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 02/18] arm64: move SCTLR_EL{1,2} assertions to <asm/sysreg.h>
Date: Mon, 14 May 2018 12:20:37 +0100 [thread overview]
Message-ID: <20180514112036.GI7753@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20180514100858.4xjp5d3axbyy74ap@lakrids.cambridge.arm.com>
On Mon, May 14, 2018 at 11:08:59AM +0100, Mark Rutland wrote:
> On Mon, May 14, 2018 at 11:00:53AM +0100, Dave Martin wrote:
> > On Mon, May 14, 2018 at 10:46:24AM +0100, Mark Rutland wrote:
> > > -/* Check all the bits are accounted for */
> > > -#define SCTLR_EL2_BUILD_BUG_ON_MISSING_BITS BUILD_BUG_ON((SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != ~0)
> > > -
> > > +#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffff
> > > +#error "Inconsistent SCTLR_EL2 set/clear bits"
> > > +#endif
> >
> > Can we have a comment on the != 0xffffffff versus != ~0 here?
> >
> > The subtle differences in evaluation semantics between #if and
> > other contexts here may well trip people up during maintenance...
>
> Do you have any suggestion as to the wording?
>
> I'm happy to add a comment, but I don't really know what to say.
How about the following?
/* Watch out for #if evaluation rules: ~0 is not ~(int)0! */
Cheers
---Dave
next prev parent reply other threads:[~2018-05-14 11:20 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 [this message]
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
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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