Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On 02/24/2015 01:48 PM, Ross Zwisler wrote: > On Tue, 2015-02-24 at 13:41 -0800, H. Peter Anvin wrote: >> On 02/24/2015 01:40 PM, H. Peter Anvin wrote: >>> On 02/24/2015 01:30 AM, Borislav Petkov wrote: On Mon, Feb 23, 2015 at 03:14:01PM -0800, H. Peter Anvin wrote: > That may cause the same line to be flushed twice. I would suggest, > instead, also removing the arithmetic on void *: Btw, should we hold down all those suggested usages somewhere in Documentation/x86/ as commit messages are generally harder to find? >>> >>> Yes, and commit messages can't be corrected after the fact. >>> >> >> Either that, or perhaps even better in kerneldoc comments in the source >> itself. > > Either sounds like a good idea to me. :) Let me know which you'd prefer > and I'll get something written up. > Kerneldoc would be better, as it is more likely to be maintained in proximity for the source. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On Tue, 2015-02-24 at 13:41 -0800, H. Peter Anvin wrote: > On 02/24/2015 01:40 PM, H. Peter Anvin wrote: > > On 02/24/2015 01:30 AM, Borislav Petkov wrote: > >> On Mon, Feb 23, 2015 at 03:14:01PM -0800, H. Peter Anvin wrote: > >>> That may cause the same line to be flushed twice. I would suggest, > >>> instead, also removing the arithmetic on void *: > >> > >> Btw, should we hold down all those suggested usages somewhere in > >> Documentation/x86/ as commit messages are generally harder to find? > >> > > > > Yes, and commit messages can't be corrected after the fact. > > > > Either that, or perhaps even better in kerneldoc comments in the source > itself. Either sounds like a good idea to me. :) Let me know which you'd prefer and I'll get something written up. - Ross -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On 02/24/2015 01:40 PM, H. Peter Anvin wrote: > On 02/24/2015 01:30 AM, Borislav Petkov wrote: >> On Mon, Feb 23, 2015 at 03:14:01PM -0800, H. Peter Anvin wrote: >>> That may cause the same line to be flushed twice. I would suggest, >>> instead, also removing the arithmetic on void *: >> >> Btw, should we hold down all those suggested usages somewhere in >> Documentation/x86/ as commit messages are generally harder to find? >> > > Yes, and commit messages can't be corrected after the fact. > Either that, or perhaps even better in kerneldoc comments in the source itself. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On 02/24/2015 01:30 AM, Borislav Petkov wrote: > On Mon, Feb 23, 2015 at 03:14:01PM -0800, H. Peter Anvin wrote: >> That may cause the same line to be flushed twice. I would suggest, >> instead, also removing the arithmetic on void *: > > Btw, should we hold down all those suggested usages somewhere in > Documentation/x86/ as commit messages are generally harder to find? > Yes, and commit messages can't be corrected after the fact. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On Mon, Feb 23, 2015 at 03:14:01PM -0800, H. Peter Anvin wrote: > That may cause the same line to be flushed twice. I would suggest, > instead, also removing the arithmetic on void *: Btw, should we hold down all those suggested usages somewhere in Documentation/x86/ as commit messages are generally harder to find? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [tip:x86/asm] x86/asm: Add support for the pcommit instruction
On 02/20/2015 02:31 AM, tip-bot for Ross Zwisler wrote:
>
> This function shows how to properly use clwb/clflushopt/clflush
> and pcommit with appropriate fencing:
>
> void flush_and_commit_buffer(void *vaddr, unsigned int size)
> {
> void *vend = vaddr + size - 1;
>
> for (; vaddr < vend; vaddr += boot_cpu_data.x86_clflush_size)
> clwb(vaddr);
>
> /* Flush any possible final partial cacheline */
> clwb(vend);
>
> /*
>* sfence to order clwb/clflushopt/clflush cache flushes
>* mfence via mb() also works
>*/
> wmb();
>
> /* pcommit and the required sfence for ordering */
> pcommit_sfence();
> }
>
That may cause the same line to be flushed twice. I would suggest,
instead, also removing the arithmetic on void *:
Totally untested, yadda yadda...
void flush_and_commit_buffer(void *vaddr, unsigned int size)
{
unsigned long clflush_mask = boot_cpu_data.x86_clflush_size - 1;
char *vend = (char *)vaddr + size;
char *p;
for (p = (char *)((unsigned long)vaddr & ~clflush_mask);
p < vend; p += boot_cpu_data.x86_clflush_size)
clwb(vaddr);
/*
* sfence to order clwb/clflushopt/clflush cache flushes
* mfence via mb() also works
*/
wmb();
/* pcommit and the required sfence for ordering */
pcommit_sfence();
}
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