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From: Mark Rutland <mark.rutland@arm.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, 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
Subject: Re: [PATCH 10/18] arm64: convert native/compat syscall entry to C
Date: Mon, 14 May 2018 12:58:05 +0100	[thread overview]
Message-ID: <20180514115805.bdlcxsw6q3xsbjb7@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20180514110729.GF7753@e103592.cambridge.arm.com>

On Mon, May 14, 2018 at 12:07:30PM +0100, Dave Martin wrote:
> On Mon, May 14, 2018 at 10:46:32AM +0100, Mark Rutland wrote:

> > diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> > index 5df857e32b48..4706f841e758 100644
> > --- a/arch/arm64/kernel/syscall.c
> > +++ b/arch/arm64/kernel/syscall.c
> > @@ -6,7 +6,9 @@
> >  #include <linux/ptrace.h>
> >  
> >  #include <asm/daifflags.h>
> > +#include <asm/fpsimd.h>
> >  #include <asm/thread_info.h>
> > +#include <asm/unistd.h>
> >  
> >  long do_ni_syscall(struct pt_regs *regs);
> >  
> > @@ -41,8 +43,8 @@ static inline bool has_syscall_work(unsigned long flags)
> >  int syscall_trace_enter(struct pt_regs *regs);
> >  void syscall_trace_exit(struct pt_regs *regs);
> >  
> > -asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> > -			       syscall_fn_t syscall_table[])
> > +static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> > +			   syscall_fn_t syscall_table[])
> >  {
> >  	unsigned long flags = current_thread_info()->flags;
> >  
> > @@ -79,3 +81,37 @@ asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> >  trace_exit:
> >  	syscall_trace_exit(regs);
> >  }
> > +
> > +static inline void sve_user_reset(void)
> 
> Static function with no caller...

Ugh, this was intended to be called below in el0_svc_handler().

> > +{
> > +	if (!system_supports_sve())
> > +		return;
> > +
> > +	/*
> > +	 * task_fpsimd_load() won't be called to update CPACR_EL1 in
> > +	 * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
> > +	 * happens if a context switch or kernel_neon_begin() or context
> > +	 * modification (sigreturn, ptrace) intervenes.
> > +	 * So, ensure that CPACR_EL1 is already correct for the fast-path case.
> > +	 */
> > +	if (test_and_clear_thread_flag(TIF_SVE))
> > +		sve_user_disable();
> 
> sve_user_disable() is already inline, and incorporates the if()
> internally via sysreg_clear_set().
> 
> So, should this just be
> 
> 	clear_thread_flag(TIF_SVE);
> 	sve_user_disable();

Sure. That does mean we'll unconditionally read cpacr_el1, but I assume
you're happy with that. I'll note the difference in the commit message.

> > +}
> > +
> > +extern syscall_fn_t sys_call_table[];
> > +
> > +asmlinkage void el0_svc_handler(struct pt_regs *regs)
> > +{
> 
> if (system_supports_sve()) ?
> 
> > +	sve_user_disable();
> 
> Or should this be replaced by a call to sve_user_reset()?
> 
> I suspect the latter, since we do want to be clearing TIF_SVE here too.

Yes, this was mean to be sve_user_reset().

Thanks,
Mark.

  reply	other threads:[~2018-05-14 11:58 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
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 [this message]
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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