05-14 10:05 ` Dave Martin
2018-05-14 9:46 ` [PATCH 05/18] arm64: kill change_cpacr() Mark Rutland
2018-05-14 10:06 ` Dave Martin
2018-05-14 9:46 ` [PATCH 06/18] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h> Mark Rutland
2018-05-14 11:06 ` [PATCH 06/18] arm64: move sve_user_{enable, disable} " Dave Martin
2018-05-15 10:39 ` Mark Rutland
2018-05-15 12:19 ` Dave Martin [this message]
2018-05-15 16:33 ` Mark Rutland
2018-05-16 9:01 ` Dave Martin
2018-06-01 10:29 ` Mark Rutland
2018-06-01 10:42 ` Dave Martin
2018-05-14 9:46 ` [PATCH 07/18] arm64: remove sigreturn wrappers Mark Rutland
2018-05-14 11:07 ` Dave Martin
2018-05-14 9:46 ` [PATCH 08/18] arm64: convert raw syscall invocation to C Mark Rutland
2018-05-14 11:07 ` Dave Martin
2018-05-14 11:41 ` Mark Rutland
2018-05-14 12:53 ` Dave Martin
2018-05-14 20:24 ` Dominik Brodowski
2018-05-15 8:22 ` Mark Rutland
2018-05-15 10:01 ` Dominik Brodowski
2018-05-15 10:13 ` Mark Rutland
2018-05-14 18:00 ` Dominik Brodowski
2018-05-15 8:18 ` Mark Rutland
2018-05-14 9:46 ` [PATCH 09/18] arm64: convert syscall trace logic " Mark Rutland
2018-05-14 9:46 ` [PATCH 10/18] arm64: convert native/compat syscall entry " Mark Rutland
2018-05-14 11:07 ` Dave Martin
2018-05-14 11:58 ` Mark Rutland
2018-05-14 14:43 ` Dave Martin
2018-05-14 15:01 ` Mark Rutland
2018-05-14 9:46 ` [PATCH 11/18] arm64: zero GPRs upon entry from EL0 Mark Rutland
2018-05-14 11:07 ` Dave Martin
2018-05-14 9:46 ` [PATCH 12/18] kernel: add ksys_personality() Mark Rutland
2018-05-14 11:08 ` Dave Martin
2018-05-14 12:07 ` Christoph Hellwig
2018-05-15 9:56 ` Mark Rutland
2018-05-14 9:46 ` [PATCH 13/18] kernel: add kcompat_sys_{f,}statfs64() Mark Rutland
2018-05-14 17:14 ` Mark Rutland
2018-05-14 20:34 ` Dominik Brodowski
2018-05-15 9:53 ` Mark Rutland
2018-05-15 9:58 ` Dominik Brodowski
2018-05-14 9:46 ` [PATCH 14/18] arm64: remove in-kernel call to sys_personality() Mark Rutland
2018-05-14 9:46 ` [PATCH 15/18] arm64: use {COMPAT,}SYSCALL_DEFINE0 for sigreturn Mark Rutland
2018-05-14 9:46 ` [PATCH 16/18] arm64: use SYSCALL_DEFINE6() for mmap Mark Rutland
2018-05-14 9:46 ` [PATCH 17/18] arm64: convert compat wrappers to C Mark Rutland
2018-05-14 12:10 ` Christoph Hellwig
2018-05-14 12:43 ` Mark Rutland
2018-05-14 9:46 ` [PATCH 18/18] arm64: implement syscall wrappers Mark Rutland
2018-05-14 20:57 ` Dominik Brodowski
2018-05-15 8:37 ` Mark Rutland
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